Top-level macros and type aliases can get @available attributes and @unsafe

Author: DougGregor

lib/Sema/TypeCheckAvailability.cpp

@@ -1853,8 +1853,8 @@ static bool isTypeLevelDeclForAvailabilityFixit(const Decl *D) {
 
   bool IsModuleScopeContext = D->getDeclContext()->isModuleScopeContext();
 
-  // We consider global functions to be "type level"
-  if (isa<FuncDecl>(D)) {
+  // We consider global functions, type aliases, and macros to be "type level"
+  if (isa<FuncDecl>(D) || isa<MacroDecl>(D) || isa<TypeAliasDecl>(D)) {
     return IsModuleScopeContext;
   }
 
@@ -4073,8 +4073,6 @@ class ExprAvailabilityWalker : public BaseDiagnosticWalker {
 };
 } // end anonymous namespace
 
-llvm::DenseSet<const Decl *> reportedDecls;
-
 static void suggestUnsafeOnEnclosingDecl(
     SourceRange referenceRange, const DeclContext *referenceDC) {
   if (referenceRange.isInvalid())
@@ -4092,9 +4090,6 @@ static void suggestUnsafeOnEnclosingDecl(
   if (!decl)
     return;
 
-  if (!reportedDecls.insert(decl).second)
-    return;
-  
   if (versionCheckNode.has_value()) {
     // The unsafe construct is inside the body of the entity, so suggest
     // @safe(unchecked) on the declaration.

test/Macros/macro_availability_macosx.swift

@@ -10,6 +10,7 @@ struct X { }
 
 @freestanding(expression) macro m1() -> X = #externalMacro(module: "A", type: "B") // expected-error{{'X' is only available in macOS 12.0 or newer}}
 // expected-warning@-1{{external macro implementation type 'A.B' could not be found for macro 'm1()'}}
+// expected-note@-2{{add @available attribute to enclosing macro}}
 
 @available(macOS 12.0, *)
 @freestanding(expression) macro m2() -> X = #externalMacro(module: "A", type: "B")

test/Unsafe/unsafe.swift

@@ -92,6 +92,7 @@ func testMe(
 // -----------------------------------------------------------------------
 // Various declaration kinds
 // -----------------------------------------------------------------------
+// expected-note@+1{{make type alias 'SuperUnsafe' @unsafe to indicate that its use is not memory-safe}}{{1-1=@unsafe }}
 typealias SuperUnsafe = UnsafeSuper // expected-warning{{reference to unsafe class 'UnsafeSuper' [Unsafe]}}
 @unsafe typealias SuperUnsafe2 = UnsafeSuper