Fix for PR20110: Don't assume that the subexpression of a bit cast has pointer type if the bit cast has pointer type

[rtrieu]

Summary

When a bit cast expression has pointer type, don't assume that the subexpression also has pointer type. It is possible that the subexpression is a value type instead. This patch checks the type of the subexpression and calls the proper function. Prevents the assertion failure reported in PR20110.

http://llvm.org/bugs/show_bug.cgi?id=20110

[rtrieu]

Have the bit cast return a null pointer if the sub expression is not a pointer. Also note in the test that the template definitions should produce an error in C++11 mode.

[rsmith]

LGTM

[rtrieu]

Closed by commit rL212160 (authored by @rtrieu).

lib/Sema/SemaChecking.cpp

static Expr *EvalAddr(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars,
   case Stmt::CXXFunctionalCastExprClass:
   case Stmt::ObjCBridgedCastExprClass:
   case Stmt::CXXStaticCastExprClass:
   case Stmt::CXXDynamicCastExprClass:
   case Stmt::CXXConstCastExprClass:
   case Stmt::CXXReinterpretCastExprClass: {
     Expr* SubExpr = cast<CastExpr>(E)->getSubExpr();
     switch (cast<CastExpr>(E)->getCastKind()) {
-    case CK_BitCast:
     case CK_LValueToRValue:
     case CK_NoOp:
     case CK_BaseToDerived:
     case CK_DerivedToBase:
     case CK_UncheckedDerivedToBase:
     case CK_Dynamic:
     case CK_CPointerToObjCPointerCast:
     case CK_BlockPointerToObjCPointerCast:
     case CK_AnyPointerToBlockPointerCast:
       return EvalAddr(SubExpr, refVars, ParentDecl);
 
     case CK_ArrayToPointerDecay:
       return EvalVal(SubExpr, refVars, ParentDecl);
 
+    case CK_BitCast:
+      if (SubExpr->getType()->isAnyPointerType() ||
+          SubExpr->getType()->isBlockPointerType() ||
+          SubExpr->getType()->isObjCQualifiedIdType())
+        return EvalAddr(SubExpr, refVars, ParentDecl);
+      else
+        return nullptr;
+
     default:
       return nullptr;
     }
   }
 
   case Stmt::MaterializeTemporaryExprClass:
     if (Expr *Result = EvalAddr(
                          cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),

test/SemaCXX/PR20110.cpp

+// RUN: %clang_cc1 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
+// expected-no-diagnostics
+
+// FIXME: These templates should trigger errors in C++11 mode.
+
+template <char const *p>
+class A {
+  char const *get_p() { return *p; }
+};
+template <int p>
+class B {
+  char const *get_p() { return p; }
+};
+