[PATCH] D125521: [Diagnostic] Warn if the size argument of memset is character literal zero

[Chuanqi Xu via Phabricator via cfe-commits]

ChuanqiXu created this revision.
ChuanqiXu added a reviewer: efriedma.
ChuanqiXu added a project: clang.
Herald added a project: All.
ChuanqiXu requested review of this revision.
Herald added a subscriber: cfe-commits.

This tries to fix https://github.com/llvm/llvm-project/issues/55402


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D125521

Files:
  clang/lib/Sema/SemaChecking.cpp
  clang/test/Sema/transpose-memset.c


Index: clang/test/Sema/transpose-memset.c
===================================================================
--- clang/test/Sema/transpose-memset.c
+++ clang/test/Sema/transpose-memset.c
@@ -11,8 +11,10 @@
 int main(void) {
   memset(array, sizeof(array), 0); // expected-warning{{'size' argument to memset is '0'; did you mean to transpose the last two arguments?}} expected-note{{parenthesize the third argument to silence}}
   memset(array, sizeof(array), 0xff); // expected-warning{{setting buffer to a 'sizeof' expression; did you mean to transpose the last two arguments?}} expected-note{{cast the second argument to 'int' to silence}} expected-warning{{'memset' will always overflow; destination buffer has size 40, but size argument is 255}}
+  memset(array, sizeof(array), '\0'); // expected-warning{{'size' argument to memset is '0'; did you mean to transpose the last two arguments?}} expected-note{{parenthesize the third argument to silence}}
   memset(ptr, sizeof(ptr), 0); // expected-warning{{'size' argument to memset is '0'; did you mean to transpose the last two arguments?}} expected-note{{parenthesize the third argument to silence}}
   memset(ptr, sizeof(*ptr) * 10, 1); // expected-warning{{setting buffer to a 'sizeof' expression; did you mean to transpose the last two arguments?}} expected-note{{cast the second argument to 'int' to silence}}
+  memset(ptr, sizeof(ptr), '\0');    // expected-warning{{'size' argument to memset is '0'; did you mean to transpose the last two arguments?}} expected-note{{parenthesize the third argument to silence}}
   memset(ptr, 10 * sizeof(int *), 1); // expected-warning{{setting buffer to a 'sizeof' expression; did you mean to transpose the last two arguments?}} expected-note{{cast the second argument to 'int' to silence}}
   memset(ptr, 10 * sizeof(int *) + 10, 0xff); // expected-warning{{setting buffer to a 'sizeof' expression; did you mean to transpose the last two arguments?}} expected-note{{cast the second argument to 'int' to silence}}
   memset(ptr, sizeof(char) * sizeof(int *), 0xff); // expected-warning{{setting buffer to a 'sizeof' expression; did you mean to transpose the last two arguments?}} expected-note{{cast the second argument to 'int' to silence}}
Index: clang/lib/Sema/SemaChecking.cpp
===================================================================
--- clang/lib/Sema/SemaChecking.cpp
+++ clang/lib/Sema/SemaChecking.cpp
@@ -11200,7 +11200,10 @@
     Call->getArg(BId == Builtin::BImemset ? 2 : 1)->IgnoreImpCasts();
 
   auto isLiteralZero = [](const Expr *E) {
-    return isa<IntegerLiteral>(E) && cast<IntegerLiteral>(E)->getValue() == 0;
+    return (isa<IntegerLiteral>(E) &&
+            cast<IntegerLiteral>(E)->getValue() == 0) ||
+           (isa<CharacterLiteral>(E) &&
+            cast<CharacterLiteral>(E)->getValue() == 0);
   };
 
   // If we're memsetting or bzeroing 0 bytes, then this is likely an error.


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