[PATCH] D149000: Update with warning message for comparison to NULL pointer

[Krishna Narayanan via Phabricator via cfe-commits]

Krishna-13-cyber updated this revision to Diff 516397.
Krishna-13-cyber added a comment.

- Update with addition of testcase
- There is an issue for which the build fails,actually when I replace the diagnostic by `comparison of address of 'x' not equal to a null pointer is always true` in **/clang/test/Sema/conditional-expr.c Line 89**,it shows `C99 forbids conditional expressions with only one void side` and vice versa.It regresses either ways.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D149000/new/

https://reviews.llvm.org/D149000

Files:
  clang/lib/Sema/SemaChecking.cpp
  clang/test/Sema/conditional-expr.c
  clang/test/Sema/warn-tautological-compare.c
  clang/test/SemaCXX/constant-expression-cxx2a.cpp


Index: clang/test/SemaCXX/constant-expression-cxx2a.cpp
===================================================================
--- clang/test/SemaCXX/constant-expression-cxx2a.cpp
+++ clang/test/SemaCXX/constant-expression-cxx2a.cpp
@@ -249,7 +249,7 @@
   // During construction of C, A is unambiguous subobject of dynamic type C.
   static_assert(g.c == (C*)&g);
   // ... but in the complete object, the same is not true, so the runtime fails.
-  static_assert(dynamic_cast<const A*>(static_cast<const C2*>(&g)) == nullptr);
+  static_assert(dynamic_cast<const A*>(static_cast<const C2*>(&g)) == nullptr); // expected-warning {{comparison of address of 'g' equal to a null pointer is always false}}
 
   // dynamic_cast<void*> produces a pointer to the object of the dynamic type.
   static_assert(g.f == (void*)(F*)&g);
Index: clang/test/Sema/warn-tautological-compare.c
===================================================================
--- clang/test/Sema/warn-tautological-compare.c
+++ clang/test/Sema/warn-tautological-compare.c
@@ -93,3 +93,9 @@
   x = array ? 1 : 0; // expected-warning {{address of array}}
   x = &x ? 1 : 0;    // expected-warning {{address of 'x'}}
 }
+
+void test4(void)
+{
+int *a = (void *) 0;
+int b = (&a) == ((void *) 0); // expected-warning {{comparison of address of 'a' equal to a null pointer is always false}}
+}
\ No newline at end of file
Index: clang/test/Sema/conditional-expr.c
===================================================================
--- clang/test/Sema/conditional-expr.c
+++ clang/test/Sema/conditional-expr.c
@@ -86,7 +86,7 @@
 
 int Postgresql(void) {
   char x;
-  return ((((&x) != ((void *) 0)) ? (*(&x) = ((char) 1)) : (void) ((void *) 0)), (unsigned long) ((void *) 0)); // expected-warning {{C99 forbids conditional expressions with only one void side}}
+  return ((((&x) != ((void *) 0)) ? (*(&x) = ((char) 1)) : (void) ((void *) 0)), (unsigned long) ((void *) 0)); // expected-warning {{comparison of address of 'x' not equal to a null pointer is always true}}
 }
 
 #define nil ((void*) 0)
Index: clang/lib/Sema/SemaChecking.cpp
===================================================================
--- clang/lib/Sema/SemaChecking.cpp
+++ clang/lib/Sema/SemaChecking.cpp
@@ -14723,7 +14723,7 @@
 
   bool IsAddressOf = false;
 
-  if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
+  if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E->IgnoreParenCasts())) {
     if (UO->getOpcode() != UO_AddrOf)
       return;
     IsAddressOf = true;


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