diff --git a/docs/release-notes/.FSharp.Core/9.0.300.md b/docs/release-notes/.FSharp.Core/9.0.300.md
index 3b2fdab5cfe..d730ff12486 100644
--- a/docs/release-notes/.FSharp.Core/9.0.300.md
+++ b/docs/release-notes/.FSharp.Core/9.0.300.md
@@ -3,6 +3,7 @@
 
 ### Added
 * Added nullability annotations to `.Using` builder method for `async` and `task` builders ([PR #18292](https://github.com/dotnet/fsharp/pull/18292))
+* Support for `and!` in `TaskBuilder` ([LanguageSuggestion #1363](https://github.com/fsharp/fslang-suggestions/issues/1363), [PR #18451](https://github.com/dotnet/fsharp/pull/18451))
 
 ### Changed
 
diff --git a/eng/Publishing.props b/eng/Publishing.props
new file mode 100644
index 00000000000..5f9650d32dc
--- /dev/null
+++ b/eng/Publishing.props
@@ -0,0 +1,9 @@
+<Project>
+
+  <!-- Update Artifacts with Kind=Package to have additional metadata item Category="ToolingPackage".
+       Depending on channel configuration, this means that these assets could be pushed to a different feed. -->
+  <ItemGroup>
+    <Artifact Update="@(Artifact->WithMetadataValue('Kind', 'Package'))" Category="ToolingPackage" />
+  </ItemGroup>
+
+</Project>
diff --git a/eng/Version.Details.xml b/eng/Version.Details.xml
index 32ba644ba75..0f64f53dbf3 100644
--- a/eng/Version.Details.xml
+++ b/eng/Version.Details.xml
@@ -2,9 +2,9 @@
 <Dependencies>
   <Source Uri="https://github.com/dotnet/dotnet" Mapping="fsharp" Sha="721dc7a2a59416b21fc49447d264009d708d6000" BarId="265489" />
   <ProductDependencies>
-    <Dependency Name="Microsoft.SourceBuild.Intermediate.source-build-reference-packages" Version="9.0.0-alpha.1.25209.1">
+    <Dependency Name="Microsoft.SourceBuild.Intermediate.source-build-reference-packages" Version="9.0.0-alpha.1.25223.3">
       <Uri>https://github.com/dotnet/source-build-reference-packages</Uri>
-      <Sha>7dbf5deea5bdccf513df73cba179c4c0ad106010</Sha>
+      <Sha>19eb5ea4e5f9c4e5256843a92805c8c9e942207d</Sha>
       <SourceBuild RepoName="source-build-reference-packages" ManagedOnly="true" />
     </Dependency>
     <!-- Intermediate is necessary for source build. -->
diff --git a/src/Compiler/Checking/Expressions/CheckComputationExpressions.fs b/src/Compiler/Checking/Expressions/CheckComputationExpressions.fs
index 45a35970af7..a7bcc1f9f87 100644
--- a/src/Compiler/Checking/Expressions/CheckComputationExpressions.fs
+++ b/src/Compiler/Checking/Expressions/CheckComputationExpressions.fs
@@ -849,6 +849,20 @@ let (|OptionalSequential|) e =
     | SynExpr.Sequential(debugPoint = _sp; isTrueSeq = true; expr1 = dataComp1; expr2 = dataComp2) -> (dataComp1, Some dataComp2)
     | _ -> (e, None)
 
+[<return: Struct>]
+let (|ExprAsUseBang|_|) expr =
+    match expr with
+    | SynExpr.LetOrUseBang(
+        bindDebugPoint = spBind
+        isUse = true
+        isFromSource = isFromSource
+        pat = pat
+        rhs = rhsExpr
+        andBangs = andBangs
+        body = innerComp
+        trivia = { LetOrUseBangKeyword = mBind }) -> ValueSome(spBind, isFromSource, pat, rhsExpr, andBangs, innerComp, mBind)
+    | _ -> ValueNone
+
 // "cexpr; cexpr" is treated as builder.Combine(cexpr1, cexpr1)
 // This is not pretty - we have to decide which range markers we use for the calls to Combine and Delay
 // NOTE: we should probably suppress these sequence points altogether
@@ -910,6 +924,11 @@ let inline addVarsToVarSpace (varSpace: LazyWithContext<Val list * TcEnv, range>
         id
     )
 
+/// Checks if a builder method exists and reports an error if it doesn't
+let requireBuilderMethod methodName m1 cenv env ad builderTy m2 =
+    if isNil (TryFindIntrinsicOrExtensionMethInfo ResultCollectionSettings.AtMostOneResult cenv env m1 ad methodName builderTy) then
+        error (Error(FSComp.SR.tcRequireBuilderMethod methodName, m2))
+
 /// <summary>
 /// Try translate the syntax sugar
 /// </summary>
@@ -1211,19 +1230,7 @@ let rec TryTranslateComputationExpression
 
             let mPat = pat.Range
 
-            if
-                isNil (
-                    TryFindIntrinsicOrExtensionMethInfo
-                        ResultCollectionSettings.AtMostOneResult
-                        cenv
-                        ceenv.env
-                        mFor
-                        ceenv.ad
-                        "For"
-                        ceenv.builderTy
-                )
-            then
-                error (Error(FSComp.SR.tcRequireBuilderMethod ("For"), mFor))
+            requireBuilderMethod "For" mFor cenv ceenv.env ceenv.ad ceenv.builderTy mFor
 
             // Add the variables to the query variable space, on demand
             let varSpace =
@@ -1296,33 +1303,8 @@ let rec TryTranslateComputationExpression
             if ceenv.isQuery then
                 error (Error(FSComp.SR.tcNoWhileInQuery (), mWhile))
 
-            if
-                isNil (
-                    TryFindIntrinsicOrExtensionMethInfo
-                        ResultCollectionSettings.AtMostOneResult
-                        cenv
-                        ceenv.env
-                        mWhile
-                        ceenv.ad
-                        "While"
-                        ceenv.builderTy
-                )
-            then
-                error (Error(FSComp.SR.tcRequireBuilderMethod ("While"), mWhile))
-
-            if
-                isNil (
-                    TryFindIntrinsicOrExtensionMethInfo
-                        ResultCollectionSettings.AtMostOneResult
-                        cenv
-                        ceenv.env
-                        mWhile
-                        ceenv.ad
-                        "Delay"
-                        ceenv.builderTy
-                )
-            then
-                error (Error(FSComp.SR.tcRequireBuilderMethod ("Delay"), mWhile))
+            requireBuilderMethod "While" mWhile cenv ceenv.env ceenv.ad ceenv.builderTy mWhile
+            requireBuilderMethod "Delay" mWhile cenv ceenv.env ceenv.ad ceenv.builderTy mWhile
 
             // 'while' is hit just before each time the guard is called
             let guardExpr =
@@ -1451,33 +1433,8 @@ let rec TryTranslateComputationExpression
             if ceenv.isQuery then
                 error (Error(FSComp.SR.tcNoTryFinallyInQuery (), mTry))
 
-            if
-                isNil (
-                    TryFindIntrinsicOrExtensionMethInfo
-                        ResultCollectionSettings.AtMostOneResult
-                        cenv
-                        ceenv.env
-                        mTry
-                        ceenv.ad
-                        "TryFinally"
-                        ceenv.builderTy
-                )
-            then
-                error (Error(FSComp.SR.tcRequireBuilderMethod ("TryFinally"), mTry))
-
-            if
-                isNil (
-                    TryFindIntrinsicOrExtensionMethInfo
-                        ResultCollectionSettings.AtMostOneResult
-                        cenv
-                        ceenv.env
-                        mTry
-                        ceenv.ad
-                        "Delay"
-                        ceenv.builderTy
-                )
-            then
-                error (Error(FSComp.SR.tcRequireBuilderMethod ("Delay"), mTry))
+            requireBuilderMethod "TryFinally" mTry cenv ceenv.env ceenv.ad ceenv.builderTy mTry
+            requireBuilderMethod "Delay" mTry cenv ceenv.env ceenv.ad ceenv.builderTy mTry
 
             let innerExpr = TranslateComputationExpressionNoQueryOps ceenv innerComp
 
@@ -1618,34 +1575,8 @@ let rec TryTranslateComputationExpression
                         | SynExpr.YieldOrReturnFrom(trivia = yieldOrReturnFrom) -> yieldOrReturnFrom.YieldOrReturnFromKeyword
                         | expr -> expr.Range
 
-                    if
-                        isNil (
-                            TryFindIntrinsicOrExtensionMethInfo
-                                ResultCollectionSettings.AtMostOneResult
-                                cenv
-                                ceenv.env
-                                m
-                                ceenv.ad
-                                "Combine"
-                                ceenv.builderTy
-                        )
-                    then
-
-                        error (Error(FSComp.SR.tcRequireBuilderMethod "Combine", combineDelayRange))
-
-                    if
-                        isNil (
-                            TryFindIntrinsicOrExtensionMethInfo
-                                ResultCollectionSettings.AtMostOneResult
-                                cenv
-                                ceenv.env
-                                m
-                                ceenv.ad
-                                "Delay"
-                                ceenv.builderTy
-                        )
-                    then
-                        error (Error(FSComp.SR.tcRequireBuilderMethod "Delay", combineDelayRange))
+                    requireBuilderMethod "Combine" m cenv ceenv.env ceenv.ad ceenv.builderTy combineDelayRange
+                    requireBuilderMethod "Delay" m cenv ceenv.env ceenv.ad ceenv.builderTy combineDelayRange
 
                     let combineCall =
                         mkSynCall
@@ -1748,19 +1679,7 @@ let rec TryTranslateComputationExpression
                 )
             | None ->
                 let elseComp =
-                    if
-                        isNil (
-                            TryFindIntrinsicOrExtensionMethInfo
-                                ResultCollectionSettings.AtMostOneResult
-                                cenv
-                                ceenv.env
-                                trivia.IfToThenRange
-                                ceenv.ad
-                                "Zero"
-                                ceenv.builderTy
-                        )
-                    then
-                        error (Error(FSComp.SR.tcRequireBuilderMethod ("Zero"), trivia.IfToThenRange))
+                    requireBuilderMethod "Zero" trivia.IfToThenRange cenv ceenv.env ceenv.ad ceenv.builderTy trivia.IfToThenRange
 
                     mkSynCall "Zero" trivia.IfToThenRange [] ceenv.builderValName
 
@@ -1838,19 +1757,7 @@ let rec TryTranslateComputationExpression
                     innerCompRange
                 )
 
-            if
-                isNil (
-                    TryFindIntrinsicOrExtensionMethInfo
-                        ResultCollectionSettings.AtMostOneResult
-                        cenv
-                        ceenv.env
-                        mBind
-                        ceenv.ad
-                        "Using"
-                        ceenv.builderTy
-                )
-            then
-                error (Error(FSComp.SR.tcRequireBuilderMethod ("Using"), mBind))
+            requireBuilderMethod "Using" mBind cenv ceenv.env ceenv.ad ceenv.builderTy mBind
 
             Some(
                 translatedCtxt (mkSynCall "Using" mBind [ rhsExpr; consumeExpr ] ceenv.builderValName)
@@ -1903,102 +1810,59 @@ let rec TryTranslateComputationExpression
             )
 
         // 'use! pat = e1 in e2' --> build.Bind(e1, (function  _argN -> match _argN with pat -> build.Using(x, (fun _argN -> match _argN with pat -> e2))))
-        | SynExpr.LetOrUseBang(
-            bindDebugPoint = spBind
-            isUse = true
-            isFromSource = isFromSource
-            pat = SynPat.Named(ident = SynIdent(id, _); isThisVal = false) as pat
-            rhs = rhsExpr
-            andBangs = []
-            body = innerComp
-            trivia = { LetOrUseBangKeyword = mBind })
-        | SynExpr.LetOrUseBang(
-            bindDebugPoint = spBind
-            isUse = true
-            isFromSource = isFromSource
-            pat = SynPat.LongIdent(longDotId = SynLongIdent(id = [ id ])) as pat
-            rhs = rhsExpr
-            andBangs = []
-            body = innerComp
-            trivia = { LetOrUseBangKeyword = mBind }) ->
-
+        | ExprAsUseBang(spBind, isFromSource, pat, rhsExpr, andBangs, innerComp, mBind) ->
             if ceenv.isQuery then
                 error (Error(FSComp.SR.tcBindMayNotBeUsedInQueries (), mBind))
 
-            if
-                isNil (
-                    TryFindIntrinsicOrExtensionMethInfo
-                        ResultCollectionSettings.AtMostOneResult
-                        cenv
-                        ceenv.env
-                        mBind
-                        ceenv.ad
-                        "Using"
-                        ceenv.builderTy
-                )
-            then
-                error (Error(FSComp.SR.tcRequireBuilderMethod ("Using"), mBind))
-
-            if
-                isNil (
-                    TryFindIntrinsicOrExtensionMethInfo
-                        ResultCollectionSettings.AtMostOneResult
-                        cenv
-                        ceenv.env
-                        mBind
-                        ceenv.ad
-                        "Bind"
-                        ceenv.builderTy
-                )
-            then
-                error (Error(FSComp.SR.tcRequireBuilderMethod ("Bind"), mBind))
+            match pat, andBangs with
+            | (SynPat.Named(ident = SynIdent(id, _); isThisVal = false) | SynPat.LongIdent(longDotId = SynLongIdent(id = [ id ]))), [] ->
+                // Valid pattern case - handle with Using + Bind
+                requireBuilderMethod "Using" mBind cenv ceenv.env ceenv.ad ceenv.builderTy mBind
+                requireBuilderMethod "Bind" mBind cenv ceenv.env ceenv.ad ceenv.builderTy mBind
 
-            let bindExpr =
-                let consumeExpr =
-                    SynExpr.MatchLambda(
-                        false,
-                        mBind,
-                        [
-                            SynMatchClause(
-                                pat,
-                                None,
-                                TranslateComputationExpressionNoQueryOps ceenv innerComp,
-                                innerComp.Range,
-                                DebugPointAtTarget.Yes,
-                                SynMatchClauseTrivia.Zero
-                            )
-                        ],
-                        DebugPointAtBinding.NoneAtInvisible,
-                        mBind
-                    )
-
-                let consumeExpr =
-                    mkSynCall "Using" mBind [ SynExpr.Ident id; consumeExpr ] ceenv.builderValName
+                let bindExpr =
+                    let consumeExpr =
+                        SynExpr.MatchLambda(
+                            false,
+                            mBind,
+                            [
+                                SynMatchClause(
+                                    pat,
+                                    None,
+                                    TranslateComputationExpressionNoQueryOps ceenv innerComp,
+                                    innerComp.Range,
+                                    DebugPointAtTarget.Yes,
+                                    SynMatchClauseTrivia.Zero
+                                )
+                            ],
+                            DebugPointAtBinding.NoneAtInvisible,
+                            mBind
+                        )
 
-                let consumeExpr =
-                    SynExpr.MatchLambda(
-                        false,
-                        mBind,
-                        [
-                            SynMatchClause(pat, None, consumeExpr, id.idRange, DebugPointAtTarget.No, SynMatchClauseTrivia.Zero)
-                        ],
-                        DebugPointAtBinding.NoneAtInvisible,
-                        mBind
-                    )
+                    let consumeExpr =
+                        mkSynCall "Using" mBind [ SynExpr.Ident id; consumeExpr ] ceenv.builderValName
 
-                let rhsExpr =
-                    mkSourceExprConditional isFromSource rhsExpr ceenv.sourceMethInfo ceenv.builderValName
+                    let consumeExpr =
+                        SynExpr.MatchLambda(
+                            false,
+                            mBind,
+                            [
+                                SynMatchClause(pat, None, consumeExpr, id.idRange, DebugPointAtTarget.No, SynMatchClauseTrivia.Zero)
+                            ],
+                            DebugPointAtBinding.NoneAtInvisible,
+                            mBind
+                        )
 
-                mkSynCall "Bind" mBind [ rhsExpr; consumeExpr ] ceenv.builderValName
-                |> addBindDebugPoint spBind
+                    let rhsExpr =
+                        mkSourceExprConditional isFromSource rhsExpr ceenv.sourceMethInfo ceenv.builderValName
 
-            Some(translatedCtxt bindExpr)
+                    mkSynCall "Bind" mBind [ rhsExpr; consumeExpr ] ceenv.builderValName
+                    |> addBindDebugPoint spBind
 
-        // 'use! pat = e1 ... in e2' where 'pat' is not a simple name -> error
-        | SynExpr.LetOrUseBang(isUse = true; andBangs = andBangs; trivia = { LetOrUseBangKeyword = mBind }) ->
-            if isNil andBangs then
-                error (Error(FSComp.SR.tcInvalidUseBangBinding (), mBind))
-            else
+                Some(translatedCtxt bindExpr)
+            | _pat, [] -> error (Error(FSComp.SR.tcInvalidUseBangBinding (), mBind))
+            | _pat, _ands ->
+                // Has andBangs
                 let m =
                     match andBangs with
                     | [] -> comp.Range
@@ -2182,19 +2046,7 @@ let rec TryTranslateComputationExpression
                             // Call MergeSources2(e1, e2), MergeSources3(e1, e2, e3) etc
                             let mergeSourcesName = mkMergeSourcesName numSourcesAndPats
 
-                            if
-                                isNil (
-                                    TryFindIntrinsicOrExtensionMethInfo
-                                        ResultCollectionSettings.AtMostOneResult
-                                        cenv
-                                        ceenv.env
-                                        mBind
-                                        ceenv.ad
-                                        mergeSourcesName
-                                        ceenv.builderTy
-                                )
-                            then
-                                error (Error(FSComp.SR.tcRequireMergeSourcesOrBindN (bindNName), mBind))
+                            requireBuilderMethod mergeSourcesName mBind cenv ceenv.env ceenv.ad ceenv.builderTy mBind
 
                             let source =
                                 mkSynCall mergeSourcesName sourcesRange (List.map fst sourcesAndPats) ceenv.builderValName
@@ -2210,19 +2062,7 @@ let rec TryTranslateComputationExpression
 
                             let mergeSourcesName = mkMergeSourcesName maxMergeSources
 
-                            if
-                                isNil (
-                                    TryFindIntrinsicOrExtensionMethInfo
-                                        ResultCollectionSettings.AtMostOneResult
-                                        cenv
-                                        ceenv.env
-                                        mBind
-                                        ceenv.ad
-                                        mergeSourcesName
-                                        ceenv.builderTy
-                                )
-                            then
-                                error (Error(FSComp.SR.tcRequireMergeSourcesOrBindN (bindNName), mBind))
+                            requireBuilderMethod mergeSourcesName mBind cenv ceenv.env ceenv.ad ceenv.builderTy mBind
 
                             let laterSource, laterPat = mergeSources laterSourcesAndPats
 
@@ -2285,19 +2125,7 @@ let rec TryTranslateComputationExpression
             if ceenv.isQuery then
                 error (Error(FSComp.SR.tcMatchMayNotBeUsedWithQuery (), trivia.MatchBangKeyword))
 
-            if
-                isNil (
-                    TryFindIntrinsicOrExtensionMethInfo
-                        ResultCollectionSettings.AtMostOneResult
-                        cenv
-                        ceenv.env
-                        trivia.MatchBangKeyword
-                        ceenv.ad
-                        "Bind"
-                        ceenv.builderTy
-                )
-            then
-                error (Error(FSComp.SR.tcRequireBuilderMethod ("Bind"), trivia.MatchBangKeyword))
+            requireBuilderMethod "Bind" trivia.MatchBangKeyword cenv ceenv.env ceenv.ad ceenv.builderTy trivia.MatchBangKeyword
 
             let clauses =
                 clauses
@@ -2335,33 +2163,8 @@ let rec TryTranslateComputationExpression
             let consumeExpr =
                 SynExpr.MatchLambda(true, mTryToLast, clauses, spWith2, mTryToLast)
 
-            if
-                isNil (
-                    TryFindIntrinsicOrExtensionMethInfo
-                        ResultCollectionSettings.AtMostOneResult
-                        cenv
-                        ceenv.env
-                        mTry
-                        ceenv.ad
-                        "TryWith"
-                        ceenv.builderTy
-                )
-            then
-                error (Error(FSComp.SR.tcRequireBuilderMethod ("TryWith"), mTry))
-
-            if
-                isNil (
-                    TryFindIntrinsicOrExtensionMethInfo
-                        ResultCollectionSettings.AtMostOneResult
-                        cenv
-                        ceenv.env
-                        mTry
-                        ceenv.ad
-                        "Delay"
-                        ceenv.builderTy
-                )
-            then
-                error (Error(FSComp.SR.tcRequireBuilderMethod ("Delay"), mTry))
+            requireBuilderMethod "TryWith" mTry cenv ceenv.env ceenv.ad ceenv.builderTy mTry
+            requireBuilderMethod "Delay" mTry cenv ceenv.env ceenv.ad ceenv.builderTy mTry
 
             let innerExpr = TranslateComputationExpressionNoQueryOps ceenv innerComp
 
@@ -2386,19 +2189,7 @@ let rec TryTranslateComputationExpression
             let yieldFromExpr =
                 mkSourceExpr synYieldExpr ceenv.sourceMethInfo ceenv.builderValName
 
-            if
-                isNil (
-                    TryFindIntrinsicOrExtensionMethInfo
-                        ResultCollectionSettings.AtMostOneResult
-                        cenv
-                        ceenv.env
-                        m
-                        ceenv.ad
-                        "YieldFrom"
-                        ceenv.builderTy
-                )
-            then
-                error (Error(FSComp.SR.tcRequireBuilderMethod ("YieldFrom"), m))
+            requireBuilderMethod "YieldFrom" m cenv ceenv.env ceenv.ad ceenv.builderTy m
 
             let yieldFromCall =
                 mkSynCall "YieldFrom" synYieldExpr.Range [ yieldFromExpr ] ceenv.builderValName
@@ -2418,19 +2209,7 @@ let rec TryTranslateComputationExpression
             if ceenv.isQuery then
                 error (Error(FSComp.SR.tcReturnMayNotBeUsedInQueries (), m))
 
-            if
-                isNil (
-                    TryFindIntrinsicOrExtensionMethInfo
-                        ResultCollectionSettings.AtMostOneResult
-                        cenv
-                        ceenv.env
-                        m
-                        ceenv.ad
-                        "ReturnFrom"
-                        ceenv.builderTy
-                )
-            then
-                error (Error(FSComp.SR.tcRequireBuilderMethod ("ReturnFrom"), m))
+            requireBuilderMethod "ReturnFrom" m cenv ceenv.env ceenv.ad ceenv.builderTy m
 
             let returnFromCall =
                 mkSynCall "ReturnFrom" synReturnExpr.Range [ returnFromExpr ] ceenv.builderValName
@@ -2449,19 +2228,7 @@ let rec TryTranslateComputationExpression
             if ceenv.isQuery && not isYield then
                 error (Error(FSComp.SR.tcReturnMayNotBeUsedInQueries (), m))
 
-            if
-                isNil (
-                    TryFindIntrinsicOrExtensionMethInfo
-                        ResultCollectionSettings.AtMostOneResult
-                        cenv
-                        ceenv.env
-                        m
-                        ceenv.ad
-                        methName
-                        ceenv.builderTy
-                )
-            then
-                error (Error(FSComp.SR.tcRequireBuilderMethod methName, m))
+            requireBuilderMethod methName m cenv ceenv.env ceenv.ad ceenv.builderTy m
 
             let yieldOrReturnCall =
                 mkSynCall methName synYieldOrReturnExpr.Range [ synYieldOrReturnExpr ] ceenv.builderValName
@@ -2731,19 +2498,7 @@ and TranslateComputationExpressionBind
 
     | _ ->
 
-        if
-            isNil (
-                TryFindIntrinsicOrExtensionMethInfo
-                    ResultCollectionSettings.AtMostOneResult
-                    ceenv.cenv
-                    ceenv.env
-                    bindRange
-                    ceenv.ad
-                    bindName
-                    ceenv.builderTy
-            )
-        then
-            error (Error(FSComp.SR.tcRequireBuilderMethod (bindName), bindRange))
+        requireBuilderMethod bindName bindRange ceenv.cenv ceenv.env ceenv.ad ceenv.builderTy bindRange
 
         // Build the `Bind` call
         TranslateComputationExpression ceenv CompExprTranslationPass.Initial q varSpace innerComp (fun holeFill ->
diff --git a/src/FSharp.Core/fslib-extra-pervasives.fs b/src/FSharp.Core/fslib-extra-pervasives.fs
index 07a03675937..08d4ee2308b 100644
--- a/src/FSharp.Core/fslib-extra-pervasives.fs
+++ b/src/FSharp.Core/fslib-extra-pervasives.fs
@@ -325,6 +325,7 @@ module ExtraTopLevelOperators =
     [<assembly: AutoOpen("Microsoft.FSharp.Collections")>]
     [<assembly: AutoOpen("Microsoft.FSharp.Control")>]
     [<assembly: AutoOpen("Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority")>]
+    [<assembly: AutoOpen("Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority")>]
     [<assembly: AutoOpen("Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority")>]
     [<assembly: AutoOpen("Microsoft.FSharp.Control.TaskBuilderExtensions.HighPriority")>]
     [<assembly: AutoOpen("Microsoft.FSharp.Linq.QueryRunExtensions.LowPriority")>]
diff --git a/src/FSharp.Core/tasks.fs b/src/FSharp.Core/tasks.fs
index 687bae5af85..a4ba6b2dbd7 100644
--- a/src/FSharp.Core/tasks.fs
+++ b/src/FSharp.Core/tasks.fs
@@ -370,7 +370,48 @@ module LowPriority =
             =
             ResumableCode.Using(resource, body)
 
+    type TaskBuilder with
+        member inline this.MergeSources< ^TaskLike1, ^TaskLike2, ^TResult1, ^TResult2, ^Awaiter1, ^Awaiter2
+            when ^TaskLike1: (member GetAwaiter: unit -> ^Awaiter1)
+            and ^TaskLike2: (member GetAwaiter: unit -> ^Awaiter2)
+            and ^Awaiter1 :> ICriticalNotifyCompletion
+            and ^Awaiter2 :> ICriticalNotifyCompletion
+            and ^Awaiter1: (member get_IsCompleted: unit -> bool)
+            and ^Awaiter1: (member GetResult: unit -> ^TResult1)
+            and ^Awaiter2: (member get_IsCompleted: unit -> bool)
+            and ^Awaiter2: (member GetResult: unit -> ^TResult2)>
+            (task1: ^TaskLike1, task2: ^TaskLike2)
+            : Task<struct (^TResult1 * ^TResult2)> =
+            this.Run(
+                this.Bind(
+                    task1,
+                    fun (result1: ^TResult1) ->
+                        this.Bind(task2, fun (result2: ^TResult2) -> this.Return struct (result1, result2))
+                )
+            )
+
+    type BackgroundTaskBuilder with
+        member inline this.MergeSources< ^TaskLike1, ^TaskLike2, ^TResult1, ^TResult2, ^Awaiter1, ^Awaiter2
+            when ^TaskLike1: (member GetAwaiter: unit -> ^Awaiter1)
+            and ^TaskLike2: (member GetAwaiter: unit -> ^Awaiter2)
+            and ^Awaiter1 :> ICriticalNotifyCompletion
+            and ^Awaiter2 :> ICriticalNotifyCompletion
+            and ^Awaiter1: (member get_IsCompleted: unit -> bool)
+            and ^Awaiter1: (member GetResult: unit -> ^TResult1)
+            and ^Awaiter2: (member get_IsCompleted: unit -> bool)
+            and ^Awaiter2: (member GetResult: unit -> ^TResult2)>
+            (task1: ^TaskLike1, task2: ^TaskLike2)
+            : Task<struct (^TResult1 * ^TResult2)> =
+            this.Run(
+                this.Bind(
+                    task1,
+                    fun (result1: ^TResult1) ->
+                        this.Bind(task2, fun (result2: ^TResult2) -> this.Return struct (result1, result2))
+                )
+            )
+
 module HighPriority =
+
     // High priority extensions
     type TaskBuilderBase with
 
@@ -424,7 +465,36 @@ module HighPriority =
         member inline this.ReturnFrom(task: Task<'T>) : TaskCode<'T, 'T> =
             this.Bind(task, this.Return)
 
+    type TaskBuilder with
+
+        // This overload is required for type inference in tasks cases
+        member inline this.MergeSources
+            (task1: Task< ^TResult1 >, task2: Task< ^TResult2 >)
+            : Task<struct (^TResult1 * ^TResult2)> =
+            this.Run(
+                this.Bind(
+                    task1,
+                    fun (result1: ^TResult1) ->
+                        this.Bind(task2, fun (result2: ^TResult2) -> this.Return struct (result1, result2))
+                )
+            )
+
+    type BackgroundTaskBuilder with
+
+        // This overload is required for type inference in tasks cases
+        member inline this.MergeSources
+            (task1: Task< ^TResult1 >, task2: Task< ^TResult2 >)
+            : Task<struct (^TResult1 * ^TResult2)> =
+            this.Run(
+                this.Bind(
+                    task1,
+                    fun (result1: ^TResult1) ->
+                        this.Bind(task2, fun (result2: ^TResult2) -> this.Return struct (result1, result2))
+                )
+            )
+
 module MediumPriority =
+    open LowPriority
     open HighPriority
 
     // Medium priority extensions
@@ -437,3 +507,213 @@ module MediumPriority =
 
         member inline this.ReturnFrom(computation: Async<'T>) : TaskCode<'T, 'T> =
             this.ReturnFrom(Async.StartImmediateAsTask computation)
+
+    type TaskBuilder with
+
+        // This overload is required for type inference in tasks cases
+        member inline this.MergeSources< ^TaskLike2, ^TResult1, ^TResult2, ^Awaiter2
+            when ^TaskLike2: (member GetAwaiter: unit -> ^Awaiter2)
+            and ^Awaiter2 :> ICriticalNotifyCompletion
+            and ^Awaiter2: (member get_IsCompleted: unit -> bool)
+            and ^Awaiter2: (member GetResult: unit -> 'TResult2)>
+            (task1: Task< ^TResult1 >, task2: ^TaskLike2)
+            : Task<struct (^TResult1 * ^TResult2)> =
+            this.Run(
+                this.Bind(
+                    task1,
+                    fun (result1: ^TResult1) ->
+                        this.Bind(task2, fun (result2: ^TResult2) -> this.Return struct (result1, result2))
+                )
+            )
+
+        // This overload is required for type inference in tasks cases
+        member inline this.MergeSources< ^TaskLike1, ^TResult1, ^TResult2, ^Awaiter1
+            when ^TaskLike1: (member GetAwaiter: unit -> ^Awaiter1)
+            and ^Awaiter1 :> ICriticalNotifyCompletion
+            and ^Awaiter1: (member get_IsCompleted: unit -> bool)
+            and ^Awaiter1: (member GetResult: unit -> 'TResult1)>
+            (task1: ^TaskLike1, task2: Task< ^TResult2 >)
+            : Task<struct (^TResult1 * ^TResult2)> =
+            this.Run(
+                this.Bind(
+                    task1,
+                    fun (result1: ^TResult1) ->
+                        this.Bind(task2, fun (result2: ^TResult2) -> this.Return struct (result1, result2))
+                )
+            )
+
+        // This overload is required for type inference in async cases
+        member inline this.MergeSources
+            (computation1: Async< ^TResult1 >, computation2: Async< ^TResult2 >)
+            : Task<struct (^TResult1 * ^TResult2)> =
+            this.Run(
+                this.Bind(
+                    computation1,
+                    fun (result1: ^TResult1) ->
+                        this.Bind(computation2, fun (result2: ^TResult2) -> this.Return struct (result1, result2))
+                )
+            )
+
+        // This overload is required for type inference in task + async cases
+        member inline this.MergeSources
+            (task: Task< ^TResult1 >, computation: Async< ^TResult2 >)
+            : Task<struct (^TResult1 * ^TResult2)> =
+            this.Run(
+                this.Bind(
+                    task,
+                    fun (result1: ^TResult1) ->
+                        this.Bind(computation, fun (result2: ^TResult2) -> this.Return struct (result1, result2))
+                )
+            )
+
+        // This overload is required for type inference in async + task case
+        member inline this.MergeSources
+            (computation: Async< ^TResult1 >, task: Task< ^TResult2 >)
+            : Task<struct (^TResult1 * ^TResult2)> =
+            this.Run(
+                this.Bind(
+                    computation,
+                    fun (result1: ^TResult1) ->
+                        this.Bind(task, fun (result2: ^TResult2) -> this.Return struct (result1, result2))
+                )
+            )
+
+    type BackgroundTaskBuilder with
+
+        // This overload is required for type inference in tasks cases
+        member inline this.MergeSources< ^TaskLike2, ^TResult1, ^TResult2, ^Awaiter2
+            when ^TaskLike2: (member GetAwaiter: unit -> ^Awaiter2)
+            and ^Awaiter2 :> ICriticalNotifyCompletion
+            and ^Awaiter2: (member get_IsCompleted: unit -> bool)
+            and ^Awaiter2: (member GetResult: unit -> 'TResult2)>
+            (task1: Task< ^TResult1 >, task2: ^TaskLike2)
+            : Task<struct (^TResult1 * ^TResult2)> =
+            this.Run(
+                this.Bind(
+                    task1,
+                    fun (result1: ^TResult1) ->
+                        this.Bind(task2, fun (result2: ^TResult2) -> this.Return struct (result1, result2))
+                )
+            )
+
+        // This overload is required for type inference in tasks cases
+        member inline this.MergeSources< ^TaskLike1, ^TResult1, ^TResult2, ^Awaiter1
+            when ^TaskLike1: (member GetAwaiter: unit -> ^Awaiter1)
+            and ^Awaiter1 :> ICriticalNotifyCompletion
+            and ^Awaiter1: (member get_IsCompleted: unit -> bool)
+            and ^Awaiter1: (member GetResult: unit -> 'TResult1)>
+            (task1: ^TaskLike1, task2: Task< ^TResult2 >)
+            : Task<struct (^TResult1 * ^TResult2)> =
+            this.Run(
+                this.Bind(
+                    task1,
+                    fun (result1: ^TResult1) ->
+                        this.Bind(task2, fun (result2: ^TResult2) -> this.Return struct (result1, result2))
+                )
+            )
+
+        // This overload is required for type inference in async cases
+        member inline this.MergeSources
+            (computation1: Async< ^TResult1 >, computation2: Async< ^TResult2 >)
+            : Task<struct (^TResult1 * ^TResult2)> =
+            this.Run(
+                this.Bind(
+                    computation1,
+                    fun (result1: ^TResult1) ->
+                        this.Bind(computation2, fun (result2: ^TResult2) -> this.Return struct (result1, result2))
+                )
+            )
+
+        // This overload is required for type inference in task + async cases
+        member inline this.MergeSources
+            (task: Task< ^TResult1 >, computation: Async< ^TResult2 >)
+            : Task<struct (^TResult1 * ^TResult2)> =
+            this.Run(
+                this.Bind(
+                    task,
+                    fun (result1: ^TResult1) ->
+                        this.Bind(computation, fun (result2: ^TResult2) -> this.Return struct (result1, result2))
+                )
+            )
+
+        // This overload is required for type inference in async + task case
+        member inline this.MergeSources
+            (computation: Async< ^TResult1 >, task: Task< ^TResult2 >)
+            : Task<struct (^TResult1 * ^TResult2)> =
+            this.Run(
+                this.Bind(
+                    computation,
+                    fun (result1: ^TResult1) ->
+                        this.Bind(task, fun (result2: ^TResult2) -> this.Return struct (result1, result2))
+                )
+            )
+
+module LowPlusPriority =
+    open LowPriority
+    open MediumPriority
+
+    type TaskBuilder with
+        // This overload is required for type inference in async cases
+        member inline this.MergeSources< ^TaskLike2, ^TResult1, ^TResult2, ^Awaiter2
+            when ^TaskLike2: (member GetAwaiter: unit -> ^Awaiter2)
+            and ^Awaiter2 :> ICriticalNotifyCompletion
+            and ^Awaiter2: (member get_IsCompleted: unit -> bool)
+            and ^Awaiter2: (member GetResult: unit -> 'TResult2)>
+            (computation: Async< ^TResult1 >, task: ^TaskLike2)
+            : Task<struct (^TResult1 * ^TResult2)> =
+            this.Run(
+                this.Bind(
+                    computation,
+                    fun (result1: ^TResult1) ->
+                        this.Bind(task, fun (result2: ^TResult2) -> this.Return struct (result1, result2))
+                )
+            )
+
+        // This overload is required for type inference in async cases
+        member inline this.MergeSources< ^TaskLike1, ^TResult1, ^TResult2, ^Awaiter1
+            when ^TaskLike1: (member GetAwaiter: unit -> ^Awaiter1)
+            and ^Awaiter1 :> ICriticalNotifyCompletion
+            and ^Awaiter1: (member get_IsCompleted: unit -> bool)
+            and ^Awaiter1: (member GetResult: unit -> 'TResult1)>
+            (task: ^TaskLike1, computation: Async< ^TResult2 >)
+            : Task<struct (^TResult1 * ^TResult2)> =
+            this.Run(
+                this.Bind(
+                    task,
+                    fun (result1: ^TResult1) ->
+                        this.Bind(computation, fun (result2: ^TResult2) -> this.Return struct (result1, result2))
+                )
+            )
+
+    type BackgroundTaskBuilder with
+        // This overload is required for type inference in async cases
+        member inline this.MergeSources< ^TaskLike2, ^TResult1, ^TResult2, ^Awaiter2
+            when ^TaskLike2: (member GetAwaiter: unit -> ^Awaiter2)
+            and ^Awaiter2 :> ICriticalNotifyCompletion
+            and ^Awaiter2: (member get_IsCompleted: unit -> bool)
+            and ^Awaiter2: (member GetResult: unit -> 'TResult2)>
+            (computation: Async< ^TResult1 >, task: ^TaskLike2)
+            : Task<struct (^TResult1 * ^TResult2)> =
+            this.Run(
+                this.Bind(
+                    computation,
+                    fun (result1: ^TResult1) ->
+                        this.Bind(task, fun (result2: ^TResult2) -> this.Return struct (result1, result2))
+                )
+            )
+
+        // This overload is required for type inference in async cases
+        member inline this.MergeSources< ^TaskLike1, ^TResult1, ^TResult2, ^Awaiter1
+            when ^TaskLike1: (member GetAwaiter: unit -> ^Awaiter1)
+            and ^Awaiter1 :> ICriticalNotifyCompletion
+            and ^Awaiter1: (member get_IsCompleted: unit -> bool)
+            and ^Awaiter1: (member GetResult: unit -> 'TResult1)>
+            (task: ^TaskLike1, computation: Async< ^TResult2 >)
+            : Task<struct (^TResult1 * ^TResult2)> =
+            this.Run(
+                this.Bind(
+                    task,
+                    fun (result1: ^TResult1) ->
+                        this.Bind(computation, fun (result2: ^TResult2) -> this.Return struct (result1, result2))
+                )
+            )
diff --git a/src/FSharp.Core/tasks.fsi b/src/FSharp.Core/tasks.fsi
index e6c801351a1..2db377cb2a1 100644
--- a/src/FSharp.Core/tasks.fsi
+++ b/src/FSharp.Core/tasks.fsi
@@ -239,6 +239,84 @@ module LowPriority =
             resource: 'Resource * body: ('Resource -> TaskCode<'TOverall, 'T>) -> TaskCode<'TOverall, 'T>
                 when 'Resource :> IDisposable | null
 
+    type TaskBuilder with
+
+        /// <summary>
+        /// Implementation of the `and!` operation for two task-like values.
+        /// </summary>
+        member inline MergeSources< ^TaskLike1, ^TaskLike2, ^TResult1, ^TResult2, ^Awaiter1, ^Awaiter2> :
+            task1: ^TaskLike1 * task2: ^TaskLike2 -> Task<struct (^TResult1 * ^TResult2)>
+                when ^TaskLike1: (member GetAwaiter: unit -> ^Awaiter1)
+                and ^TaskLike2: (member GetAwaiter: unit -> ^Awaiter2)
+                and ^Awaiter1 :> ICriticalNotifyCompletion
+                and ^Awaiter2 :> ICriticalNotifyCompletion
+                and ^Awaiter1: (member get_IsCompleted: unit -> bool)
+                and ^Awaiter1: (member GetResult: unit -> ^TResult1)
+                and ^Awaiter2: (member get_IsCompleted: unit -> bool)
+                and ^Awaiter2: (member GetResult: unit -> ^TResult2)
+
+    type BackgroundTaskBuilder with
+
+        /// <summary>
+        /// Implementation of the `and!` operation for two task-like values.
+        /// </summary>
+        member inline MergeSources< ^TaskLike1, ^TaskLike2, ^TResult1, ^TResult2, ^Awaiter1, ^Awaiter2> :
+            task1: ^TaskLike1 * task2: ^TaskLike2 -> Task<struct (^TResult1 * ^TResult2)>
+                when ^TaskLike1: (member GetAwaiter: unit -> ^Awaiter1)
+                and ^TaskLike2: (member GetAwaiter: unit -> ^Awaiter2)
+                and ^Awaiter1 :> ICriticalNotifyCompletion
+                and ^Awaiter2 :> ICriticalNotifyCompletion
+                and ^Awaiter1: (member get_IsCompleted: unit -> bool)
+                and ^Awaiter1: (member GetResult: unit -> ^TResult1)
+                and ^Awaiter2: (member get_IsCompleted: unit -> bool)
+                and ^Awaiter2: (member GetResult: unit -> ^TResult2)
+
+module LowPlusPriority =
+
+    type TaskBuilder with
+
+        /// <summary>
+        /// Implementation of the `and!` operation for an async and a task-like value.
+        /// </summary>
+        member inline MergeSources< ^TaskLike2, ^TResult1, ^TResult2, ^Awaiter2> :
+            computation: Async< ^TResult1 > * task: ^TaskLike2 -> Task<struct (^TResult1 * ^TResult2)>
+                when ^TaskLike2: (member GetAwaiter: unit -> ^Awaiter2)
+                and ^Awaiter2 :> ICriticalNotifyCompletion
+                and ^Awaiter2: (member get_IsCompleted: unit -> bool)
+                and ^Awaiter2: (member GetResult: unit -> ^TResult2)
+
+        /// <summary>
+        /// Implementation of the `and!` operation for a task-like value and an async.
+        /// </summary>
+        member inline MergeSources< ^TaskLike1, ^TResult1, ^TResult2, ^Awaiter1> :
+            task: ^TaskLike1 * computation: Async< ^TResult2 > -> Task<struct (^TResult1 * ^TResult2)>
+                when ^TaskLike1: (member GetAwaiter: unit -> ^Awaiter1)
+                and ^Awaiter1 :> ICriticalNotifyCompletion
+                and ^Awaiter1: (member get_IsCompleted: unit -> bool)
+                and ^Awaiter1: (member GetResult: unit -> ^TResult1)
+
+    type BackgroundTaskBuilder with
+
+        /// <summary>
+        /// Implementation of the `and!` operation for an async and a task-like value.
+        /// </summary>
+        member inline MergeSources< ^TaskLike2, ^TResult1, ^TResult2, ^Awaiter2> :
+            computation: Async< ^TResult1 > * task: ^TaskLike2 -> Task<struct (^TResult1 * ^TResult2)>
+                when ^TaskLike2: (member GetAwaiter: unit -> ^Awaiter2)
+                and ^Awaiter2 :> ICriticalNotifyCompletion
+                and ^Awaiter2: (member get_IsCompleted: unit -> bool)
+                and ^Awaiter2: (member GetResult: unit -> ^TResult2)
+
+        /// <summary>
+        /// Implementation of the `and!` operation for a task-like value and an async.
+        /// </summary>
+        member inline MergeSources< ^TaskLike1, ^TResult1, ^TResult2, ^Awaiter1> :
+            task: ^TaskLike1 * computation: Async< ^TResult2 > -> Task<struct (^TResult1 * ^TResult2)>
+                when ^TaskLike1: (member GetAwaiter: unit -> ^Awaiter1)
+                and ^Awaiter1 :> ICriticalNotifyCompletion
+                and ^Awaiter1: (member get_IsCompleted: unit -> bool)
+                and ^Awaiter1: (member GetResult: unit -> ^TResult1)
+
 /// <summary>
 /// Contains medium-priority overloads for the `task` computation expression builder.
 /// </summary>
@@ -258,6 +336,86 @@ module MediumPriority =
         /// </summary>
         member inline ReturnFrom: computation: Async<'T> -> TaskCode<'T, 'T>
 
+    type TaskBuilder with
+
+        /// <summary>
+        /// Implementation of the `and!` operation for a a task and a task-like value.
+        /// </summary>
+        member inline MergeSources< ^TaskLike2, ^TResult1, ^TResult2, ^Awaiter2> :
+            task1: Task< ^TResult1 > * task2: ^TaskLike2 -> Task<struct (^TResult1 * ^TResult2)>
+                when ^TaskLike2: (member GetAwaiter: unit -> ^Awaiter2)
+                and ^Awaiter2 :> ICriticalNotifyCompletion
+                and ^Awaiter2: (member get_IsCompleted: unit -> bool)
+                and ^Awaiter2: (member GetResult: unit -> ^TResult2)
+
+        /// <summary>
+        /// Implementation of the `and!` operation for a task-like value and a task.
+        /// </summary>
+        member inline MergeSources< ^TaskLike1, ^TResult1, ^TResult2, ^Awaiter1> :
+            task1: ^TaskLike1 * task2: Task< ^TResult2 > -> Task<struct (^TResult1 * ^TResult2)>
+                when ^TaskLike1: (member GetAwaiter: unit -> ^Awaiter1)
+                and ^Awaiter1 :> ICriticalNotifyCompletion
+                and ^Awaiter1: (member get_IsCompleted: unit -> bool)
+                and ^Awaiter1: (member GetResult: unit -> ^TResult1)
+
+        /// <summary>
+        /// Implementation of the `and!` operation for two asyncs.
+        /// </summary>
+        member inline MergeSources< ^TResult1, ^TResult2> :
+            computation1: Async< ^TResult1 > * computation2: Async< ^TResult2 > -> Task<struct (^TResult1 * ^TResult2)>
+
+        /// <summary>
+        /// Implementation of the `and!` operation for a task and an async.
+        /// </summary>
+        member inline MergeSources< ^TResult1, ^TResult2> :
+            task: Task< ^TResult1 > * computation: Async< ^TResult2 > -> Task<struct (^TResult1 * ^TResult2)>
+
+        /// <summary>
+        /// Implementation of the `and!` operation for an async and a task.
+        /// </summary>
+        member inline MergeSources< ^TResult1, ^TResult2> :
+            computation: Async< ^TResult1 > * task: Task< ^TResult2 > -> Task<struct (^TResult1 * ^TResult2)>
+
+    type BackgroundTaskBuilder with
+
+        /// <summary>
+        /// Implementation of the `and!` operation for a a task and a task-like value.
+        /// </summary>
+        member inline MergeSources< ^TaskLike2, ^TResult1, ^TResult2, ^Awaiter2> :
+            task1: Task< ^TResult1 > * task2: ^TaskLike2 -> Task<struct (^TResult1 * ^TResult2)>
+                when ^TaskLike2: (member GetAwaiter: unit -> ^Awaiter2)
+                and ^Awaiter2 :> ICriticalNotifyCompletion
+                and ^Awaiter2: (member get_IsCompleted: unit -> bool)
+                and ^Awaiter2: (member GetResult: unit -> ^TResult2)
+
+        /// <summary>
+        /// Implementation of the `and!` operation for a task-like value and a task.
+        /// </summary>
+        member inline MergeSources< ^TaskLike1, ^TResult1, ^TResult2, ^Awaiter1> :
+            task1: ^TaskLike1 * task2: Task< ^TResult2 > -> Task<struct (^TResult1 * ^TResult2)>
+                when ^TaskLike1: (member GetAwaiter: unit -> ^Awaiter1)
+                and ^Awaiter1 :> ICriticalNotifyCompletion
+                and ^Awaiter1: (member get_IsCompleted: unit -> bool)
+                and ^Awaiter1: (member GetResult: unit -> ^TResult1)
+
+        /// <summary>
+        /// Implementation of the `and!` operation for two asyncs.
+        /// </summary>
+        member inline MergeSources< ^TResult1, ^TResult2> :
+            computation1: Async< ^TResult1 > * computation2: Async< ^TResult2 > -> Task<struct (^TResult1 * ^TResult2)>
+
+        /// <summary>
+        /// Implementation of the `and!` operation for a task and an async.
+        /// </summary>
+        member inline MergeSources< ^TResult1, ^TResult2> :
+            task: Task< ^TResult1 > * computation: Async< ^TResult2 > -> Task<struct (^TResult1 * ^TResult2)>
+
+        /// <summary>
+        /// Implementation of the `and!` operation for an async and a task.
+        /// </summary>
+        member inline MergeSources< ^TResult1, ^TResult2> :
+            computation: Async< ^TResult1 > * task: Task< ^TResult2 > -> Task<struct (^TResult1 * ^TResult2)>
+
 /// <summary>
 /// Contains high-priority overloads for the `task` computation expression builder.
 /// </summary>
@@ -285,3 +443,17 @@ module HighPriority =
             task: Task<'TResult1> *
             continuation: ('TResult1 -> TaskCode<'TOverall, 'TResult2>) ->
                 bool
+
+    type TaskBuilder with
+        /// <summary>
+        /// Implementation of the `and!` operation for two tasks.
+        /// </summary>
+        member inline MergeSources< ^TResult1, ^TResult2> :
+            task1: Task< ^TResult1 > * task2: Task< ^TResult2 > -> Task<struct (^TResult1 * ^TResult2)>
+
+    type BackgroundTaskBuilder with
+        /// <summary>
+        /// Implementation of the `and!` operation for two tasks.
+        /// </summary>
+        member inline MergeSources< ^TResult1, ^TResult2> :
+            task1: Task< ^TResult1 > * task2: Task< ^TResult2 > -> Task<struct (^TResult1 * ^TResult2)>
diff --git a/tests/FSharp.Core.UnitTests/FSharp.Core.SurfaceArea.netstandard20.debug.bsl b/tests/FSharp.Core.UnitTests/FSharp.Core.SurfaceArea.netstandard20.debug.bsl
index 8b927e77440..5bd39b09a39 100644
--- a/tests/FSharp.Core.UnitTests/FSharp.Core.SurfaceArea.netstandard20.debug.bsl
+++ b/tests/FSharp.Core.UnitTests/FSharp.Core.SurfaceArea.netstandard20.debug.bsl
@@ -754,6 +754,16 @@ Microsoft.FSharp.Control.TaskBuilderBase: Microsoft.FSharp.Core.CompilerServices
 Microsoft.FSharp.Control.TaskBuilderExtensions.HighPriority: Boolean TaskBuilderBase.BindDynamic.Static[TOverall,TResult1,TResult2](Microsoft.FSharp.Core.CompilerServices.ResumableStateMachine`1[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall]] ByRef, System.Threading.Tasks.Task`1[TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TResult1,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2]])
 Microsoft.FSharp.Control.TaskBuilderExtensions.HighPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2] TaskBuilderBase.Bind[TResult1,TOverall,TResult2](Microsoft.FSharp.Control.TaskBuilderBase, System.Threading.Tasks.Task`1[TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TResult1,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2]])
 Microsoft.FSharp.Control.TaskBuilderExtensions.HighPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[T],T] TaskBuilderBase.ReturnFrom[T](Microsoft.FSharp.Control.TaskBuilderBase, System.Threading.Tasks.Task`1[T])
+Microsoft.FSharp.Control.TaskBuilderExtensions.HighPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.BackgroundTaskBuilder, System.Threading.Tasks.Task`1[TResult1], System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.HighPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.TaskBuilder, System.Threading.Tasks.Task`1[TResult1], System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources$W[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike1,TAwaiter1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,System.Boolean], Microsoft.FSharp.Control.BackgroundTaskBuilder, TTaskLike1, Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources$W[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike2,TAwaiter2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,TResult2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,System.Boolean], Microsoft.FSharp.Control.BackgroundTaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Control.BackgroundTaskBuilder, TTaskLike1, Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Control.BackgroundTaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources$W[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike1,TAwaiter1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,System.Boolean], Microsoft.FSharp.Control.TaskBuilder, TTaskLike1, Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources$W[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike2,TAwaiter2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,TResult2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,System.Boolean], Microsoft.FSharp.Control.TaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Control.TaskBuilder, TTaskLike1, Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Control.TaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], TTaskLike2)
 Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Boolean TaskBuilderBase.BindDynamic.Static$W[TTaskLike,TResult1,TResult2,TAwaiter,TOverall](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike,TAwaiter], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter,System.Boolean], Microsoft.FSharp.Core.CompilerServices.ResumableStateMachine`1[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall]] ByRef, TTaskLike, Microsoft.FSharp.Core.FSharpFunc`2[TResult1,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2]])
 Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Boolean TaskBuilderBase.BindDynamic.Static[TTaskLike,TResult1,TResult2,TAwaiter,TOverall](Microsoft.FSharp.Core.CompilerServices.ResumableStateMachine`1[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall]] ByRef, TTaskLike, Microsoft.FSharp.Core.FSharpFunc`2[TResult1,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2]])
 Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2] TaskBuilderBase.Bind$W[TTaskLike,TResult1,TResult2,TAwaiter,TOverall](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike,TAwaiter], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter,System.Boolean], Microsoft.FSharp.Control.TaskBuilderBase, TTaskLike, Microsoft.FSharp.Core.FSharpFunc`2[TResult1,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2]])
@@ -761,8 +771,26 @@ Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Microsoft.FSharp.Cor
 Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],T] TaskBuilderBase.Using[TResource,TOverall,T](Microsoft.FSharp.Control.TaskBuilderBase, TResource, Microsoft.FSharp.Core.FSharpFunc`2[TResource,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],T]])
 Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[T],T] TaskBuilderBase.ReturnFrom$W[TTaskLike,TAwaiter,T](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike,TAwaiter], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter,T], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter,System.Boolean], Microsoft.FSharp.Control.TaskBuilderBase, TTaskLike)
 Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[T],T] TaskBuilderBase.ReturnFrom[TTaskLike,TAwaiter,T](Microsoft.FSharp.Control.TaskBuilderBase, TTaskLike)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources$W[TTaskLike1,TTaskLike2,TResult1,TResult2,TAwaiter1,TAwaiter2](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike1,TAwaiter1], Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike2,TAwaiter2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,TResult2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,System.Boolean], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,System.Boolean], Microsoft.FSharp.Control.BackgroundTaskBuilder, TTaskLike1, TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TTaskLike1,TTaskLike2,TResult1,TResult2,TAwaiter1,TAwaiter2](Microsoft.FSharp.Control.BackgroundTaskBuilder, TTaskLike1, TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources$W[TTaskLike1,TTaskLike2,TResult1,TResult2,TAwaiter1,TAwaiter2](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike1,TAwaiter1], Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike2,TAwaiter2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,TResult2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,System.Boolean], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,System.Boolean], Microsoft.FSharp.Control.TaskBuilder, TTaskLike1, TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TTaskLike1,TTaskLike2,TResult1,TResult2,TAwaiter1,TAwaiter2](Microsoft.FSharp.Control.TaskBuilder, TTaskLike1, TTaskLike2)
 Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2] TaskBuilderBase.Bind[TResult1,TOverall,TResult2](Microsoft.FSharp.Control.TaskBuilderBase, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TResult1,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2]])
 Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[T],T] TaskBuilderBase.ReturnFrom[T](Microsoft.FSharp.Control.TaskBuilderBase, Microsoft.FSharp.Control.FSharpAsync`1[T])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources$W[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike1,TAwaiter1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,System.Boolean], Microsoft.FSharp.Control.BackgroundTaskBuilder, TTaskLike1, System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources$W[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike2,TAwaiter2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,TResult2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,System.Boolean], Microsoft.FSharp.Control.BackgroundTaskBuilder, System.Threading.Tasks.Task`1[TResult1], TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.BackgroundTaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.BackgroundTaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.BackgroundTaskBuilder, System.Threading.Tasks.Task`1[TResult1], Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Control.BackgroundTaskBuilder, TTaskLike1, System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Control.BackgroundTaskBuilder, System.Threading.Tasks.Task`1[TResult1], TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources$W[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike1,TAwaiter1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,System.Boolean], Microsoft.FSharp.Control.TaskBuilder, TTaskLike1, System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources$W[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike2,TAwaiter2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,TResult2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,System.Boolean], Microsoft.FSharp.Control.TaskBuilder, System.Threading.Tasks.Task`1[TResult1], TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.TaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.TaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.TaskBuilder, System.Threading.Tasks.Task`1[TResult1], Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Control.TaskBuilder, TTaskLike1, System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Control.TaskBuilder, System.Threading.Tasks.Task`1[TResult1], TTaskLike2)
 Microsoft.FSharp.Control.TaskBuilderModule: Microsoft.FSharp.Control.BackgroundTaskBuilder backgroundTask
 Microsoft.FSharp.Control.TaskBuilderModule: Microsoft.FSharp.Control.BackgroundTaskBuilder get_backgroundTask()
 Microsoft.FSharp.Control.TaskBuilderModule: Microsoft.FSharp.Control.TaskBuilder get_task()
diff --git a/tests/FSharp.Core.UnitTests/FSharp.Core.SurfaceArea.netstandard20.release.bsl b/tests/FSharp.Core.UnitTests/FSharp.Core.SurfaceArea.netstandard20.release.bsl
index cac2ceae8ed..8096acb15a1 100644
--- a/tests/FSharp.Core.UnitTests/FSharp.Core.SurfaceArea.netstandard20.release.bsl
+++ b/tests/FSharp.Core.UnitTests/FSharp.Core.SurfaceArea.netstandard20.release.bsl
@@ -754,6 +754,16 @@ Microsoft.FSharp.Control.TaskBuilderBase: Microsoft.FSharp.Core.CompilerServices
 Microsoft.FSharp.Control.TaskBuilderExtensions.HighPriority: Boolean TaskBuilderBase.BindDynamic.Static[TOverall,TResult1,TResult2](Microsoft.FSharp.Core.CompilerServices.ResumableStateMachine`1[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall]] ByRef, System.Threading.Tasks.Task`1[TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TResult1,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2]])
 Microsoft.FSharp.Control.TaskBuilderExtensions.HighPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2] TaskBuilderBase.Bind[TResult1,TOverall,TResult2](Microsoft.FSharp.Control.TaskBuilderBase, System.Threading.Tasks.Task`1[TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TResult1,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2]])
 Microsoft.FSharp.Control.TaskBuilderExtensions.HighPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[T],T] TaskBuilderBase.ReturnFrom[T](Microsoft.FSharp.Control.TaskBuilderBase, System.Threading.Tasks.Task`1[T])
+Microsoft.FSharp.Control.TaskBuilderExtensions.HighPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.BackgroundTaskBuilder, System.Threading.Tasks.Task`1[TResult1], System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.HighPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.TaskBuilder, System.Threading.Tasks.Task`1[TResult1], System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources$W[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike1,TAwaiter1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,System.Boolean], Microsoft.FSharp.Control.BackgroundTaskBuilder, TTaskLike1, Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources$W[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike2,TAwaiter2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,TResult2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,System.Boolean], Microsoft.FSharp.Control.BackgroundTaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Control.BackgroundTaskBuilder, TTaskLike1, Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Control.BackgroundTaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources$W[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike1,TAwaiter1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,System.Boolean], Microsoft.FSharp.Control.TaskBuilder, TTaskLike1, Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources$W[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike2,TAwaiter2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,TResult2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,System.Boolean], Microsoft.FSharp.Control.TaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Control.TaskBuilder, TTaskLike1, Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Control.TaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], TTaskLike2)
 Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Boolean TaskBuilderBase.BindDynamic.Static$W[TTaskLike,TResult1,TResult2,TAwaiter,TOverall](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike,TAwaiter], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter,System.Boolean], Microsoft.FSharp.Core.CompilerServices.ResumableStateMachine`1[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall]] ByRef, TTaskLike, Microsoft.FSharp.Core.FSharpFunc`2[TResult1,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2]])
 Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Boolean TaskBuilderBase.BindDynamic.Static[TTaskLike,TResult1,TResult2,TAwaiter,TOverall](Microsoft.FSharp.Core.CompilerServices.ResumableStateMachine`1[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall]] ByRef, TTaskLike, Microsoft.FSharp.Core.FSharpFunc`2[TResult1,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2]])
 Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2] TaskBuilderBase.Bind$W[TTaskLike,TResult1,TResult2,TAwaiter,TOverall](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike,TAwaiter], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter,System.Boolean], Microsoft.FSharp.Control.TaskBuilderBase, TTaskLike, Microsoft.FSharp.Core.FSharpFunc`2[TResult1,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2]])
@@ -761,8 +771,26 @@ Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Microsoft.FSharp.Cor
 Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],T] TaskBuilderBase.Using[TResource,TOverall,T](Microsoft.FSharp.Control.TaskBuilderBase, TResource, Microsoft.FSharp.Core.FSharpFunc`2[TResource,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],T]])
 Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[T],T] TaskBuilderBase.ReturnFrom$W[TTaskLike,TAwaiter,T](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike,TAwaiter], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter,T], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter,System.Boolean], Microsoft.FSharp.Control.TaskBuilderBase, TTaskLike)
 Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[T],T] TaskBuilderBase.ReturnFrom[TTaskLike,TAwaiter,T](Microsoft.FSharp.Control.TaskBuilderBase, TTaskLike)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources$W[TTaskLike1,TTaskLike2,TResult1,TResult2,TAwaiter1,TAwaiter2](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike1,TAwaiter1], Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike2,TAwaiter2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,TResult2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,System.Boolean], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,System.Boolean], Microsoft.FSharp.Control.BackgroundTaskBuilder, TTaskLike1, TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TTaskLike1,TTaskLike2,TResult1,TResult2,TAwaiter1,TAwaiter2](Microsoft.FSharp.Control.BackgroundTaskBuilder, TTaskLike1, TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources$W[TTaskLike1,TTaskLike2,TResult1,TResult2,TAwaiter1,TAwaiter2](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike1,TAwaiter1], Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike2,TAwaiter2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,TResult2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,System.Boolean], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,System.Boolean], Microsoft.FSharp.Control.TaskBuilder, TTaskLike1, TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TTaskLike1,TTaskLike2,TResult1,TResult2,TAwaiter1,TAwaiter2](Microsoft.FSharp.Control.TaskBuilder, TTaskLike1, TTaskLike2)
 Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2] TaskBuilderBase.Bind[TResult1,TOverall,TResult2](Microsoft.FSharp.Control.TaskBuilderBase, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TResult1,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2]])
 Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[T],T] TaskBuilderBase.ReturnFrom[T](Microsoft.FSharp.Control.TaskBuilderBase, Microsoft.FSharp.Control.FSharpAsync`1[T])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources$W[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike1,TAwaiter1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,System.Boolean], Microsoft.FSharp.Control.BackgroundTaskBuilder, TTaskLike1, System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources$W[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike2,TAwaiter2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,TResult2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,System.Boolean], Microsoft.FSharp.Control.BackgroundTaskBuilder, System.Threading.Tasks.Task`1[TResult1], TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.BackgroundTaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.BackgroundTaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.BackgroundTaskBuilder, System.Threading.Tasks.Task`1[TResult1], Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Control.BackgroundTaskBuilder, TTaskLike1, System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Control.BackgroundTaskBuilder, System.Threading.Tasks.Task`1[TResult1], TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources$W[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike1,TAwaiter1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,System.Boolean], Microsoft.FSharp.Control.TaskBuilder, TTaskLike1, System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources$W[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike2,TAwaiter2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,TResult2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,System.Boolean], Microsoft.FSharp.Control.TaskBuilder, System.Threading.Tasks.Task`1[TResult1], TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.TaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.TaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.TaskBuilder, System.Threading.Tasks.Task`1[TResult1], Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Control.TaskBuilder, TTaskLike1, System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Control.TaskBuilder, System.Threading.Tasks.Task`1[TResult1], TTaskLike2)
 Microsoft.FSharp.Control.TaskBuilderModule: Microsoft.FSharp.Control.BackgroundTaskBuilder backgroundTask
 Microsoft.FSharp.Control.TaskBuilderModule: Microsoft.FSharp.Control.BackgroundTaskBuilder get_backgroundTask()
 Microsoft.FSharp.Control.TaskBuilderModule: Microsoft.FSharp.Control.TaskBuilder get_task()
diff --git a/tests/FSharp.Core.UnitTests/FSharp.Core.SurfaceArea.netstandard21.debug.bsl b/tests/FSharp.Core.UnitTests/FSharp.Core.SurfaceArea.netstandard21.debug.bsl
index a49aac19aaa..95ebeea8a37 100644
--- a/tests/FSharp.Core.UnitTests/FSharp.Core.SurfaceArea.netstandard21.debug.bsl
+++ b/tests/FSharp.Core.UnitTests/FSharp.Core.SurfaceArea.netstandard21.debug.bsl
@@ -757,6 +757,16 @@ Microsoft.FSharp.Control.TaskBuilderBase: Microsoft.FSharp.Core.CompilerServices
 Microsoft.FSharp.Control.TaskBuilderExtensions.HighPriority: Boolean TaskBuilderBase.BindDynamic.Static[TOverall,TResult1,TResult2](Microsoft.FSharp.Core.CompilerServices.ResumableStateMachine`1[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall]] ByRef, System.Threading.Tasks.Task`1[TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TResult1,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2]])
 Microsoft.FSharp.Control.TaskBuilderExtensions.HighPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2] TaskBuilderBase.Bind[TResult1,TOverall,TResult2](Microsoft.FSharp.Control.TaskBuilderBase, System.Threading.Tasks.Task`1[TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TResult1,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2]])
 Microsoft.FSharp.Control.TaskBuilderExtensions.HighPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[T],T] TaskBuilderBase.ReturnFrom[T](Microsoft.FSharp.Control.TaskBuilderBase, System.Threading.Tasks.Task`1[T])
+Microsoft.FSharp.Control.TaskBuilderExtensions.HighPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.BackgroundTaskBuilder, System.Threading.Tasks.Task`1[TResult1], System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.HighPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.TaskBuilder, System.Threading.Tasks.Task`1[TResult1], System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources$W[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike1,TAwaiter1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,System.Boolean], Microsoft.FSharp.Control.BackgroundTaskBuilder, TTaskLike1, Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources$W[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike2,TAwaiter2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,TResult2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,System.Boolean], Microsoft.FSharp.Control.BackgroundTaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Control.BackgroundTaskBuilder, TTaskLike1, Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Control.BackgroundTaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources$W[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike1,TAwaiter1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,System.Boolean], Microsoft.FSharp.Control.TaskBuilder, TTaskLike1, Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources$W[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike2,TAwaiter2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,TResult2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,System.Boolean], Microsoft.FSharp.Control.TaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Control.TaskBuilder, TTaskLike1, Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Control.TaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], TTaskLike2)
 Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Boolean TaskBuilderBase.BindDynamic.Static$W[TTaskLike,TResult1,TResult2,TAwaiter,TOverall](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike,TAwaiter], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter,System.Boolean], Microsoft.FSharp.Core.CompilerServices.ResumableStateMachine`1[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall]] ByRef, TTaskLike, Microsoft.FSharp.Core.FSharpFunc`2[TResult1,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2]])
 Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Boolean TaskBuilderBase.BindDynamic.Static[TTaskLike,TResult1,TResult2,TAwaiter,TOverall](Microsoft.FSharp.Core.CompilerServices.ResumableStateMachine`1[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall]] ByRef, TTaskLike, Microsoft.FSharp.Core.FSharpFunc`2[TResult1,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2]])
 Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2] TaskBuilderBase.Bind$W[TTaskLike,TResult1,TResult2,TAwaiter,TOverall](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike,TAwaiter], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter,System.Boolean], Microsoft.FSharp.Control.TaskBuilderBase, TTaskLike, Microsoft.FSharp.Core.FSharpFunc`2[TResult1,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2]])
@@ -764,8 +774,26 @@ Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Microsoft.FSharp.Cor
 Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],T] TaskBuilderBase.Using[TResource,TOverall,T](Microsoft.FSharp.Control.TaskBuilderBase, TResource, Microsoft.FSharp.Core.FSharpFunc`2[TResource,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],T]])
 Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[T],T] TaskBuilderBase.ReturnFrom$W[TTaskLike,TAwaiter,T](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike,TAwaiter], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter,T], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter,System.Boolean], Microsoft.FSharp.Control.TaskBuilderBase, TTaskLike)
 Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[T],T] TaskBuilderBase.ReturnFrom[TTaskLike,TAwaiter,T](Microsoft.FSharp.Control.TaskBuilderBase, TTaskLike)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources$W[TTaskLike1,TTaskLike2,TResult1,TResult2,TAwaiter1,TAwaiter2](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike1,TAwaiter1], Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike2,TAwaiter2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,TResult2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,System.Boolean], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,System.Boolean], Microsoft.FSharp.Control.BackgroundTaskBuilder, TTaskLike1, TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TTaskLike1,TTaskLike2,TResult1,TResult2,TAwaiter1,TAwaiter2](Microsoft.FSharp.Control.BackgroundTaskBuilder, TTaskLike1, TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources$W[TTaskLike1,TTaskLike2,TResult1,TResult2,TAwaiter1,TAwaiter2](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike1,TAwaiter1], Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike2,TAwaiter2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,TResult2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,System.Boolean], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,System.Boolean], Microsoft.FSharp.Control.TaskBuilder, TTaskLike1, TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TTaskLike1,TTaskLike2,TResult1,TResult2,TAwaiter1,TAwaiter2](Microsoft.FSharp.Control.TaskBuilder, TTaskLike1, TTaskLike2)
 Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2] TaskBuilderBase.Bind[TResult1,TOverall,TResult2](Microsoft.FSharp.Control.TaskBuilderBase, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TResult1,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2]])
 Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[T],T] TaskBuilderBase.ReturnFrom[T](Microsoft.FSharp.Control.TaskBuilderBase, Microsoft.FSharp.Control.FSharpAsync`1[T])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources$W[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike1,TAwaiter1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,System.Boolean], Microsoft.FSharp.Control.BackgroundTaskBuilder, TTaskLike1, System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources$W[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike2,TAwaiter2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,TResult2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,System.Boolean], Microsoft.FSharp.Control.BackgroundTaskBuilder, System.Threading.Tasks.Task`1[TResult1], TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.BackgroundTaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.BackgroundTaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.BackgroundTaskBuilder, System.Threading.Tasks.Task`1[TResult1], Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Control.BackgroundTaskBuilder, TTaskLike1, System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Control.BackgroundTaskBuilder, System.Threading.Tasks.Task`1[TResult1], TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources$W[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike1,TAwaiter1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,System.Boolean], Microsoft.FSharp.Control.TaskBuilder, TTaskLike1, System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources$W[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike2,TAwaiter2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,TResult2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,System.Boolean], Microsoft.FSharp.Control.TaskBuilder, System.Threading.Tasks.Task`1[TResult1], TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.TaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.TaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.TaskBuilder, System.Threading.Tasks.Task`1[TResult1], Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Control.TaskBuilder, TTaskLike1, System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Control.TaskBuilder, System.Threading.Tasks.Task`1[TResult1], TTaskLike2)
 Microsoft.FSharp.Control.TaskBuilderModule: Microsoft.FSharp.Control.BackgroundTaskBuilder backgroundTask
 Microsoft.FSharp.Control.TaskBuilderModule: Microsoft.FSharp.Control.BackgroundTaskBuilder get_backgroundTask()
 Microsoft.FSharp.Control.TaskBuilderModule: Microsoft.FSharp.Control.TaskBuilder get_task()
diff --git a/tests/FSharp.Core.UnitTests/FSharp.Core.SurfaceArea.netstandard21.release.bsl b/tests/FSharp.Core.UnitTests/FSharp.Core.SurfaceArea.netstandard21.release.bsl
index b17d1201a5a..c4106d360c4 100644
--- a/tests/FSharp.Core.UnitTests/FSharp.Core.SurfaceArea.netstandard21.release.bsl
+++ b/tests/FSharp.Core.UnitTests/FSharp.Core.SurfaceArea.netstandard21.release.bsl
@@ -757,6 +757,16 @@ Microsoft.FSharp.Control.TaskBuilderBase: Microsoft.FSharp.Core.CompilerServices
 Microsoft.FSharp.Control.TaskBuilderExtensions.HighPriority: Boolean TaskBuilderBase.BindDynamic.Static[TOverall,TResult1,TResult2](Microsoft.FSharp.Core.CompilerServices.ResumableStateMachine`1[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall]] ByRef, System.Threading.Tasks.Task`1[TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TResult1,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2]])
 Microsoft.FSharp.Control.TaskBuilderExtensions.HighPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2] TaskBuilderBase.Bind[TResult1,TOverall,TResult2](Microsoft.FSharp.Control.TaskBuilderBase, System.Threading.Tasks.Task`1[TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TResult1,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2]])
 Microsoft.FSharp.Control.TaskBuilderExtensions.HighPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[T],T] TaskBuilderBase.ReturnFrom[T](Microsoft.FSharp.Control.TaskBuilderBase, System.Threading.Tasks.Task`1[T])
+Microsoft.FSharp.Control.TaskBuilderExtensions.HighPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.BackgroundTaskBuilder, System.Threading.Tasks.Task`1[TResult1], System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.HighPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.TaskBuilder, System.Threading.Tasks.Task`1[TResult1], System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources$W[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike1,TAwaiter1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,System.Boolean], Microsoft.FSharp.Control.BackgroundTaskBuilder, TTaskLike1, Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources$W[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike2,TAwaiter2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,TResult2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,System.Boolean], Microsoft.FSharp.Control.BackgroundTaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Control.BackgroundTaskBuilder, TTaskLike1, Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Control.BackgroundTaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources$W[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike1,TAwaiter1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,System.Boolean], Microsoft.FSharp.Control.TaskBuilder, TTaskLike1, Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources$W[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike2,TAwaiter2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,TResult2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,System.Boolean], Microsoft.FSharp.Control.TaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Control.TaskBuilder, TTaskLike1, Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Control.TaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], TTaskLike2)
 Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Boolean TaskBuilderBase.BindDynamic.Static$W[TTaskLike,TResult1,TResult2,TAwaiter,TOverall](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike,TAwaiter], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter,System.Boolean], Microsoft.FSharp.Core.CompilerServices.ResumableStateMachine`1[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall]] ByRef, TTaskLike, Microsoft.FSharp.Core.FSharpFunc`2[TResult1,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2]])
 Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Boolean TaskBuilderBase.BindDynamic.Static[TTaskLike,TResult1,TResult2,TAwaiter,TOverall](Microsoft.FSharp.Core.CompilerServices.ResumableStateMachine`1[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall]] ByRef, TTaskLike, Microsoft.FSharp.Core.FSharpFunc`2[TResult1,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2]])
 Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2] TaskBuilderBase.Bind$W[TTaskLike,TResult1,TResult2,TAwaiter,TOverall](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike,TAwaiter], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter,System.Boolean], Microsoft.FSharp.Control.TaskBuilderBase, TTaskLike, Microsoft.FSharp.Core.FSharpFunc`2[TResult1,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2]])
@@ -764,8 +774,26 @@ Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Microsoft.FSharp.Cor
 Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],T] TaskBuilderBase.Using[TResource,TOverall,T](Microsoft.FSharp.Control.TaskBuilderBase, TResource, Microsoft.FSharp.Core.FSharpFunc`2[TResource,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],T]])
 Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[T],T] TaskBuilderBase.ReturnFrom$W[TTaskLike,TAwaiter,T](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike,TAwaiter], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter,T], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter,System.Boolean], Microsoft.FSharp.Control.TaskBuilderBase, TTaskLike)
 Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[T],T] TaskBuilderBase.ReturnFrom[TTaskLike,TAwaiter,T](Microsoft.FSharp.Control.TaskBuilderBase, TTaskLike)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources$W[TTaskLike1,TTaskLike2,TResult1,TResult2,TAwaiter1,TAwaiter2](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike1,TAwaiter1], Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike2,TAwaiter2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,TResult2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,System.Boolean], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,System.Boolean], Microsoft.FSharp.Control.BackgroundTaskBuilder, TTaskLike1, TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TTaskLike1,TTaskLike2,TResult1,TResult2,TAwaiter1,TAwaiter2](Microsoft.FSharp.Control.BackgroundTaskBuilder, TTaskLike1, TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources$W[TTaskLike1,TTaskLike2,TResult1,TResult2,TAwaiter1,TAwaiter2](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike1,TAwaiter1], Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike2,TAwaiter2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,TResult2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,System.Boolean], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,System.Boolean], Microsoft.FSharp.Control.TaskBuilder, TTaskLike1, TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TTaskLike1,TTaskLike2,TResult1,TResult2,TAwaiter1,TAwaiter2](Microsoft.FSharp.Control.TaskBuilder, TTaskLike1, TTaskLike2)
 Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2] TaskBuilderBase.Bind[TResult1,TOverall,TResult2](Microsoft.FSharp.Control.TaskBuilderBase, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TResult1,Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[TOverall],TResult2]])
 Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: Microsoft.FSharp.Core.CompilerServices.ResumableCode`2[Microsoft.FSharp.Control.TaskStateMachineData`1[T],T] TaskBuilderBase.ReturnFrom[T](Microsoft.FSharp.Control.TaskBuilderBase, Microsoft.FSharp.Control.FSharpAsync`1[T])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources$W[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike1,TAwaiter1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,System.Boolean], Microsoft.FSharp.Control.BackgroundTaskBuilder, TTaskLike1, System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources$W[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike2,TAwaiter2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,TResult2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,System.Boolean], Microsoft.FSharp.Control.BackgroundTaskBuilder, System.Threading.Tasks.Task`1[TResult1], TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.BackgroundTaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.BackgroundTaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.BackgroundTaskBuilder, System.Threading.Tasks.Task`1[TResult1], Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Control.BackgroundTaskBuilder, TTaskLike1, System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] BackgroundTaskBuilder.MergeSources[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Control.BackgroundTaskBuilder, System.Threading.Tasks.Task`1[TResult1], TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources$W[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike1,TAwaiter1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,TResult1], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter1,System.Boolean], Microsoft.FSharp.Control.TaskBuilder, TTaskLike1, System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources$W[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Core.FSharpFunc`2[TTaskLike2,TAwaiter2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,TResult2], Microsoft.FSharp.Core.FSharpFunc`2[TAwaiter2,System.Boolean], Microsoft.FSharp.Control.TaskBuilder, System.Threading.Tasks.Task`1[TResult1], TTaskLike2)
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.TaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.TaskBuilder, Microsoft.FSharp.Control.FSharpAsync`1[TResult1], System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TResult1,TResult2](Microsoft.FSharp.Control.TaskBuilder, System.Threading.Tasks.Task`1[TResult1], Microsoft.FSharp.Control.FSharpAsync`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TTaskLike1,TResult1,TResult2,TAwaiter1](Microsoft.FSharp.Control.TaskBuilder, TTaskLike1, System.Threading.Tasks.Task`1[TResult2])
+Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority: System.Threading.Tasks.Task`1[System.ValueTuple`2[TResult1,TResult2]] TaskBuilder.MergeSources[TTaskLike2,TResult1,TResult2,TAwaiter2](Microsoft.FSharp.Control.TaskBuilder, System.Threading.Tasks.Task`1[TResult1], TTaskLike2)
 Microsoft.FSharp.Control.TaskBuilderModule: Microsoft.FSharp.Control.BackgroundTaskBuilder backgroundTask
 Microsoft.FSharp.Control.TaskBuilderModule: Microsoft.FSharp.Control.BackgroundTaskBuilder get_backgroundTask()
 Microsoft.FSharp.Control.TaskBuilderModule: Microsoft.FSharp.Control.TaskBuilder get_task()
diff --git a/tests/FSharp.Core.UnitTests/FSharp.Core/Microsoft.FSharp.Control/Tasks.fs b/tests/FSharp.Core.UnitTests/FSharp.Core/Microsoft.FSharp.Control/Tasks.fs
index cce271d58bb..f60a3562f75 100644
--- a/tests/FSharp.Core.UnitTests/FSharp.Core/Microsoft.FSharp.Control/Tasks.fs
+++ b/tests/FSharp.Core.UnitTests/FSharp.Core/Microsoft.FSharp.Control/Tasks.fs
@@ -183,6 +183,179 @@ type SmokeTestsForCompilation() =
             t.Wait()
             if t.Result <> 5 then failwith "failed"
 
+    [<Fact>]
+    member _.merge2tasks() =
+        task {
+            let! x = Task.FromResult(1)
+            and! y = Task.FromResult(2)
+            return x + y
+        }
+        |> fun t -> 
+            t.Wait()
+            if t.Result <> 3 then failwith "failed"    
+            
+    [<Fact>]
+    member _.merge3tasks() =
+        task {
+            let! x = Task.FromResult(1)
+            and! y = Task.FromResult(2)
+            and! z = Task.FromResult(3)
+            return x + y + z
+        }
+        |> fun t -> 
+            t.Wait()
+            if t.Result <> 6 then failwith "failed"
+
+    [<Fact>]
+    member _.mergeYieldAndTask() =
+        task {
+            let! _ = Task.Yield()
+            and! y = Task.FromResult(1)
+            return y
+        }
+        |> fun t -> 
+            t.Wait()
+            if t.Result <> 1 then failwith "failed"
+
+    [<Fact>]
+    member _.mergeTaskAndYield() =
+        task {
+            let! x = Task.FromResult(1)
+            and! _ = Task.Yield()
+            return x
+        }
+        |> fun t -> 
+            t.Wait()
+            if t.Result <> 1 then failwith "failed"
+
+    [<Fact>]
+    member _.merge2valueTasks() =
+        task {
+            let! x = ValueTask<int>(Task.FromResult(1))
+            and! y = ValueTask<int>(Task.FromResult(2))
+            return x + y
+        }
+        |> fun t -> 
+            t.Wait()
+            if t.Result <> 3 then failwith "failed"
+
+    [<Fact>]
+    member _.merge2valueTasksAndYield() =
+        task {
+            let! x = ValueTask<int>(Task.FromResult(1))
+            and! y = ValueTask<int>(Task.FromResult(2))
+            and! _ = Task.Yield()
+            return x + y
+        }
+        |> fun t -> 
+            t.Wait()
+            if t.Result <> 3 then failwith "failed"
+
+    [<Fact>]
+    member _.mergeYieldAnd2tasks() =
+        task {
+            let! _ = Task.Yield()
+            and! x = Task.FromResult(1)
+            and! y = Task.FromResult(2)
+            return x + y
+        }
+        |> fun t -> 
+            t.Wait()
+            if t.Result <> 3 then failwith "failed"
+
+    [<Fact>]
+    member _.merge2tasksAndValueTask() =
+        task {
+            let! x = Task.FromResult(1)
+            and! y = Task.FromResult(2)
+            and! z = ValueTask<int>(Task.FromResult(3))
+            return x + y + z
+        }
+        |> fun t -> 
+            t.Wait()
+            if t.Result <> 6 then failwith "failed"
+
+    [<Fact>]
+    member _.merge2asyncs() =
+        task {
+            let! x = async { return 1 }
+            and! y = async { return 2 }
+            return x + y
+        }
+        |> fun t -> 
+            t.Wait()
+            if t.Result <> 3 then failwith "failed"
+
+    [<Fact>]
+    member _.merge3asyncs() =
+        task {
+            let! x = async { return 1 }
+            and! y = async { return 2 }
+            and! z = async { return 3 }
+            return x + y + z
+        }
+        |> fun t -> 
+            t.Wait()
+            if t.Result <> 6 then failwith "failed"
+
+    [<Fact>]
+    member _.mergeYieldAndAsync() =
+        task {
+            let! _ = Task.Yield()
+            and! y = async { return 1 }
+            return y
+        }
+        |> fun t -> 
+            t.Wait()
+            if t.Result <> 1 then failwith "failed"
+
+    [<Fact>]
+    member _.mergeAsyncAndYield() =
+        task {
+            let! x = async { return 1 }
+            and! _ = Task.Yield()
+            return x
+        }
+        |> fun t -> 
+            t.Wait()
+            if t.Result <> 1 then failwith "failed"
+
+    [<Fact>]
+    member _.mergeYieldAnd2asyncs() =
+        task {
+            let! _ = Task.Yield()
+            and! x = async { return 1 }
+            and! y = async { return 2 }
+            return x + y
+        }
+        |> fun t -> 
+            t.Wait()
+            if t.Result <> 3 then failwith "failed"
+
+    [<Fact>]
+    member _.merge2asyncsAndValueTask() =
+        task {
+            let! x = async { return 1 }
+            and! y = async { return 2 }
+            and! z = ValueTask<int>(Task.FromResult(3))
+            return x + y + z
+        }
+        |> fun t -> 
+            t.Wait()
+            if t.Result <> 6 then failwith "failed"
+
+    [<Fact>]
+    member _.mergeBackgroundTask() =
+        backgroundTask {
+            let! x = async { return 1 }
+            and! y = task { return 2 }
+            and! z = ValueTask<int>(Task.FromResult(3))
+            return x + y + z
+        }
+        |> fun t -> 
+            t.Wait()
+            if t.Result <> 6 then failwith "failed"
+
 exception TestException of string
 
 [<AutoOpen>]
@@ -296,6 +469,33 @@ type Basics() =
         require (y = 1) "bailed after exn"
         require (x = 0) "ran past failure"
 
+    [<Fact>]
+    member _.testCatchingInApplicative() =
+        printfn "Running testCatchingInApplicative..."
+        let mutable x = 0
+        let mutable y = 0
+        let t =
+            task {
+                try
+                    let! _ = task { 
+                        do! Task.Delay(100)
+                        x <- 1
+                    }
+                    and! _ = task { 
+                        failtest "hello"
+                    }
+                    ()
+                with
+                | TestException msg ->
+                    require (msg = "hello") "message tampered"
+                | _ ->
+                    require false "other exn type"
+                y <- 1
+            }
+        t.Wait()
+        require (y = 1) "bailed after exn"
+        require (x = 1) "exit too early"
+
     [<Fact>]
     member _.testNestedCatching() =
         printfn "Running testNestedCatching..."
diff --git a/tests/ILVerify/ilverify_FSharp.Core_Debug_netstandard2.0.bsl b/tests/ILVerify/ilverify_FSharp.Core_Debug_netstandard2.0.bsl
index 4e6bca186fd..7f00cdfe046 100644
--- a/tests/ILVerify/ilverify_FSharp.Core_Debug_netstandard2.0.bsl
+++ b/tests/ILVerify/ilverify_FSharp.Core_Debug_netstandard2.0.bsl
@@ -1,3 +1,23 @@
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!1>, !!0)][offset 0x0000000E][found ref '[FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<T1>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!1>, !!0)][offset 0x00000016][found value 'TTaskLike2'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T2>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, !!0, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!2>)][offset 0x0000000E][found value 'TTaskLike1'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, !!0, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!2>)][offset 0x00000016][found ref '[FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<T2>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T1>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!1>, !!0)][offset 0x0000000E][found ref '[FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<T1>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!1>, !!0)][offset 0x00000016][found value 'TTaskLike2'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T2>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, !!0, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!2>)][offset 0x0000000E][found value 'TTaskLike1'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, !!0, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!2>)][offset 0x00000016][found ref '[FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<T2>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T1>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!1>, !!0)][offset 0x0000000E][found ref '[S.P.CoreLib]System.Threading.Tasks.Task`1<T1>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!1>, !!0)][offset 0x00000016][found value 'TTaskLike2'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T2>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, !!0, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!2>)][offset 0x0000000E][found value 'TTaskLike1'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, !!0, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!2>)][offset 0x00000016][found ref '[S.P.CoreLib]System.Threading.Tasks.Task`1<T2>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T1>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!1>, !!0)][offset 0x0000000E][found ref '[S.P.CoreLib]System.Threading.Tasks.Task`1<T1>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!1>, !!0)][offset 0x00000016][found value 'TTaskLike2'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T2>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, !!0, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!2>)][offset 0x0000000E][found value 'TTaskLike1'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, !!0, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!2>)][offset 0x00000016][found ref '[S.P.CoreLib]System.Threading.Tasks.Task`1<T2>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T1>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!4>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!1,!!5>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,bool>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, !!0, !!1)][offset 0x0000000E][found value 'TTaskLike2'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T4>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!4>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!1,!!5>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,bool>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, !!0, !!1)][offset 0x00000016][found value 'TTaskLike1'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T1,T5>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!4>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!1,!!5>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,bool>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, !!0, !!1)][offset 0x0000000E][found value 'TTaskLike2'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T4>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!4>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!1,!!5>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,bool>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, !!0, !!1)][offset 0x00000016][found value 'TTaskLike1'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T1,T5>'] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : Microsoft.FSharp.Collections.ArrayModule+Parallel::Choose([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,Microsoft.FSharp.Core.FSharpOption`1<!!1>>, !!0[])][offset 0x000000A0][found Byte] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : Microsoft.FSharp.Collections.ArrayModule+Parallel::Filter([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,bool>, !!0[])][offset 0x00000029][found Byte] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : Microsoft.FSharp.Collections.ArrayModule+Parallel::Partition([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,bool>, !!0[])][offset 0x00000038][found Byte] Unexpected type on the stack.
diff --git a/tests/ILVerify/ilverify_FSharp.Core_Debug_netstandard2.1.bsl b/tests/ILVerify/ilverify_FSharp.Core_Debug_netstandard2.1.bsl
index 4e6bca186fd..7f00cdfe046 100644
--- a/tests/ILVerify/ilverify_FSharp.Core_Debug_netstandard2.1.bsl
+++ b/tests/ILVerify/ilverify_FSharp.Core_Debug_netstandard2.1.bsl
@@ -1,3 +1,23 @@
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!1>, !!0)][offset 0x0000000E][found ref '[FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<T1>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!1>, !!0)][offset 0x00000016][found value 'TTaskLike2'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T2>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, !!0, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!2>)][offset 0x0000000E][found value 'TTaskLike1'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, !!0, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!2>)][offset 0x00000016][found ref '[FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<T2>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T1>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!1>, !!0)][offset 0x0000000E][found ref '[FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<T1>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!1>, !!0)][offset 0x00000016][found value 'TTaskLike2'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T2>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, !!0, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!2>)][offset 0x0000000E][found value 'TTaskLike1'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, !!0, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!2>)][offset 0x00000016][found ref '[FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<T2>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T1>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!1>, !!0)][offset 0x0000000E][found ref '[S.P.CoreLib]System.Threading.Tasks.Task`1<T1>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!1>, !!0)][offset 0x00000016][found value 'TTaskLike2'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T2>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, !!0, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!2>)][offset 0x0000000E][found value 'TTaskLike1'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, !!0, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!2>)][offset 0x00000016][found ref '[S.P.CoreLib]System.Threading.Tasks.Task`1<T2>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T1>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!1>, !!0)][offset 0x0000000E][found ref '[S.P.CoreLib]System.Threading.Tasks.Task`1<T1>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!1>, !!0)][offset 0x00000016][found value 'TTaskLike2'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T2>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, !!0, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!2>)][offset 0x0000000E][found value 'TTaskLike1'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, !!0, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!2>)][offset 0x00000016][found ref '[S.P.CoreLib]System.Threading.Tasks.Task`1<T2>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T1>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!4>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!1,!!5>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,bool>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, !!0, !!1)][offset 0x0000000E][found value 'TTaskLike2'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T4>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!4>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!1,!!5>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,bool>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, !!0, !!1)][offset 0x00000016][found value 'TTaskLike1'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T1,T5>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!4>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!1,!!5>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,bool>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, !!0, !!1)][offset 0x0000000E][found value 'TTaskLike2'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T4>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!4>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!1,!!5>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,bool>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, !!0, !!1)][offset 0x00000016][found value 'TTaskLike1'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T1,T5>'] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : Microsoft.FSharp.Collections.ArrayModule+Parallel::Choose([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,Microsoft.FSharp.Core.FSharpOption`1<!!1>>, !!0[])][offset 0x000000A0][found Byte] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : Microsoft.FSharp.Collections.ArrayModule+Parallel::Filter([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,bool>, !!0[])][offset 0x00000029][found Byte] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : Microsoft.FSharp.Collections.ArrayModule+Parallel::Partition([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,bool>, !!0[])][offset 0x00000038][found Byte] Unexpected type on the stack.
diff --git a/tests/ILVerify/ilverify_FSharp.Core_Release_netstandard2.0.bsl b/tests/ILVerify/ilverify_FSharp.Core_Release_netstandard2.0.bsl
index 6ab50914fdd..05a10ae7797 100644
--- a/tests/ILVerify/ilverify_FSharp.Core_Release_netstandard2.0.bsl
+++ b/tests/ILVerify/ilverify_FSharp.Core_Release_netstandard2.0.bsl
@@ -1,3 +1,23 @@
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!1>, !!0)][offset 0x0000000E][found ref '[FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<T1>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!1>, !!0)][offset 0x00000016][found value 'TTaskLike2'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T2>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, !!0, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!2>)][offset 0x0000000E][found value 'TTaskLike1'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, !!0, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!2>)][offset 0x00000016][found ref '[FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<T2>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T1>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!1>, !!0)][offset 0x0000000E][found ref '[FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<T1>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!1>, !!0)][offset 0x00000016][found value 'TTaskLike2'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T2>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, !!0, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!2>)][offset 0x0000000E][found value 'TTaskLike1'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, !!0, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!2>)][offset 0x00000016][found ref '[FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<T2>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T1>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!1>, !!0)][offset 0x0000000E][found ref '[S.P.CoreLib]System.Threading.Tasks.Task`1<T1>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!1>, !!0)][offset 0x00000016][found value 'TTaskLike2'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T2>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, !!0, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!2>)][offset 0x0000000E][found value 'TTaskLike1'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, !!0, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!2>)][offset 0x00000016][found ref '[S.P.CoreLib]System.Threading.Tasks.Task`1<T2>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T1>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!1>, !!0)][offset 0x0000000E][found ref '[S.P.CoreLib]System.Threading.Tasks.Task`1<T1>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!1>, !!0)][offset 0x00000016][found value 'TTaskLike2'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T2>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, !!0, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!2>)][offset 0x0000000E][found value 'TTaskLike1'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, !!0, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!2>)][offset 0x00000016][found ref '[S.P.CoreLib]System.Threading.Tasks.Task`1<T2>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T1>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!4>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!1,!!5>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,bool>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, !!0, !!1)][offset 0x0000000E][found value 'TTaskLike1'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T4>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!4>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!1,!!5>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,bool>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, !!0, !!1)][offset 0x00000016][found value 'TTaskLike2'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T1,T5>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!4>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!1,!!5>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,bool>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, !!0, !!1)][offset 0x0000000E][found value 'TTaskLike1'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T4>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!4>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!1,!!5>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,bool>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, !!0, !!1)][offset 0x00000016][found value 'TTaskLike2'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T1,T5>'] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : Microsoft.FSharp.Collections.ArrayModule+Parallel::Choose([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,Microsoft.FSharp.Core.FSharpOption`1<!!1>>, !!0[])][offset 0x00000081][found Byte] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : Microsoft.FSharp.Collections.ArrayModule+Parallel::Filter([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,bool>, !!0[])][offset 0x00000029][found Byte] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : Microsoft.FSharp.Collections.ArrayModule+Parallel::Partition([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,bool>, !!0[])][offset 0x00000038][found Byte] Unexpected type on the stack.
diff --git a/tests/ILVerify/ilverify_FSharp.Core_Release_netstandard2.1.bsl b/tests/ILVerify/ilverify_FSharp.Core_Release_netstandard2.1.bsl
index 6ab50914fdd..05a10ae7797 100644
--- a/tests/ILVerify/ilverify_FSharp.Core_Release_netstandard2.1.bsl
+++ b/tests/ILVerify/ilverify_FSharp.Core_Release_netstandard2.1.bsl
@@ -1,3 +1,23 @@
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!1>, !!0)][offset 0x0000000E][found ref '[FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<T1>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!1>, !!0)][offset 0x00000016][found value 'TTaskLike2'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T2>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, !!0, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!2>)][offset 0x0000000E][found value 'TTaskLike1'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, !!0, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!2>)][offset 0x00000016][found ref '[FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<T2>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T1>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!1>, !!0)][offset 0x0000000E][found ref '[FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<T1>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!1>, !!0)][offset 0x00000016][found value 'TTaskLike2'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T2>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, !!0, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!2>)][offset 0x0000000E][found value 'TTaskLike1'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPlusPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, !!0, [FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<!!2>)][offset 0x00000016][found ref '[FSharp.Core]Microsoft.FSharp.Control.FSharpAsync`1<T2>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T1>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!1>, !!0)][offset 0x0000000E][found ref '[S.P.CoreLib]System.Threading.Tasks.Task`1<T1>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!1>, !!0)][offset 0x00000016][found value 'TTaskLike2'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T2>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, !!0, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!2>)][offset 0x0000000E][found value 'TTaskLike1'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, !!0, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!2>)][offset 0x00000016][found ref '[S.P.CoreLib]System.Threading.Tasks.Task`1<T2>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T1>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!1>, !!0)][offset 0x0000000E][found ref '[S.P.CoreLib]System.Threading.Tasks.Task`1<T1>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!1>, !!0)][offset 0x00000016][found value 'TTaskLike2'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T2>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, !!0, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!2>)][offset 0x0000000E][found value 'TTaskLike1'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T3>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.MediumPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,!!1>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!3,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, !!0, [S.P.CoreLib]System.Threading.Tasks.Task`1<!!2>)][offset 0x00000016][found ref '[S.P.CoreLib]System.Threading.Tasks.Task`1<T2>'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T3,T1>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!4>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!1,!!5>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,bool>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, !!0, !!1)][offset 0x0000000E][found value 'TTaskLike1'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T4>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority::TaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!4>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!1,!!5>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,bool>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,bool>, [FSharp.Core]Microsoft.FSharp.Control.TaskBuilder, !!0, !!1)][offset 0x00000016][found value 'TTaskLike2'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T1,T5>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!4>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!1,!!5>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,bool>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, !!0, !!1)][offset 0x0000000E][found value 'TTaskLike1'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T0,T4>'] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : Microsoft.FSharp.Control.TaskBuilderExtensions.LowPriority::BackgroundTaskBuilder.MergeSources$W([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,!!4>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!1,!!5>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,!!2>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,!!3>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!4,bool>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!5,bool>, [FSharp.Core]Microsoft.FSharp.Control.BackgroundTaskBuilder, !!0, !!1)][offset 0x00000016][found value 'TTaskLike2'][expected ref '[FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<T1,T5>'] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : Microsoft.FSharp.Collections.ArrayModule+Parallel::Choose([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,Microsoft.FSharp.Core.FSharpOption`1<!!1>>, !!0[])][offset 0x00000081][found Byte] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : Microsoft.FSharp.Collections.ArrayModule+Parallel::Filter([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,bool>, !!0[])][offset 0x00000029][found Byte] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : Microsoft.FSharp.Collections.ArrayModule+Parallel::Partition([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<!!0,bool>, !!0[])][offset 0x00000038][found Byte] Unexpected type on the stack.