From eefa76e29e9f4a6c01e8c1e8d2f1a1d34a98817c Mon Sep 17 00:00:00 2001
From: Fariborz Jahanian <fjahanian@apple.com>
Date: Fri, 15 Apr 2011 17:04:42 +0000
Subject: [PATCH] Allow shadowin of 'self' in objc methods in cases where
 stand-alone ivar can be looked up in shadowed object. To fix gcc
 compatibility breakage. // rdar://9284603

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@129576 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Sema/SemaExpr.cpp                  | 10 ++++++++
 test/SemaObjC/self-declared-in-block.m | 33 ++++++++++++++++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index d2a3441f4c..9415673a77 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -2089,11 +2089,21 @@ Sema::LookupInObjCMethod(LookupResult &Lookup, Scope *S,
       if (const DeclRefExpr *DE = dyn_cast<DeclRefExpr>(base)) {
         const NamedDecl *ND = DE->getDecl();
         if (!isa<ImplicitParamDecl>(ND)) {
+          // relax the rule such that it is allowed to have a shadow 'self'
+          // where stand-alone ivar can be found in this 'self' object. 
+          // This is to match gcc's behavior.
+          ObjCInterfaceDecl *selfIFace = 0;
+          if (const ObjCObjectPointerType *OPT =
+              base->getType()->getAsObjCInterfacePointerType())
+            selfIFace = OPT->getInterfaceDecl();
+          if (!selfIFace || 
+              !selfIFace->lookupInstanceVariable(IV->getIdentifier())) {
             Diag(Loc, diag::error_implicit_ivar_access)
             << IV->getDeclName();
             Diag(ND->getLocation(), diag::note_declared_at);
             return ExprError();
           }
+        }
       }
       return Owned(new (Context)
                    ObjCIvarRefExpr(IV, IV->getType(), Loc,
diff --git a/test/SemaObjC/self-declared-in-block.m b/test/SemaObjC/self-declared-in-block.m
index c82089999c..4bd7202144 100644
--- a/test/SemaObjC/self-declared-in-block.m
+++ b/test/SemaObjC/self-declared-in-block.m
@@ -16,3 +16,36 @@
 
 @end
 
+
+// rdar://9284603
+@interface ShadowSelf
+{
+    int _anIvar;
+}
+@end
+
+@interface C {
+  int _cIvar;
+}
+@end
+
+@implementation ShadowSelf 
+- (void)doSomething {
+    __typeof(self) newSelf = self;
+    {
+        __typeof(self) self = newSelf;
+        (void)_anIvar;
+    }
+    {
+      C* self;	// expected-note {{declared here}}
+      (void) _anIvar; // expected-error {{instance variable '_anIvar' cannot be accessed because 'self' has been redeclared}}
+    }
+}
+- (void)doAThing {
+    ^{
+        id self;	// expected-note {{declared here}}
+	(void)_anIvar; // expected-error {{instance variable '_anIvar' cannot be accessed because 'self' has been redeclared}}
+    }();
+}
+@end
+
-- 
2.50.1