[objc_direct] fix uniquing when re-declaring a readwrite-direct property

[MadCoder]

Summary

ObjCMethodDecl::getCanonicalDecl() for re-declared readwrite properties,
only looks in the ObjCInterface for the declaration of the setter
method, which it won't find.

When the method is a property accessor, we must look in extensions for a
possible redeclaration.

Extend the CG test to cover this issue.

Radar-Id: rdar://problem/57991337

[arphaman]

LGTM, But we should also have a test in Sema that verifies it works, and also covers class properties in addition to the instance ones. I can add one when committing (@MadCoder still doesn't have commit access).

[arphaman]

I couldn't come up with a reasonable Sema-based test, so I'm going to commit this as it is.

clang/lib/AST/DeclObjC.cpp

ObjCMethodDecl *ObjCMethodDecl::getNextRedeclarationImpl() {
 
   return Redecl ? Redecl : this;
 }
 
 ObjCMethodDecl *ObjCMethodDecl::getCanonicalDecl() {
   auto *CtxD = cast<Decl>(getDeclContext());
 
   if (auto *ImplD = dyn_cast<ObjCImplementationDecl>(CtxD)) {
-    if (ObjCInterfaceDecl *IFD = ImplD->getClassInterface())
+    if (ObjCInterfaceDecl *IFD = ImplD->getClassInterface()) {
       if (ObjCMethodDecl *MD = IFD->getMethod(getSelector(),
                                               isInstanceMethod()))
         return MD;
+      // readwrite properties may have been re-declared in an extension.
+      // look harder.
+      if (isPropertyAccessor())
+        for (auto *Ext : IFD->known_extensions())
+          if (ObjCMethodDecl *MD =
+                  Ext->getMethod(getSelector(), isInstanceMethod()))
+            return MD;
+    }
   } else if (auto *CImplD = dyn_cast<ObjCCategoryImplDecl>(CtxD)) {
     if (ObjCCategoryDecl *CatD = CImplD->getCategoryDecl())
       if (ObjCMethodDecl *MD = CatD->getMethod(getSelector(),
                                                isInstanceMethod()))
         return MD;
   }
 
   if (isRedeclaration()) {

clang/test/CodeGenObjC/direct-method.m

 int useRoot(Root *r) {
   // CHECK-LABEL: define i32 @useRoot
   // CHECK: %{{[^ ]*}} = call i32 bitcast {{.*}} @"\01-[Root getInt]"
   // CHECK: %{{[^ ]*}} = call i32 bitcast {{.*}} @"\01-[Root intProperty]"
   // CHECK: %{{[^ ]*}} = call i32 bitcast {{.*}} @"\01-[Root intProperty2]"
   return [r getInt] + [r intProperty] + [r intProperty2];
 }
 
+int useFoo(Foo *f) {
+  // CHECK-LABEL: define i32 @useFoo
+  // CHECK: call void bitcast {{.*}} @"\01-[Foo setGetDynamic_setDirect:]"
+  // CHECK: %{{[^ ]*}} = call i32 bitcast {{.*}} @"\01-[Foo getDirect_setDynamic]"
+  [f setGetDynamic_setDirect:1];
+  return [f getDirect_setDynamic];
+}
+
 __attribute__((objc_root_class))
 @interface RootDeclOnly
 @property(direct, readonly) int intProperty;
 @end
 
 int useRootDeclOnly(RootDeclOnly *r) {
   // CHECK-LABEL: define i32 @useRootDeclOnly
   // CHECK: %{{[^ ]*}} = call i32 bitcast {{.*}} @"\01-[RootDeclOnly intProperty]"
   return [r intProperty];
 }