[Objective-c] Fix a crash in WeakObjectProfileTy::getBaseInfo

[ahatanak]

Summary

The crash occurs in WeakObjectProfileTy::getBaseInfo when getBase() is called on an ObjCPropertyRefExpr object whose receiver is an interface. This patch fixes the crash by checking the type of the receiver and setting IsExact to true if it is an interface.

[jordan_rose]

Ah, of course! Thanks for catching this, Akira. Can you add this case to the table in the doc comment for WeakObjectProfileTy? (That's how I convinced myself it was correct.)

cfe/trunk/lib/Sema/ScopeInfo.cpp

FunctionScopeInfo::WeakObjectProfileTy::getBaseInfo(const Expr *E) {
   }
   case Stmt::PseudoObjectExprClass: {
     const PseudoObjectExpr *POE = cast<PseudoObjectExpr>(E);
     const ObjCPropertyRefExpr *BaseProp =
       dyn_cast<ObjCPropertyRefExpr>(POE->getSyntacticForm());
     if (BaseProp) {
       D = getBestPropertyDecl(BaseProp);
 
+      if (BaseProp->isClassReceiver())
+        IsExact = true;
+      else {
         const Expr *DoubleBase = BaseProp->getBase();
         if (const OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(DoubleBase))
           DoubleBase = OVE->getSourceExpr();
 
         IsExact = DoubleBase->isObjCSelfExpr();
       }
+    }
     break;
   }
   default:
     break;
   }
 
   return BaseInfoTy(D, IsExact);
 }

cfe/trunk/test/SemaObjC/arc-repeated-weak.mm

 
 @implementation INTF
 - (void) Meth : (id) data
 {
   data = data ?: NSNull.null;
 }
 @end
 
+// This used to crash in WeakObjectProfileTy::getBaseInfo when getBase() was
+// called on an ObjCPropertyRefExpr object whose receiver was an interface.
+
+@class NSString;
+@interface NSBundle
++(NSBundle *)foo;
+@property NSString *prop;
+@end
+
+void foo() {
+  NSString * t = NSBundle.foo.prop;
+}