Support all null pointer literals in format strings.

llvm-svn: 150276

clang/lib/Sema/SemaChecking.cpp

@@ -1369,6 +1369,13 @@ bool Sema::SemaCheckStringLiteral(const Expr *E, Expr **Args,
 
   E = E->IgnoreParenCasts();
 
+  if (E->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNotNull))
+    // Technically -Wformat-nonliteral does not warn about this case.
+    // The behavior of printf and friends in this case is implementation
+    // dependent.  Ideally if the format string cannot be null then
+    // it should have a 'nonnull' attribute in the function prototype.
+    return true;
+
   switch (E->getStmtClass()) {
   case Stmt::BinaryConditionalOperatorClass:
   case Stmt::ConditionalOperatorClass: {
@@ -1381,14 +1388,6 @@ bool Sema::SemaCheckStringLiteral(const Expr *E, Expr **Args,
                                  inFunctionCall);
   }
 
-  case Stmt::GNUNullExprClass:
-  case Stmt::IntegerLiteralClass:
-    // Technically -Wformat-nonliteral does not warn about this case.
-    // The behavior of printf and friends in this case is implementation
-    // dependent.  Ideally if the format string cannot be null then
-    // it should have a 'nonnull' attribute in the function prototype.
-    return true;
-
   case Stmt::ImplicitCastExprClass: {
     E = cast<ImplicitCastExpr>(E)->getSubExpr();
     goto tryAgain;

clang/test/SemaCXX/format-strings-0x.cpp

@@ -10,4 +10,6 @@ void f(char **sp, float *fp) {
 
   printf("%a", 1.0);
   scanf("%afoobar", fp);
+  printf(nullptr);
+  printf(*sp); // expected-warning {{not a string literal}}
 }

clang/test/SemaCXX/format-strings.cpp

@@ -47,6 +47,8 @@ extern "C" {
 
 void rdar8269537(const char *f)
 {
+  test_null_format(false); // expected-warning {{null from a constant boolean}}
+  test_null_format(0); // no-warning
   test_null_format(__null); // no-warning
   test_null_format(f); // expected-warning {{not a string literal}}
 }