Further enhancements to nameof (dotnet#8754)

* Implement `nameof x` as a constant pattern

* Resolve ident to find `nameof` in patterns

* fix build

* fix build

* re-enable tests

* fix test

* fix operators

* align code

* test and fix pattern matching

* fix 8661, 7416

* fix tests and error messages

* 'fix test'

* 'fix test'

* add message for C# and old compilers

* fix build

* suppress error 3501 when a compiler supports nameof

Co-authored-by: Don Syme <[email protected]>

Author: 2 people

src/fsharp/AttributeChecking.fs

@@ -299,7 +299,11 @@ let CheckFSharpAttributes (g:TcGlobals) attribs m =
                 match namedArgs with 
                 | ExtractAttribNamedArg "IsError" (AttribBoolArg v) -> v 
                 | _ -> false 
-            if isError && (not g.compilingFslib || n <> 1204) then ErrorD msg else WarnD msg
+            // If we are using a compiler that supports nameof then error 3501 is always suppressed.
+            // See attribute on FSharp.Core 'nameof'
+            if n = 3501 then CompleteD
+            elif isError && (not g.compilingFslib || n <> 1204) then ErrorD msg 
+            else WarnD msg
         | _ -> 
             CompleteD
         ) ++ (fun () -> 

src/fsharp/FSComp.txt

@@ -1515,4 +1515,5 @@ featureWitnessPassing,"witness passing for trait constraints in F# quotations"
 3361,typrelInterfaceWithConcreteAndVariableObjectExpression,"You cannot implement the interface '%s' with the two instantiations '%s' and '%s' because they may unify."
 featureInterfacesWithMultipleGenericInstantiation,"interfaces with multiple generic instantiation"
 3362,tcLiteralFieldAssignmentWithArg,"Cannot assign '%s' to a value marked literal"
-3363,tcLiteralFieldAssignmentNoArg,"Cannot assign a value to another value marked literal"
+3363,tcLiteralFieldAssignmentNoArg,"Cannot assign a value to another value marked literal"
+#3501   "This construct is not supported by your version of the F# compiler" CompilerMessage(ExperimentalAttributeMessages.NotSupportedYet, 3501, IsError=true)

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

@@ -251,6 +251,9 @@ namespace Microsoft.FSharp.Core
         [<Literal>]
         let RequiresPreview : string = "Experimental library feature, requires '--langversion:preview'"
 
+        [<Literal>]
+        let NotSupportedYet : string = "This construct is not supported by your version of the F# compiler"
+
     [<AttributeUsage(AttributeTargets.All, AllowMultiple=false)>]
     [<Sealed>]
     type ExperimentalAttribute(message:string) =
@@ -4718,7 +4721,7 @@ namespace Microsoft.FSharp.Core
         [<CompiledName("TypeOf")>]
         let inline typeof<'T> = BasicInlinedOperations.typeof<'T>
 
-        [<CompiledName("NameOf")>]
+        [<CompiledName("NameOf"); CompilerMessage(ExperimentalAttributeMessages.NotSupportedYet, 3501, IsError=true)>]
         let inline nameof (_: 'T) : string = raise (Exception "may not call directly, should always be optimized away")
 
         [<CompiledName("MethodHandleOf")>]

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

@@ -653,10 +653,11 @@ namespace Microsoft.FSharp.Core
         /// <summary>Indicates one or more adjustments to the compiled representation of an F# type or member</summary>
         member Flags : CompilationRepresentationFlags
 
-    module internal ExperimentalAttributeMessages = begin
+    module internal ExperimentalAttributeMessages =
         [<Literal>]
         val RequiresPreview : string = "Experimental library feature, requires '--langversion:preview'"
-    end
+        [<Literal>]
+        val NotSupportedYet : string = "This construct is not supported by your version of the F# compiler"
 
     /// <summary>This attribute is used to tag values that are part of an experimental library
     /// feature.</summary>
@@ -2846,7 +2847,7 @@ namespace Microsoft.FSharp.Core
         val inline typeof<'T> : System.Type
 
         /// <summary>Returns the name of the given symbol.</summary>        
-        [<CompiledName("NameOf")>]
+        [<CompiledName("NameOf"); CompilerMessage(ExperimentalAttributeMessages.NotSupportedYet, 3501, IsError=true)>]
         val inline nameof : 'T -> string
 
         /// <summary>An internal, library-only compiler intrinsic for compile-time 

src/fsharp/NameResolution.fs

@@ -2579,7 +2579,7 @@ let rec ResolveExprLongIdentPrim sink (ncenv: NameResolver) first fullyQualified
     if first && id.idText = MangledGlobalName then
         match rest with
         | [] ->
-            error (Error(FSComp.SR.nrGlobalUsedOnlyAsFirstName(), id.idRange))
+            raze (Error(FSComp.SR.nrGlobalUsedOnlyAsFirstName(), id.idRange))
         | [next] ->
             ResolveExprLongIdentPrim sink ncenv false fullyQualified m ad nenv typeNameResInfo next [] isOpenDecl
         | id2 :: rest2 ->
@@ -2603,11 +2603,12 @@ let rec ResolveExprLongIdentPrim sink (ncenv: NameResolver) first fullyQualified
 
                     let search = ChooseTyconRefInExpr (ncenv, m, ad, nenv, id, typeNameResInfo, resInfo, tcrefs)
                     match AtMostOneResult m search with
-                    | Result _ as res ->
-                        let resInfo, item, rest = ForceRaise res
+                    | Result (resInfo, item, rest) ->
                         ResolutionInfo.SendEntityPathToSink(sink, ncenv, nenv, ItemOccurence.Use, ad, resInfo, ResultTyparChecker(fun () -> CheckAllTyparsInferrable ncenv.amap m item))
                         Some(item, rest)
-                    | Exception e -> typeError <- Some e; None
+                    | Exception e -> 
+                        typeError <- Some e
+                        None
 
                 | true, res ->
                     let fresh = FreshenUnqualifiedItem ncenv m res
@@ -2624,7 +2625,7 @@ let rec ResolveExprLongIdentPrim sink (ncenv: NameResolver) first fullyQualified
                     None
 
             match envSearch with
-            | Some res -> res
+            | Some res -> success res
             | None ->
                 let innerSearch =
                     // Check if it's a type name, e.g. a constructor call or a type instantiation
@@ -2640,9 +2641,9 @@ let rec ResolveExprLongIdentPrim sink (ncenv: NameResolver) first fullyQualified
 
                     ctorSearch +++ implicitOpSearch
 
-                let resInfo, item, rest =
+                let res =
                     match AtMostOneResult m innerSearch with
-                    | Result _ as res -> ForceRaise res
+                    | Result _ as res -> res
                     | _ ->
                         let failingCase =
                             match typeError with
@@ -2671,11 +2672,12 @@ let rec ResolveExprLongIdentPrim sink (ncenv: NameResolver) first fullyQualified
                                                 addToBuffer (e.Value.DisplayName + "." + id.idText)
 
                                 raze (UndefinedName(0, FSComp.SR.undefinedNameValueOfConstructor, id, suggestNamesAndTypes))
-                        ForceRaise failingCase
-
+                        failingCase
+                match res with 
+                | Exception e -> raze e
+                | Result (resInfo, item, rest) -> 
                 ResolutionInfo.SendEntityPathToSink(sink, ncenv, nenv, ItemOccurence.Use, ad, resInfo, ResultTyparChecker(fun () -> CheckAllTyparsInferrable ncenv.amap m item))
-                item, rest
-
+                success (item, rest)
 
         // A compound identifier.
         // It still might be a value in the environment, or something in an F# module, namespace, type, or nested type
@@ -2693,13 +2695,13 @@ let rec ResolveExprLongIdentPrim sink (ncenv: NameResolver) first fullyQualified
                     | _ -> false
 
             if ValIsInEnv id.idText then
-              nenv.eUnqualifiedItems.[id.idText], rest
+              success (nenv.eUnqualifiedItems.[id.idText], rest)
             else
               // Otherwise modules are searched first. REVIEW: modules and types should be searched together.
               // For each module referenced by 'id', search the module as if it were an F# module and/or a .NET namespace.
               let moduleSearch ad () =
-                   ResolveLongIndentAsModuleOrNamespaceThen sink ResultCollectionSettings.AtMostOneResult ncenv.amap m fullyQualified nenv ad id rest isOpenDecl
-                       (ResolveExprLongIdentInModuleOrNamespace ncenv nenv typeNameResInfo ad)
+                 ResolveLongIndentAsModuleOrNamespaceThen sink ResultCollectionSettings.AtMostOneResult ncenv.amap m fullyQualified nenv ad id rest isOpenDecl
+                     (ResolveExprLongIdentInModuleOrNamespace ncenv nenv typeNameResInfo ad)
 
               // REVIEW: somewhat surprisingly, this shows up on performance traces, with tcrefs non-nil.
               // This seems strange since we would expect in the vast majority of cases tcrefs is empty here.
@@ -2717,59 +2719,59 @@ let rec ResolveExprLongIdentPrim sink (ncenv: NameResolver) first fullyQualified
                     NoResultsOrUsefulErrors
 
               let search =
-                  let envSearch () =
-                      match fullyQualified with
-                      | FullyQualified ->
-                          NoResultsOrUsefulErrors
-                      | OpenQualified ->
-                          match nenv.eUnqualifiedItems.TryGetValue id.idText with
-                          | true, Item.UnqualifiedType _
-                          | false, _ -> NoResultsOrUsefulErrors
-                          | true, res -> OneSuccess (resInfo, FreshenUnqualifiedItem ncenv m res, rest)
-
-                  moduleSearch ad () +++ tyconSearch ad +++ envSearch
-
-              let resInfo, item, rest =
+                let envSearch () =
+                    match fullyQualified with
+                    | FullyQualified ->
+                        NoResultsOrUsefulErrors
+                    | OpenQualified ->
+                        match nenv.eUnqualifiedItems.TryGetValue id.idText with
+                        | true, Item.UnqualifiedType _
+                        | false, _ -> NoResultsOrUsefulErrors
+                        | true, res -> OneSuccess (resInfo, FreshenUnqualifiedItem ncenv m res, rest)
+
+                moduleSearch ad () +++ tyconSearch ad +++ envSearch
+
+              let res =
                   match AtMostOneResult m search with
-                  | Result _ as res -> ForceRaise res
+                  | Result _ as res -> res
                   | _ ->
                       let innerSearch = search +++ (moduleSearch AccessibleFromSomeFSharpCode) +++ (tyconSearch AccessibleFromSomeFSharpCode)
 
                       let suggestEverythingInScope (addToBuffer: string -> unit) =
-                          for kv in nenv.ModulesAndNamespaces fullyQualified do
-                              for modref in kv.Value do
-                                  if IsEntityAccessible ncenv.amap m ad modref then
-                                      addToBuffer modref.DisplayName
-                                      addToBuffer modref.DemangledModuleOrNamespaceName
+                        for kv in nenv.ModulesAndNamespaces fullyQualified do
+                            for modref in kv.Value do
+                                if IsEntityAccessible ncenv.amap m ad modref then
+                                    addToBuffer modref.DisplayName
+                                    addToBuffer modref.DemangledModuleOrNamespaceName
 
-                          for e in nenv.TyconsByDemangledNameAndArity fullyQualified do
-                              if IsEntityAccessible ncenv.amap m ad e.Value then
-                                  addToBuffer e.Value.DisplayName
+                        for e in nenv.TyconsByDemangledNameAndArity fullyQualified do
+                            if IsEntityAccessible ncenv.amap m ad e.Value then
+                                addToBuffer e.Value.DisplayName
 
-                          for e in nenv.eUnqualifiedItems do
-                              if canSuggestThisItem e.Value then
-                                  addToBuffer e.Value.DisplayName
+                        for e in nenv.eUnqualifiedItems do
+                            if canSuggestThisItem e.Value then
+                                addToBuffer e.Value.DisplayName
 
                       match innerSearch with
                       | Exception (UndefinedName(0, _, id1, suggestionsF)) when Range.equals id.idRange id1.idRange ->
-                            let mergeSuggestions addToBuffer = 
-                                suggestionsF addToBuffer 
-                                suggestEverythingInScope addToBuffer
-
-                            let failingCase = raze (UndefinedName(0, FSComp.SR.undefinedNameValueNamespaceTypeOrModule, id, mergeSuggestions))
-                            ForceRaise failingCase
-                      | Exception err -> ForceRaise(Exception err)
-                      | Result (res :: _) -> ForceRaise(Result res)
+                          let mergeSuggestions addToBuffer = 
+                              suggestionsF addToBuffer 
+                              suggestEverythingInScope addToBuffer
+                          raze (UndefinedName(0, FSComp.SR.undefinedNameValueNamespaceTypeOrModule, id, mergeSuggestions))
+                      | Exception err -> raze err
+                      | Result (res :: _) -> success res
                       | Result [] ->
-                            let failingCase = raze (UndefinedName(0, FSComp.SR.undefinedNameValueNamespaceTypeOrModule, id, suggestEverythingInScope))
-                            ForceRaise failingCase
+                            raze (UndefinedName(0, FSComp.SR.undefinedNameValueNamespaceTypeOrModule, id, suggestEverythingInScope))
 
-              ResolutionInfo.SendEntityPathToSink(sink, ncenv, nenv, ItemOccurence.Use, ad, resInfo, ResultTyparChecker(fun () -> CheckAllTyparsInferrable ncenv.amap m item))
-              item, rest
+              match res with 
+              | Exception e -> raze e
+              | Result (resInfo, item, rest) -> 
+                  ResolutionInfo.SendEntityPathToSink(sink, ncenv, nenv, ItemOccurence.Use, ad, resInfo, ResultTyparChecker(fun () -> CheckAllTyparsInferrable ncenv.amap m item))
+                  success (item, rest)
 
 let ResolveExprLongIdent sink (ncenv: NameResolver) m ad nenv typeNameResInfo lid =
     match lid with
-    | [] -> error (Error(FSComp.SR.nrInvalidExpression(textOfLid lid), m))
+    | [] -> raze (Error(FSComp.SR.nrInvalidExpression(textOfLid lid), m))
     | id :: rest -> ResolveExprLongIdentPrim sink ncenv true OpenQualified m ad nenv typeNameResInfo id rest false
 
 //-------------------------------------------------------------------------
@@ -3414,15 +3416,17 @@ type AfterResolution =
 ///
 /// Called for 'TypeName.Bar' - for VS IntelliSense, we can filter out instance members from method groups
 let ResolveLongIdentAsExprAndComputeRange (sink: TcResultsSink) (ncenv: NameResolver) wholem ad nenv typeNameResInfo lid =
-    let item1, rest = ResolveExprLongIdent sink ncenv wholem ad nenv typeNameResInfo lid
+    match ResolveExprLongIdent sink ncenv wholem ad nenv typeNameResInfo lid with 
+    | Exception e -> Exception e 
+    | Result (item1, rest) ->
     let itemRange = ComputeItemRange wholem lid rest
 
     let item = FilterMethodGroups ncenv itemRange item1 true
 
     match item1, item with
     | Item.MethodGroup(name, minfos1, _), Item.MethodGroup(_, [], _) when not (isNil minfos1) ->
-        error(Error(FSComp.SR.methodIsNotStatic name, wholem))
-    | _ -> ()
+        raze(Error(FSComp.SR.methodIsNotStatic name, wholem))
+    | _ -> 
 
     // Fake idents e.g. 'Microsoft.FSharp.Core.None' have identical ranges for each part
     let isFakeIdents =
@@ -3462,16 +3466,14 @@ let ResolveLongIdentAsExprAndComputeRange (sink: TcResultsSink) (ncenv: NameReso
                callSink (item, emptyTyparInst)
                AfterResolution.DoNothing
 
-    item, itemRange, rest, afterResolution
+    success (item, itemRange, rest, afterResolution)
 
 let (|NonOverridable|_|) namedItem =
     match namedItem with
     |   Item.MethodGroup(_, minfos, _) when minfos |> List.exists(fun minfo -> minfo.IsVirtual || minfo.IsAbstract) -> None
     |   Item.Property(_, pinfos) when pinfos |> List.exists(fun pinfo -> pinfo.IsVirtualProperty) -> None
     |   _ -> Some ()
 
-
-
 /// Called for 'expression.Bar' - for VS IntelliSense, we can filter out static members from method groups
 /// Also called for 'GenericType<Args>.Bar' - for VS IntelliSense, we can filter out non-static members from method groups
 let ResolveExprDotLongIdentAndComputeRange (sink: TcResultsSink) (ncenv: NameResolver) wholem ad nenv ty lid findFlag thisIsActuallyATyAppNotAnExpr =
@@ -3571,7 +3573,9 @@ let IsUnionCaseUnseen ad g amap m (ucref: UnionCaseRef) =
 
 let ItemIsUnseen ad g amap m item =
     match item with
-    | Item.Value x -> IsValUnseen ad  g m x
+    | Item.Value x -> 
+        let isUnseenNameOfOperator = valRefEq g g.nameof_vref x && not (g.langVersion.SupportsFeature LanguageFeature.NameOf)
+        isUnseenNameOfOperator || IsValUnseen ad  g m x
     | Item.UnionCase(x, _) -> IsUnionCaseUnseen ad g amap m x.UnionCaseRef
     | Item.ExnCase x -> IsTyconUnseen ad g amap m x
     | _ -> false

src/fsharp/NameResolution.fsi

@@ -545,7 +545,7 @@ val internal ResolveTypeLongIdent                   : TcResultsSink -> NameResol
 val internal ResolveField                           : TcResultsSink -> NameResolver -> NameResolutionEnv -> AccessorDomain -> TType -> Ident list * Ident -> Ident list -> FieldResolution list
 
 /// Resolve a long identifier occurring in an expression position
-val internal ResolveExprLongIdent                   : TcResultsSink -> NameResolver -> range -> AccessorDomain -> NameResolutionEnv -> TypeNameResolutionInfo -> Ident list -> Item * Ident list
+val internal ResolveExprLongIdent                   : TcResultsSink -> NameResolver -> range -> AccessorDomain -> NameResolutionEnv -> TypeNameResolutionInfo -> Ident list -> ResultOrException<Item * Ident list>
 
 /// Resolve a (possibly incomplete) long identifier to a loist of possible class or record fields
 val internal ResolvePartialLongIdentToClassOrRecdFields : NameResolver -> NameResolutionEnv -> range -> AccessorDomain -> string list -> bool -> Item list
@@ -571,7 +571,7 @@ type AfterResolution =
     | RecordResolution of Item option * (TyparInst -> unit) * (MethInfo * PropInfo option * TyparInst -> unit) * (unit -> unit)
 
 /// Resolve a long identifier occurring in an expression position.
-val internal ResolveLongIdentAsExprAndComputeRange  : TcResultsSink -> NameResolver -> range -> AccessorDomain -> NameResolutionEnv -> TypeNameResolutionInfo -> Ident list -> Item * range * Ident list * AfterResolution
+val internal ResolveLongIdentAsExprAndComputeRange  : TcResultsSink -> NameResolver -> range -> AccessorDomain -> NameResolutionEnv -> TypeNameResolutionInfo -> Ident list -> ResultOrException<Item * range * Ident list * AfterResolution>
 
 /// Resolve a long identifier occurring in an expression position, qualified by a type.
 val internal ResolveExprDotLongIdentAndComputeRange : TcResultsSink -> NameResolver -> range -> AccessorDomain -> NameResolutionEnv -> TType -> Ident list -> FindMemberFlag -> bool -> Item * range * Ident list * AfterResolution