[ObjCXX] Warn undeclared identifiers.

Instantiation dependence were not being handled correctly for OpqaueValueExpr
AST nodes. As a result, if an undeclared identifier was used in a CXXNewExpr
that is assigned to a ObjC property, there would be no error during parsing, and
there would be a crash during code gen. This patch makes sure that an error
will be issued during parsing in this case.

Before the fix, if CXXNewExpr has a typo, its InstantiationDependent will be
set to true, but if it is wrapped in a OpaqueValueExpr, the OpaqueValueExpr will
not be instantiation dependent, causing the TypoExpr not be to resolved. The fix
propagates InstantiationDependent to OpaqueValueExpr from its SourceExpr. It
also propagates the other instantiation bits.

rdar://24975562

Differential Revision: http://reviews.llvm.org/D18461

llvm-svn: 264444

clang/include/clang/AST/Expr.h

@@ -847,10 +847,12 @@ public:
                   ExprObjectKind OK = OK_Ordinary,
                   Expr *SourceExpr = nullptr)
     : Expr(OpaqueValueExprClass, T, VK, OK,
-           T->isDependentType(), 
+           T->isDependentType() ||
+           (SourceExpr && SourceExpr->isTypeDependent()),
            T->isDependentType() || 
            (SourceExpr && SourceExpr->isValueDependent()),
-           T->isInstantiationDependentType(),
+           T->isInstantiationDependentType() ||
+           (SourceExpr && SourceExpr->isInstantiationDependent()),
            false),
       SourceExpr(SourceExpr), Loc(Loc) {
   }

clang/include/clang/AST/Stmt.h

@@ -115,6 +115,7 @@ protected:
     friend class OverloadExpr; // ctor
     friend class PseudoObjectExpr; // ctor
     friend class AtomicExpr; // ctor
+    friend class OpaqueValueExpr; // ctor
     unsigned : NumStmtBits;
 
     unsigned ValueKind : 2;

clang/test/SemaObjCXX/typo-correction.mm

@@ -0,0 +1,23 @@
+// RUN: %clang_cc1 %s -verify -fsyntax-only
+
+class ClassA {};
+
+class ClassB {
+public:
+  ClassB(ClassA* parent=0);
+  ~ClassB();
+};
+
+@interface NSObject
+@end
+
+@interface InterfaceA : NSObject
+@property(nonatomic, assign) ClassA *m_prop1; // expected-note {{here}}
+@property(nonatomic, assign) ClassB *m_prop2;
+@end
+
+@implementation InterfaceA
+- (id)test {
+  self.m_prop2 = new ClassB(m_prop1); // expected-error {{use of undeclared identifier 'm_prop1'; did you mean '_m_prop1'?}}
+}
+@end