Name resolution: resolve interfaces in expressions

src/Compiler/Checking/CheckExpressions.fs

@@ -7011,31 +7011,34 @@ and TcObjectExpr (cenv: cenv) env tpenv (objTy, realObjTy, argopt, binds, extraI
 
         TcRecordConstruction cenv objTy true env tpenv None objTy fldsList mWholeExpr
     else
-        let item = ForceRaise (ResolveObjectConstructor cenv.nameResolver env.DisplayEnv mObjTy ad objTy)
+        let ctorCall, baseIdOpt, tpenv =
+            if isInterfaceTy g objTy then
+                match argopt with
+                | None ->
+                    BuildObjCtorCall g mWholeExpr, None, tpenv
+                | Some _ ->
+                    error(Error(FSComp.SR.tcConstructorForInterfacesDoNotTakeArguments(), mNewExpr))
+            else
+                let item = ForceRaise (ResolveObjectConstructor cenv.nameResolver env.DisplayEnv mObjTy ad objTy)
 
-        if isFSharpObjModelTy g objTy && GetCtorShapeCounter env = 1 then
-            error(Error(FSComp.SR.tcObjectsMustBeInitializedWithObjectExpression(), mNewExpr))
+                if isFSharpObjModelTy g objTy && GetCtorShapeCounter env = 1 then
+                    error(Error(FSComp.SR.tcObjectsMustBeInitializedWithObjectExpression(), mNewExpr))
 
-        let ctorCall, baseIdOpt, tpenv =
-            match item, argopt with
-            | Item.CtorGroup(methodName, minfos), Some (arg, baseIdOpt) ->
-                let meths = minfos |> List.map (fun minfo -> minfo, None)
-                let afterResolution = ForNewConstructors cenv.tcSink env mObjTy methodName minfos
-                let ad = env.AccessRights
-
-                let expr, tpenv = TcMethodApplicationThen cenv env (MustEqual objTy) None tpenv None [] mWholeExpr mObjTy methodName ad PossiblyMutates false meths afterResolution CtorValUsedAsSuperInit [arg] ExprAtomicFlag.Atomic None []
-                // The 'base' value is always bound
-                let baseIdOpt = (match baseIdOpt with None -> Some(ident("base", mObjTy)) | Some id -> Some id)
-                expr, baseIdOpt, tpenv
-            | Item.FakeInterfaceCtor intfTy, None ->
-                UnifyTypes cenv env mWholeExpr objTy intfTy
-                let expr = BuildObjCtorCall g mWholeExpr
-                expr, None, tpenv
-            | Item.FakeInterfaceCtor _, Some _ ->
-                error(Error(FSComp.SR.tcConstructorForInterfacesDoNotTakeArguments(), mNewExpr))
-            | Item.CtorGroup _, None ->
-                error(Error(FSComp.SR.tcConstructorRequiresArguments(), mNewExpr))
-            | _ -> error(Error(FSComp.SR.tcNewRequiresObjectConstructor(), mNewExpr))
+                match item, argopt with
+                | Item.CtorGroup(methodName, minfos), Some (arg, baseIdOpt) ->
+                    let meths = minfos |> List.map (fun minfo -> minfo, None)
+                    let afterResolution = ForNewConstructors cenv.tcSink env mObjTy methodName minfos
+                    let ad = env.AccessRights
+
+                    let expr, tpenv = TcMethodApplicationThen cenv env (MustEqual objTy) None tpenv None [] mWholeExpr mObjTy methodName ad PossiblyMutates false meths afterResolution CtorValUsedAsSuperInit [arg] ExprAtomicFlag.Atomic None []
+                    // The 'base' value is always bound
+                    let baseIdOpt = (match baseIdOpt with None -> Some(ident("base", mObjTy)) | Some id -> Some id)
+                    expr, baseIdOpt, tpenv
+
+                | Item.CtorGroup _, None ->
+                    error(Error(FSComp.SR.tcConstructorRequiresArguments(), mNewExpr))
+
+                | _ -> error(Error(FSComp.SR.tcNewRequiresObjectConstructor(), mNewExpr))
 
         let baseValOpt = MakeAndPublishBaseVal cenv env baseIdOpt objTy
         let env = Option.foldBack (AddLocalVal g cenv.tcSink mNewExpr) baseValOpt env
@@ -8141,8 +8144,11 @@ and TcNameOfExpr (cenv: cenv) env tpenv (synArg: SynExpr) =
                     when
                          (match item with
                           | Item.DelegateCtor _
-                          | Item.CtorGroup _
-                          | Item.FakeInterfaceCtor _ -> false
+                          | Item.CtorGroup _ -> false
+                          | Item.Types _ when delayed.IsEmpty ->
+                              match delayed with
+                              | [] | [DelayedTypeApp _] -> false
+                              | _ -> true
                           | _ -> true) ->
                     let overallTy = match overallTyOpt with None -> MustEqual (NewInferenceType g) | Some t -> t
                     let _, _ = TcItemThen cenv overallTy env tpenv res None delayed
@@ -8374,9 +8380,6 @@ and TcItemThen (cenv: cenv) (overallTy: OverallTy) env tpenv (tinstEnclosing, it
     | Item.CtorGroup(nm, minfos) ->
         TcCtorItemThen cenv overallTy env item nm minfos tinstEnclosing tpenv mItem afterResolution delayed
 
-    | Item.FakeInterfaceCtor _ ->
-        error(Error(FSComp.SR.tcInvalidUseOfInterfaceType(), mItem))
-
     | Item.ImplicitOp(id, sln) ->
         TcImplicitOpItemThen cenv overallTy env id sln tpenv mItem delayed
 
@@ -8614,7 +8617,10 @@ and TcTypeItemThen (cenv: cenv) overallTy env nm ty tpenv mItem tinstEnclosing d
         // In this case the type is not generic, and indeed we should never have returned Item.Types.
         // That's because ResolveTypeNamesToCtors should have been set at the original
         // call to ResolveLongIdentAsExprAndComputeRange
-        error(Error(FSComp.SR.tcInvalidUseOfTypeName(), mItem))
+        if isInterfaceTy g ty then
+            error(Error(FSComp.SR.tcInvalidUseOfInterfaceType(), mItem))
+        else
+            error(Error(FSComp.SR.tcInvalidUseOfTypeName(), mItem))
 
 and TcMethodItemThen (cenv: cenv) overallTy env item methodName minfos tpenv mItem afterResolution staticTyOpt delayed =
     let ad = env.eAccessRights
@@ -9305,7 +9311,7 @@ and TcLookupItemThen cenv overallTy env tpenv mObjExpr objExpr objExprTy delayed
     | Item.Trait traitInfo ->
         TcTraitItemThen cenv overallTy env (Some objExpr) traitInfo tpenv mItem delayed
 
-    | Item.FakeInterfaceCtor _ | Item.DelegateCtor _ -> error (Error (FSComp.SR.tcConstructorsCannotBeFirstClassValues(), mItem))
+    | Item.DelegateCtor _ -> error (Error (FSComp.SR.tcConstructorsCannotBeFirstClassValues(), mItem))
 
     // These items are not expected here - they can't be the result of a instance member dot-lookup "expr.Ident"
     | Item.ActivePatternResult _

src/Compiler/Checking/NameResolution.fs

@@ -201,9 +201,6 @@ type Item =
     /// Represents the resolution of a name to a constructor
     | CtorGroup of string * MethInfo list
 
-    /// Represents the resolution of a name to the fake constructor simulated for an interface type.
-    | FakeInterfaceCtor of TType
-
     /// Represents the resolution of a name to a delegate
     | DelegateCtor of TType
 
@@ -276,8 +273,7 @@ type Item =
             | ValueSome tcref -> tcref.DisplayNameCore
             | _ -> nm
             |> DemangleGenericTypeName
-        | Item.CtorGroup(nm, _) -> nm |> DemangleGenericTypeName
-        | Item.FakeInterfaceCtor ty
+        | Item.CtorGroup(nm, _) -> nm |> DemangleGenericTypeName 
         | Item.DelegateCtor ty ->
             match ty with 
             | AbbrevOrAppTy tcref -> tcref.DisplayNameCore
@@ -1713,6 +1709,8 @@ type ItemOccurence =
     | RelatedText
     /// This is a usage of a module or namespace name in open statement
     | Open
+    /// Not permitted item uses like interface names used as expressions
+    | InvalidUse
 
 type FormatStringCheckContext =
     { SourceText: ISourceText
@@ -1786,8 +1784,7 @@ let (|EntityUse|_|) (item: Item) =
     | Item.UnqualifiedType (tcref :: _) -> Some tcref
     | Item.ExnCase tcref -> Some tcref
     | Item.Types(_, [AbbrevOrAppTy tcref])
-    | Item.DelegateCtor(AbbrevOrAppTy tcref)
-    | Item.FakeInterfaceCtor(AbbrevOrAppTy tcref) -> Some tcref
+    | Item.DelegateCtor(AbbrevOrAppTy tcref) -> Some tcref
     | Item.CtorGroup(_, ctor :: _) ->
         match ctor.ApparentEnclosingType with
         | AbbrevOrAppTy tcref -> Some tcref
@@ -2229,7 +2226,6 @@ let CheckAllTyparsInferrable amap m item =
 
     | Item.Trait _
     | Item.CtorGroup _
-    | Item.FakeInterfaceCtor _
     | Item.DelegateCtor _
     | Item.Types _
     | Item.ModuleOrNamespaces _
@@ -2470,7 +2466,8 @@ let private ResolveObjectConstructorPrim (ncenv: NameResolver) edenv resInfo m a
     else
         let ctorInfos = GetIntrinsicConstructorInfosOfType ncenv.InfoReader m ty
         if isNil ctorInfos && isInterfaceTy g ty then
-            success (resInfo, Item.FakeInterfaceCtor ty)
+            let tcref = tcrefOfAppTy g ty
+            success (resInfo, Item.Types(tcref.DisplayName, [ty]))
         else
             let defaultStructCtorInfo =
                 if (not (ctorInfos |> List.exists (fun x -> x.IsNullary)) &&
@@ -3070,33 +3067,49 @@ let rec ResolveExprLongIdentPrim sink (ncenv: NameResolver) first fullyQualified
                     match AtMostOneResult m innerSearch with
                     | Result _ as res -> res
                     | _ ->
-                        let failingCase =
-                            match typeError with
-                            | Some e -> raze e
-                            | _ ->
-                                let suggestNamesAndTypes (addToBuffer: string -> unit) =
-                                    for e in nenv.eUnqualifiedItems do
-                                        if canSuggestThisItem 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 kv in nenv.ModulesAndNamespaces fullyQualified do
-                                        for modref in kv.Value do
-                                            if IsEntityAccessible ncenv.amap m ad modref then
-                                                addToBuffer modref.DisplayName
-
-                                    // check if the user forgot to use qualified access
-                                    for e in nenv.eTyconsByDemangledNameAndArity do                                    
-                                        let hasRequireQualifiedAccessAttribute = HasFSharpAttribute ncenv.g ncenv.g.attrib_RequireQualifiedAccessAttribute e.Value.Attribs
-                                        if hasRequireQualifiedAccessAttribute then
-                                            if e.Value.IsUnionTycon && e.Value.UnionCasesArray |> Array.exists (fun c -> c.LogicalName = id.idText) then
-                                                addToBuffer (e.Value.DisplayName + "." + id.idText)
-
-                                raze (UndefinedName(0, FSComp.SR.undefinedNameValueOfConstructor, id, suggestNamesAndTypes))
-                        failingCase
+
+                    match typeError with
+                    | Some e -> raze e
+                    | _ ->
+
+                    let tyconSearch () =
+                        let tcrefs = LookupTypeNameInEnvNoArity fullyQualified id.idText nenv
+                        if isNil tcrefs then NoResultsOrUsefulErrors else
+
+                        let tcrefs = ResolveUnqualifiedTyconRefs nenv tcrefs
+                        let typeNameResInfo = TypeNameResolutionInfo.ResolveToTypeRefs typeNameResInfo.StaticArgsInfo
+                        CheckForTypeLegitimacyAndMultipleGenericTypeAmbiguities (tcrefs, typeNameResInfo, PermitDirectReferenceToGeneratedType.No, unionRanges m id.idRange)
+                        |> CollectResults success
+
+                    match tyconSearch () with
+                    | Result ((resInfo, tcref) :: _) ->
+                        let item = Item.Types(id.idText, [ generalizedTyconRef ncenv.g tcref ])
+                        success (resInfo, item)
+                    | _ ->
+
+                    let suggestNamesAndTypes (addToBuffer: string -> unit) =
+                        for e in nenv.eUnqualifiedItems do
+                            if canSuggestThisItem 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 kv in nenv.ModulesAndNamespaces fullyQualified do
+                            for modref in kv.Value do
+                                if IsEntityAccessible ncenv.amap m ad modref then
+                                    addToBuffer modref.DisplayName
+
+                        // check if the user forgot to use qualified access
+                        for e in nenv.eTyconsByDemangledNameAndArity do                                    
+                            let hasRequireQualifiedAccessAttribute = HasFSharpAttribute ncenv.g ncenv.g.attrib_RequireQualifiedAccessAttribute e.Value.Attribs
+                            if hasRequireQualifiedAccessAttribute then
+                                if e.Value.IsUnionTycon && e.Value.UnionCasesArray |> Array.exists (fun c -> c.LogicalName = id.idText) then
+                                    addToBuffer (e.Value.DisplayName + "." + id.idText)
+
+                    raze (UndefinedName(0, FSComp.SR.undefinedNameValueOfConstructor, id, suggestNamesAndTypes))
+
                 match res with 
                 | Exception e -> raze e
                 | Result (resInfo, item) -> 
@@ -3997,6 +4010,11 @@ let NeedsWorkAfterResolution namedItem =
     | Item.ActivePatternCase apref -> not (List.isEmpty apref.ActivePatternVal.Typars)
     | _ -> false
 
+let isWrongItemInExpr item =
+    match item with
+    | Item.Types _ -> true
+    | _ -> false
+
 /// Specifies additional work to do after an item has been processed further in type checking.
 [<RequireQualifiedAccess>]
 type AfterResolution =
@@ -4059,6 +4077,11 @@ let ResolveLongIdentAsExprAndComputeRange (sink: TcResultsSink) (ncenv: NameReso
         | Some _ ->
             if NeedsWorkAfterResolution item then
                 AfterResolution.RecordResolution(None, (fun tpinst -> callSink(item, tpinst)), callSinkWithSpecificOverload, (fun () -> callSink (item, emptyTyparInst)))
+
+            elif isWrongItemInExpr item then
+               CallNameResolutionSink sink (itemRange, nenv, item, emptyTyparInst, ItemOccurence.InvalidUse, ad)
+               AfterResolution.DoNothing
+
             else
                callSink (item, emptyTyparInst)
                AfterResolution.DoNothing
@@ -4500,7 +4523,6 @@ let InfosForTyconConstructors (ncenv: NameResolver) m ad (tcref: TyconRef) =
         match ResolveObjectConstructor ncenv (DisplayEnv.Empty g) m ad ty with
         | Result item ->
             match item with
-            | Item.FakeInterfaceCtor _ -> None
             | Item.CtorGroup(nm, ctorInfos) ->
                 let ctors =
                     ctorInfos
@@ -5301,7 +5323,6 @@ let rec GetCompletionForItem (ncenv: NameResolver) (nenv: NameResolutionEnv) m a
                    | _ -> ()
 
            | Item.DelegateCtor _
-           | Item.FakeInterfaceCtor _
            | Item.CtorGroup _
            | Item.UnqualifiedType _ ->
                for tcref in nenv.TyconsByDemangledNameAndArity(OpenQualified).Values do

src/Compiler/Checking/NameResolution.fsi

@@ -94,9 +94,6 @@ type Item =
     /// Represents the resolution of a name to a constructor
     | CtorGroup of string * MethInfo list
 
-    /// Represents the resolution of a name to the fake constructor simulated for an interface type.
-    | FakeInterfaceCtor of TType
-
     /// Represents the resolution of a name to a delegate
     | DelegateCtor of TType
 
@@ -385,6 +382,7 @@ type internal ItemOccurence =
     | Implemented
     | RelatedText
     | Open
+    | InvalidUse
 
 /// Check for equality, up to signature matching
 val ItemsAreEffectivelyEqual: TcGlobals -> Item -> Item -> bool

src/Compiler/Service/FSharpCheckerResults.fs

@@ -483,6 +483,8 @@ type internal TypeCheckInfo
         //
         // If we're looking for members using a residue, we'd expect only
         // a single item (pick the first one) and we need the residue (which may be "")
+        | CNR(_, ItemOccurence.InvalidUse, _, _, _, _) :: _, _ -> NameResResult.Empty
+
         | CNR(Item.Types(_, ty :: _), _, denv, nenv, ad, m) :: _, Some _ ->
             let targets =
                 ResolveCompletionTargets.All(ConstraintSolver.IsApplicableMethApprox g amap m)
@@ -891,7 +893,6 @@ type internal TypeCheckInfo
     let CompletionItem (ty: TyconRef voption) (assemblySymbol: AssemblySymbol voption) (item: ItemWithInst) =
         let kind =
             match item.Item with
-            | Item.FakeInterfaceCtor _
             | Item.DelegateCtor _
             | Item.CtorGroup _ -> CompletionItemKind.Method false
             | Item.MethodGroup(_, minfos, _) ->
@@ -1802,7 +1803,6 @@ type internal TypeCheckInfo
                                 match d.Item with
                                 | Item.Types(_, AbbrevOrAppTy tcref :: _) -> 1 + tcref.TyparsNoRange.Length
                                 // Put delegate ctors after types, sorted by #typars. RemoveDuplicateItems will remove FakeInterfaceCtor and DelegateCtor if an earlier type is also reported with this name
-                                | Item.FakeInterfaceCtor(AbbrevOrAppTy tcref)
                                 | Item.DelegateCtor(AbbrevOrAppTy tcref) -> 1000 + tcref.TyparsNoRange.Length
                                 // Put type ctors after types, sorted by #typars. RemoveDuplicateItems will remove DefaultStructCtors if a type is also reported with this name
                                 | Item.CtorGroup(_, cinfo :: _) -> 1000 + 10 * cinfo.DeclaringTyconRef.TyparsNoRange.Length
@@ -1822,7 +1822,6 @@ type internal TypeCheckInfo
                             | Item.Types(_, AbbrevOrAppTy tcref :: _)
                             | Item.ExnCase tcref -> tcref.LogicalName
                             | Item.UnqualifiedType(tcref :: _)
-                            | Item.FakeInterfaceCtor(AbbrevOrAppTy tcref)
                             | Item.DelegateCtor(AbbrevOrAppTy tcref) -> tcref.CompiledName
                             | Item.CtorGroup(_, cinfo :: _) -> cinfo.ApparentEnclosingTyconRef.CompiledName
                             | _ -> d.Item.DisplayName)

src/Compiler/Service/ItemKey.fs

@@ -562,7 +562,6 @@ and [<Sealed>] ItemKeyStoreBuilder(tcGlobals: TcGlobals) =
 
         // We should consider writing ItemKey for each of these
         | Item.OtherName _ -> ()
-        | Item.FakeInterfaceCtor _ -> ()
         | Item.CustomOperation _ -> ()
         | Item.CustomBuilder _ -> ()
         | Item.ImplicitOp _ -> ()

src/Compiler/Service/SemanticClassification.fs

@@ -287,8 +287,6 @@ module TcResolutionsExtensions =
 
                         | Item.DelegateCtor _, _, m -> add m SemanticClassificationType.ConstructorForReferenceType
 
-                        | Item.FakeInterfaceCtor _, _, m -> add m SemanticClassificationType.ConstructorForReferenceType
-
                         | Item.MethodGroup(_, minfos, _), _, m ->
                             match minfos with
                             | [] -> add m SemanticClassificationType.Method