Fix [<RequireQualifiedAccess>] on a DU shadows types in the same module

src/fsharp/NameResolution.fs

@@ -845,7 +845,6 @@ let AtMostOneResult m res =
     match res with 
     | Exception err -> raze err
     | Result [] -> raze (Error(FSComp.SR.nrInvalidModuleExprType(),m))
-    | Result [res] -> success res
     | Result (res :: _) -> success res 
 
 //-------------------------------------------------------------------------
@@ -1976,25 +1975,31 @@ let rec ResolveExprLongIdentInModuleOrNamespace (ncenv:NameResolver) nenv (typeN
         | Some vspec when IsValAccessible ad (mkNestedValRef modref vspec) -> 
             success(resInfo,Item.Value (mkNestedValRef modref vspec),rest)
         | _->
-        match  TryFindTypeWithUnionCase modref id with
-        | Some tycon when IsTyconReprAccessible ncenv.amap m ad (modref.NestedTyconRef tycon) -> 
-            let ucref = mkUnionCaseRef (modref.NestedTyconRef tycon) id.idText 
-            let showDeprecated = HasFSharpAttribute ncenv.g ncenv.g.attrib_RequireQualifiedAccessAttribute tycon.Attribs
-            let ucinfo = FreshenUnionCaseRef ncenv m ucref
-            success (resInfo,Item.UnionCase(ucinfo,showDeprecated),rest)
-        | _ -> 
         match mty.ExceptionDefinitionsByDemangledName.TryFind(id.idText) with
         | Some excon when IsTyconReprAccessible ncenv.amap m ad (modref.NestedTyconRef excon) -> 
             success (resInfo,Item.ExnCase (modref.NestedTyconRef excon),rest)
         | _ ->
-
-            // Something in a type? 
+            // Something in a discriminated union without RequireQualifiedAccess attribute?
+            let unionSearch,hasRequireQualifiedAccessAttribute =
+                match TryFindTypeWithUnionCase modref id with
+                | Some tycon when IsTyconReprAccessible ncenv.amap m ad (modref.NestedTyconRef tycon) -> 
+                    let ucref = mkUnionCaseRef (modref.NestedTyconRef tycon) id.idText
+                    let ucinfo = FreshenUnionCaseRef ncenv m ucref
+                    let hasRequireQualifiedAccessAttribute = HasFSharpAttribute ncenv.g ncenv.g.attrib_RequireQualifiedAccessAttribute tycon.Attribs
+                    success [resInfo,Item.UnionCase(ucinfo,hasRequireQualifiedAccessAttribute),rest],hasRequireQualifiedAccessAttribute
+                | _ -> NoResultsOrUsefulErrors,false
+
+            match unionSearch with
+            | Result (res :: _) when not hasRequireQualifiedAccessAttribute -> success res
+            | _ ->
+
+            // Something in a type?
             let tyconSearch = 
                 let tcrefs = LookupTypeNameInEntityMaybeHaveArity (ncenv.amap, id.idRange, ad, id.idText, (if isNil rest then typeNameResInfo.StaticArgsInfo else TypeNameResolutionStaticArgsInfo.Indefinite), modref)
                 let tcrefs = tcrefs |> List.map (fun tcref -> (resInfo,tcref))
                 if not (isNil rest) then 
                     let tcrefs = CheckForTypeLegitimacyAndMultipleGenericTypeAmbiguities (tcrefs, TypeNameResolutionInfo (ResolveTypeNamesToTypeRefs,TypeNameResolutionStaticArgsInfo.Indefinite), PermitDirectReferenceToGeneratedType.No, unionRanges m id.idRange)
-                    ResolveLongIdentInTyconRefs ncenv nenv  LookupKind.Expr (depth+1) m ad rest typeNameResInfo id.idRange tcrefs
+                    ResolveLongIdentInTyconRefs ncenv nenv LookupKind.Expr (depth+1) m ad rest typeNameResInfo id.idRange tcrefs
                 // Check if we've got some explicit type arguments 
                 else 
                     let tcrefs = CheckForTypeLegitimacyAndMultipleGenericTypeAmbiguities (tcrefs, typeNameResInfo, PermitDirectReferenceToGeneratedType.No, unionRanges m id.idRange)
@@ -2012,7 +2017,7 @@ let rec ResolveExprLongIdentInModuleOrNamespace (ncenv:NameResolver) nenv (typeN
 
             match tyconSearch with
             | Result (res :: _) -> success res
-            | _ -> 
+            | _ ->
 
             // Something in a sub-namespace or sub-module 
             let moduleSearch = 
@@ -2027,7 +2032,7 @@ let rec ResolveExprLongIdentInModuleOrNamespace (ncenv:NameResolver) nenv (typeN
                 else 
                     NoResultsOrUsefulErrors
 
-            match tyconSearch +++ moduleSearch with
+            match tyconSearch +++ moduleSearch +++ unionSearch with
             | Result [] ->
                 let predictedPossibleTypes =
                     modref.ModuleOrNamespaceType.AllEntities

tests/fsharpqa/Source/Conformance/InferenceProcedures/NameResolution/RequireQualifiedAccess/OnRecordVsUnion.fs

@@ -0,0 +1,11 @@
+// #Conformance #TypeInference #Attributes 
+// Verify the RequireQualifiedAccess attribute works on unions
+
+module A =
+    [<RequireQualifiedAccess>]
+    type U = | C
+
+    type C() =
+        static member M() = ()
+
+let x = A.C.M()

tests/fsharpqa/Source/Conformance/InferenceProcedures/NameResolution/RequireQualifiedAccess/OnRecordVsUnion2.fs

@@ -0,0 +1,19 @@
+// #Conformance #TypeInference #Attributes
+
+module Module =
+    type R = { a: int } with static member New = { a = 1 }
+    type Choice = | R of R
+open Module
+
+let record1 = R.New
+let choice1 v =
+    match v with
+    | R r -> r
+
+let newChoice = R { a = 1}
+
+let choice2 v =
+    match v with
+    | Module.R r -> r
+
+let newChoice2 = Module.R { a = 1}

tests/fsharpqa/Source/Conformance/InferenceProcedures/NameResolution/RequireQualifiedAccess/OnRecordVsUnion_NoRQA.fs

@@ -0,0 +1,10 @@
+// #Conformance #TypeInference #Attributes 
+// Verify the access works on unions without RQA
+
+module A =
+    type U = | C
+
+    type C() =
+        static member M() = ()
+
+let x:A.U = A.C

tests/fsharpqa/Source/Conformance/InferenceProcedures/NameResolution/RequireQualifiedAccess/OnRecordVsUnion_NoRQA2.fs

@@ -0,0 +1,10 @@
+// #Conformance #TypeInference #Attributes 
+// Verify the access works on unions without RQA
+
+module A =
+    type U = | C
+
+    type C() =
+        static member M() = ()
+
+let x = A.C

tests/fsharpqa/Source/Conformance/InferenceProcedures/NameResolution/RequireQualifiedAccess/OnUnionWithCaseOfSameName.fs

@@ -0,0 +1,9 @@
+// #Conformance #TypeInference #Attributes 
+// Verify the access works on unions where type name is case name
+
+module A =
+    type C =
+    | B 
+    | C
+
+let x = A.C

tests/fsharpqa/Source/Conformance/InferenceProcedures/NameResolution/RequireQualifiedAccess/OnUnionWithCaseOfSameName2.fs

@@ -0,0 +1,10 @@
+// #Conformance #TypeInference #Attributes 
+// Verify the access works on unions where type name is case name
+
+module A =
+    [<RequireQualifiedAccess>]
+    type C =
+    | B 
+    | C
+
+let x = A.C

tests/fsharpqa/Source/Conformance/InferenceProcedures/NameResolution/RequireQualifiedAccess/env.lst

@@ -1,5 +1,12 @@
 	SOURCE=OnRecord.fs			# OnRecord.fs
 	SOURCE=E_OnRecord.fs			# E_OnRecord.fs
 
+	SOURCE=OnRecordVsUnion.fs		# OnRecordVsUnion.fs
+	SOURCE=OnRecordVsUnion2.fs		# OnRecordVsUnion2.fs
 	SOURCE=OnDiscriminatedUnion.fs		# OnDiscriminatedUnion.fs
 	SOURCE=E_OnDiscriminatedUnion.fs	# E_OnDiscriminatedUnion.fs
+
+	SOURCE=OnRecordVsUnion_NoRQA.fs	# OnRecordVsUnion_NoRQA.fs
+	SOURCE=OnRecordVsUnion_NoRQA2.fs	# OnRecordVsUnion_NoRQA2.fs
+	SOURCE=OnUnionWithCaseOfSameName.fs	# OnUnionWithCaseOfSameName.fs
+	SOURCE=OnUnionWithCaseOfSameName2.fs	# OnUnionWithCaseOfSameName2.fs