[PR36008] Avoid -Wsign-compare warning for enum constants in
typeof expressions
This commit looks through typeof type at the original expression when diagnosing
-Wsign-compare to avoid an unfriendly diagnostic.
rdar://36588828
Differential Revision: https://reviews.llvm.org/D42561
llvm-svn: 324514
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 31c1b89..8f6eef5 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -8955,6 +8955,16 @@
LHS = LHS->IgnoreParenImpCasts();
RHS = RHS->IgnoreParenImpCasts();
+ if (!S.getLangOpts().CPlusPlus) {
+ // Avoid warning about comparison of integers with different signs when
+ // RHS/LHS has a `typeof(E)` type whose sign is different from the sign of
+ // the type of `E`.
+ if (const auto *TET = dyn_cast<TypeOfExprType>(LHS->getType()))
+ LHS = TET->getUnderlyingExpr()->IgnoreParenImpCasts();
+ if (const auto *TET = dyn_cast<TypeOfExprType>(RHS->getType()))
+ RHS = TET->getUnderlyingExpr()->IgnoreParenImpCasts();
+ }
+
// Check to see if one of the (unmodified) operands is of different
// signedness.
Expr *signedOperand, *unsignedOperand;
diff --git a/clang/test/Sema/compare.c b/clang/test/Sema/compare.c
index 7cd8ada..b2b486f 100644
--- a/clang/test/Sema/compare.c
+++ b/clang/test/Sema/compare.c
@@ -391,3 +391,16 @@
void test12(unsigned a) {
if (0 && -1 > a) { }
}
+
+// PR36008
+
+enum PR36008EnumTest {
+ kPR36008Value = 0,
+};
+
+void pr36008(enum PR36008EnumTest lhs) {
+ __typeof__(lhs) x = lhs;
+ __typeof__(kPR36008Value) y = (kPR36008Value);
+ if (x == y) x = y; // no warning
+ if (y == x) y = x; // no warning
+}