[Sema][ObjC] Allow silencing -Wobjc-designated-initializers warnings by

declaring an unavailable method in the subclass's extension that
overrides the designated initializer in the base class.

r243676 made changes to allow declaring the unavailable method in the
subclass interface to silence the warning. This commit additionally
allows declaring the unavailable method in the class extension.

rdar://problem/42731306

llvm-svn: 355175

2 files changed, 22 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaObjCProperty.cpp b/clang/lib/Sema/SemaObjCProperty.cpp
index 82e8def14ac..cea362fb425 100644
--- a/clang/lib/Sema/SemaObjCProperty.cpp
+++ b/clang/lib/Sema/SemaObjCProperty.cpp
@@ -2280,9 +2280,18 @@ void Sema::DiagnoseMissingDesignatedInitOverrides(
          I = DesignatedInits.begin(), E = DesignatedInits.end(); I != E; ++I) {
     const ObjCMethodDecl *MD = *I;
     if (!InitSelSet.count(MD->getSelector())) {
+      // Don't emit a diagnostic if the overriding method in the subclass is
+      // marked as unavailable.
       bool Ignore = false;
       if (auto *IMD = IFD->getInstanceMethod(MD->getSelector())) {
         Ignore = IMD->isUnavailable();
+      } else {
+        // Check the methods declared in the class extensions too.
+        for (auto *Ext : IFD->visible_extensions())
+          if (auto *IMD = Ext->getInstanceMethod(MD->getSelector())) {
+            Ignore = IMD->isUnavailable();
+            break;
+          }
       }
       if (!Ignore) {
         Diag(ImplD->getLocation(),
diff --git a/clang/test/SemaObjC/attr-designated-init.m b/clang/test/SemaObjC/attr-designated-init.m
index 3558916dbe5..7d1e7008e8e 100644
--- a/clang/test/SemaObjC/attr-designated-init.m
+++ b/clang/test/SemaObjC/attr-designated-init.m
@@ -389,6 +389,19 @@ __attribute__((objc_root_class))
 }
 @end
 
+@interface SubTest1Ext : Test1
+-(instancetype)initWithRequiredParameter:(id)foo NS_DESIGNATED_INITIALIZER;
+@end
+// Mark 'init' as unavailable in the extension to silence warning.
+@interface SubTest1Ext()
+-(instancetype)init NS_UNAVAILABLE;
+@end
+@implementation SubTest1Ext
+-(instancetype)initWithRequiredParameter:(id)foo {
+  return [super init];
+}
+@end
+
 @interface Test2 : NSObject
 @end
 @interface SubTest2 : Test2