When warning about comparing an unsigned int to being >= 0, don't issue a warning if the zero value was an

enum or was expanded from a macro.

Fixes: <rdar://problem/8414119>
llvm-svn: 114695

1 files changed, 11 insertions, 1 deletions

diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 790e7671ed9..c4e86875ed8 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -2449,7 +2449,17 @@ bool IsSameFloatAfterCast(const APValue &value,
 
 void AnalyzeImplicitConversions(Sema &S, Expr *E);
 
-bool IsZero(Sema &S, Expr *E) {
+static bool IsZero(Sema &S, Expr *E) {
+  // Suppress cases where we are comparing against an enum constant.
+  if (const DeclRefExpr *DR =
+      dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts()))
+    if (isa<EnumConstantDecl>(DR->getDecl()))
+      return false;
+
+  // Suppress cases where the '0' value is expanded from a macro.
+  if (E->getLocStart().isMacroID())
+    return false;
+
   llvm::APSInt Value;
   return E->isIntegerConstantExpr(Value, S.Context) && Value == 0;
 }