Use error=true in Obsolete attribute on IsByRefLikeAttribute for ref struct (#22492)

src/Compilers/CSharp/Portable/Symbols/Source/SourceNamedTypeSymbol.cs

@@ -1135,8 +1135,8 @@ internal override void AddSynthesizedAttributes(PEModuleBuilder moduleBuilder, r
                 {
                     AddSynthesizedAttribute(ref attributes, compilation.TrySynthesizeAttribute(WellKnownMember.System_ObsoleteAttribute__ctor,
                         ImmutableArray.Create(
-                                       new TypedConstant(compilation.GetSpecialType(SpecialType.System_String), TypedConstantKind.Primitive, PEModule.ByRefLikeMarker),
-                                       new TypedConstant(compilation.GetSpecialType(SpecialType.System_Boolean), TypedConstantKind.Primitive, false)), 
+                            new TypedConstant(compilation.GetSpecialType(SpecialType.System_String), TypedConstantKind.Primitive, PEModule.ByRefLikeMarker), // message
+                            new TypedConstant(compilation.GetSpecialType(SpecialType.System_Boolean), TypedConstantKind.Primitive, true)), // error=true
                         isOptionalUse: true));
                 }
             }

src/Compilers/CSharp/Test/Emit/Attributes/AttributeTests_IsByRefLike.cs

@@ -870,6 +870,36 @@ public struct S1 {}
                 );
         }
 
+        [Fact]
+        public void ObsoleteHasErrorEqualsTrue()
+        {
+            var text = @"public ref struct S {}";
+
+            CompileAndVerify(text, verify: false, symbolValidator: module =>
+            {
+                var type = module.ContainingAssembly.GetTypeByMetadataName("S");
+                Assert.True(type.IsByRefLikeType);
+
+                var attributes = type.GetAttributes();
+
+                Assert.Equal(2, attributes.Length);
+
+                var attributeType = attributes[0].AttributeClass;
+                Assert.Equal("System.Runtime.CompilerServices.IsByRefLikeAttribute", attributeType.ToDisplayString());
+                var assemblyName = module.ContainingAssembly.Name;
+                Assert.Equal(assemblyName, attributeType.ContainingAssembly.Name);
+                var accessibility = Accessibility.Internal;
+                Assert.Equal(accessibility, attributeType.DeclaredAccessibility);
+
+                var attribute = attributes[1];
+                Assert.Equal("System.ObsoleteAttribute", attribute.AttributeClass.ToDisplayString());
+                TypedConstant[] constructorArguments = attribute.ConstructorArguments.ToArray();
+                Assert.Equal(2, constructorArguments.Length);
+                Assert.Equal("Types with embedded references are not supported in this version of your compiler.", constructorArguments[0].Value);
+                Assert.Equal(true, constructorArguments[1].Value);
+            });
+        }
+
         [Fact]
         public void ObsoleteInWrongPlaces()
         {
@@ -1032,7 +1062,7 @@ namespace System
                 var attribute = attributes[1];
                 Assert.Equal("System.ObsoleteAttribute", attribute.AttributeClass.ToDisplayString());
                 Assert.Equal("Types with embedded references are not supported in this version of your compiler.", attribute.ConstructorArguments.ElementAt(0).Value);
-                Assert.Equal(false, attribute.ConstructorArguments.ElementAt(1).Value);
+                Assert.Equal(true, attribute.ConstructorArguments.ElementAt(1).Value); // error=true
             }
         }
 

src/Compilers/VisualBasic/Test/Emit/Attributes/AttributeTests_ObsoleteAttribute.vb

@@ -1469,6 +1469,39 @@ BC40000: 'Public Sub Bar()' is obsolete: 'hi'.
             compilation3.AssertTheseDiagnostics(expected2)
         End Sub
 
+        <Fact>
+        <WorkItem(22447, "https://github.com/dotnet/roslyn/issues/22447")>
+        Public Sub TestRefLikeType()
+            Dim csSource = <![CDATA[
+public ref struct S { }
+]]>
+
+            Dim csCompilation = CreateCSharpCompilation("Dll1", csSource.Value, parseOptions:=New CSharp.CSharpParseOptions(CSharp.LanguageVersion.CSharp7_2))
+            Dim ref = csCompilation.EmitToImageReference()
+
+            Dim vbSource =
+<compilation>
+    <file name="test.vb"><![CDATA[
+Module Program
+    Sub M(s As S)
+    End Sub
+End Module
+]]>
+    </file>
+</compilation>
+
+            Dim vbCompilation = CreateCompilationWithMscorlibAndVBRuntimeAndReferences(vbSource, {ref})
+
+            vbCompilation.AssertTheseDiagnostics((<![CDATA[
+BC30668: 'S' is obsolete: 'Types with embedded references are not supported in this version of your compiler.'.
+    Sub M(s As S)
+               ~
+]]>))
+            vbCompilation.VerifyDiagnostics(
+                Diagnostic(ERRID.ERR_UseOfObsoleteSymbol2, "S").WithArguments("S", "Types with embedded references are not supported in this version of your compiler.").WithLocation(2, 16)
+                )
+        End Sub
+
         <Fact(), WorkItem(858839, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/858839")>
         Public Sub Bug858839_1()
             Dim source1 =