[Diagnostics] Emit better -Wbool-operation's warning message if we known that the result is always true

llvm-svn: 373973
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index eeddff6..de8e1ef 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -11896,6 +11896,13 @@
   if (E->isTypeDependent() || E->isValueDependent())
     return;
 
+  if (const auto *UO = dyn_cast<UnaryOperator>(E))
+    if (UO->getOpcode() == UO_Not &&
+        UO->getSubExpr()->isKnownToHaveBooleanValue())
+      S.Diag(UO->getBeginLoc(), diag::warn_bitwise_negation_bool)
+          << OrigE->getSourceRange() << T->isBooleanType()
+          << FixItHint::CreateReplacement(UO->getBeginLoc(), "!");
+
   // For conditional operators, we analyze the arguments as if they
   // were being fed directly into the output.
   if (isa<ConditionalOperator>(E)) {