r194540 - PR10837: Warn if a null pointer constant is formed by a zero integer constant

[Richard Smith]

Author: rsmith
Date: Tue Nov 12 19:24:28 2013
New Revision: 194540

URL: http://llvm.org/viewvc/llvm-project?rev=194540&view=rev
Log:
PR10837: Warn if a null pointer constant is formed by a zero integer constant
expression that is not a zero literal, in C. Patch by Ivan A. Kosarev!

Added:
    cfe/trunk/test/Sema/warn-null.c
Modified:
    cfe/trunk/lib/Sema/SemaExpr.cpp

Modified: cfe/trunk/lib/Sema/SemaExpr.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExpr.cpp?rev=194540&r1=194539&r2=194540&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaExpr.cpp (original)
+++ cfe/trunk/lib/Sema/SemaExpr.cpp Tue Nov 12 19:24:28 2013
@@ -10614,8 +10614,17 @@ bool Sema::DiagnoseAssignmentResult(Assi
 
   switch (ConvTy) {
   case Compatible:
-      DiagnoseAssignmentEnum(DstType, SrcType, SrcExpr);
-      return false;
+    // See if a proper null pointer constant is to be assigned.
+    if (DstType->isAnyPointerType() && !SrcType->isAnyPointerType() &&
+        SrcExpr->isNullPointerConstant(Context,
+                                       Expr::NPC_NeverValueDependent) ==
+            Expr::NPCK_ZeroExpression &&
+        !isUnevaluatedContext())
+      Diag(SrcExpr->getExprLoc(), diag::warn_non_literal_null_pointer)
+        << DstType << SrcExpr->getSourceRange();
+
+    DiagnoseAssignmentEnum(DstType, SrcType, SrcExpr);
+    return false;
 
   case PointerToInt:
     DiagKind = diag::ext_typecheck_convert_pointer_int;

Added: cfe/trunk/test/Sema/warn-null.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/warn-null.c?rev=194540&view=auto
==============================================================================
--- cfe/trunk/test/Sema/warn-null.c (added)
+++ cfe/trunk/test/Sema/warn-null.c Tue Nov 12 19:24:28 2013
@@ -0,0 +1,6 @@
+// RUN: %clang_cc1 %s -verify -fsyntax-only
+
+// PR10837: warn if a non-pointer-typed expression is folded to a null pointer
+int *p = 0;
+int *q = '\0';  // expected-warning{{expression which evaluates to zero treated as a null pointer constant}}
+int *r = (1 - 1);  // expected-warning{{expression which evaluates to zero treated as a null pointer constant}}