[Macros] Diagnose availability of attached macros

(cherry picked from commit c3af8cb)

Author: DougGregor

lib/Sema/TypeCheckAccess.cpp

@@ -528,6 +528,7 @@ class AccessControlChecker : public AccessControlCheckerBase,
 
     DeclVisitor<AccessControlChecker>::visit(D);
     checkGlobalActorAccess(D);
+    checkAttachedMacrosAccess(D);
   }
 
   // Force all kinds to be handled at a lower level.
@@ -1260,6 +1261,18 @@ class AccessControlChecker : public AccessControlCheckerBase,
       noteLimitingImport(MD->getASTContext(), minImportLimit, complainRepr);
     }
   }
+
+  void checkAttachedMacrosAccess(const Decl *D) {
+    for (auto customAttrC : D->getSemanticAttrs().getAttributes<CustomAttr>()) {
+      auto customAttr = const_cast<CustomAttr *>(customAttrC);
+      auto *macroDecl = D->getResolvedMacro(customAttr);
+      if (macroDecl) {
+        diagnoseDeclAvailability(
+          macroDecl, customAttr->getTypeRepr()->getSourceRange(), nullptr,
+          ExportContext::forDeclSignature(const_cast<Decl *>(D)), llvm::None);
+      }
+    }
+  }
 };
 
 class UsableFromInlineChecker : public AccessControlCheckerBase,

test/Macros/macro_expand_peers.swift

@@ -231,3 +231,18 @@ func testStructWithPeers() {
   let x = SomeStructWithPeerProperties()
   print(x)
 }
+
+
+#if TEST_DIAGNOSTICS
+@available(*, deprecated, message: "This macro is deprecated.")
+@attached(peer, names: overloaded)
+macro deprecatedAddCompletionHandler() = #externalMacro(module: "MacroDefinition", type: "AddCompletionHandler")
+
+
+// expected-warning@+1{{'deprecatedAddCompletionHandler()' is deprecated: This macro is deprecated.}}
+@deprecatedAddCompletionHandler
+func fDeprecated(a: Int, for b: String, _ value: Double) async -> String {
+  return b
+}
+
+#endif