Merge pull request #29184 from slavapestov/weak-link-extension-fix

AST: Weak-link declarations in extensions of weak-linked types

Author: slavapestov

lib/AST/Decl.cpp

@@ -785,6 +785,10 @@ AvailabilityContext Decl::getAvailabilityForLinkage() const {
   if (auto *accessor = dyn_cast<AccessorDecl>(this))
     return accessor->getStorage()->getAvailabilityForLinkage();
 
+  if (auto *ext = dyn_cast<ExtensionDecl>(this))
+    if (auto *nominal = ext->getExtendedNominal())
+      return nominal->getAvailabilityForLinkage();
+
   auto *dc = getDeclContext();
   if (auto *ext = dyn_cast<ExtensionDecl>(dc))
     return ext->getAvailabilityForLinkage();
@@ -806,6 +810,10 @@ bool Decl::isAlwaysWeakImported() const {
   if (auto *accessor = dyn_cast<AccessorDecl>(this))
     return accessor->getStorage()->isAlwaysWeakImported();
 
+  if (auto *ext = dyn_cast<ExtensionDecl>(this))
+    if (auto *nominal = ext->getExtendedNominal())
+      return nominal->isAlwaysWeakImported();
+
   auto *dc = getDeclContext();
   if (auto *ext = dyn_cast<ExtensionDecl>(dc))
     return ext->isAlwaysWeakImported();

test/IRGen/Inputs/weak_import_extension_helper.swift

@@ -0,0 +1,8 @@
+@available(macOS 10.60, *)
+public struct Foo {
+  public init() {}
+}
+
+extension Foo {
+  public func extensionMethod() {}
+}

test/IRGen/weak_import_extension.swift

@@ -0,0 +1,22 @@
+// RUN: %empty-directory(%t)
+//
+// RUN: %target-swift-frontend -enable-library-evolution -emit-module -target x86_64-apple-macosx10.60 -emit-module-path %t/weak_import_extension_helper.swiftmodule -parse-as-library %S/Inputs/weak_import_extension_helper.swift
+// RUN: %target-swift-frontend -primary-file %s -I %t -emit-ir -target x86_64-apple-macosx10.50 | %FileCheck %s --check-prefix=CHECK-OLD
+// RUN: %target-swift-frontend -primary-file %s -I %t -emit-ir -target x86_64-apple-macosx10.60 | %FileCheck %s --check-prefix=CHECK-NEW
+//
+// REQUIRES: OS=macosx
+
+import weak_import_extension_helper
+
+@available(macOS 10.60, *)
+public func callsExtensionMethod() {
+  Foo().extensionMethod()
+}
+
+// CHECK-OLD: declare extern_weak swiftcc %swift.metadata_response @"$s28weak_import_extension_helper3FooVMa"
+// CHECK-OLD: declare extern_weak swiftcc void @"$s28weak_import_extension_helper3FooVACycfC"
+// CHECK-OLD: declare extern_weak swiftcc void @"$s28weak_import_extension_helper3FooV0C6MethodyyF"
+
+// CHECK-NEW: declare swiftcc %swift.metadata_response @"$s28weak_import_extension_helper3FooVMa"
+// CHECK-NEW: declare swiftcc void @"$s28weak_import_extension_helper3FooVACycfC"
+// CHECK-NEW: declare swiftcc void @"$s28weak_import_extension_helper3FooV0C6MethodyyF"