Exempt char array initializers from -Wconstant-converion.
Sometimes, char arrays are used as bit storage, with no difference made between
signed and unsigned char. Thus, it is reasonable to use 0 to 255 instead of
-128 to 127 and not trigger this warning.
llvm-svn: 259947
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 295ff71..9c3f721 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -7400,6 +7400,32 @@
}
}
+// Helper function to filter out cases for constant width constant conversion.
+// Don't warn on char array initialization or for non-decimal values.
+static bool isSameWidthConstantConversion(Sema &S, Expr *E, QualType T,
+ SourceLocation CC) {
+ // If initializing from a constant, and the constant starts with '0',
+ // then it is a binary, octal, or hexadecimal. Allow these constants
+ // to fill all the bits, even if there is a sign change.
+ if (auto *IntLit = dyn_cast<IntegerLiteral>(E->IgnoreParenImpCasts())) {
+ const char FirstLiteralCharacter =
+ S.getSourceManager().getCharacterData(IntLit->getLocStart())[0];
+ if (FirstLiteralCharacter == '0')
+ return false;
+ }
+
+ // If the CC location points to a '{', and the type is char, then assume
+ // assume it is an array initialization.
+ if (CC.isValid() && T->isCharType()) {
+ const char FirstContextCharacter =
+ S.getSourceManager().getCharacterData(CC)[0];
+ if (FirstContextCharacter == '{')
+ return false;
+ }
+
+ return true;
+}
+
void CheckImplicitConversion(Sema &S, Expr *E, QualType T,
SourceLocation CC, bool *ICContext = nullptr) {
if (E->isTypeDependent() || E->isValueDependent()) return;
@@ -7610,32 +7636,21 @@
// cause a negative value to be stored.
llvm::APSInt Value;
- if (E->EvaluateAsInt(Value, S.Context, Expr::SE_AllowSideEffects)) {
- if (!S.SourceMgr.isInSystemMacro(CC)) {
+ if (E->EvaluateAsInt(Value, S.Context, Expr::SE_AllowSideEffects) &&
+ !S.SourceMgr.isInSystemMacro(CC)) {
+ if (isSameWidthConstantConversion(S, E, T, CC)) {
+ std::string PrettySourceValue = Value.toString(10);
+ std::string PrettyTargetValue = PrettyPrintInRange(Value, TargetRange);
- IntegerLiteral *IntLit =
- dyn_cast<IntegerLiteral>(E->IgnoreParenImpCasts());
-
- // If initializing from a constant, and the constant starts with '0',
- // then it is a binary, octal, or hexadecimal. Allow these constants
- // to fill all the bits, even if there is a sign change.
- if (!IntLit ||
- *(S.getSourceManager().getCharacterData(IntLit->getLocStart())) !=
- '0') {
-
- std::string PrettySourceValue = Value.toString(10);
- std::string PrettyTargetValue =
- PrettyPrintInRange(Value, TargetRange);
-
- S.DiagRuntimeBehavior(
- E->getExprLoc(), E,
- S.PDiag(diag::warn_impcast_integer_precision_constant)
- << PrettySourceValue << PrettyTargetValue << E->getType() << T
- << E->getSourceRange() << clang::SourceRange(CC));
- return;
- }
+ S.DiagRuntimeBehavior(
+ E->getExprLoc(), E,
+ S.PDiag(diag::warn_impcast_integer_precision_constant)
+ << PrettySourceValue << PrettyTargetValue << E->getType() << T
+ << E->getSourceRange() << clang::SourceRange(CC));
+ return;
}
}
+
// Fall through for non-constants to give a sign conversion warning.
}