Implicit constructors should only target AttributeTargets.Constructor

docs/release-notes/.FSharp.Compiler.Service/8.0.300.md

@@ -16,6 +16,7 @@
 * Enforce AttributeTargets on let values and functions. ([PR #16692](https://github.com/dotnet/fsharp/pull/16692))
 * Enforce AttributeTargets on union case declarations. ([PR #16764](https://github.com/dotnet/fsharp/pull/16764))
 * Disallow using base to invoke an abstract base method. ([Issue #13926](https://github.com/dotnet/fsharp/issues/13926), [PR #16773](https://github.com/dotnet/fsharp/pull/16773))
+* Enforce AttributeTargets on implicit constructors. ([PR #16845](https://github.com/dotnet/fsharp/pull/16845/))
 * Enforce AttributeTargets on structs and classes ([PR #16790](https://github.com/dotnet/fsharp/pull/16790))
 * Parser: fix pattern range for idents with trivia ([PR #16824](https://github.com/dotnet/fsharp/pull/16824))
 * Fix broken code completion after a record type declaration ([PR #16813](https://github.com/dotnet/fsharp/pull/16813))

docs/release-notes/.Language/preview.md

@@ -11,6 +11,7 @@
 * Allow extension methods without type attribute work for types from imported assemblies. ([PR #16368](https://github.com/dotnet/fsharp/pull/16368))
 * Enforce AttributeTargets on let values and functions. ([PR #16692](https://github.com/dotnet/fsharp/pull/16692))
 * Enforce AttributeTargets on union case declarations. ([PR #16764](https://github.com/dotnet/fsharp/pull/16764))
+* Enforce AttributeTargets on implicit constructors. ([PR #16845](https://github.com/dotnet/fsharp/pull/16845/))
 * Enforce AttributeTargets on structs and classes ([PR #16790](https://github.com/dotnet/fsharp/pull/16790))
 
 ### Changed

src/Compiler/Checking/CheckDeclarations.fs

@@ -574,7 +574,7 @@ module TcRecdUnionAndEnumDeclarations =
                     type SomeUnion =
                     | Case1 // Compiles down to a static property
             *)
-            if g.langVersion.SupportsFeature(LanguageFeature.EnforceAttributeTargetsUnionCaseDeclarations) then
+            if g.langVersion.SupportsFeature(LanguageFeature.EnforceAttributeTargets) then
                 let target = if rfields.IsEmpty then AttributeTargets.Property else AttributeTargets.Method
                 TcAttributes cenv env target synAttrs
             else
@@ -2927,13 +2927,13 @@ module EstablishTypeDefinitionCores =
                     let kind = 
                         match kind with
                         | SynTypeDefnKind.Class ->
-                            if g.langVersion.SupportsFeature(LanguageFeature.EnforceAttributeTargetsOnStructAndClasses) then
+                            if g.langVersion.SupportsFeature(LanguageFeature.EnforceAttributeTargets) then
                                 TcAttributesWithPossibleTargets false cenv envinner AttributeTargets.Class synAttrs |> ignore
                             TFSharpClass
                         | SynTypeDefnKind.Interface -> TFSharpInterface
                         | SynTypeDefnKind.Delegate _ -> TFSharpDelegate (MakeSlotSig("Invoke", g.unit_ty, [], [], [], None))
                         | SynTypeDefnKind.Struct ->
-                            if g.langVersion.SupportsFeature(LanguageFeature.EnforceAttributeTargetsOnStructAndClasses) then
+                            if g.langVersion.SupportsFeature(LanguageFeature.EnforceAttributeTargets) then
                                 TcAttributesWithPossibleTargets false cenv envinner AttributeTargets.Struct synAttrs |> ignore
                             TFSharpStruct 
                         | _ -> error(InternalError("should have inferred tycon kind", m))

src/Compiler/Checking/CheckExpressions.fs

@@ -10874,7 +10874,7 @@ and TcNormalizedBinding declKind (cenv: cenv) env tpenv overallTy safeThisValOpt
             if not (isNil declaredTypars) then
                 errorR(Error(FSComp.SR.tcLiteralCannotHaveGenericParameters(), mBinding))
 
-        if g.langVersion.SupportsFeature(LanguageFeature.EnforceAttributeTargetsOnFunctions) && memberFlagsOpt.IsNone && not attrs.IsEmpty then
+        if g.langVersion.SupportsFeature(LanguageFeature.EnforceAttributeTargets) && memberFlagsOpt.IsNone && not attrs.IsEmpty then
             TcAttributeTargetsOnLetBindings cenv env attrs overallPatTy overallExprTy (not declaredTypars.IsEmpty)
 
         CheckedBindingInfo(inlineFlag, valAttribs, xmlDoc, tcPatPhase2, explicitTyparInfo, nameToPrelimValSchemeMap, rhsExprChecked, argAndRetAttribs, overallPatTy, mBinding, debugPoint, isCompGen, literalValue, isFixed), tpenv

src/Compiler/Checking/CheckIncrementalClasses.fs

@@ -5,6 +5,7 @@ module internal FSharp.Compiler.CheckIncrementalClasses
 open System
 
 open FSharp.Compiler.Diagnostics
+open FSharp.Compiler.Features
 open Internal.Utilities.Collections
 open Internal.Utilities.Library
 open Internal.Utilities.Library.Extras
@@ -173,7 +174,13 @@ let TcImplicitCtorInfo_Phase2A(cenv: cenv, env, tpenv, tcref: TyconRef, vis, att
         let ctorTy = mkFunTy g argTy objTy    
 
         // NOTE: no attributes can currently be specified for the implicit constructor 
-        let attribs = TcAttributes cenv env (AttributeTargets.Constructor ||| AttributeTargets.Method) attrs
+        let attribs =
+            // Implicit constructors can only target AttributeTargets.Constructor
+            if g.langVersion.SupportsFeature(LanguageFeature.EnforceAttributeTargets) then
+                TcAttributes cenv env AttributeTargets.Constructor attrs
+            else
+                TcAttributes cenv env (AttributeTargets.Constructor ||| AttributeTargets.Method) attrs
+
         let memberFlags = CtorMemberFlags
 
         let synArgInfos = List.map (SynInfo.InferSynArgInfoFromSimplePat []) spats

src/Compiler/FSComp.txt

@@ -1593,10 +1593,8 @@ featureWarningIndexedPropertiesGetSetSameType,"Indexed properties getter and set
 featureChkTailCallAttrOnNonRec,"Raises warnings if the 'TailCall' attribute is used on non-recursive functions."
 featureUnionIsPropertiesVisible,"Union case test properties"
 featureBooleanReturningAndReturnTypeDirectedPartialActivePattern,"Boolean-returning and return-type-directed partial active patterns"
-featureEnforceAttributeTargetsOnFunctions,"Enforce AttributeTargets on functions"
-featureEnforceAttributeTargetsUnionCaseDeclarations,"Enforce AttributeTargets on union case declarations"
+featureEnforceAttributeTargets,"Enforce AttributeTargets"
 featureLowerInterpolatedStringToConcat,"Optimizes interpolated strings in certain cases, by lowering to concatenation"
-featureEnforceAttributeTargetsOnStructAndClasses,"Enforce AttributeTargets on structs and classes"
 featureLowerIntegralRangesToFastLoops,"Optimizes certain uses of the integral range (..) and range-step (.. ..) operators to fast while-loops."
 3354,tcNotAFunctionButIndexerNamedIndexingNotYetEnabled,"This value supports indexing, e.g. '%s.[index]'. The syntax '%s[index]' requires /langversion:preview. See https://aka.ms/fsharp-index-notation."
 3354,tcNotAFunctionButIndexerIndexingNotYetEnabled,"This expression supports indexing, e.g. 'expr.[index]'. The syntax 'expr[index]' requires /langversion:preview. See https://aka.ms/fsharp-index-notation."

src/Compiler/Facilities/LanguageFeatures.fs

@@ -85,10 +85,8 @@ type LanguageFeature =
     | WarningIndexedPropertiesGetSetSameType
     | WarningWhenTailCallAttrOnNonRec
     | BooleanReturningAndReturnTypeDirectedPartialActivePattern
-    | EnforceAttributeTargetsOnFunctions
-    | EnforceAttributeTargetsUnionCaseDeclarations
+    | EnforceAttributeTargets
     | LowerInterpolatedStringToConcat
-    | EnforceAttributeTargetsOnStructAndClasses
     | LowerIntegralRangesToFastLoops
 
 /// LanguageVersion management
@@ -202,10 +200,8 @@ type LanguageVersion(versionText) =
                 LanguageFeature.WarningWhenTailCallAttrOnNonRec, previewVersion
                 LanguageFeature.UnionIsPropertiesVisible, previewVersion
                 LanguageFeature.BooleanReturningAndReturnTypeDirectedPartialActivePattern, previewVersion
-                LanguageFeature.EnforceAttributeTargetsOnFunctions, previewVersion
-                LanguageFeature.EnforceAttributeTargetsUnionCaseDeclarations, previewVersion
+                LanguageFeature.EnforceAttributeTargets, previewVersion
                 LanguageFeature.LowerInterpolatedStringToConcat, previewVersion
-                LanguageFeature.EnforceAttributeTargetsOnStructAndClasses, previewVersion
                 LanguageFeature.LowerIntegralRangesToFastLoops, previewVersion
             ]
 
@@ -350,10 +346,8 @@ type LanguageVersion(versionText) =
         | LanguageFeature.WarningWhenTailCallAttrOnNonRec -> FSComp.SR.featureChkTailCallAttrOnNonRec ()
         | LanguageFeature.BooleanReturningAndReturnTypeDirectedPartialActivePattern ->
             FSComp.SR.featureBooleanReturningAndReturnTypeDirectedPartialActivePattern ()
-        | LanguageFeature.EnforceAttributeTargetsOnFunctions -> FSComp.SR.featureEnforceAttributeTargetsOnFunctions ()
-        | LanguageFeature.EnforceAttributeTargetsUnionCaseDeclarations -> FSComp.SR.featureEnforceAttributeTargetsUnionCaseDeclarations ()
+        | LanguageFeature.EnforceAttributeTargets -> FSComp.SR.featureEnforceAttributeTargets ()
         | LanguageFeature.LowerInterpolatedStringToConcat -> FSComp.SR.featureLowerInterpolatedStringToConcat ()
-        | LanguageFeature.EnforceAttributeTargetsOnStructAndClasses -> FSComp.SR.featureEnforceAttributeTargetsOnStructAndClasses ()
         | LanguageFeature.LowerIntegralRangesToFastLoops -> FSComp.SR.featureLowerIntegralRangesToFastLoops ()
 
     /// Get a version string associated with the given feature.

src/Compiler/Facilities/LanguageFeatures.fsi

@@ -76,10 +76,8 @@ type LanguageFeature =
     | WarningIndexedPropertiesGetSetSameType
     | WarningWhenTailCallAttrOnNonRec
     | BooleanReturningAndReturnTypeDirectedPartialActivePattern
-    | EnforceAttributeTargetsOnFunctions
-    | EnforceAttributeTargetsUnionCaseDeclarations
+    | EnforceAttributeTargets
     | LowerInterpolatedStringToConcat
-    | EnforceAttributeTargetsOnStructAndClasses
     | LowerIntegralRangesToFastLoops
 
 /// LanguageVersion management