Remove always-on LowercaseDUWhenRequireQualifiedAccess feature flag

src/Compiler/Checking/CheckDeclarations.fs

@@ -515,13 +515,8 @@ module TcRecdUnionAndEnumDeclarations =
 
         CheckNamespaceModuleOrTypeName g id
 
-        if g.langVersion.SupportsFeature(LanguageFeature.LowercaseDUWhenRequireQualifiedAccess) then
-
-            if not (String.isLeadingIdentifierCharacterUpperCase name) && not hasRQAAttribute && name <> opNameCons && name <> opNameNil then
-                errorR(NotUpperCaseConstructorWithoutRQA(id.idRange))
-        else
-            if not (String.isLeadingIdentifierCharacterUpperCase name) && name <> opNameCons && name <> opNameNil then
-                errorR(NotUpperCaseConstructor(id.idRange))
+        if not (String.isLeadingIdentifierCharacterUpperCase name) && not hasRQAAttribute && name <> opNameCons && name <> opNameNil then
+            errorR(NotUpperCaseConstructorWithoutRQA(id.idRange))
 
     let private CheckUnionDuplicateFields (elems: Ident list) =
         elems |> List.iteri (fun i (uc1: Ident) -> 

src/Compiler/FSComp.txt

@@ -1578,7 +1578,6 @@ featureErrorOnDeprecatedRequireQualifiedAccess,"give error on deprecated access
 featureInterfacesWithAbstractStaticMembers,"static abstract interface members"
 featureSelfTypeConstraints,"self type constraints"
 featureRequiredProperties,"support for required properties"
-featureLowercaseDUWhenRequireQualifiedAccess,"Allow lowercase DU when RequireQualifiedAccess attribute"
 featureMatchNotAllowedForUnionCaseWithNoData,"Pattern match discard is not allowed for union case that takes no data."
 featureCSharpExtensionAttributeNotRequired,"Allow implicit Extension attribute on declaring types, modules"
 featureErrorForNonVirtualMembersOverrides,"Raises errors for non-virtual members overrides"

src/Compiler/Facilities/LanguageFeatures.fs

@@ -38,7 +38,6 @@ type LanguageFeature =
     | ReallyLongLists
     | ErrorOnDeprecatedRequireQualifiedAccess
     | RequiredPropertiesSupport
-    | LowercaseDUWhenRequireQualifiedAccess
     | InterfacesWithAbstractStaticMembers
     | SelfTypeConstraints
     | MatchNotAllowedForUnionCaseWithNoData
@@ -160,7 +159,6 @@ type LanguageVersion(versionText, ?disabledFeaturesArray: LanguageFeature array)
                 LanguageFeature.ReallyLongLists, languageVersion70
                 LanguageFeature.ErrorOnDeprecatedRequireQualifiedAccess, languageVersion70
                 LanguageFeature.RequiredPropertiesSupport, languageVersion70
-                LanguageFeature.LowercaseDUWhenRequireQualifiedAccess, languageVersion70
                 LanguageFeature.InterfacesWithAbstractStaticMembers, languageVersion70
                 LanguageFeature.SelfTypeConstraints, languageVersion70
 
@@ -355,7 +353,6 @@ type LanguageVersion(versionText, ?disabledFeaturesArray: LanguageFeature array)
         | LanguageFeature.ReallyLongLists -> FSComp.SR.featureReallyLongList ()
         | LanguageFeature.ErrorOnDeprecatedRequireQualifiedAccess -> FSComp.SR.featureErrorOnDeprecatedRequireQualifiedAccess ()
         | LanguageFeature.RequiredPropertiesSupport -> FSComp.SR.featureRequiredProperties ()
-        | LanguageFeature.LowercaseDUWhenRequireQualifiedAccess -> FSComp.SR.featureLowercaseDUWhenRequireQualifiedAccess ()
         | LanguageFeature.InterfacesWithAbstractStaticMembers -> FSComp.SR.featureInterfacesWithAbstractStaticMembers ()
         | LanguageFeature.SelfTypeConstraints -> FSComp.SR.featureSelfTypeConstraints ()
         | LanguageFeature.MatchNotAllowedForUnionCaseWithNoData -> FSComp.SR.featureMatchNotAllowedForUnionCaseWithNoData ()

src/Compiler/Facilities/LanguageFeatures.fsi

@@ -28,7 +28,6 @@ type LanguageFeature =
     | ReallyLongLists
     | ErrorOnDeprecatedRequireQualifiedAccess
     | RequiredPropertiesSupport
-    | LowercaseDUWhenRequireQualifiedAccess
     | InterfacesWithAbstractStaticMembers
     | SelfTypeConstraints
     | MatchNotAllowedForUnionCaseWithNoData