Sema: Don't emit 'add @available attribute' fixit on implicit declarations

Author: slavapestov

lib/Sema/TypeCheckAvailability.cpp

@@ -1237,7 +1237,8 @@ static const Decl *ancestorMemberLevelDeclForAvailabilityFixit(const Decl *D) {
   while (D) {
     D = relatedDeclForAvailabilityFixit(D);
 
-    if (D->getDeclContext()->isTypeContext() &&
+    if (!D->isImplicit() &&
+        D->getDeclContext()->isTypeContext() &&
         DeclAttribute::canAttributeAppearOnDecl(DeclAttrKind::DAK_Available,
                                                 D)) {
       break;

test/Sema/conformance_availability.swift

@@ -236,8 +236,7 @@ struct AssocConformanceDeprecated : Rider {
 struct AssocConformanceAvailable1 : Rider {
 // expected-error@-1 {{conformance of 'HasAvailableConformance1' to 'Horse' is only available in macOS 100 or newer}}
 // expected-note@-2 {{in associated type 'Self.H' (inferred as 'HasAvailableConformance1')}}
-// FIXME expected-note@-3 {{add @available attribute to enclosing initializer}}
-// expected-note@-4 {{add @available attribute to enclosing struct}}
+// expected-note@-3 {{add @available attribute to enclosing struct}}
 	typealias H = HasAvailableConformance1
 }