[ObjC] Add a -Wtautological-compare warning for BOOL
On macOS, BOOL is a typedef for signed char, but it should never hold a value
that isn't 1 or 0. Any code that expects a different value in their BOOL should
be fixed.
rdar://51954400
Differential revision: https://reviews.llvm.org/D63856
llvm-svn: 365408
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 92951a8..702a230 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -10188,9 +10188,16 @@
if (isa<EnumConstantDecl>(DR->getDecl()))
return true;
- // Suppress cases where the '0' value is expanded from a macro.
- if (E->getBeginLoc().isMacroID())
- return true;
+ // Suppress cases where the value is expanded from a macro, unless that macro
+ // is how a language represents a boolean literal. This is the case in both C
+ // and Objective-C.
+ SourceLocation BeginLoc = E->getBeginLoc();
+ if (BeginLoc.isMacroID()) {
+ StringRef MacroName = Lexer::getImmediateMacroName(
+ BeginLoc, S.getSourceManager(), S.getLangOpts());
+ return MacroName != "YES" && MacroName != "NO" &&
+ MacroName != "true" && MacroName != "false";
+ }
return false;
}
@@ -10382,11 +10389,17 @@
OtherT = AT->getValueType();
IntRange OtherRange = IntRange::forValueOfType(S.Context, OtherT);
+ // Special case for ObjC BOOL on targets where its a typedef for a signed char
+ // (Namely, macOS).
+ bool IsObjCSignedCharBool = S.getLangOpts().ObjC &&
+ S.NSAPIObj->isObjCBOOLType(OtherT) &&
+ OtherT->isSpecificBuiltinType(BuiltinType::SChar);
+
// Whether we're treating Other as being a bool because of the form of
// expression despite it having another type (typically 'int' in C).
bool OtherIsBooleanDespiteType =
!OtherT->isBooleanType() && Other->isKnownToHaveBooleanValue();
- if (OtherIsBooleanDespiteType)
+ if (OtherIsBooleanDespiteType || IsObjCSignedCharBool)
OtherRange = IntRange::forBoolType();
// Determine the promoted range of the other type and see if a comparison of
@@ -10417,10 +10430,21 @@
// Should be enough for uint128 (39 decimal digits)
SmallString<64> PrettySourceValue;
llvm::raw_svector_ostream OS(PrettySourceValue);
- if (ED)
+ if (ED) {
OS << '\'' << *ED << "' (" << Value << ")";
- else
+ } else if (auto *BL = dyn_cast<ObjCBoolLiteralExpr>(
+ Constant->IgnoreParenImpCasts())) {
+ OS << (BL->getValue() ? "YES" : "NO");
+ } else {
OS << Value;
+ }
+
+ if (IsObjCSignedCharBool) {
+ S.DiagRuntimeBehavior(E->getOperatorLoc(), E,
+ S.PDiag(diag::warn_tautological_compare_objc_bool)
+ << OS.str() << *Result);
+ return true;
+ }
// FIXME: We use a somewhat different formatting for the in-range cases and
// cases involving boolean values for historical reasons. We should pick a