Merge pull request #65013 from tshortli/modify-accessor-cannot-be-more-available-5.9

[5.9] Sema: Downgrade over availability diagnostics to warnings for implicit decls

Author: tshortli

lib/Sema/TypeCheckAttr.cpp

@@ -1896,7 +1896,8 @@ void AttributeChecker::visitAvailableAttr(AvailableAttr *attr) {
   }
 
   // Skip the remaining diagnostics in swiftinterfaces.
-  auto *SF = D->getDeclContext()->getParentSourceFile();
+  auto *DC = D->getDeclContext();
+  auto *SF = DC->getParentSourceFile();
   if (SF && SF->Kind == SourceFileKind::Interface)
     return;
 
@@ -1926,7 +1927,7 @@ void AttributeChecker::visitAvailableAttr(AvailableAttr *attr) {
       return;
     }
 
-    if (auto *PD = dyn_cast<ProtocolDecl>(D->getDeclContext())) {
+    if (auto *PD = dyn_cast<ProtocolDecl>(DC)) {
       if (auto *VD = dyn_cast<ValueDecl>(D)) {
         if (VD->isProtocolRequirement() && !PD->isObjC()) {
           diagnoseAndRemoveAttr(attr,
@@ -1958,13 +1959,17 @@ void AttributeChecker::visitAvailableAttr(AvailableAttr *attr) {
       EnclosingAnnotatedRange.emplace(
           AvailabilityInference::availableRange(enclosingAttr, Ctx));
       if (!AttrRange.isContainedIn(*EnclosingAnnotatedRange)) {
-        // Members of extensions of nominal types with available ranges were
-        // not diagnosed previously, so only emit a warning in that case.
-        bool inExtension = isa<ExtensionDecl>(
-            D->getDeclContext()->getTopmostDeclarationDeclContext());
-        auto limit = (enclosingDecl != parent && inExtension)
-                         ? DiagnosticBehavior::Warning
-                         : DiagnosticBehavior::Unspecified;
+        auto limit = DiagnosticBehavior::Unspecified;
+        if (D->isImplicit()) {
+          // Incorrect availability for an implicit declaration is likely a
+          // compiler bug so make the diagnostic a warning.
+          limit = DiagnosticBehavior::Warning;
+        } else if (enclosingDecl != parent) {
+          // Members of extensions of nominal types with available ranges were
+          // not diagnosed previously, so only emit a warning in that case.
+          if (isa<ExtensionDecl>(DC->getTopmostDeclarationDeclContext()))
+            limit = DiagnosticBehavior::Warning;
+        }
         diagnose(D->isImplicit() ? enclosingDecl->getLoc()
                                  : attr->getLocation(),
                  diag::availability_decl_more_than_enclosing,

test/attr/attr_availability_maccatalyst_implicit.swift

@@ -1,4 +1,4 @@
-// RUN: %target-swift-frontend -I %t -I %S/Inputs/custom-modules -parse-stdlib -parse-as-library -typecheck -verify -target x86_64-apple-ios15.4-macabi %s
+// RUN: %target-swift-frontend -I %t -I %S/Inputs/custom-modules -parse-stdlib -parse-as-library -typecheck -verify -target %target-cpu-apple-ios15.4-macabi %s
 
 // REQUIRES: objc_interop
 // REQUIRES: maccatalyst_support
@@ -7,7 +7,17 @@ import Available_NSObject
 
 @available(iOS 15.0, *)
 open class OverAvailableClass: NSBaseClass {}
-// expected-error@-1 {{initializer cannot be more available than enclosing scope}}
+// expected-warning@-1 {{initializer cannot be more available than enclosing scope}}
 // expected-note@-2 {{initializer implicitly declared here with availability of Mac Catalyst 13.1 or newer}}
 // expected-note@-3 {{enclosing scope requires availability of Mac Catalyst 15.0 or newer}}
 
+extension NSBaseClass {
+  @available(iOS 15.0, *)
+  // expected-warning@+3 {{_modify accessor cannot be more available than enclosing scope}}
+  // expected-note@+2 {{_modify accessor implicitly declared here with availability of Mac Catalyst 13.1 or newer}}
+  // expected-note@+1 {{enclosing scope requires availability of Mac Catalyst 15.0 or newer}}
+  var property: Int {
+    get { 1 }
+    set {}
+  }
+}