Revert "Refactor ResolveLongIdentAsModuleOrNamespace (dotnet#14661)"

This reverts commit 0499207.

src/Compiler/Checking/CheckDeclarations.fs

@@ -362,7 +362,7 @@ let ImplicitlyOpenOwnNamespace tcSink g amap scopem enclosingNamespacePath (env:
         match enclosingNamespacePathToOpen with
         | id :: rest ->
             let ad = env.AccessRights
-            match ResolveLongIdentAsModuleOrNamespace tcSink amap scopem true OpenQualified env.eNameResEnv ad id rest true with 
+            match ResolveLongIdentAsModuleOrNamespace tcSink ResultCollectionSettings.AllResults amap scopem true OpenQualified env.eNameResEnv ad id rest true with 
             | Result modrefs -> 
                 let modrefs = List.map p23 modrefs
                 let lid = SynLongIdent(enclosingNamespacePathToOpen, [] , [])
@@ -637,7 +637,7 @@ let TcOpenLidAndPermitAutoResolve tcSink (env: TcEnv) amap (longId : Ident list)
     | [] -> []
     | id :: rest ->
         let m = longId |> List.map (fun id -> id.idRange) |> List.reduce unionRanges
-        match ResolveLongIdentAsModuleOrNamespace tcSink amap m true OpenQualified env.NameEnv ad id rest true with 
+        match ResolveLongIdentAsModuleOrNamespace tcSink ResultCollectionSettings.AllResults amap m true OpenQualified env.NameEnv ad id rest true with 
         | Result res -> res
         | Exception err ->
             errorR(err); []
@@ -1440,7 +1440,7 @@ module MutRecBindingChecking =
         let resolved =
             match p with
             | [] -> Result []
-            | id :: rest -> ResolveLongIdentAsModuleOrNamespace cenv.tcSink cenv.amap m true OpenQualified env.NameEnv ad id rest false
+            | id :: rest -> ResolveLongIdentAsModuleOrNamespace cenv.tcSink ResultCollectionSettings.AllResults cenv.amap m true OpenQualified env.NameEnv ad id rest false
 
         let mvvs = ForceRaise resolved
 
@@ -4575,7 +4575,7 @@ let rec TcSignatureElementNonMutRec (cenv: cenv) parent typeNames endm (env: TcE
             let resolved =
                 match p with
                 | [] -> Result []
-                | id :: rest -> ResolveLongIdentAsModuleOrNamespace cenv.tcSink cenv.amap m true OpenQualified env.NameEnv ad id rest false
+                | id :: rest -> ResolveLongIdentAsModuleOrNamespace cenv.tcSink ResultCollectionSettings.AllResults cenv.amap m true OpenQualified env.NameEnv ad id rest false
             let mvvs = ForceRaise resolved
             let scopem = unionRanges m endm
             let unfilteredModrefs = mvvs |> List.map p23

src/Compiler/Checking/CheckExpressions.fs

@@ -7225,7 +7225,7 @@ and TcConstExpr cenv (overallTy: OverallTy) env m tpenv c =
         let expr =
             let modName = "NumericLiteral" + suffix
             let ad = env.eAccessRights
-            match ResolveLongIdentAsModuleOrNamespace cenv.tcSink cenv.amap m true OpenQualified env.eNameResEnv ad (ident (modName, m)) [] false with
+            match ResolveLongIdentAsModuleOrNamespace cenv.tcSink ResultCollectionSettings.AtMostOneResult cenv.amap m true OpenQualified env.eNameResEnv ad (ident (modName, m)) [] false with
             | Result []
             | Exception _ -> error(Error(FSComp.SR.tcNumericLiteralRequiresModule modName, m))
             | Result ((_, mref, _) :: _) ->
@@ -7965,7 +7965,7 @@ and TcNameOfExpr (cenv: cenv) env tpenv (synArg: SynExpr) =
             let resolvedToModuleOrNamespaceName =
                 if delayed.IsEmpty then
                     let id,rest = List.headAndTail longId
-                    match ResolveLongIdentAsModuleOrNamespace cenv.tcSink cenv.amap m true OpenQualified env.eNameResEnv ad id rest true with
+                    match ResolveLongIdentAsModuleOrNamespace cenv.tcSink ResultCollectionSettings.AllResults cenv.amap m true OpenQualified env.eNameResEnv ad id rest true with
                     | Result modref when delayed.IsEmpty && modref |> List.exists (p23 >> IsEntityAccessible cenv.amap m ad) ->
                         true // resolved to a module or namespace, done with checks
                     | _ ->

src/Compiler/Checking/NameResolution.fs

@@ -2373,13 +2373,13 @@ let CheckForTypeLegitimacyAndMultipleGenericTypeAmbiguities
 //-------------------------------------------------------------------------
 
 /// Perform name resolution for an identifier which must resolve to be a module or namespace.
-let rec ResolveLongIdentAsModuleOrNamespace sink (amap: Import.ImportMap) m first fullyQualified (nenv: NameResolutionEnv) ad (id:Ident) (rest: Ident list) isOpenDecl =
+let rec ResolveLongIdentAsModuleOrNamespace sink (atMostOne: ResultCollectionSettings) (amap: Import.ImportMap) m first fullyQualified (nenv: NameResolutionEnv) ad (id:Ident) (rest: Ident list) isOpenDecl =
     if first && id.idText = MangledGlobalName then
         match rest with
         | [] ->
             error (Error(FSComp.SR.nrGlobalUsedOnlyAsFirstName(), id.idRange))
         | id2 :: rest2 ->
-            ResolveLongIdentAsModuleOrNamespace sink amap m false FullyQualified nenv ad id2 rest2 isOpenDecl
+            ResolveLongIdentAsModuleOrNamespace sink atMostOne amap m false FullyQualified nenv ad id2 rest2 isOpenDecl
     else
         let notFoundAux (id: Ident) depth error (tcrefs: TyconRef seq) =
             let suggestNames (addToBuffer: string -> unit) =
@@ -2390,7 +2390,7 @@ let rec ResolveLongIdentAsModuleOrNamespace sink (amap: Import.ImportMap) m firs
             UndefinedName(depth, error, id, suggestNames)
 
         let moduleOrNamespaces = nenv.ModulesAndNamespaces fullyQualified
-        let namespaceOrModuleNotFound =
+        let namespaceNotFound =
             lazy
                 seq { for kv in moduleOrNamespaces do
                         for modref in kv.Value do 
@@ -2399,57 +2399,70 @@ let rec ResolveLongIdentAsModuleOrNamespace sink (amap: Import.ImportMap) m firs
 
         // Avoid generating the same error and name suggestion thunk twice It's not clear this is necessary
         // since it's just saving an allocation.
-        let mutable namespaceNotFoundErrorCache = None
-        let namespaceNotFound (modref: ModuleOrNamespaceRef) (mty: ModuleOrNamespaceType) (id: Ident) depth =
-            match namespaceNotFoundErrorCache with
+        let mutable moduleNotFoundErrorCache = None
+        let moduleNotFound (modref: ModuleOrNamespaceRef) (mty: ModuleOrNamespaceType) (id: Ident) depth =
+            match moduleNotFoundErrorCache with
             | Some (oldId, error) when equals oldId id.idRange -> error
             | _ ->
                 let error =
                     seq { for kv in mty.ModulesAndNamespacesByDemangledName do
                             modref.NestedTyconRef kv.Value }
                     |> notFoundAux id depth FSComp.SR.undefinedNameNamespace
                 let error = raze error
-                namespaceNotFoundErrorCache <- Some(id.idRange, error)
+                moduleNotFoundErrorCache <- Some(id.idRange, error)
                 error
 
         let notifyNameResolution (modref: ModuleOrNamespaceRef) m =
             let item = Item.ModuleOrNamespaces [modref]
             let occurence = if isOpenDecl then ItemOccurence.Open else ItemOccurence.Use
             CallNameResolutionSink sink (m, nenv, item, emptyTyparInst, occurence, ad)
 
-        match moduleOrNamespaces.TryGetValue id.idText with
-        | true, modrefs when not modrefs.IsEmpty -> 
+        let modrefs = 
+            match moduleOrNamespaces.TryGetValue id.idText with 
+            | true, modrefs -> modrefs 
+            | _ -> []
+
+        if not modrefs.IsEmpty then 
             /// Look through the sub-namespaces and/or modules
             let rec look depth (modref: ModuleOrNamespaceRef) (lid: Ident list) =
                 let mty = modref.ModuleOrNamespaceType
-
                 match lid with
-                | [] -> success [ (depth, modref, mty) ]
-                | id :: rest ->
-                    match mty.ModulesAndNamespacesByDemangledName.TryGetValue id.idText with
-                    | true, res ->
-                        let subref = modref.NestedTyconRef res
+                | [] -> 
+                    success  [ (depth, modref, mty) ]
 
-                        if IsEntityAccessible amap m ad subref then
-                            notifyNameResolution subref id.idRange
-                            look (depth + 1) subref rest
-                        else
-                            namespaceNotFound modref mty id depth
-                    | _ -> namespaceNotFound modref mty id depth
+                | id :: rest ->
+                    let modrefs =
+                        match mty.ModulesAndNamespacesByDemangledName.TryGetValue id.idText with 
+                        | true, res -> [res]
+                        | _ -> []
 
+                    if not modrefs.IsEmpty then 
+                        modrefs 
+                        |> List.map (fun espec ->
+                            let subref = modref.NestedTyconRef espec
+                            if IsEntityAccessible amap m ad subref then
+                                notifyNameResolution subref id.idRange
+                                look (depth+1) subref rest
+                            else
+                                moduleNotFound modref mty id depth) 
+                        |> List.reduce AddResults
+                    else
+                        moduleNotFound modref mty id depth
+
             modrefs
             |> List.map (fun modref ->
                 if IsEntityAccessible amap m ad modref then
                     notifyNameResolution modref id.idRange
                     look 1 modref rest
                 else
-                    raze (namespaceOrModuleNotFound.Force()))
+                    raze (namespaceNotFound.Force()))
             |> List.reduce AddResults
-        | _ -> raze (namespaceOrModuleNotFound.Force())
+        else
+            raze (namespaceNotFound.Force())
 
 // Note - 'rest' is annotated due to a bug currently in Unity (see: https://github.com/dotnet/fsharp/pull/7427)
 let ResolveLongIdentAsModuleOrNamespaceThen sink atMostOne amap m fullyQualified (nenv: NameResolutionEnv) ad id (rest: Ident list) isOpenDecl f =
-    match ResolveLongIdentAsModuleOrNamespace sink amap m true fullyQualified nenv ad id [] isOpenDecl with
+    match ResolveLongIdentAsModuleOrNamespace sink ResultCollectionSettings.AllResults amap m true fullyQualified nenv ad id [] isOpenDecl with
     | Result modrefs ->
         match rest with
         | [] -> error(Error(FSComp.SR.nrUnexpectedEmptyLongId(), id.idRange))

src/Compiler/Checking/NameResolution.fsi

@@ -663,6 +663,7 @@ val FreshenRecdFieldRef: NameResolver -> range -> RecdFieldRef -> RecdFieldInfo
 /// Resolve a long identifier to a namespace, module.
 val internal ResolveLongIdentAsModuleOrNamespace:
     sink: TcResultsSink ->
+    atMostOne: ResultCollectionSettings ->
     amap: ImportMap ->
     m: range ->
     first: bool ->