[Sema] Don't emit -Wmemset-transposed-args for memset(p,0,0)

Thanks to Arthur O'Dwyer for the suggestion!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@337706 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index 1e72083f3c785186326c72817d5302e1e8fb90a9..6492346f6ac567493433ef3e35d93e10321729d7 100644 (file)
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -8788,11 +8788,14 @@ static void CheckMemaccessSize(Sema &S, unsigned BId, const CallExpr *Call) {
   const Expr *SizeArg =
     Call->getArg(BId == Builtin::BImemset ? 2 : 1)->IgnoreImpCasts();
 
+  auto isLiteralZero = [](const Expr *E) {
+    return isa<IntegerLiteral>(E) && cast<IntegerLiteral>(E)->getValue() == 0;
+  };
+
   // If we're memsetting or bzeroing 0 bytes, then this is likely an error.
   SourceLocation CallLoc = Call->getRParenLoc();
   SourceManager &SM = S.getSourceManager();
-  if (isa<IntegerLiteral>(SizeArg) &&
-      cast<IntegerLiteral>(SizeArg)->getValue() == 0 &&
+  if (isLiteralZero(SizeArg) &&
       !isArgumentExpandedFromMacro(SM, CallLoc, SizeArg->getExprLoc())) {
 
     SourceLocation DiagLoc = SizeArg->getExprLoc();
@@ -8804,7 +8807,7 @@ static void CheckMemaccessSize(Sema &S, unsigned BId, const CallExpr *Call) {
                                     CallLoc, SM, S.getLangOpts()) == "bzero")) {
       S.Diag(DiagLoc, diag::warn_suspicious_bzero_size);
       S.Diag(DiagLoc, diag::note_suspicious_bzero_size_silence);
-    } else {
+    } else if (!isLiteralZero(Call->getArg(1)->IgnoreImpCasts())) {
       S.Diag(DiagLoc, diag::warn_suspicious_sizeof_memset) << 0;
       S.Diag(DiagLoc, diag::note_suspicious_sizeof_memset_silence) << 0;
     }

diff --git a/test/Sema/transpose-memset.c b/test/Sema/transpose-memset.c
index 0180d5051e5a016c9cb37e29454b6fa9fc0d9ccc..6112fde340662a574d3024f5ac2be8e8f4423cd4 100644 (file)
--- a/test/Sema/transpose-memset.c
+++ b/test/Sema/transpose-memset.c
@@ -22,6 +22,7 @@ int main() {
   memset(array, (int)sizeof(array), (0)); // no warning
   memset(array, (int)sizeof(array), 32); // no warning
   memset(array, 32, (0)); // no warning
+  memset(array, 0, 0); // no warning
 
   bzero(ptr, 0); // expected-warning{{'size' argument to bzero is '0'}} expected-note{{parenthesize the second argument to silence}}
   real_bzero(ptr, 0); // expected-warning{{'size' argument to bzero is '0'}} expected-note{{parenthesize the second argument to silence}}
@@ -55,6 +56,6 @@ void macros() {
 
   __builtin_memset(array, 0, ZERO); // no warning
   __builtin_bzero(array, ZERO);
-  __builtin_memset(array, 0, 0); // expected-warning{{'size' argument to memset}} // expected-note{{parenthesize}}
+  __builtin_memset(array, 1, 0); // expected-warning{{'size' argument to memset}} // expected-note{{parenthesize}}
   __builtin_bzero(array, 0); // expected-warning{{'size' argument to bzero}} // expected-note{{parenthesize}}
 }