Revert "[Sema] Diagnose tautological comparison with type's min/max values"
This reverts r315614,r315615,r315621,r315622
Breaks http://bb9.pgr.jp/#/builders/20/builds/59
/home/bb9/bootstrap-clang-libcxx-lld-i686-linux/llvm-project/libcxx/test/std/experimental/filesystem/fs.op.funcs/fs.op.last_write_time/last_write_time.pass.cpp:95:17: error: comparison 'long long' > 9223372036854775807 is always false [-Werror,-Wtautological-constant-compare]
if (max_sec > Lim::max()) return false;
~~~~~~~ ^ ~~~~~~~~~~
/home/bb9/bootstrap-clang-libcxx-lld-i686-linux/llvm-project/libcxx/test/std/experimental/filesystem/fs.op.funcs/fs.op.last_write_time/last_write_time.pass.cpp:124:13: error: comparison 'long long' < -9223372036854775808 is always false [-Werror,-Wtautological-constant-compare]
if (sec < Lim::min() || sec > Lim::max()) return false;
~~~ ^ ~~~~~~~~~~
/home/bb9/bootstrap-clang-libcxx-lld-i686-linux/llvm-project/libcxx/test/std/experimental/filesystem/fs.op.funcs/fs.op.last_write_time/last_write_time.pass.cpp:124:33: error: comparison 'long long' > 9223372036854775807 is always false [-Werror,-Wtautological-constant-compare]
if (sec < Lim::min() || sec > Lim::max()) return false;
~~~ ^ ~~~~~~~~~~
3 errors generated.
--
I'm not yet sure what is the proper fix.
llvm-svn: 315631
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index f0e302d..9a94900 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -8553,71 +8553,19 @@
void AnalyzeImplicitConversions(Sema &S, Expr *E, SourceLocation CC);
-bool IsEnumConstOrFromMacro(Sema &S, Expr *E) {
+bool IsZero(Sema &S, Expr *E) {
// Suppress cases where we are comparing against an enum constant.
if (const DeclRefExpr *DR =
dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts()))
if (isa<EnumConstantDecl>(DR->getDecl()))
- return true;
+ return false;
// Suppress cases where the '0' value is expanded from a macro.
if (E->getLocStart().isMacroID())
- return true;
+ return false;
- return false;
-}
-
-bool isNonBooleanIntegerValue(Expr *E) {
- return !E->isKnownToHaveBooleanValue() && E->getType()->isIntegerType();
-}
-
-bool isNonBooleanUnsignedValue(Expr *E) {
- // We are checking that the expression is not known to have boolean value,
- // is an integer type; and is either unsigned after implicit casts,
- // or was unsigned before implicit casts.
- return isNonBooleanIntegerValue(E) &&
- (!E->getType()->isSignedIntegerType() ||
- !E->IgnoreParenImpCasts()->getType()->isSignedIntegerType());
-}
-
-enum class LimitType {
- Max, // e.g. 32767 for short
- Min // e.g. -32768 for short
-};
-
-/// Checks whether Expr 'Constant' may be the
-/// std::numeric_limits<>::max() or std::numeric_limits<>::min()
-/// of the Expr 'Other'. If true, then returns the limit type (min or max).
-/// The Value is the evaluation of Constant
-llvm::Optional<LimitType> IsTypeLimit(Sema &S, Expr *Constant, Expr *Other,
- const llvm::APSInt &Value) {
- if (IsEnumConstOrFromMacro(S, Constant))
- return llvm::Optional<LimitType>();
-
- if (isNonBooleanUnsignedValue(Other) && Value == 0)
- return LimitType::Min;
-
- // TODO: Investigate using GetExprRange() to get tighter bounds
- // on the bit ranges.
- QualType OtherT = Other->IgnoreParenImpCasts()->getType();
- if (const auto *AT = OtherT->getAs<AtomicType>())
- OtherT = AT->getValueType();
-
- IntRange OtherRange = IntRange::forValueOfType(S.Context, OtherT);
-
- if (llvm::APSInt::isSameValue(
- llvm::APSInt::getMaxValue(OtherRange.Width,
- OtherT->isUnsignedIntegerType()),
- Value))
- return LimitType::Max;
-
- if (llvm::APSInt::isSameValue(
- llvm::APSInt::getMinValue(OtherRange.Width,
- OtherT->isUnsignedIntegerType()),
- Value))
- return LimitType::Min;
-
- return llvm::Optional<LimitType>();
+ llvm::APSInt Value;
+ return E->isIntegerConstantExpr(Value, S.Context) && Value == 0;
}
bool HasEnumType(Expr *E) {
@@ -8632,60 +8580,63 @@
return E->getType()->isEnumeralType();
}
-bool CheckTautologicalComparison(Sema &S, BinaryOperator *E, Expr *Constant,
- Expr *Other, const llvm::APSInt &Value,
- bool RhsConstant) {
- // Disable warning in template instantiations
- // and only analyze <, >, <= and >= operations.
- if (S.inTemplateInstantiation() || !E->isRelationalOp())
- return false;
-
- BinaryOperatorKind Op = E->getOpcode();
-
- QualType OType = Other->IgnoreParenImpCasts()->getType();
-
- llvm::Optional<LimitType> ValueType; // Which limit (min/max) is the constant?
-
- if (!(isNonBooleanIntegerValue(Other) &&
- (ValueType = IsTypeLimit(S, Constant, Other, Value))))
- return false;
-
- bool ConstIsLowerBound = (Op == BO_LT || Op == BO_LE) ^ RhsConstant;
- bool ResultWhenConstEqualsOther = (Op == BO_LE || Op == BO_GE);
- bool ResultWhenConstNeOther =
- ConstIsLowerBound ^ (ValueType == LimitType::Max);
- if (ResultWhenConstEqualsOther != ResultWhenConstNeOther)
- return false; // The comparison is not tautological.
-
- const bool Result = ResultWhenConstEqualsOther;
-
- unsigned Diag = (isNonBooleanUnsignedValue(Other) && Value == 0)
- ? (HasEnumType(Other)
- ? diag::warn_unsigned_enum_always_true_comparison
- : diag::warn_unsigned_always_true_comparison)
- : diag::warn_tautological_constant_compare;
-
- // Should be enough for uint128 (39 decimal digits)
- SmallString<64> PrettySourceValue;
- llvm::raw_svector_ostream OS(PrettySourceValue);
- OS << Value;
-
- S.Diag(E->getOperatorLoc(), Diag)
- << RhsConstant << OType << E->getOpcodeStr() << OS.str() << Result
- << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
-
- return true;
+bool isNonBooleanUnsignedValue(Expr *E) {
+ // We are checking that the expression is not known to have boolean value,
+ // is an integer type; and is either unsigned after implicit casts,
+ // or was unsigned before implicit casts.
+ return !E->isKnownToHaveBooleanValue() && E->getType()->isIntegerType() &&
+ (!E->getType()->isSignedIntegerType() ||
+ !E->IgnoreParenImpCasts()->getType()->isSignedIntegerType());
}
-bool DiagnoseOutOfRangeComparison(Sema &S, BinaryOperator *E, Expr *Constant,
- Expr *Other, const llvm::APSInt &Value,
- bool RhsConstant) {
+bool CheckTautologicalComparisonWithZero(Sema &S, BinaryOperator *E) {
// Disable warning in template instantiations.
if (S.inTemplateInstantiation())
return false;
- Constant = Constant->IgnoreParenImpCasts();
- Other = Other->IgnoreParenImpCasts();
+ // bool values are handled by DiagnoseOutOfRangeComparison().
+
+ BinaryOperatorKind Op = E->getOpcode();
+ if (E->isValueDependent())
+ return false;
+
+ Expr *LHS = E->getLHS();
+ Expr *RHS = E->getRHS();
+
+ bool Match = true;
+
+ if (Op == BO_LT && isNonBooleanUnsignedValue(LHS) && IsZero(S, RHS)) {
+ S.Diag(E->getOperatorLoc(),
+ HasEnumType(LHS) ? diag::warn_lunsigned_enum_always_true_comparison
+ : diag::warn_lunsigned_always_true_comparison)
+ << "< 0" << false << LHS->getSourceRange() << RHS->getSourceRange();
+ } else if (Op == BO_GE && isNonBooleanUnsignedValue(LHS) && IsZero(S, RHS)) {
+ S.Diag(E->getOperatorLoc(),
+ HasEnumType(LHS) ? diag::warn_lunsigned_enum_always_true_comparison
+ : diag::warn_lunsigned_always_true_comparison)
+ << ">= 0" << true << LHS->getSourceRange() << RHS->getSourceRange();
+ } else if (Op == BO_GT && isNonBooleanUnsignedValue(RHS) && IsZero(S, LHS)) {
+ S.Diag(E->getOperatorLoc(),
+ HasEnumType(RHS) ? diag::warn_runsigned_enum_always_true_comparison
+ : diag::warn_runsigned_always_true_comparison)
+ << "0 >" << false << LHS->getSourceRange() << RHS->getSourceRange();
+ } else if (Op == BO_LE && isNonBooleanUnsignedValue(RHS) && IsZero(S, LHS)) {
+ S.Diag(E->getOperatorLoc(),
+ HasEnumType(RHS) ? diag::warn_runsigned_enum_always_true_comparison
+ : diag::warn_runsigned_always_true_comparison)
+ << "0 <=" << true << LHS->getSourceRange() << RHS->getSourceRange();
+ } else
+ Match = false;
+
+ return Match;
+}
+
+void DiagnoseOutOfRangeComparison(Sema &S, BinaryOperator *E, Expr *Constant,
+ Expr *Other, const llvm::APSInt &Value,
+ bool RhsConstant) {
+ // Disable warning in template instantiations.
+ if (S.inTemplateInstantiation())
+ return;
// TODO: Investigate using GetExprRange() to get tighter bounds
// on the bit ranges.
@@ -8697,6 +8648,10 @@
bool OtherIsBooleanType = Other->isKnownToHaveBooleanValue();
+ // 0 values are handled later by CheckTautologicalComparisonWithZero().
+ if ((Value == 0) && (!OtherIsBooleanType))
+ return;
+
BinaryOperatorKind op = E->getOpcode();
bool IsTrue = true;
@@ -8712,7 +8667,7 @@
QualType CommonT = E->getLHS()->getType();
if (S.Context.hasSameUnqualifiedType(OtherT, ConstantT))
- return false;
+ return;
assert((OtherT->isIntegerType() && ConstantT->isIntegerType()) &&
"comparison with non-integer type");
@@ -8727,38 +8682,38 @@
// Check that the constant is representable in type OtherT.
if (ConstantSigned) {
if (OtherWidth >= Value.getMinSignedBits())
- return false;
+ return;
} else { // !ConstantSigned
if (OtherWidth >= Value.getActiveBits() + 1)
- return false;
+ return;
}
} else { // !OtherSigned
// Check that the constant is representable in type OtherT.
// Negative values are out of range.
if (ConstantSigned) {
if (Value.isNonNegative() && OtherWidth >= Value.getActiveBits())
- return false;
+ return;
} else { // !ConstantSigned
if (OtherWidth >= Value.getActiveBits())
- return false;
+ return;
}
}
} else { // !CommonSigned
if (OtherRange.NonNegative) {
if (OtherWidth >= Value.getActiveBits())
- return false;
+ return;
} else { // OtherSigned
assert(!ConstantSigned &&
"Two signed types converted to unsigned types.");
// Check to see if the constant is representable in OtherT.
if (OtherWidth > Value.getActiveBits())
- return false;
+ return;
// Check to see if the constant is equivalent to a negative value
// cast to CommonT.
if (S.Context.getIntWidth(ConstantT) ==
S.Context.getIntWidth(CommonT) &&
Value.isNegative() && Value.getMinSignedBits() <= OtherWidth)
- return false;
+ return;
// The constant value rests between values that OtherT can represent
// after conversion. Relational comparison still works, but equality
// comparisons will be tautological.
@@ -8771,7 +8726,7 @@
if (op == BO_EQ || op == BO_NE) {
IsTrue = op == BO_NE;
} else if (EqualityOnly) {
- return false;
+ return;
} else if (RhsConstant) {
if (op == BO_GT || op == BO_GE)
IsTrue = !PositiveConstant;
@@ -8859,7 +8814,7 @@
} else if (CmpRes == ATrue) {
IsTrue = true;
} else {
- return false;
+ return;
}
}
@@ -8882,8 +8837,6 @@
<< OS.str() << LiteralOrBoolConstant
<< OtherT << (OtherIsBooleanType && !OtherT->isBooleanType()) << IsTrue
<< E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange());
-
- return true;
}
/// Analyze the operands of the given comparison. Implements the
@@ -8909,48 +8862,44 @@
if (E->isValueDependent())
return AnalyzeImpConvsInComparison(S, E);
- Expr *LHS = E->getLHS();
- Expr *RHS = E->getRHS();
-
+ Expr *LHS = E->getLHS()->IgnoreParenImpCasts();
+ Expr *RHS = E->getRHS()->IgnoreParenImpCasts();
+
+ bool IsComparisonConstant = false;
+
+ // Check whether an integer constant comparison results in a value
+ // of 'true' or 'false'.
if (T->isIntegralType(S.Context)) {
llvm::APSInt RHSValue;
+ bool IsRHSIntegralLiteral =
+ RHS->isIntegerConstantExpr(RHSValue, S.Context);
llvm::APSInt LHSValue;
+ bool IsLHSIntegralLiteral =
+ LHS->isIntegerConstantExpr(LHSValue, S.Context);
+ if (IsRHSIntegralLiteral && !IsLHSIntegralLiteral)
+ DiagnoseOutOfRangeComparison(S, E, RHS, LHS, RHSValue, true);
+ else if (!IsRHSIntegralLiteral && IsLHSIntegralLiteral)
+ DiagnoseOutOfRangeComparison(S, E, LHS, RHS, LHSValue, false);
+ else
+ IsComparisonConstant =
+ (IsRHSIntegralLiteral && IsLHSIntegralLiteral);
+ } else if (!T->hasUnsignedIntegerRepresentation())
+ IsComparisonConstant = E->isIntegerConstantExpr(S.Context);
- bool IsRHSIntegralLiteral = RHS->isIntegerConstantExpr(RHSValue, S.Context);
- bool IsLHSIntegralLiteral = LHS->isIntegerConstantExpr(LHSValue, S.Context);
-
- // We don't care about expressions whose result is a constant.
- if (IsRHSIntegralLiteral && IsLHSIntegralLiteral)
- return AnalyzeImpConvsInComparison(S, E);
-
- // We only care about expressions where just one side is literal
- if (IsRHSIntegralLiteral ^ IsLHSIntegralLiteral) {
- // Is the constant on the RHS or LHS?
- const bool RhsConstant = IsRHSIntegralLiteral;
- Expr *Const = RhsConstant ? RHS : LHS;
- Expr *Other = RhsConstant ? LHS : RHS;
- const llvm::APSInt &Value = RhsConstant ? RHSValue : LHSValue;
-
- // Check whether an integer constant comparison results in a value
- // of 'true' or 'false'.
-
- if (CheckTautologicalComparison(S, E, Const, Other, Value, RhsConstant))
- return AnalyzeImpConvsInComparison(S, E);
-
- if (DiagnoseOutOfRangeComparison(S, E, Const, Other, Value, RhsConstant))
- return AnalyzeImpConvsInComparison(S, E);
- }
- }
-
- if (!T->hasUnsignedIntegerRepresentation()) {
- // We don't do anything special if this isn't an unsigned integral
- // comparison: we're only interested in integral comparisons, and
- // signed comparisons only happen in cases we don't care to warn about.
+ // We don't care about value-dependent expressions or expressions
+ // whose result is a constant.
+ if (IsComparisonConstant)
return AnalyzeImpConvsInComparison(S, E);
- }
- LHS = LHS->IgnoreParenImpCasts();
- RHS = RHS->IgnoreParenImpCasts();
+ // If this is a tautological comparison, suppress -Wsign-compare.
+ if (CheckTautologicalComparisonWithZero(S, E))
+ return AnalyzeImpConvsInComparison(S, E);
+
+ // We don't do anything special if this isn't an unsigned integral
+ // comparison: we're only interested in integral comparisons, and
+ // signed comparisons only happen in cases we don't care to warn about.
+ if (!T->hasUnsignedIntegerRepresentation())
+ return AnalyzeImpConvsInComparison(S, E);
// Check to see if one of the (unmodified) operands is of different
// signedness.