Remove unused ref return error codes

src/Compilers/CSharp/Portable/CSharpResources.Designer.cs

@@ -6118,24 +6118,6 @@ internal class CSharpResources {
             }
         }
         
-        /// <summary>
-        ///   Looks up a localized string similar to &apos;{0}&apos; cannot be assigned a reference because it is not a by-reference local.
-        /// </summary>
-        internal static string ERR_MustBeRefAssignable {
-            get {
-                return ResourceManager.GetString("ERR_MustBeRefAssignable", resourceCulture);
-            }
-        }
-        
-        /// <summary>
-        ///   Looks up a localized string similar to Expected a by-reference local.
-        /// </summary>
-        internal static string ERR_MustBeRefAssignableLocal {
-            get {
-                return ResourceManager.GetString("ERR_MustBeRefAssignableLocal", resourceCulture);
-            }
-        }
-        
         /// <summary>
         ///   Looks up a localized string similar to In order for &apos;{0}&apos; to be applicable as a short circuit operator, its declaring type &apos;{1}&apos; must define operator true and operator false.
         /// </summary>

src/Compilers/CSharp/Portable/CSharpResources.resx

@@ -4804,12 +4804,6 @@ To remove the warning, you can use /reference instead (set the Embed Interop Typ
   <data name="ERR_RefReturnStructThis" xml:space="preserve">
     <value>Struct members cannot return 'this' or other instance members by reference</value>
   </data>
-  <data name="ERR_MustBeRefAssignable" xml:space="preserve">
-    <value>'{0}' cannot be assigned a reference because it is not a by-reference local</value>
-  </data>
-  <data name="ERR_MustBeRefAssignableLocal" xml:space="preserve">
-    <value>Expected a by-reference local</value>
-  </data>
   <data name="ERR_InitializeByValueVariableWithReference" xml:space="preserve">
     <value>Cannot initialize a by-value variable with a reference</value>
   </data>

src/Compilers/CSharp/Portable/Errors/ErrorCode.cs

@@ -1390,44 +1390,35 @@ internal enum ErrorCode
         ERR_MustHaveRefReturn = 8150,
         ERR_RefReturnMustHaveIdentityConversion = 8151,
         ERR_CloseUnimplementedInterfaceMemberWrongRefReturn = 8152,
-        ERR_VoidReturningMethodCannotReturnByRef = 8153,
+        ERR_RefReturningCallInExpressionTree = 8153,
         ERR_BadIteratorReturnRef = 8154,
         ERR_BadRefReturnExpressionTree = 8155,
-        ERR_RefReturningCallInExpressionTree = 8156,
-
-        ERR_RefReturnLvalueExpected = 8157,
-        ERR_RefReturnNonreturnableLocal = 8158,
-        ERR_RefReturnNonreturnableLocal2 = 8159,
-        ERR_RefReturnRangeVariable = 8160,
-        ERR_RefReturnRangeVariable2 = 8170,
-        ERR_RefReturnReadonly = 8171,
-        ERR_RefReturnReadonlyStatic = 8172,
-        ERR_RefReturnReadonly2 = 8173,
-        ERR_RefReturnReadonlyStatic2 = 8174,
-        ERR_RefReturnCall = 8175,
-        ERR_RefReturnCall2 = 8176,
-        ERR_RefReturnParameter = 8177,
-        ERR_RefReturnParameter2 = 8178,
-        ERR_RefReturnLocal = 8179,
-        ERR_RefReturnLocal2 = 8180,
-        ERR_RefReturnStructThis = 8181,
-
-        // Available  = 8182, 8183
-
-        ERR_MustBeRefAssignable = 8184,
-        ERR_MustBeRefAssignableLocal = 8185,
-        ERR_InitializeByValueVariableWithReference = 8186,
-        ERR_InitializeByReferenceVariableWithValue = 8187,
-        ERR_RefAssignmentMustHaveIdentityConversion = 8188,
-        ERR_ByReferenceVariableMustBeInitialized = 8189,
-
-        ERR_AnonDelegateCantUseLocal = 8190,
-        ERR_BadIteratorLocalType = 8191,
-        ERR_BadAsyncLocalType = 8192,
-        ERR_RefReturningCallAndAwait = 8193,
+        ERR_RefReturnLvalueExpected = 8156,
+        ERR_RefReturnNonreturnableLocal = 8157,
+        ERR_RefReturnNonreturnableLocal2 = 8158,
+        ERR_RefReturnRangeVariable = 8159,
+        ERR_RefReturnReadonly = 8160,
+        ERR_RefReturnReadonlyStatic = 8161,
+        ERR_RefReturnReadonly2 = 8162,
+        ERR_RefReturnReadonlyStatic2 = 8163,
+        ERR_RefReturnCall = 8164,
+        ERR_RefReturnCall2 = 8165,
+        ERR_RefReturnParameter = 8166,
+        ERR_RefReturnParameter2 = 8167,
+        ERR_RefReturnLocal = 8168,
+        ERR_RefReturnLocal2 = 8169,
+        ERR_RefReturnStructThis = 8170,
+        ERR_InitializeByValueVariableWithReference = 8171,
+        ERR_InitializeByReferenceVariableWithValue = 8172,
+        ERR_RefAssignmentMustHaveIdentityConversion = 8173,
+        ERR_ByReferenceVariableMustBeInitialized = 8174,
+        ERR_AnonDelegateCantUseLocal = 8175,
+        ERR_BadIteratorLocalType = 8176,
+        ERR_BadAsyncLocalType = 8177,
+        ERR_RefReturningCallAndAwait = 8178,
         #endregion diagnostics for ref locals and ref returns introduced in C# 7
 
-        // Available  = 8194, 8195
+        // Available  = 8179-8195
 
         #region diagnostics for out var
         ERR_ImplicitlyTypedOutVariableUsedInTheSameArgumentList = 8196,

src/Compilers/CSharp/Test/Semantic/Semantics/LambdaTests.cs

@@ -1193,13 +1193,13 @@ static void M()
 ";
 
             CreateCompilationWithMscorlib45(text).VerifyDiagnostics(
-                // (11,22): error CS8083: By-reference returns may only be used in by-reference returning methods.
+                // (11,22): error CS8149: By-reference returns may only be used in by-reference returning methods.
                 //         ME(() => ref i);
                 Diagnostic(ErrorCode.ERR_MustNotHaveRefReturn, "i").WithLocation(11, 22),
-                // (12,20): error CS8083: By-reference returns may only be used in by-reference returning methods.
+                // (12,20): error CS8149: By-reference returns may only be used in by-reference returning methods.
                 //         ME(() => { return ref i; });
                 Diagnostic(ErrorCode.ERR_MustNotHaveRefReturn, "return").WithLocation(12, 20),
-                // (13,23): error CS8083: By-reference returns may only be used in by-reference returning methods.
+                // (13,23): error CS8149: By-reference returns may only be used in by-reference returning methods.
                 //         ME(delegate { return ref i; });
                 Diagnostic(ErrorCode.ERR_MustNotHaveRefReturn, "return").WithLocation(13, 23));
         }
@@ -1223,13 +1223,13 @@ static void M()
 ";
 
             CreateCompilationWithMscorlib45(text).VerifyDiagnostics(
-                // (9,33): error CS8083: By-reference returns may only be used in by-reference returning methods.
+                // (9,33): error CS8149: By-reference returns may only be used in by-reference returning methods.
                 //         var e = new E(() => ref i);
                 Diagnostic(ErrorCode.ERR_MustNotHaveRefReturn, "i").WithLocation(9, 33),
-                // (10,27): error CS8083: By-reference returns may only be used in by-reference returning methods.
+                // (10,27): error CS8149: By-reference returns may only be used in by-reference returning methods.
                 //         e = new E(() => { return ref i; });
                 Diagnostic(ErrorCode.ERR_MustNotHaveRefReturn, "return").WithLocation(10, 27),
-                // (11,30): error CS8083: By-reference returns may only be used in by-reference returning methods.
+                // (11,30): error CS8149: By-reference returns may only be used in by-reference returning methods.
                 //         e = new E(delegate { return ref i; });
                 Diagnostic(ErrorCode.ERR_MustNotHaveRefReturn, "return").WithLocation(11, 30));
         }
@@ -1268,10 +1268,10 @@ static void M()
 ";
 
             CreateCompilationWithMscorlib45(text).VerifyDiagnostics(
-                // (18,13): error CS8084: By-value returns may only be used in by-value returning methods.
+                // (18,13): error CS8150: By-value returns may only be used in by-value returning methods.
                 //             return i;
                 Diagnostic(ErrorCode.ERR_MustHaveRefReturn, "return").WithLocation(18, 13),
-                // (23,17): error CS8083: By-reference returns may only be used in by-reference returning methods.
+                // (23,17): error CS8149: By-reference returns may only be used in by-reference returning methods.
                 //                 return ref i;
                 Diagnostic(ErrorCode.ERR_MustNotHaveRefReturn, "return").WithLocation(23, 17));
         }

src/Compilers/CSharp/Test/Semantic/Semantics/NameOfTests.cs

@@ -293,7 +293,7 @@ class Test<T>
                 // (28,20): error CS0103: The name 'List2' does not exist in the current context
                 //         s = nameof(List2<>.Add);
                 Diagnostic(ErrorCode.ERR_NameNotInContext, "List2<>").WithArguments("List2").WithLocation(28, 20),
-                // (31,20): error CS8083: An alias-qualified name is not an expression.
+                // (31,20): error CS8149: An alias-qualified name is not an expression.
                 //         s = nameof(global::Program); // not an expression
                 Diagnostic(ErrorCode.ERR_AliasQualifiedNameNotAnExpression, "global::Program").WithLocation(31, 20),
                 // (32,20): error CS0305: Using the generic type 'Test<T>' requires 1 type arguments
@@ -305,7 +305,7 @@ class Test<T>
                 // (33,20): error CS0841: Cannot use local variable 'b' before it is declared
                 //         s = nameof(b); // cannot use before declaration
                 Diagnostic(ErrorCode.ERR_VariableUsedBeforeDeclaration, "b").WithArguments("b").WithLocation(33, 20),
-                // (35,20): error CS8084: Type parameters are not allowed on a method group as an argument to 'nameof'.
+                // (35,20): error CS8150: Type parameters are not allowed on a method group as an argument to 'nameof'.
                 //         s = nameof(System.Linq.Enumerable.Select<int, int>); // type parameters not allowed on method group in nameof
                 Diagnostic(ErrorCode.ERR_NameofMethodGroupWithTypeParameters, "System.Linq.Enumerable.Select<int, int>").WithLocation(35, 20),
                 // (43,13): error CS0103: The name 'nameof' does not exist in the current context

src/Compilers/CSharp/Test/Semantic/Semantics/OutVarTests.cs

@@ -11724,7 +11724,7 @@ static object Test1(out int x, out int x2)
                                                             parseOptions: TestOptions.Regular);
 
             compilation.VerifyDiagnostics(
-                // (7,23): error CS8927: Reference to an implicitly-typed out variable 'x1' is not permitted in the same argument list.
+                // (7,23): error CS8181: Reference to an implicitly-typed out variable 'x1' is not permitted in the same argument list.
                 //                   out x1);
                 Diagnostic(ErrorCode.ERR_ImplicitlyTypedOutVariableUsedInTheSameArgumentList, "x1").WithArguments("x1").WithLocation(7, 23)
                 );
@@ -11765,7 +11765,7 @@ static object Test1(out int x, int x2)
                                                             parseOptions: TestOptions.Regular);
 
             compilation.VerifyDiagnostics(
-                // (7,25): error CS8927: Reference to an implicitly-typed out variable 'x1' is not permitted in the same argument list.
+                // (7,25): error CS8181: Reference to an implicitly-typed out variable 'x1' is not permitted in the same argument list.
                 //               Test1(out x1,
                 Diagnostic(ErrorCode.ERR_ImplicitlyTypedOutVariableUsedInTheSameArgumentList, "x1").WithArguments("x1").WithLocation(7, 25)
                 );