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Unify implementation of our two different flavours of -Wtautological-compare. 

In so doing, fix a handful of remaining bugs where we would report false
positives or false negatives if we promote a signed value to an unsigned type
for the comparison.

llvm-svn: 320122
This commit is contained in:
Richard Smith 2017-12-08 00:45:25 +00:00
parent 9e1baeda74
commit bf0ad43503
4 changed files with 304 additions and 254 deletions
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312
clang/lib/Sema/SemaChecking.cpp
View File

@ -8662,54 +8662,113 @@ static bool isKnownToHaveUnsignedValue(Expr *E) {
}
namespace {
/// The promoted range of values of a type. In general this has the
/// following structure:
///
/// |-----------| . . . |-----------|
/// ^ ^ ^ ^
/// Min HoleMin HoleMax Max
///
/// ... where there is only a hole if a signed type is promoted to unsigned
/// (in which case Min and Max are the smallest and largest representable
/// values).
struct PromotedRange {
// Min, or HoleMax if there is a hole.
llvm::APSInt PromotedMin;
// Max, or HoleMin if there is a hole.
llvm::APSInt PromotedMax;
enum class LimitType {
Max = 1U << 0U, // e.g. 32767 for short
Min = 1U << 1U, // e.g. -32768 for short
Both = Max | Min // When the value is both the Min and the Max limit at the
// same time; e.g. in C++, A::a in enum A { a = 0 };
PromotedRange(IntRange R, unsigned BitWidth, bool Unsigned) {
if (R.Width == 0)
PromotedMin = PromotedMax = llvm::APSInt(BitWidth, Unsigned);
else {
PromotedMin = llvm::APSInt::getMinValue(R.Width, R.NonNegative)
.extOrTrunc(BitWidth);
PromotedMin.setIsUnsigned(Unsigned);
PromotedMax = llvm::APSInt::getMaxValue(R.Width, R.NonNegative)
.extOrTrunc(BitWidth);
PromotedMax.setIsUnsigned(Unsigned);
}
}
// Determine whether this range is contiguous (has no hole).
bool isContiguous() const { return PromotedMin <= PromotedMax; }
// Where a constant value is within the range.
enum ComparisonResult {
LT = 0x1,
LE = 0x2,
GT = 0x4,
GE = 0x8,
EQ = 0x10,
NE = 0x20,
InRangeFlag = 0x40,
Less = LE | LT | NE,
Min = LE | InRangeFlag,
InRange = InRangeFlag,
Max = GE | InRangeFlag,
Greater = GE | GT | NE,
OnlyValue = LE | GE | EQ | InRangeFlag,
InHole = NE
};
ComparisonResult compare(const llvm::APSInt &Value) const {
assert(Value.getBitWidth() == PromotedMin.getBitWidth() &&
Value.isUnsigned() == PromotedMin.isUnsigned());
if (!isContiguous()) {
assert(Value.isUnsigned() && "discontiguous range for signed compare");
if (Value.isMinValue()) return Min;
if (Value.isMaxValue()) return Max;
if (Value >= PromotedMin) return InRange;
if (Value <= PromotedMax) return InRange;
return InHole;
}
switch (llvm::APSInt::compareValues(Value, PromotedMin)) {
case -1: return Less;
case 0: return PromotedMin == PromotedMax ? OnlyValue : Min;
case 1:
switch (llvm::APSInt::compareValues(Value, PromotedMax)) {
case -1: return InRange;
case 0: return Max;
case 1: return Greater;
}
}
llvm_unreachable("impossible compare result");
}
static llvm::Optional<bool> constantValue(BinaryOperatorKind Op,
ComparisonResult R,
bool ConstantOnRHS) {
ComparisonResult TrueFlag, FalseFlag;
if (Op == BO_EQ) {
TrueFlag = EQ;
FalseFlag = NE;
} else if (Op == BO_NE) {
TrueFlag = NE;
FalseFlag = EQ;
} else {
if ((Op == BO_LT || Op == BO_GE) ^ ConstantOnRHS) {
TrueFlag = LT;
FalseFlag = GE;
} else {
TrueFlag = GT;
FalseFlag = LE;
}
if (Op == BO_GE || Op == BO_LE)
std::swap(TrueFlag, FalseFlag);
}
if (R & TrueFlag)
return true;
if (R & FalseFlag)
return false;
return llvm::None;
}
};
} // namespace
/// 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
static llvm::Optional<LimitType> IsTypeLimit(Sema &S, Expr *Constant,
Expr *Other,
const llvm::APSInt &Value) {
if (IsEnumConstOrFromMacro(S, Constant))
return llvm::Optional<LimitType>();
if (isKnownToHaveUnsignedValue(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 (Other->isKnownToHaveBooleanValue())
OtherRange = IntRange::forBoolType();
// Special-case for C++ for enum with one enumerator with value of 0.
if (OtherRange.Width == 0)
return Value == 0 ? LimitType::Both : llvm::Optional<LimitType>();
if (llvm::APSInt::isSameValue(
llvm::APSInt::getMaxValue(OtherRange.Width, OtherRange.NonNegative),
Value))
return LimitType::Max;
if (llvm::APSInt::isSameValue(
llvm::APSInt::getMinValue(OtherRange.Width, OtherRange.NonNegative),
Value))
return LimitType::Min;
return llvm::None;
}
static bool HasEnumType(Expr *E) {
@ -8747,28 +8806,46 @@ static bool CheckTautologicalComparison(Sema &S, BinaryOperator *E,
if (S.inTemplateInstantiation() || !E->isRelationalOp())
return false;
BinaryOperatorKind Op = E->getOpcode();
QualType OType = Other->IgnoreParenImpCasts()->getType();
if (!OType->isIntegerType())
if (IsEnumConstOrFromMacro(S, Constant))
return false;
// Determine which limit (min/max) the constant is, if either.
llvm::Optional<LimitType> ValueType = IsTypeLimit(S, Constant, Other, Value);
if (!ValueType)
Expr *OriginalOther = Other;
Constant = Constant->IgnoreParenImpCasts();
Other = Other->IgnoreParenImpCasts();
// TODO: Investigate using GetExprRange() to get tighter bounds
// on the bit ranges.
QualType OtherT = Other->getType();
if (const auto *AT = OtherT->getAs<AtomicType>())
OtherT = AT->getValueType();
IntRange OtherRange = IntRange::forValueOfType(S.Context, OtherT);
// 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)
OtherRange = IntRange::forBoolType();
if (FieldDecl *Bitfield = Other->getSourceBitField())
if (!Bitfield->getBitWidth()->isValueDependent())
OtherRange.Width =
std::min(Bitfield->getBitWidthValue(S.Context), OtherRange.Width);
// Check whether the constant value can be represented in OtherRange. Bail
// out if so; this isn't an out-of-range comparison.
PromotedRange OtherPromotedRange(OtherRange, Value.getBitWidth(),
Value.isUnsigned());
auto Cmp = OtherPromotedRange.compare(Value);
if (Cmp != PromotedRange::Min && Cmp != PromotedRange::Max &&
Cmp != PromotedRange::OnlyValue)
return false;
bool ConstIsLowerBound = (Op == BO_LT || Op == BO_LE) ^ RhsConstant;
bool ResultWhenConstEqualsOther = (Op == BO_LE || Op == BO_GE);
if (ValueType != LimitType::Both) {
bool ResultWhenConstNeOther =
ConstIsLowerBound ^ (ValueType == LimitType::Max);
if (ResultWhenConstEqualsOther != ResultWhenConstNeOther)
return false; // The comparison is not tautological.
} else if (ResultWhenConstEqualsOther == ConstIsLowerBound)
return false; // The comparison is not tautological.
const bool Result = ResultWhenConstEqualsOther;
auto Result = PromotedRange::constantValue(E->getOpcode(), Cmp, RhsConstant);
if (!Result)
return false;
// Should be enough for uint128 (39 decimal digits)
SmallString<64> PrettySourceValue;
@ -8782,20 +8859,20 @@ static bool CheckTautologicalComparison(Sema &S, BinaryOperator *E,
S.DiagRuntimeBehavior(
E->getOperatorLoc(), E,
S.PDiag(diag::warn_tautological_bool_compare)
<< OS.str() << classifyConstantValue(Constant->IgnoreParenImpCasts())
<< OType << !OType->isBooleanType() << Result
<< OS.str() << classifyConstantValue(Constant)
<< OtherT << !OtherT->isBooleanType() << *Result
<< E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange());
return true;
}
unsigned Diag = (isKnownToHaveUnsignedValue(Other) && Value == 0)
? (HasEnumType(Other)
unsigned Diag = (isKnownToHaveUnsignedValue(OriginalOther) && Value == 0)
? (HasEnumType(OriginalOther)
? diag::warn_unsigned_enum_always_true_comparison
: diag::warn_unsigned_always_true_comparison)
: diag::warn_tautological_constant_compare;
S.Diag(E->getOperatorLoc(), Diag)
<< RhsConstant << OType << E->getOpcodeStr() << OS.str() << Result
<< RhsConstant << OtherT << E->getOpcodeStr() << OS.str() << *Result
<< E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
return true;
@ -8817,7 +8894,6 @@ static bool DiagnoseOutOfRangeComparison(Sema &S, BinaryOperator *E,
QualType OtherT = Other->getType();
if (const auto *AT = OtherT->getAs<AtomicType>())
OtherT = AT->getValueType();
IntRange OtherRange = IntRange::forValueOfType(S.Context, OtherT);
// Whether we're treating Other as being a bool because of the form of
@ -8827,91 +8903,25 @@ static bool DiagnoseOutOfRangeComparison(Sema &S, BinaryOperator *E,
if (OtherIsBooleanDespiteType)
OtherRange = IntRange::forBoolType();
unsigned OtherWidth = OtherRange.Width;
BinaryOperatorKind op = E->getOpcode();
bool IsTrue = true;
if (FieldDecl *Bitfield = Other->getSourceBitField())
if (!Bitfield->getBitWidth()->isValueDependent())
OtherRange.Width =
std::min(Bitfield->getBitWidthValue(S.Context), OtherRange.Width);
// Check whether the constant value can be represented in OtherRange. Bail
// out if so; this isn't an out-of-range comparison.
{
QualType ConstantT = Constant->getType();
QualType CommonT = E->getLHS()->getType();
PromotedRange OtherPromotedRange(OtherRange, Value.getBitWidth(),
Value.isUnsigned());
auto Cmp = OtherPromotedRange.compare(Value);
if (S.Context.hasSameUnqualifiedType(OtherT, ConstantT) &&
!OtherIsBooleanDespiteType)
return false;
assert((OtherT->isIntegerType() && ConstantT->isIntegerType()) &&
"comparison with non-integer type");
// If Value is in the range of possible Other values, this comparison is not
// tautological.
if (Cmp & PromotedRange::InRangeFlag)
return false;
bool ConstantSigned = ConstantT->isSignedIntegerType();
bool CommonSigned = CommonT->isSignedIntegerType();
bool EqualityOnly = false;
if (CommonSigned) {
// The common type is signed, therefore no signed to unsigned conversion.
if (!OtherRange.NonNegative) {
// Check that the constant is representable in type OtherT.
if (ConstantSigned) {
if (OtherWidth >= Value.getMinSignedBits())
return false;
} else { // !ConstantSigned
if (OtherWidth >= Value.getActiveBits() + 1)
return false;
}
} 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;
} else { // !ConstantSigned
if (OtherWidth >= Value.getActiveBits())
return false;
}
}
} else { // !CommonSigned
if (OtherRange.NonNegative) {
if (OtherWidth >= Value.getActiveBits())
return false;
} 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;
// 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;
// The constant value rests between values that OtherT can represent
// after conversion. Relational comparison still works, but equality
// comparisons will be tautological.
EqualityOnly = true;
}
}
bool PositiveConstant = !ConstantSigned || Value.isNonNegative();
if (op == BO_EQ || op == BO_NE) {
IsTrue = op == BO_NE;
} else if (EqualityOnly) {
return false;
} else if (RhsConstant) {
if (op == BO_GT || op == BO_GE)
IsTrue = !PositiveConstant;
else // op == BO_LT || op == BO_LE
IsTrue = PositiveConstant;
} else {
if (op == BO_LT || op == BO_LE)
IsTrue = !PositiveConstant;
else // op == BO_GT || op == BO_GE
IsTrue = PositiveConstant;
}
}
auto IsTrue = PromotedRange::constantValue(E->getOpcode(), Cmp, RhsConstant);
if (!IsTrue)
return false;
// If this is a comparison to an enum constant, include that
// constant in the diagnostic.
@ -8930,7 +8940,7 @@ static bool DiagnoseOutOfRangeComparison(Sema &S, BinaryOperator *E,
E->getOperatorLoc(), E,
S.PDiag(diag::warn_out_of_range_compare)
<< OS.str() << classifyConstantValue(Constant)
<< OtherT << OtherIsBooleanDespiteType << IsTrue
<< OtherT << OtherIsBooleanDespiteType << *IsTrue
<< E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange());
return true;

65
clang/test/Sema/tautological-constant-compare.c
View File

@ -94,15 +94,17 @@ int main()
if (-32768 >= s)
return 0;
// Note: both sides are promoted to unsigned long prior to the comparison, so
// it is perfectly possible for a short to compare greater than 32767UL.
if (s == 32767UL)
return 0;
if (s != 32767UL)
return 0;
if (s < 32767UL)
return 0;
if (s <= 32767UL) // expected-warning {{comparison 'short' <= 32767 is always true}}
if (s <= 32767UL)
return 0;
if (s > 32767UL) // expected-warning {{comparison 'short' > 32767 is always false}}
if (s > 32767UL)
return 0;
if (s >= 32767UL)
return 0;
@ -111,13 +113,66 @@ int main()
return 0;
if (32767UL != s)
return 0;
if (32767UL < s) // expected-warning {{comparison 32767 < 'short' is always false}}
if (32767UL < s)
return 0;
if (32767UL <= s)
return 0;
if (32767UL > s)
return 0;
if (32767UL >= s) // expected-warning {{comparison 32767 >= 'short' is always true}}
if (32767UL >= s)
return 0;
if (s == 0UL)
return 0;
if (s != 0UL)
return 0;
if (s < 0UL) // expected-warning {{comparison of unsigned expression < 0 is always false}}
return 0;
if (s <= 0UL)
return 0;
if (s > 0UL)
return 0;
if (s >= 0UL) // expected-warning {{comparison of unsigned expression >= 0 is always true}}
return 0;
if (0UL == s)
return 0;
if (0UL != s)
return 0;
if (0UL < s)
return 0;
if (0UL <= s) // expected-warning {{comparison of 0 <= unsigned expression is always true}}
return 0;
if (0UL > s) // expected-warning {{comparison of 0 > unsigned expression is always false}}
return 0;
if (0UL >= s)
return 0;
enum { ULONG_MAX = (2UL * (unsigned long)__LONG_MAX__ + 1UL) };
if (s == 2UL * (unsigned long)__LONG_MAX__ + 1UL)
return 0;
if (s != 2UL * (unsigned long)__LONG_MAX__ + 1UL)
return 0;
if (s < 2UL * (unsigned long)__LONG_MAX__ + 1UL)
return 0;
if (s <= 2UL * (unsigned long)__LONG_MAX__ + 1UL) // expected-warning-re {{comparison 'short' <= {{.*}} is always true}}
return 0;
if (s > 2UL * (unsigned long)__LONG_MAX__ + 1UL) // expected-warning-re {{comparison 'short' > {{.*}} is always false}}
return 0;
if (s >= 2UL * (unsigned long)__LONG_MAX__ + 1UL)
return 0;
if (2UL * (unsigned long)__LONG_MAX__ + 1UL == s)
return 0;
if (2UL * (unsigned long)__LONG_MAX__ + 1UL != s)
return 0;
if (2UL * (unsigned long)__LONG_MAX__ + 1UL < s) // expected-warning-re {{comparison {{.*}} < 'short' is always false}}
return 0;
if (2UL * (unsigned long)__LONG_MAX__ + 1UL <= s)
return 0;
if (2UL * (unsigned long)__LONG_MAX__ + 1UL > s)
return 0;
if (2UL * (unsigned long)__LONG_MAX__ + 1UL >= s) // expected-warning-re {{comparison {{.*}} >= 'short' is always true}}
return 0;
// FIXME: assumes two's complement
@ -281,8 +336,6 @@ int main()
if (0 >= s)
return 0;
// However the comparison with 0U would warn
unsigned short us = value();
#ifdef TEST

177
clang/test/Sema/tautological-constant-enum-compare.c
View File

@ -9,27 +9,9 @@ int main() {
#ifdef SILENCE
// expected-no-diagnostics
#endif
#ifdef UNSIGNED
#ifndef SILENCE
if (a < 0) // expected-warning {{comparison of unsigned enum expression < 0 is always false}}
return 0;
if (0 >= a)
return 0;
if (a > 0)
return 0;
if (0 <= a) // expected-warning {{comparison of 0 <= unsigned enum expression is always true}}
return 0;
if (a <= 0)
return 0;
if (0 > a) // expected-warning {{comparison of 0 > unsigned enum expression is always false}}
return 0;
if (a >= 0) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
return 0;
if (0 < a)
return 0;
#else
// If we promote to unsigned, it doesn't matter whether the enum's underlying
// type was signed.
if (a < 0U) // expected-warning {{comparison of unsigned enum expression < 0 is always false}}
return 0;
if (0U >= a)
@ -47,23 +29,6 @@ int main() {
if (0U < a)
return 0;
if (a < 4294967295)
return 0;
if (4294967295 >= a) // expected-warning {{comparison 4294967295 >= 'enum A' is always true}}
return 0;
if (a > 4294967295) // expected-warning {{comparison 'enum A' > 4294967295 is always false}}
return 0;
if (4294967295 <= a)
return 0;
if (a <= 4294967295) // expected-warning {{comparison 'enum A' <= 4294967295 is always true}}
return 0;
if (4294967295 > a)
return 0;
if (a >= 4294967295)
return 0;
if (4294967295 < a) // expected-warning {{comparison 4294967295 < 'enum A' is always false}}
return 0;
if (a < 4294967295U)
return 0;
if (4294967295U >= a) // expected-warning {{comparison 4294967295 >= 'enum A' is always true}}
@ -80,7 +45,60 @@ int main() {
return 0;
if (4294967295U < a) // expected-warning {{comparison 4294967295 < 'enum A' is always false}}
return 0;
#else // SILENCE
if (a < 2147483647U)
return 0;
if (2147483647U >= a)
return 0;
if (a > 2147483647U)
return 0;
if (2147483647U <= a)
return 0;
if (a <= 2147483647U)
return 0;
if (2147483647U > a)
return 0;
if (a >= 2147483647U)
return 0;
if (2147483647U < a)
return 0;
#endif
#if defined(UNSIGNED) && !defined(SILENCE)
if (a < 0) // expected-warning {{comparison of unsigned enum expression < 0 is always false}}
return 0;
if (0 >= a)
return 0;
if (a > 0)
return 0;
if (0 <= a) // expected-warning {{comparison of 0 <= unsigned enum expression is always true}}
return 0;
if (a <= 0)
return 0;
if (0 > a) // expected-warning {{comparison of 0 > unsigned enum expression is always false}}
return 0;
if (a >= 0) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
return 0;
if (0 < a)
return 0;
if (a < 4294967295)
return 0;
if (4294967295 >= a) // expected-warning {{comparison 4294967295 >= 'enum A' is always true}}
return 0;
if (a > 4294967295) // expected-warning {{comparison 'enum A' > 4294967295 is always false}}
return 0;
if (4294967295 <= a)
return 0;
if (a <= 4294967295) // expected-warning {{comparison 'enum A' <= 4294967295 is always true}}
return 0;
if (4294967295 > a)
return 0;
if (a >= 4294967295)
return 0;
if (4294967295 < a) // expected-warning {{comparison 4294967295 < 'enum A' is always false}}
return 0;
#else // SIGNED || SILENCE
if (a < 0)
return 0;
if (0 >= a)
@ -98,23 +116,24 @@ int main() {
if (0 < a)
return 0;
if (a < 0U)
#ifndef SILENCE
if (a < 4294967295) // expected-warning {{comparison of constant 4294967295 with expression of type 'enum A' is always true}}
return 0;
if (0U >= a)
if (4294967295 >= a) // expected-warning {{comparison of constant 4294967295 with expression of type 'enum A' is always true}}
return 0;
if (a > 0U)
if (a > 4294967295) // expected-warning {{comparison of constant 4294967295 with expression of type 'enum A' is always false}}
return 0;
if (0U <= a)
if (4294967295 <= a) // expected-warning {{comparison of constant 4294967295 with expression of type 'enum A' is always false}}
return 0;
if (a <= 0U)
if (a <= 4294967295) // expected-warning {{comparison of constant 4294967295 with expression of type 'enum A' is always true}}
return 0;
if (0U > a)
if (4294967295 > a) // expected-warning {{comparison of constant 4294967295 with expression of type 'enum A' is always true}}
return 0;
if (a >= 0U)
if (a >= 4294967295) // expected-warning {{comparison of constant 4294967295 with expression of type 'enum A' is always false}}
return 0;
if (0U < a)
if (4294967295 < a) // expected-warning {{comparison of constant 4294967295 with expression of type 'enum A' is always false}}
return 0;
#else
if (a < 4294967295)
return 0;
if (4294967295 >= a)
@ -131,26 +150,10 @@ int main() {
return 0;
if (4294967295 < a)
return 0;
if (a < 4294967295U)
return 0;
if (4294967295U >= a)
return 0;
if (a > 4294967295U)
return 0;
if (4294967295U <= a)
return 0;
if (a <= 4294967295U)
return 0;
if (4294967295U > a)
return 0;
if (a >= 4294967295U)
return 0;
if (4294967295U < a)
return 0;
#endif
#elif defined(SIGNED)
#ifndef SILENCE
#endif
#if defined(SIGNED) && !defined(SILENCE)
if (a < -2147483648) // expected-warning {{comparison 'enum A' < -2147483648 is always false}}
return 0;
if (-2147483648 >= a)
@ -184,24 +187,25 @@ int main() {
return 0;
if (2147483647 < a) // expected-warning {{comparison 2147483647 < 'enum A' is always false}}
return 0;
if (a < 2147483647U)
#elif defined(UNSIGNED) && !defined(SILENCE)
#ifndef SILENCE
if (a < -2147483648) // expected-warning {{comparison of constant -2147483648 with expression of type 'enum A' is always false}}
return 0;
if (2147483647U >= a) // expected-warning {{comparison 2147483647 >= 'enum A' is always true}}
if (-2147483648 >= a) // expected-warning {{comparison of constant -2147483648 with expression of type 'enum A' is always false}}
return 0;
if (a > 2147483647U) // expected-warning {{comparison 'enum A' > 2147483647 is always false}}
if (a > -2147483648) // expected-warning {{comparison of constant -2147483648 with expression of type 'enum A' is always true}}
return 0;
if (2147483647U <= a)
if (-2147483648 <= a) // expected-warning {{comparison of constant -2147483648 with expression of type 'enum A' is always true}}
return 0;
if (a <= 2147483647U) // expected-warning {{comparison 'enum A' <= 2147483647 is always true}}
if (a <= -2147483648) // expected-warning {{comparison of constant -2147483648 with expression of type 'enum A' is always false}}
return 0;
if (2147483647U > a)
if (-2147483648 > a) // expected-warning {{comparison of constant -2147483648 with expression of type 'enum A' is always false}}
return 0;
if (a >= 2147483647U)
if (a >= -2147483648) // expected-warning {{comparison of constant -2147483648 with expression of type 'enum A' is always true}}
return 0;
if (2147483647U < a) // expected-warning {{comparison 2147483647 < 'enum A' is always false}}
if (-2147483648 < a) // expected-warning {{comparison of constant -2147483648 with expression of type 'enum A' is always true}}
return 0;
#else // SILENCE
#else
if (a < -2147483648)
return 0;
if (-2147483648 >= a)
@ -218,6 +222,7 @@ int main() {
return 0;
if (-2147483648 < a)
return 0;
#endif
if (a < 2147483647)
return 0;
@ -235,24 +240,6 @@ int main() {
return 0;
if (2147483647 < a)
return 0;
if (a < 2147483647U)
return 0;
if (2147483647U >= a)
return 0;
if (a > 2147483647U)
return 0;
if (2147483647U <= a)
return 0;
if (a <= 2147483647U)
return 0;
if (2147483647U > a)
return 0;
if (a >= 2147483647U)
return 0;
if (2147483647U < a)
return 0;
#endif
#endif
return 1;

4
clang/test/SemaCXX/compare.cpp
View File

@ -245,8 +245,8 @@ void test4(short s) {
// unsigned.
const unsigned B = -1;
void (s < B); // expected-warning{{comparison of integers of different signs: 'short' and 'const unsigned int'}}
void (s > B); // expected-warning{{comparison of integers of different signs: 'short' and 'const unsigned int'}}
void (s <= B); // expected-warning{{comparison of integers of different signs: 'short' and 'const unsigned int'}}
void (s > B); // expected-warning{{comparison 'short' > 4294967295 is always false}}
void (s <= B); // expected-warning{{comparison 'short' <= 4294967295 is always true}}
void (s >= B); // expected-warning{{comparison of integers of different signs: 'short' and 'const unsigned int'}}
void (s == B); // expected-warning{{comparison of integers of different signs: 'short' and 'const unsigned int'}}
void (s != B); // expected-warning{{comparison of integers of different signs: 'short' and 'const unsigned int'}}