r324514 - [PR36008] Avoid -Wsign-compare warning for enum constants in

[Alex Lorenz via cfe-commits]

Author: arphaman
Date: Wed Feb  7 12:45:39 2018
New Revision: 324514

URL: http://llvm.org/viewvc/llvm-project?rev=324514&view=rev
Log:
[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

Modified:
    cfe/trunk/lib/Sema/SemaChecking.cpp
    cfe/trunk/test/Sema/compare.c

Modified: cfe/trunk/lib/Sema/SemaChecking.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=324514&r1=324513&r2=324514&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaChecking.cpp (original)
+++ cfe/trunk/lib/Sema/SemaChecking.cpp Wed Feb  7 12:45:39 2018
@@ -8955,6 +8955,16 @@ static void AnalyzeComparison(Sema &S, B
   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;

Modified: cfe/trunk/test/Sema/compare.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/compare.c?rev=324514&r1=324513&r2=324514&view=diff
==============================================================================
--- cfe/trunk/test/Sema/compare.c (original)
+++ cfe/trunk/test/Sema/compare.c Wed Feb  7 12:45:39 2018
@@ -391,3 +391,16 @@ typedef char two_chars[2];
 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
+}