Merge pull request #6809 from dotnet/feature/nameof

[RFC FS-1003] Nameof operator redux

eng/Build.ps1

@@ -182,6 +182,7 @@ function BuildSolution() {
         /p:QuietRestore=$quietRestore `
         /p:QuietRestoreBinaryLog=$binaryLog `
         /p:TestTargetFrameworks=$testTargetFrameworks `
+        /v:$verbosity `
         $suppressExtensionDeployment `
         @properties
 }

eng/build.sh

@@ -242,6 +242,7 @@ function BuildSolution {
   # do real build
   MSBuild $toolset_build_proj \
     $bl \
+    /v:$verbosity \
     /p:Configuration=$configuration \
     /p:Projects="$projects" \
     /p:RepoRoot="$repo_root" \
@@ -273,3 +274,4 @@ if [[ "$test_core_clr" == true ]]; then
 fi
 
 ExitWithExitCode 0
+

src/fsharp/FSComp.txt

@@ -1461,6 +1461,8 @@ notAFunctionButMaybeDeclaration,"This value is not a function and cannot be appl
 3243,parsInvalidAnonRecdExpr,"Invalid anonymous record expression"
 3244,parsInvalidAnonRecdType,"Invalid anonymous record type"
 3245,tcCopyAndUpdateNeedsRecordType,"The input to a copy-and-update expression that creates an anonymous record must be either an anonymous record or a record"
+3250,expressionHasNoName,"Expression does not have a name."
+3251,chkNoFirstClassNameOf,"Using the 'nameof' operator as a first-class function value is not permitted."
 3300,chkInvalidFunctionParameterType,"The parameter '%s' has an invalid type '%s'. This is not permitted by the rules of Common IL."
 3301,chkInvalidFunctionReturnType,"The function or method has an invalid return type '%s'. This is not permitted by the rules of Common IL."
 useSdkRefs,"Use reference assemblies for .NET framework references when available (Enabled by default)."

src/fsharp/FSharp.Core/prim-types.fs

@@ -4142,6 +4142,9 @@ namespace Microsoft.FSharp.Core
         [<CompiledName("TypeOf")>]
         let inline typeof<'T> = BasicInlinedOperations.typeof<'T>
 
+        [<CompiledName("NameOf")>]
+        let inline nameof (_: 'T) : string = raise (Exception "may not call directly, should always be optimized away")
+
         [<CompiledName("MethodHandleOf")>]
         let methodhandleof (_call: ('T -> 'TResult)) : System.RuntimeMethodHandle = raise (Exception "may not call directly, should always be optimized away")
 

src/fsharp/FSharp.Core/prim-types.fsi

@@ -2401,6 +2401,10 @@ namespace Microsoft.FSharp.Core
         [<CompiledName("TypeOf")>]
         val inline typeof<'T> : System.Type
 
+        /// <summary>Returns the name of the given symbol.</summary>        
+        [<CompiledName("NameOf")>]
+        val inline nameof : 'T -> string
+
         /// <summary>An internal, library-only compiler intrinsic for compile-time 
         /// generation of a RuntimeMethodHandle.</summary>
         [<CompiledName("MethodHandleOf")>]

src/fsharp/NameResolution.fs

@@ -1259,7 +1259,7 @@ type FormatStringCheckContext =
 type ITypecheckResultsSink =
     abstract NotifyEnvWithScope: range * NameResolutionEnv * AccessorDomain -> unit
     abstract NotifyExprHasType: pos * TType * Tastops.DisplayEnv * NameResolutionEnv * AccessorDomain * range -> unit
-    abstract NotifyNameResolution: pos * Item * Item * TyparInst * ItemOccurence * Tastops.DisplayEnv * NameResolutionEnv * AccessorDomain * range * bool -> unit
+    abstract NotifyNameResolution: pos * item: Item * itemMethodGroup: Item * TyparInst * ItemOccurence * Tastops.DisplayEnv * NameResolutionEnv * AccessorDomain * range * replace: bool -> unit
     abstract NotifyFormatSpecifierLocation: range * int -> unit
     abstract NotifyOpenDeclaration: OpenDeclaration -> unit
     abstract CurrentSourceText: ISourceText option

src/fsharp/PostInferenceChecks.fs

@@ -678,6 +678,7 @@ and CheckValRef (cenv: cenv) (env: env) v m (context: PermitByRefExpr) =
         if isSpliceOperator cenv.g v then errorR(Error(FSComp.SR.chkNoFirstClassSplicing(), m))
         if valRefEq cenv.g v cenv.g.addrof_vref  then errorR(Error(FSComp.SR.chkNoFirstClassAddressOf(), m))
         if valRefEq cenv.g v cenv.g.reraise_vref then errorR(Error(FSComp.SR.chkNoFirstClassRethrow(), m))
+        if valRefEq cenv.g v cenv.g.nameof_vref then errorR(Error(FSComp.SR.chkNoFirstClassNameOf(), m))
 
         // ByRefLike-typed values can only occur in permitting contexts 
         if context.Disallow && isByrefLikeTy cenv.g m v.Type then 

src/fsharp/TastOps.fs

@@ -3206,6 +3206,11 @@ let isSizeOfValRef g vref =
     // There is an internal version of typeof defined in prim-types.fs that needs to be detected
     || (g.compilingFslib && vref.LogicalName = "sizeof") 
 
+let isNameOfValRef g vref = 
+    valRefEq g vref g.nameof_vref 
+    // There is an internal version of nameof defined in prim-types.fs that needs to be detected
+    || (g.compilingFslib && vref.LogicalName = "nameof") 
+
 let isTypeDefOfValRef g vref = 
     valRefEq g vref g.typedefof_vref 
     // There is an internal version of typedefof defined in prim-types.fs that needs to be detected
@@ -3231,6 +3236,16 @@ let (|TypeDefOfExpr|_|) g expr =
     | Expr.App (Expr.Val (vref, _, _), _, [ty], [], _) when isTypeDefOfValRef g vref -> Some ty
     | _ -> None
 
+let (|NameOfExpr|_|) g expr = 
+    match expr with 
+    | Expr.App(Expr.Val(vref,_,_),_,[ty],[],_) when isNameOfValRef g vref  -> Some ty
+    | _ -> None
+
+let (|SeqExpr|_|) g expr = 
+    match expr with 
+    | Expr.App(Expr.Val(vref,_,_),_,_,_,_) when valRefEq g vref g.seq_vref -> Some()
+    | _ -> None
+
 //--------------------------------------------------------------------------
 // DEBUG layout
 //---------------------------------------------------------------------------
@@ -8553,7 +8568,8 @@ let IsSimpleSyntacticConstantExpr g inputExpr =
         | Expr.Op (TOp.UnionCase _, _, [], _)         // Nullary union cases
         | UncheckedDefaultOfExpr g _ 
         | SizeOfExpr g _ 
-        | TypeOfExpr g _ -> true
+        | TypeOfExpr g _ 
+        | NameOfExpr g _ -> true
         // All others are not simple constant expressions
         | _ -> false
 

src/fsharp/TastOps.fsi

@@ -2231,6 +2231,8 @@ val (|EnumExpr|_|) : TcGlobals -> Expr -> Expr option
 val (|TypeOfExpr|_|) : TcGlobals -> Expr -> TType option
 
 val (|TypeDefOfExpr|_|) : TcGlobals -> Expr -> TType option
+val (|NameOfExpr|_|) : TcGlobals -> Expr -> TType option
+val (|SeqExpr|_|) : TcGlobals -> Expr -> unit option
 
 val EvalLiteralExprOrAttribArg: TcGlobals -> Expr -> Expr
 

src/fsharp/TcGlobals.fs

@@ -664,6 +664,8 @@ type public TcGlobals(compilingFslib: bool, ilg:ILGlobals, fslibCcu: CcuThunk, d
   let v_typeof_info                = makeIntrinsicValRef(fslib_MFOperators_nleref,                             "typeof"                               , None                 , Some "TypeOf" , [vara],     ([], v_system_Type_ty))  
   let v_methodhandleof_info        = makeIntrinsicValRef(fslib_MFOperators_nleref,                             "methodhandleof"                       , None                 , Some "MethodHandleOf", [vara;varb], ([[varaTy --> varbTy]], v_system_RuntimeMethodHandle_ty))
   let v_sizeof_info                = makeIntrinsicValRef(fslib_MFOperators_nleref,                             "sizeof"                               , None                 , Some "SizeOf" , [vara],     ([], v_int_ty))  
+  let v_nameof_info                = makeIntrinsicValRef(fslib_MFOperators_nleref,                             "nameof"                               , None                 , Some "NameOf" , [vara],     ([[varaTy]], v_string_ty))
+
   let v_unchecked_defaultof_info   = makeIntrinsicValRef(fslib_MFOperatorsUnchecked_nleref,                    "defaultof"                            , None                 , Some "DefaultOf", [vara],     ([], varaTy))  
   let v_typedefof_info             = makeIntrinsicValRef(fslib_MFOperators_nleref,                             "typedefof"                            , None                 , Some "TypeDefOf", [vara],     ([], v_system_Type_ty))  
   let v_range_op_info              = makeIntrinsicValRef(fslib_MFOperators_nleref,                             "op_Range"                             , None                 , None          , [vara],     ([[varaTy];[varaTy]], mkSeqTy varaTy))
@@ -1331,6 +1333,7 @@ type public TcGlobals(compilingFslib: bool, ilg:ILGlobals, fslibCcu: CcuThunk, d
   member val methodhandleof_vref        = ValRefForIntrinsic v_methodhandleof_info
   member val typeof_vref                = ValRefForIntrinsic v_typeof_info
   member val sizeof_vref                = ValRefForIntrinsic v_sizeof_info
+  member val nameof_vref                = ValRefForIntrinsic v_nameof_info
   member val typedefof_vref             = ValRefForIntrinsic v_typedefof_info
   member val enum_vref                  = ValRefForIntrinsic v_enum_operator_info
   member val enumOfValue_vref           = ValRefForIntrinsic v_enumOfValue_info
@@ -1358,15 +1361,15 @@ type public TcGlobals(compilingFslib: bool, ilg:ILGlobals, fslibCcu: CcuThunk, d
   member val unbox_fast_vref            = ValRefForIntrinsic v_unbox_fast_info
   member val istype_vref                = ValRefForIntrinsic v_istype_info
   member val istype_fast_vref           = ValRefForIntrinsic v_istype_fast_info
-  member val query_source_vref            = ValRefForIntrinsic v_query_source_info
-  member val query_value_vref            = ValRefForIntrinsic v_query_value_info
-  member val query_run_value_vref            = ValRefForIntrinsic v_query_run_value_info
-  member val query_run_enumerable_vref            = ValRefForIntrinsic v_query_run_enumerable_info
-  member val query_for_vref            = ValRefForIntrinsic v_query_for_value_info
-  member val query_yield_vref            = ValRefForIntrinsic v_query_yield_value_info
-  member val query_yield_from_vref        = ValRefForIntrinsic v_query_yield_from_value_info
-  member val query_select_vref            = ValRefForIntrinsic v_query_select_value_info
-  member val query_where_vref            = ValRefForIntrinsic v_query_where_value_info
+  member val query_source_vref          = ValRefForIntrinsic v_query_source_info
+  member val query_value_vref           = ValRefForIntrinsic v_query_value_info
+  member val query_run_value_vref       = ValRefForIntrinsic v_query_run_value_info
+  member val query_run_enumerable_vref  = ValRefForIntrinsic v_query_run_enumerable_info
+  member val query_for_vref             = ValRefForIntrinsic v_query_for_value_info
+  member val query_yield_vref           = ValRefForIntrinsic v_query_yield_value_info
+  member val query_yield_from_vref      = ValRefForIntrinsic v_query_yield_from_value_info
+  member val query_select_vref          = ValRefForIntrinsic v_query_select_value_info
+  member val query_where_vref           = ValRefForIntrinsic v_query_where_value_info
   member val query_zero_vref            = ValRefForIntrinsic v_query_zero_value_info
 
   member __.seq_collect_info           = v_seq_collect_info

src/fsharp/TypeChecker.fs

@@ -8711,37 +8711,87 @@ and delayRest rest mPrior delayed =
         let mPriorAndLongId = unionRanges mPrior (rangeOfLid longId)
         DelayedDotLookup (rest, mPriorAndLongId) :: delayed
 
+/// Typecheck "nameof" expressions
+and TcNameOfExpr cenv env tpenv (synArg: SynExpr) = 
+
+    let rec stripParens expr =
+        match expr with
+        | SynExpr.Paren(expr, _, _, _) -> stripParens expr
+        | _ -> expr
+
+    let cleanSynArg = stripParens synArg
+    let m = cleanSynArg.Range
+    let rec check overallTyOpt expr (delayed: DelayedItem list) = 
+        match expr with
+        | LongOrSingleIdent (false, (LongIdentWithDots(longId, _) as lidd), _, _) when longId.Length > 0 ->
+            let ad = env.eAccessRights
+            let id, rest = List.headAndTail longId
+            match ResolveLongIndentAsModuleOrNamespace 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) -> 
+                () // resolved to a module or namespace, done with checks
+            | _ -> 
+                let (TypeNameResolutionInfo(_, staticArgsInfo)) = GetLongIdentTypeNameInfo delayed
+                match ResolveTypeLongIdent cenv.tcSink cenv.nameResolver ItemOccurence.UseInAttribute OpenQualified env.eNameResEnv ad longId staticArgsInfo PermitDirectReferenceToGeneratedType.No with
+                | Result tcref when IsEntityAccessible cenv.amap m ad tcref -> 
+                    () // resolved to a type name, done with checks
+                | _ -> 
+                    let overallTy = match overallTyOpt with None -> NewInferenceType() | Some t -> t 
+                    let _, _ = TcLongIdentThen cenv overallTy env tpenv lidd delayed
+                    () // checked as an expression, done with checks
+            List.last longId
+
+        | SynExpr.TypeApp (hd, _, types, _, _, _, m) ->
+            check overallTyOpt hd (DelayedTypeApp(types, m, m) :: delayed)
+
+        | SynExpr.Paren(expr, _, _, _) when overallTyOpt.IsNone && delayed.IsEmpty -> 
+            check overallTyOpt expr []
+
+        | SynExpr.Typed (synBodyExpr, synType, _m) when delayed.IsEmpty && overallTyOpt.IsNone ->
+            let tgtTy, _tpenv = TcTypeAndRecover cenv NewTyparsOK CheckCxs ItemOccurence.UseInType  env tpenv synType
+            check (Some tgtTy) synBodyExpr []
+
+        | _ -> 
+            error (Error(FSComp.SR.expressionHasNoName(), m))
 
+    let lastIdent = check None cleanSynArg [] 
+    let constRange = mkRange m.FileName m.Start (mkPos m.StartLine (m.StartColumn + lastIdent.idText.Length + 2)) // `2` are for quotes
+    Expr.Const(Const.String(lastIdent.idText), constRange, cenv.g.string_ty)
+
 //-------------------------------------------------------------------------
 // TcFunctionApplicationThen: Typecheck "expr x" + projections
 //------------------------------------------------------------------------- 
 
 and TcFunctionApplicationThen cenv overallTy env tpenv mExprAndArg expr exprty (synArg: SynExpr) atomicFlag delayed = 
-
     let denv = env.DisplayEnv
     let mArg = synArg.Range
     let mFunExpr = expr.Range
+
     // If the type of 'synArg' unifies as a function type, then this is a function application, otherwise
     // it is an error or a computation expression
     match UnifyFunctionTypeUndoIfFailed cenv denv mFunExpr exprty with
     | ValueSome (domainTy, resultTy) -> 
-
-        // Notice the special case 'seq { ... }'. In this case 'seq' is actually a function in the F# library.
-        // Set a flag in the syntax tree to say we noticed a leading 'seq'
-        match synArg with 
-        | SynExpr.CompExpr (false, isNotNakedRefCell, _comp, _m) -> 
-            isNotNakedRefCell := 
-                !isNotNakedRefCell
-                || 
-                (match expr with 
-                 | ApplicableExpr(_, Expr.Op (TOp.Coerce, _, [Expr.App (Expr.Val (vf, _, _), _, _, _, _)], _), _) when valRefEq cenv.g vf cenv.g.seq_vref -> true 
-                 | _ -> false)
-        | _ -> ()
-
-        let arg, tpenv = TcExpr cenv domainTy env tpenv synArg
-        let exprAndArg, resultTy = buildApp cenv expr resultTy arg mExprAndArg
-        TcDelayed cenv overallTy env tpenv mExprAndArg exprAndArg resultTy atomicFlag delayed
-    | _ -> 
+        match expr with
+        | ApplicableExpr(_, NameOfExpr cenv.g _, _) ->
+            let replacementExpr = TcNameOfExpr cenv env tpenv synArg
+            TcDelayed cenv overallTy env tpenv mExprAndArg (ApplicableExpr(cenv, replacementExpr, true)) cenv.g.string_ty ExprAtomicFlag.Atomic delayed
+        | _ ->
+            // Notice the special case 'seq { ... }'. In this case 'seq' is actually a function in the F# library.
+            // Set a flag in the syntax tree to say we noticed a leading 'seq'
+            match synArg with 
+            | SynExpr.CompExpr (false, isNotNakedRefCell, _comp, _m) -> 
+                isNotNakedRefCell := 
+                    !isNotNakedRefCell
+                    || 
+                    (match expr with 
+                     | ApplicableExpr(_, Expr.Op(TOp.Coerce, _, [SeqExpr cenv.g], _), _) -> true 
+                     | _ -> false)
+            | _ -> ()
+
+            let arg, tpenv = TcExpr cenv domainTy env tpenv synArg
+            let exprAndArg, resultTy = buildApp cenv expr resultTy arg mExprAndArg
+            TcDelayed cenv overallTy env tpenv mExprAndArg exprAndArg resultTy atomicFlag delayed
+
+    | ValueNone -> 
         // OK, 'expr' doesn't have function type, but perhaps 'expr' is a computation expression builder, and 'arg' is '{ ... }' 
         match synArg with 
         | SynExpr.CompExpr (false, _isNotNakedRefCell, comp, _m) -> 
@@ -8754,25 +8804,26 @@ and TcFunctionApplicationThen cenv overallTy env tpenv mExprAndArg expr exprty (
 // TcLongIdentThen: Typecheck "A.B.C<D>.E.F ... " constructs
 //------------------------------------------------------------------------- 
 
-and TcLongIdentThen cenv overallTy env tpenv (LongIdentWithDots(longId, _)) delayed =
+and GetLongIdentTypeNameInfo delayed =
+    // Given 'MyOverloadedType<int>.MySubType...' use the number of given type arguments to help 
+    // resolve type name lookup of 'MyOverloadedType' 
+    // Also determine if type names should resolve to Item.Types or Item.CtorGroup 
+    match delayed with 
+    | DelayedTypeApp (tyargs, _, _) :: (DelayedDot | DelayedDotLookup _) :: _ -> 
+        // cases like 'MyType<int>.Sth' 
+        TypeNameResolutionInfo(ResolveTypeNamesToTypeRefs, TypeNameResolutionStaticArgsInfo.FromTyArgs tyargs.Length)
 
-    let ad = env.eAccessRights
-    let typeNameResInfo = 
-        // Given 'MyOverloadedType<int>.MySubType...' use arity of #given type arguments to help 
-        // resolve type name lookup of 'MyOverloadedType' 
-        // Also determine if type names should resolve to Item.Types or Item.CtorGroup 
-        match delayed with 
-        | DelayedTypeApp (tyargs, _, _) :: (DelayedDot | DelayedDotLookup _) :: _ -> 
-            // cases like 'MyType<int>.Sth' 
-            TypeNameResolutionInfo(ResolveTypeNamesToTypeRefs, TypeNameResolutionStaticArgsInfo.FromTyArgs tyargs.Length)
+    | DelayedTypeApp (tyargs, _, _) :: _ -> 
+        // Note, this also covers the case 'MyType<int>.' (without LValue_get), which is needed for VS (when typing)
+        TypeNameResolutionInfo(ResolveTypeNamesToCtors, TypeNameResolutionStaticArgsInfo.FromTyArgs tyargs.Length)
 
-        | DelayedTypeApp (tyargs, _, _) :: _ -> 
-            // Note, this also covers the case 'MyType<int>.' (without LValue_get), which is needed for VS (when typing)
-            TypeNameResolutionInfo(ResolveTypeNamesToCtors, TypeNameResolutionStaticArgsInfo.FromTyArgs tyargs.Length)
+    | _ -> 
+        TypeNameResolutionInfo.Default
 
-        | _ -> 
-            TypeNameResolutionInfo.Default
+and TcLongIdentThen cenv overallTy env tpenv (LongIdentWithDots(longId, _)) delayed =
 
+    let ad = env.eAccessRights
+    let typeNameResInfo = GetLongIdentTypeNameInfo delayed
     let nameResolutionResult = ResolveLongIdentAsExprAndComputeRange cenv.tcSink cenv.nameResolver (rangeOfLid longId) ad env.eNameResEnv typeNameResInfo longId
     TcItemThen cenv overallTy env tpenv nameResolutionResult delayed
 

src/fsharp/xlf/FSComp.txt.cs.xlf

@@ -7182,6 +7182,16 @@
         <target state="translated">Následující členy nemají žádnou implementaci (některé výsledky jsou vynechané): {0} Všechny členy rozhraní je potřeba implementovat a uvést pod příslušnou deklarací interface, třeba takto: interface ... with member ...</target>
         <note />
       </trans-unit>
+      <trans-unit id="expressionHasNoName">
+        <source>Expression does not have a name.</source>
+        <target state="new">Expression does not have a name.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="chkNoFirstClassNameOf">
+        <source>Using the 'nameof' operator as a first-class function value is not permitted.</source>
+        <target state="new">Using the 'nameof' operator as a first-class function value is not permitted.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="optsPathMap">
         <source>Maps physical paths to source path names output by the compiler</source>
         <target state="translated">Mapuje fyzické cesty na názvy zdrojových cest z výstupu kompilátoru.</target>