[clang] 3bef90d - [Diagnostic] Warn if the size argument of memset is character literal

[Chuanqi Xu via cfe-commits]

Author: Chuanqi Xu
Date: 2022-05-16T10:07:01+08:00
New Revision: 3bef90dff64fc717c5d5e33a4d5fb47a4566d04a

URL: https://github.com/llvm/llvm-project/commit/3bef90dff64fc717c5d5e33a4d5fb47a4566d04a
DIFF: https://github.com/llvm/llvm-project/commit/3bef90dff64fc717c5d5e33a4d5fb47a4566d04a.diff

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

Closing https://github.com/llvm/llvm-project/issues/55402

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D125521

Added: 
    

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

Removed: 
    


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diff  --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 0cdceb47b7389..4c4041a2d68ab 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -11200,7 +11200,10 @@ static void CheckMemaccessSize(Sema &S, unsigned BId, const CallExpr *Call) {
     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.

diff  --git a/clang/test/Sema/transpose-memset.c b/clang/test/Sema/transpose-memset.c
index 2503fe43458c8..7d83b8e336a08 100644
--- a/clang/test/Sema/transpose-memset.c
+++ b/clang/test/Sema/transpose-memset.c
@@ -11,8 +11,10 @@ int *ptr;
 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}}