r316268 - [Sema] Fixes for enum handling for tautological comparison diagnostics
Hans Wennborg via cfe-commits
cfe-commits at lists.llvm.org
Mon Oct 23 04:13:47 PDT 2017
This seems to have had the side effect of introducing a new warning in
Chromium builds:
../../third_party/expat/files/lib/xmlparse.c(2429,24): error:
comparison of integers of different signs: 'enum XML_Error' and
'unsigned int' [-Werror,-Wsign-compare]
if (code > 0 && code < sizeof(message)/sizeof(message[0]))
~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I'm not sure if this was intentional or not.
The warning seems technically correct here, though not very useful in
this specific case.
On Sat, Oct 21, 2017 at 6:44 PM, Roman Lebedev via cfe-commits
<cfe-commits at lists.llvm.org> wrote:
> Author: lebedevri
> Date: Sat Oct 21 09:44:03 2017
> New Revision: 316268
>
> URL: http://llvm.org/viewvc/llvm-project?rev=316268&view=rev
> Log:
> [Sema] Fixes for enum handling for tautological comparison diagnostics
>
> Summary:
> As Mattias Eriksson has reported in PR35009, in C, for enums, the underlying type should
> be used when checking for the tautological comparison, unlike C++, where the enumerator
> values define the value range. So if not in CPlusPlus mode, use the enum underlying type.
>
> Also, i have discovered a problem (a crash) when evaluating tautological-ness of the following comparison:
> ```
> enum A { A_a = 0 };
> if (a < 0) // expected-warning {{comparison of unsigned enum expression < 0 is always false}}
> return 0;
> ```
> This affects both the C and C++, but after the first fix, only C++ code was affected.
> That was also fixed, while preserving (i think?) the proper diagnostic output.
>
> And while there, attempt to enhance the test coverage.
> Yes, some tests got moved around, sorry about that :)
>
> Fixes PR35009
>
> Reviewers: aaron.ballman, rsmith, rjmccall
>
> Reviewed By: aaron.ballman
>
> Subscribers: Rakete1111, efriedma, materi, cfe-commits
>
> Tags: #clang
>
> Differential Revision: https://reviews.llvm.org/D39122
>
> Added:
> cfe/trunk/test/Sema/outof-range-enum-constant-compare.c
> cfe/trunk/test/Sema/tautological-constant-enum-compare.c
> Modified:
> cfe/trunk/lib/Sema/SemaChecking.cpp
> cfe/trunk/test/Sema/tautological-unsigned-enum-zero-compare.c
> cfe/trunk/test/Sema/tautological-unsigned-enum-zero-compare.cpp
>
> Modified: cfe/trunk/lib/Sema/SemaChecking.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=316268&r1=316267&r2=316268&view=diff
> ==============================================================================
> --- cfe/trunk/lib/Sema/SemaChecking.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaChecking.cpp Sat Oct 21 09:44:03 2017
> @@ -8181,8 +8181,12 @@ struct IntRange {
> if (const AtomicType *AT = dyn_cast<AtomicType>(T))
> T = AT->getValueType().getTypePtr();
>
> - // For enum types, use the known bit width of the enumerators.
> - if (const EnumType *ET = dyn_cast<EnumType>(T)) {
> + if (!C.getLangOpts().CPlusPlus) {
> + // For enum types in C code, use the underlying datatype.
> + if (const EnumType *ET = dyn_cast<EnumType>(T))
> + T = ET->getDecl()->getIntegerType().getDesugaredType(C).getTypePtr();
> + } else if (const EnumType *ET = dyn_cast<EnumType>(T)) {
> + // For enum types in C++, use the known bit width of the enumerators.
> EnumDecl *Enum = ET->getDecl();
> // In C++11, enums without definitions can have an explicitly specified
> // underlying type. Use this type to compute the range.
> @@ -8584,8 +8588,10 @@ bool isNonBooleanUnsignedValue(Expr *E)
> }
>
> enum class LimitType {
> - Max, // e.g. 32767 for short
> - Min // e.g. -32768 for short
> + 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 };
> };
>
> /// Checks whether Expr 'Constant' may be the
> @@ -8608,6 +8614,10 @@ llvm::Optional<LimitType> IsTypeLimit(Se
>
> IntRange OtherRange = IntRange::forValueOfType(S.Context, OtherT);
>
> + // 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,
> OtherT->isUnsignedIntegerType()),
> @@ -8620,7 +8630,7 @@ llvm::Optional<LimitType> IsTypeLimit(Se
> Value))
> return LimitType::Min;
>
> - return llvm::Optional<LimitType>();
> + return llvm::None;
> }
>
> bool HasEnumType(Expr *E) {
> @@ -8655,9 +8665,12 @@ bool CheckTautologicalComparison(Sema &S
>
> 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)
> + 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;
>
> Added: cfe/trunk/test/Sema/outof-range-enum-constant-compare.c
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/outof-range-enum-constant-compare.c?rev=316268&view=auto
> ==============================================================================
> --- cfe/trunk/test/Sema/outof-range-enum-constant-compare.c (added)
> +++ cfe/trunk/test/Sema/outof-range-enum-constant-compare.c Sat Oct 21 09:44:03 2017
> @@ -0,0 +1,379 @@
> +// RUN: %clang_cc1 -triple=x86_64-pc-linux-gnu -fsyntax-only -DUNSIGNED -verify %s
> +// RUN: %clang_cc1 -triple=x86_64-pc-win32 -fsyntax-only -DSIGNED -verify %s
> +// RUN: %clang_cc1 -triple=x86_64-pc-linux-gnu -fsyntax-only -DUNSIGNED -DSILENCE -Wno-tautological-constant-out-of-range-compare -verify %s
> +// RUN: %clang_cc1 -triple=x86_64-pc-win32 -fsyntax-only -DSIGNED -DSILENCE -Wno-tautological-constant-out-of-range-compare -verify %s
> +
> +int main() {
> + enum A { A_a = 2 };
> + enum A a;
> +
> +#ifdef SILENCE
> + // expected-no-diagnostics
> +#endif
> +
> +#ifdef UNSIGNED
> +#ifndef SILENCE
> + if (a < 4294967296) // expected-warning {{comparison of constant 4294967296 with expression of type 'enum A' is always true}}
> + return 0;
> + if (4294967296 >= a) // expected-warning {{comparison of constant 4294967296 with expression of type 'enum A' is always true}}
> + return 0;
> + if (a > 4294967296) // expected-warning {{comparison of constant 4294967296 with expression of type 'enum A' is always false}}
> + return 0;
> + if (4294967296 <= a) // expected-warning {{comparison of constant 4294967296 with expression of type 'enum A' is always false}}
> + return 0;
> + if (a <= 4294967296) // expected-warning {{comparison of constant 4294967296 with expression of type 'enum A' is always true}}
> + return 0;
> + if (4294967296 > a) // expected-warning {{comparison of constant 4294967296 with expression of type 'enum A' is always true}}
> + return 0;
> + if (a >= 4294967296) // expected-warning {{comparison of constant 4294967296 with expression of type 'enum A' is always false}}
> + return 0;
> + if (4294967296 < a) // expected-warning {{comparison of constant 4294967296 with expression of type 'enum A' is always false}}
> + return 0;
> + if (a == 4294967296) // expected-warning {{comparison of constant 4294967296 with expression of type 'enum A' is always false}}
> + return 0;
> + if (4294967296 != a) // expected-warning {{comparison of constant 4294967296 with expression of type 'enum A' is always true}}
> + return 0;
> + if (a != 4294967296) // expected-warning {{comparison of constant 4294967296 with expression of type 'enum A' is always true}}
> + return 0;
> + if (4294967296 == a) // expected-warning {{comparison of constant 4294967296 with expression of type 'enum A' is always false}}
> + return 0;
> +
> + if (a < 4294967296U) // expected-warning {{comparison of constant 4294967296 with expression of type 'enum A' is always true}}
> + return 0;
> + if (4294967296U >= a) // expected-warning {{comparison of constant 4294967296 with expression of type 'enum A' is always true}}
> + return 0;
> + if (a > 4294967296U) // expected-warning {{comparison of constant 4294967296 with expression of type 'enum A' is always false}}
> + return 0;
> + if (4294967296U <= a) // expected-warning {{comparison of constant 4294967296 with expression of type 'enum A' is always false}}
> + return 0;
> + if (a <= 4294967296U) // expected-warning {{comparison of constant 4294967296 with expression of type 'enum A' is always true}}
> + return 0;
> + if (4294967296U > a) // expected-warning {{comparison of constant 4294967296 with expression of type 'enum A' is always true}}
> + return 0;
> + if (a >= 4294967296U) // expected-warning {{comparison of constant 4294967296 with expression of type 'enum A' is always false}}
> + return 0;
> + if (4294967296U < a) // expected-warning {{comparison of constant 4294967296 with expression of type 'enum A' is always false}}
> + return 0;
> + if (a == 4294967296U) // expected-warning {{comparison of constant 4294967296 with expression of type 'enum A' is always false}}
> + return 0;
> + if (4294967296U != a) // expected-warning {{comparison of constant 4294967296 with expression of type 'enum A' is always true}}
> + return 0;
> + if (a != 4294967296U) // expected-warning {{comparison of constant 4294967296 with expression of type 'enum A' is always true}}
> + return 0;
> + if (4294967296U == a) // expected-warning {{comparison of constant 4294967296 with expression of type 'enum A' is always false}}
> + return 0;
> +#else // SILENCE
> + if (a < 4294967296)
> + return 0;
> + if (4294967296 >= a)
> + return 0;
> + if (a > 4294967296)
> + return 0;
> + if (4294967296 <= a)
> + return 0;
> + if (a <= 4294967296)
> + return 0;
> + if (4294967296 > a)
> + return 0;
> + if (a >= 4294967296)
> + return 0;
> + if (4294967296 < a)
> + return 0;
> + if (a == 4294967296)
> + return 0;
> + if (4294967296 != a)
> + return 0;
> + if (a != 4294967296)
> + return 0;
> + if (4294967296 == a)
> + return 0;
> +
> + if (a < 4294967296U)
> + return 0;
> + if (4294967296U >= a)
> + return 0;
> + if (a > 4294967296U)
> + return 0;
> + if (4294967296U <= a)
> + return 0;
> + if (a <= 4294967296U)
> + return 0;
> + if (4294967296U > a)
> + return 0;
> + if (a >= 4294967296U)
> + return 0;
> + if (4294967296U < a)
> + return 0;
> + if (a == 4294967296U)
> + return 0;
> + if (4294967296U != a)
> + return 0;
> + if (a != 4294967296U)
> + return 0;
> + if (4294967296U == a)
> + return 0;
> +#endif
> +#elif defined(SIGNED)
> +#ifndef SILENCE
> + if (a < -2147483649) // expected-warning {{comparison of constant -2147483649 with expression of type 'enum A' is always false}}
> + return 0;
> + if (-2147483649 >= a) // expected-warning {{comparison of constant -2147483649 with expression of type 'enum A' is always false}}
> + return 0;
> + if (a > -2147483649) // expected-warning {{comparison of constant -2147483649 with expression of type 'enum A' is always true}}
> + return 0;
> + if (-2147483649 <= a) // expected-warning {{comparison of constant -2147483649 with expression of type 'enum A' is always true}}
> + return 0;
> + if (a <= -2147483649) // expected-warning {{comparison of constant -2147483649 with expression of type 'enum A' is always false}}
> + return 0;
> + if (-2147483649 > a) // expected-warning {{comparison of constant -2147483649 with expression of type 'enum A' is always false}}
> + return 0;
> + if (a >= -2147483649) // expected-warning {{comparison of constant -2147483649 with expression of type 'enum A' is always true}}
> + return 0;
> + if (-2147483649 < a) // expected-warning {{comparison of constant -2147483649 with expression of type 'enum A' is always true}}
> + return 0;
> + if (a == -2147483649) // expected-warning {{comparison of constant -2147483649 with expression of type 'enum A' is always false}}
> + return 0;
> + if (-2147483649 != a) // expected-warning {{comparison of constant -2147483649 with expression of type 'enum A' is always true}}
> + return 0;
> + if (a != -2147483649) // expected-warning {{comparison of constant -2147483649 with expression of type 'enum A' is always true}}
> + return 0;
> + if (-2147483649 == a) // expected-warning {{comparison of constant -2147483649 with expression of type 'enum A' is always false}}
> + return 0;
> +
> + if (a < 2147483648) // expected-warning {{comparison of constant 2147483648 with expression of type 'enum A' is always true}}
> + return 0;
> + if (2147483648 >= a) // expected-warning {{comparison of constant 2147483648 with expression of type 'enum A' is always true}}
> + return 0;
> + if (a > 2147483648) // expected-warning {{comparison of constant 2147483648 with expression of type 'enum A' is always false}}
> + return 0;
> + if (2147483648 <= a) // expected-warning {{comparison of constant 2147483648 with expression of type 'enum A' is always false}}
> + return 0;
> + if (a <= 2147483648) // expected-warning {{comparison of constant 2147483648 with expression of type 'enum A' is always true}}
> + return 0;
> + if (2147483648 > a) // expected-warning {{comparison of constant 2147483648 with expression of type 'enum A' is always true}}
> + return 0;
> + if (a >= 2147483648) // expected-warning {{comparison of constant 2147483648 with expression of type 'enum A' is always false}}
> + return 0;
> + if (2147483648 < a) // expected-warning {{comparison of constant 2147483648 with expression of type 'enum A' is always false}}
> + return 0;
> + if (a == 2147483648) // expected-warning {{comparison of constant 2147483648 with expression of type 'enum A' is always false}}
> + return 0;
> + if (2147483648 != a) // expected-warning {{comparison of constant 2147483648 with expression of type 'enum A' is always true}}
> + return 0;
> + if (a != 2147483648) // expected-warning {{comparison of constant 2147483648 with expression of type 'enum A' is always true}}
> + return 0;
> + if (2147483648 == a) // expected-warning {{comparison of constant 2147483648 with expression of type 'enum A' is always false}}
> + return 0;
> +#else // SILENCE
> + if (a < -2147483649)
> + return 0;
> + if (-2147483649 >= a)
> + return 0;
> + if (a > -2147483649)
> + return 0;
> + if (-2147483649 <= a)
> + return 0;
> + if (a <= -2147483649)
> + return 0;
> + if (-2147483649 > a)
> + return 0;
> + if (a >= -2147483649)
> + return 0;
> + if (-2147483649 < a)
> + return 0;
> + if (a == -2147483649)
> + return 0;
> + if (-2147483649 != a)
> + return 0;
> + if (a != -2147483649)
> + return 0;
> + if (-2147483649 == a)
> + return 0;
> +
> + if (a < 2147483648)
> + return 0;
> + if (2147483648 >= a)
> + return 0;
> + if (a > 2147483648)
> + return 0;
> + if (2147483648 <= a)
> + return 0;
> + if (a <= 2147483648)
> + return 0;
> + if (2147483648 > a)
> + return 0;
> + if (a >= 2147483648)
> + return 0;
> + if (2147483648 < a)
> + return 0;
> + if (a == 2147483648)
> + return 0;
> + if (2147483648 != a)
> + return 0;
> + if (a != 2147483648)
> + return 0;
> + if (2147483648 == a)
> + return 0;
> +#endif
> +#endif
> +}
> +
> +// https://bugs.llvm.org/show_bug.cgi?id=35009
> +int PR35009() {
> + enum A { A_a = 2 };
> + enum A a;
> +
> + // in C, this should not warn.
> +
> + if (a < 1)
> + return 0;
> + if (1 >= a)
> + return 0;
> + if (a > 1)
> + return 0;
> + if (1 <= a)
> + return 0;
> + if (a <= 1)
> + return 0;
> + if (1 > a)
> + return 0;
> + if (a >= 1)
> + return 0;
> + if (1 < a)
> + return 0;
> + if (a == 1)
> + return 0;
> + if (1 != a)
> + return 0;
> + if (a != 1)
> + return 0;
> + if (1 == a)
> + return 0;
> +
> + if (a < 1U)
> + return 0;
> + if (1U >= a)
> + return 0;
> + if (a > 1U)
> + return 0;
> + if (1U <= a)
> + return 0;
> + if (a <= 1U)
> + return 0;
> + if (1U > a)
> + return 0;
> + if (a >= 1U)
> + return 0;
> + if (1U < a)
> + return 0;
> + if (a == 1U)
> + return 0;
> + if (1U != a)
> + return 0;
> + if (a != 1U)
> + return 0;
> + if (1U == a)
> + return 0;
> +
> + if (a < 2)
> + return 0;
> + if (2 >= a)
> + return 0;
> + if (a > 2)
> + return 0;
> + if (2 <= a)
> + return 0;
> + if (a <= 2)
> + return 0;
> + if (2 > a)
> + return 0;
> + if (a >= 2)
> + return 0;
> + if (2 < a)
> + return 0;
> + if (a == 2)
> + return 0;
> + if (2 != a)
> + return 0;
> + if (a != 2)
> + return 0;
> + if (2 == a)
> + return 0;
> +
> + if (a < 2U)
> + return 0;
> + if (2U >= a)
> + return 0;
> + if (a > 2U)
> + return 0;
> + if (2U <= a)
> + return 0;
> + if (a <= 2U)
> + return 0;
> + if (2U > a)
> + return 0;
> + if (a >= 2U)
> + return 0;
> + if (2U < a)
> + return 0;
> + if (a == 2U)
> + return 0;
> + if (2U != a)
> + return 0;
> + if (a != 2U)
> + return 0;
> + if (2U == a)
> + return 0;
> +
> + if (a < 3)
> + return 0;
> + if (3 >= a)
> + return 0;
> + if (a > 3)
> + return 0;
> + if (3 <= a)
> + return 0;
> + if (a <= 3)
> + return 0;
> + if (3 > a)
> + return 0;
> + if (a >= 3)
> + return 0;
> + if (3 < a)
> + return 0;
> + if (a == 3)
> + return 0;
> + if (3 != a)
> + return 0;
> + if (a != 3)
> + return 0;
> + if (3 == a)
> + return 0;
> +
> + if (a < 3U)
> + return 0;
> + if (3U >= a)
> + return 0;
> + if (a > 3U)
> + return 0;
> + if (3U <= a)
> + return 0;
> + if (a <= 3U)
> + return 0;
> + if (3U > a)
> + return 0;
> + if (a >= 3U)
> + return 0;
> + if (3U < a)
> + return 0;
> + if (a == 3U)
> + return 0;
> + if (3U != a)
> + return 0;
> + if (a != 3U)
> + return 0;
> + if (3U == a)
> + return 0;
> +
> + return 1;
> +}
>
> Added: cfe/trunk/test/Sema/tautological-constant-enum-compare.c
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/tautological-constant-enum-compare.c?rev=316268&view=auto
> ==============================================================================
> --- cfe/trunk/test/Sema/tautological-constant-enum-compare.c (added)
> +++ cfe/trunk/test/Sema/tautological-constant-enum-compare.c Sat Oct 21 09:44:03 2017
> @@ -0,0 +1,419 @@
> +// RUN: %clang_cc1 -triple=x86_64-pc-linux-gnu -fsyntax-only -DUNSIGNED -verify %s
> +// RUN: %clang_cc1 -triple=x86_64-pc-win32 -fsyntax-only -DSIGNED -verify %s
> +// RUN: %clang_cc1 -triple=x86_64-pc-linux-gnu -fsyntax-only -DUNSIGNED -DSILENCE -Wno-tautological-constant-compare -verify %s
> +// RUN: %clang_cc1 -triple=x86_64-pc-win32 -fsyntax-only -DSIGNED -DSILENCE -Wno-tautological-constant-compare -verify %s
> +
> +int main() {
> + enum A { A_a = 2 };
> + enum A a;
> +
> +#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;
> +
> + if (a < 0U) // expected-warning {{comparison of unsigned enum expression < 0 is always false}}
> + return 0;
> + if (0U >= a)
> + return 0;
> + if (a > 0U)
> + return 0;
> + if (0U <= a) // expected-warning {{comparison of 0 <= unsigned enum expression is always true}}
> + return 0;
> + if (a <= 0U)
> + return 0;
> + if (0U > a) // expected-warning {{comparison of 0 > unsigned enum expression is always false}}
> + return 0;
> + if (a >= 0U) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> + return 0;
> + 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}}
> + return 0;
> + if (a > 4294967295U) // expected-warning {{comparison 'enum A' > 4294967295 is always false}}
> + return 0;
> + if (4294967295U <= a)
> + return 0;
> + if (a <= 4294967295U) // expected-warning {{comparison 'enum A' <= 4294967295 is always true}}
> + return 0;
> + if (4294967295U > a)
> + return 0;
> + if (a >= 4294967295U)
> + return 0;
> + if (4294967295U < a) // expected-warning {{comparison 4294967295 < 'enum A' is always false}}
> + return 0;
> +#else // SILENCE
> + if (a < 0)
> + return 0;
> + if (0 >= a)
> + return 0;
> + if (a > 0)
> + return 0;
> + if (0 <= a)
> + return 0;
> + if (a <= 0)
> + return 0;
> + if (0 > a)
> + return 0;
> + if (a >= 0)
> + return 0;
> + if (0 < a)
> + return 0;
> +
> + if (a < 0U)
> + return 0;
> + if (0U >= a)
> + return 0;
> + if (a > 0U)
> + return 0;
> + if (0U <= a)
> + return 0;
> + if (a <= 0U)
> + return 0;
> + if (0U > a)
> + return 0;
> + if (a >= 0U)
> + return 0;
> + if (0U < a)
> + return 0;
> +
> + if (a < 4294967295)
> + return 0;
> + if (4294967295 >= a)
> + return 0;
> + if (a > 4294967295)
> + return 0;
> + if (4294967295 <= a)
> + return 0;
> + if (a <= 4294967295)
> + return 0;
> + if (4294967295 > a)
> + return 0;
> + if (a >= 4294967295)
> + 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
> + if (a < -2147483648) // expected-warning {{comparison 'enum A' < -2147483648 is always false}}
> + return 0;
> + if (-2147483648 >= a)
> + return 0;
> + if (a > -2147483648)
> + return 0;
> + if (-2147483648 <= a) // expected-warning {{comparison -2147483648 <= 'enum A' is always true}}
> + return 0;
> + if (a <= -2147483648)
> + return 0;
> + if (-2147483648 > a) // expected-warning {{comparison -2147483648 > 'enum A' is always false}}
> + return 0;
> + if (a >= -2147483648) // expected-warning {{comparison 'enum A' >= -2147483648 is always true}}
> + return 0;
> + if (-2147483648 < a)
> + return 0;
> +
> + if (a < 2147483647)
> + return 0;
> + if (2147483647 >= a) // expected-warning {{comparison 2147483647 >= 'enum A' is always true}}
> + return 0;
> + if (a > 2147483647) // expected-warning {{comparison 'enum A' > 2147483647 is always false}}
> + return 0;
> + if (2147483647 <= a)
> + return 0;
> + if (a <= 2147483647) // expected-warning {{comparison 'enum A' <= 2147483647 is always true}}
> + return 0;
> + if (2147483647 > a)
> + return 0;
> + if (a >= 2147483647)
> + return 0;
> + if (2147483647 < a) // expected-warning {{comparison 2147483647 < 'enum A' is always false}}
> + return 0;
> +
> + if (a < 2147483647U)
> + return 0;
> + if (2147483647U >= a) // expected-warning {{comparison 2147483647 >= 'enum A' is always true}}
> + return 0;
> + if (a > 2147483647U) // expected-warning {{comparison 'enum A' > 2147483647 is always false}}
> + return 0;
> + if (2147483647U <= a)
> + return 0;
> + if (a <= 2147483647U) // expected-warning {{comparison 'enum A' <= 2147483647 is always true}}
> + return 0;
> + if (2147483647U > a)
> + return 0;
> + if (a >= 2147483647U)
> + return 0;
> + if (2147483647U < a) // expected-warning {{comparison 2147483647 < 'enum A' is always false}}
> + return 0;
> +#else // SILENCE
> + if (a < -2147483648)
> + return 0;
> + if (-2147483648 >= a)
> + return 0;
> + if (a > -2147483648)
> + return 0;
> + if (-2147483648 <= a)
> + return 0;
> + if (a <= -2147483648)
> + return 0;
> + if (-2147483648 > a)
> + return 0;
> + if (a >= -2147483648)
> + return 0;
> + if (-2147483648 < a)
> + return 0;
> +
> + if (a < 2147483647)
> + return 0;
> + if (2147483647 >= a)
> + return 0;
> + if (a > 2147483647)
> + return 0;
> + if (2147483647 <= a)
> + return 0;
> + if (a <= 2147483647)
> + return 0;
> + if (2147483647 > a)
> + return 0;
> + if (a >= 2147483647)
> + 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;
> +}
> +
> +// https://bugs.llvm.org/show_bug.cgi?id=35009
> +int PR35009() {
> + enum A { A_a = 2 };
> + enum A a;
> +
> + // in C, this should not warn.
> +
> + if (a < 1)
> + return 0;
> + if (1 >= a)
> + return 0;
> + if (a > 1)
> + return 0;
> + if (1 <= a)
> + return 0;
> + if (a <= 1)
> + return 0;
> + if (1 > a)
> + return 0;
> + if (a >= 1)
> + return 0;
> + if (1 < a)
> + return 0;
> + if (a == 1)
> + return 0;
> + if (1 != a)
> + return 0;
> + if (a != 1)
> + return 0;
> + if (1 == a)
> + return 0;
> +
> + if (a < 1U)
> + return 0;
> + if (1U >= a)
> + return 0;
> + if (a > 1U)
> + return 0;
> + if (1U <= a)
> + return 0;
> + if (a <= 1U)
> + return 0;
> + if (1U > a)
> + return 0;
> + if (a >= 1U)
> + return 0;
> + if (1U < a)
> + return 0;
> + if (a == 1U)
> + return 0;
> + if (1U != a)
> + return 0;
> + if (a != 1U)
> + return 0;
> + if (1U == a)
> + return 0;
> +
> + if (a < 2)
> + return 0;
> + if (2 >= a)
> + return 0;
> + if (a > 2)
> + return 0;
> + if (2 <= a)
> + return 0;
> + if (a <= 2)
> + return 0;
> + if (2 > a)
> + return 0;
> + if (a >= 2)
> + return 0;
> + if (2 < a)
> + return 0;
> + if (a == 2)
> + return 0;
> + if (2 != a)
> + return 0;
> + if (a != 2)
> + return 0;
> + if (2 == a)
> + return 0;
> +
> + if (a < 2U)
> + return 0;
> + if (2U >= a)
> + return 0;
> + if (a > 2U)
> + return 0;
> + if (2U <= a)
> + return 0;
> + if (a <= 2U)
> + return 0;
> + if (2U > a)
> + return 0;
> + if (a >= 2U)
> + return 0;
> + if (2U < a)
> + return 0;
> + if (a == 2U)
> + return 0;
> + if (2U != a)
> + return 0;
> + if (a != 2U)
> + return 0;
> + if (2U == a)
> + return 0;
> +
> + if (a < 3)
> + return 0;
> + if (3 >= a)
> + return 0;
> + if (a > 3)
> + return 0;
> + if (3 <= a)
> + return 0;
> + if (a <= 3)
> + return 0;
> + if (3 > a)
> + return 0;
> + if (a >= 3)
> + return 0;
> + if (3 < a)
> + return 0;
> + if (a == 3)
> + return 0;
> + if (3 != a)
> + return 0;
> + if (a != 3)
> + return 0;
> + if (3 == a)
> + return 0;
> +
> + if (a < 3U)
> + return 0;
> + if (3U >= a)
> + return 0;
> + if (a > 3U)
> + return 0;
> + if (3U <= a)
> + return 0;
> + if (a <= 3U)
> + return 0;
> + if (3U > a)
> + return 0;
> + if (a >= 3U)
> + return 0;
> + if (3U < a)
> + return 0;
> + if (a == 3U)
> + return 0;
> + if (3U != a)
> + return 0;
> + if (a != 3U)
> + return 0;
> + if (3U == a)
> + return 0;
> +
> + return 1;
> +}
>
> Modified: cfe/trunk/test/Sema/tautological-unsigned-enum-zero-compare.c
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/tautological-unsigned-enum-zero-compare.c?rev=316268&r1=316267&r2=316268&view=diff
> ==============================================================================
> --- cfe/trunk/test/Sema/tautological-unsigned-enum-zero-compare.c (original)
> +++ cfe/trunk/test/Sema/tautological-unsigned-enum-zero-compare.c Sat Oct 21 09:44:03 2017
> @@ -1,5 +1,5 @@
> -// RUN: %clang_cc1 -triple=x86_64-pc-linux-gnu -fsyntax-only -DALL_WARN -verify %s
> -// RUN: %clang_cc1 -triple=x86_64-pc-win32 -fsyntax-only -DSIGN_WARN -verify %s
> +// RUN: %clang_cc1 -triple=x86_64-pc-linux-gnu -fsyntax-only -DUNSIGNED -verify %s
> +// RUN: %clang_cc1 -triple=x86_64-pc-win32 -fsyntax-only -DSIGNED -verify %s
> // RUN: %clang_cc1 -triple=x86_64-pc-win32 -fsyntax-only -Wno-tautological-unsigned-enum-zero-compare -verify %s
>
> // Okay, this is where it gets complicated.
> @@ -7,62 +7,254 @@
> // On windows, it is signed by default. We do not want to warn in that case.
>
> int main() {
> - enum A { A_foo, A_bar };
> + enum A { A_a = 0 };
> enum A a;
> + enum B { B_a = -1 };
> + enum B b;
>
> -#ifdef ALL_WARN
> +#ifdef UNSIGNED
> if (a < 0) // expected-warning {{comparison of unsigned enum expression < 0 is always false}}
> return 0;
> - if (a >= 0) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> + 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 < 0U) // expected-warning {{comparison of unsigned enum expression < 0 is always false}}
> return 0;
> - if (a >= 0U) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> + if (0U >= a)
> + return 0;
> + if (a > 0U)
> return 0;
> if (0U <= a) // expected-warning {{comparison of 0 <= unsigned enum expression is always true}}
> return 0;
> + if (a <= 0U)
> + return 0;
> if (0U > a) // expected-warning {{comparison of 0 > unsigned enum expression is always false}}
> return 0;
> -#elif defined(SIGN_WARN)
> - if (a < 0) // ok
> + if (a >= 0U) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> + return 0;
> + if (0U < a)
> + return 0;
> +
> + if (b < 0)
> + return 0;
> + if (0 >= b)
> + return 0;
> + if (b > 0)
> + return 0;
> + if (0 <= b)
> + return 0;
> + if (b <= 0)
> + return 0;
> + if (0 > b)
> + return 0;
> + if (b >= 0)
> + return 0;
> + if (0 < b)
> + return 0;
> +
> + if (b < 0U) // expected-warning {{comparison of unsigned enum expression < 0 is always false}}
> + return 0;
> + if (0U >= b)
> + return 0;
> + if (b > 0U)
> + return 0;
> + if (0U <= b) // expected-warning {{comparison of 0 <= unsigned enum expression is always true}}
> + return 0;
> + if (b <= 0U)
> + return 0;
> + if (0U > b) // expected-warning {{comparison of 0 > unsigned enum expression is always false}}
> + return 0;
> + if (b >= 0U) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> return 0;
> - if (a >= 0) // ok
> + if (0U < b)
> return 0;
> - if (0 <= a) // ok
> +#elif defined(SIGNED)
> + if (a < 0)
> + return 0;
> + if (0 >= a)
> + return 0;
> + if (a > 0)
> + return 0;
> + if (0 <= a)
> + return 0;
> + if (a <= 0)
> return 0;
> - if (0 > a) // ok
> + if (0 > a)
> return 0;
> + if (a >= 0)
> + return 0;
> + if (0 < a)
> + return 0;
> +
> if (a < 0U) // expected-warning {{comparison of unsigned enum expression < 0 is always false}}
> return 0;
> - if (a >= 0U) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> + if (0U >= a)
> + return 0;
> + if (a > 0U)
> return 0;
> if (0U <= a) // expected-warning {{comparison of 0 <= unsigned enum expression is always true}}
> return 0;
> + if (a <= 0U)
> + return 0;
> if (0U > a) // expected-warning {{comparison of 0 > unsigned enum expression is always false}}
> return 0;
> + if (a >= 0U) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> + return 0;
> + if (0U < a)
> + return 0;
> +
> + if (b < 0)
> + return 0;
> + if (0 >= b)
> + return 0;
> + if (b > 0)
> + return 0;
> + if (0 <= b)
> + return 0;
> + if (b <= 0)
> + return 0;
> + if (0 > b)
> + return 0;
> + if (b >= 0)
> + return 0;
> + if (0 < b)
> + return 0;
> +
> + if (b < 0U) // expected-warning {{comparison of unsigned enum expression < 0 is always false}}
> + return 0;
> + if (0U >= b)
> + return 0;
> + if (b > 0U)
> + return 0;
> + if (0U <= b) // expected-warning {{comparison of 0 <= unsigned enum expression is always true}}
> + return 0;
> + if (b <= 0U)
> + return 0;
> + if (0U > b) // expected-warning {{comparison of 0 > unsigned enum expression is always false}}
> + return 0;
> + if (b >= 0U) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> + return 0;
> + if (0U < b)
> + return 0;
> #else
> // expected-no-diagnostics
> +
> if (a < 0)
> return 0;
> - if (a >= 0)
> + if (0 >= a)
> + return 0;
> + if (a > 0)
> return 0;
> if (0 <= a)
> return 0;
> + if (a <= 0)
> + return 0;
> if (0 > a)
> return 0;
> + if (a >= 0)
> + return 0;
> + if (0 < a)
> + return 0;
> +
> if (a < 0U)
> return 0;
> - if (a >= 0U)
> + if (0U >= a)
> + return 0;
> + if (a > 0U)
> return 0;
> if (0U <= a)
> return 0;
> + if (a <= 0U)
> + return 0;
> if (0U > a)
> return 0;
> + if (a >= 0U)
> + return 0;
> + if (0U < a)
> + return 0;
> +
> + if (b < 0)
> + return 0;
> + if (0 >= b)
> + return 0;
> + if (b > 0)
> + return 0;
> + if (0 <= b)
> + return 0;
> + if (b <= 0)
> + return 0;
> + if (0 > b)
> + return 0;
> + if (b >= 0)
> + return 0;
> + if (0 < b)
> + return 0;
> +
> + if (b < 0U)
> + return 0;
> + if (0U >= b)
> + return 0;
> + if (b > 0U)
> + return 0;
> + if (0U <= b)
> + return 0;
> + if (b <= 0U)
> + return 0;
> + if (0U > b)
> + return 0;
> + if (b >= 0U)
> + return 0;
> + if (0U < b)
> + return 0;
> #endif
>
> + if (a == 0)
> + return 0;
> + if (0 != a)
> + return 0;
> + if (a != 0)
> + return 0;
> + if (0 == a)
> + return 0;
> +
> + if (a == 0U)
> + return 0;
> + if (0U != a)
> + return 0;
> + if (a != 0U)
> + return 0;
> + if (0U == a)
> + return 0;
> +
> + if (b == 0)
> + return 0;
> + if (0 != b)
> + return 0;
> + if (b != 0)
> + return 0;
> + if (0 == b)
> + return 0;
> +
> + if (b == 0U)
> + return 0;
> + if (0U != b)
> + return 0;
> + if (b != 0U)
> + return 0;
> + if (0U == b)
> + return 0;
> +
> return 1;
> }
>
> Modified: cfe/trunk/test/Sema/tautological-unsigned-enum-zero-compare.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/tautological-unsigned-enum-zero-compare.cpp?rev=316268&r1=316267&r2=316268&view=diff
> ==============================================================================
> --- cfe/trunk/test/Sema/tautological-unsigned-enum-zero-compare.cpp (original)
> +++ cfe/trunk/test/Sema/tautological-unsigned-enum-zero-compare.cpp Sat Oct 21 09:44:03 2017
> @@ -1,176 +1,347 @@
> -// RUN: %clang_cc1 -std=c++11 -triple=x86_64-pc-linux-gnu -fsyntax-only -DALL_WARN -verify %s
> -// RUN: %clang_cc1 -std=c++11 -triple=x86_64-pc-win32 -fsyntax-only -DSIGN_WARN -verify %s
> -// RUN: %clang_cc1 -std=c++11 -triple=x86_64-pc-win32 -fsyntax-only -Wno-tautological-unsigned-enum-zero-compare -verify %s
> +// RUN: %clang_cc1 -std=c++11 -triple=x86_64-pc-linux-gnu -fsyntax-only -DUNSIGNED -verify %s
> +// RUN: %clang_cc1 -std=c++11 -triple=x86_64-pc-win32 -fsyntax-only -DSIGNED -verify %s
> +// RUN: %clang_cc1 -std=c++11 -triple=x86_64-pc-win32 -fsyntax-only -DSILENCE -Wno-tautological-unsigned-enum-zero-compare -verify %s
>
> // Okay, this is where it gets complicated.
> // Then default enum sigdness is target-specific.
> // On windows, it is signed by default. We do not want to warn in that case.
>
> int main() {
> - enum A { A_foo, A_bar };
> + enum A { A_foo = 0, A_bar, };
> enum A a;
>
> - enum B : unsigned { B_foo, B_bar };
> + enum B : unsigned { B_foo = 0, B_bar, };
> enum B b;
>
> - enum C : signed { c_foo, c_bar };
> + enum C : signed { C_foo = 0, C_bar, };
> enum C c;
>
> -#ifdef ALL_WARN
> +#ifdef UNSIGNED
> if (a < 0) // expected-warning {{comparison of unsigned enum expression < 0 is always false}}
> return 0;
> - if (a >= 0) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> + 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 < 0U) // expected-warning {{comparison of unsigned enum expression < 0 is always false}}
> return 0;
> - if (a >= 0U) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> + if (0U >= a)
> + return 0;
> + if (a > 0U)
> return 0;
> if (0U <= a) // expected-warning {{comparison of 0 <= unsigned enum expression is always true}}
> return 0;
> + if (a <= 0U)
> + return 0;
> if (0U > a) // expected-warning {{comparison of 0 > unsigned enum expression is always false}}
> return 0;
> + if (a >= 0U) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> + return 0;
> + if (0U < a)
> + return 0;
>
> if (b < 0) // expected-warning {{comparison of unsigned enum expression < 0 is always false}}
> return 0;
> - if (b >= 0) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> + if (0 >= b)
> + return 0;
> + if (b > 0)
> return 0;
> if (0 <= b) // expected-warning {{comparison of 0 <= unsigned enum expression is always true}}
> return 0;
> + if (b <= 0)
> + return 0;
> if (0 > b) // expected-warning {{comparison of 0 > unsigned enum expression is always false}}
> return 0;
> + if (b >= 0) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> + return 0;
> + if (0 < b)
> + return 0;
> +
> if (b < 0U) // expected-warning {{comparison of unsigned enum expression < 0 is always false}}
> return 0;
> - if (b >= 0U) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> + if (0U >= b)
> + return 0;
> + if (b > 0U)
> return 0;
> if (0U <= b) // expected-warning {{comparison of 0 <= unsigned enum expression is always true}}
> return 0;
> + if (b <= 0U)
> + return 0;
> if (0U > b) // expected-warning {{comparison of 0 > unsigned enum expression is always false}}
> return 0;
> + if (b >= 0U) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> + return 0;
> + if (0U < b)
> + return 0;
>
> - if (c < 0) // ok
> + if (c < 0)
> + return 0;
> + if (0 >= c) // expected-warning {{comparison 0 >= 'enum C' is always true}}
> + return 0;
> + if (c > 0) // expected-warning {{comparison 'enum C' > 0 is always false}}
> + return 0;
> + if (0 <= c)
> + return 0;
> + if (c <= 0) // expected-warning {{comparison 'enum C' <= 0 is always true}}
> return 0;
> - if (c >= 0) // ok
> + if (0 > c)
> return 0;
> - if (0 <= c) // ok
> + if (c >= 0)
> return 0;
> - if (0 > c) // ok
> + if (0 < c) // expected-warning {{0 < 'enum C' is always false}}
> return 0;
> +
> if (c < 0U) // expected-warning {{comparison of unsigned enum expression < 0 is always false}}
> return 0;
> - if (c >= 0U) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> + if (0U >= c)
> + return 0;
> + if (c > 0U)
> return 0;
> if (0U <= c) // expected-warning {{comparison of 0 <= unsigned enum expression is always true}}
> return 0;
> + if (c <= 0U)
> + return 0;
> if (0U > c) // expected-warning {{comparison of 0 > unsigned enum expression is always false}}
> return 0;
> -#elif defined(SIGN_WARN)
> - if (a < 0) // ok
> + if (c >= 0U) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> return 0;
> - if (a >= 0) // ok
> + if (0U < c)
> return 0;
> - if (0 <= a) // ok
> +#elif defined(SIGNED)
> + if (a < 0)
> + return 0;
> + if (0 >= a) // expected-warning {{comparison 0 >= 'enum A' is always true}}
> return 0;
> - if (0 > a) // ok
> + if (a > 0) // expected-warning {{comparison 'enum A' > 0 is always false}}
> + return 0;
> + if (0 <= a)
> return 0;
> + if (a <= 0) // expected-warning {{comparison 'enum A' <= 0 is always true}}
> + return 0;
> + if (0 > a)
> + return 0;
> + if (a >= 0)
> + return 0;
> + if (0 < a) // expected-warning {{comparison 0 < 'enum A' is always false}}
> + return 0;
> +
> if (a < 0U) // expected-warning {{comparison of unsigned enum expression < 0 is always false}}
> return 0;
> - if (a >= 0U) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> + if (0U >= a)
> + return 0;
> + if (a > 0U)
> return 0;
> if (0U <= a) // expected-warning {{comparison of 0 <= unsigned enum expression is always true}}
> return 0;
> + if (a <= 0U)
> + return 0;
> if (0U > a) // expected-warning {{comparison of 0 > unsigned enum expression is always false}}
> return 0;
> + if (a >= 0U) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> + return 0;
> + if (0U < a)
> + return 0;
>
> if (b < 0) // expected-warning {{comparison of unsigned enum expression < 0 is always false}}
> return 0;
> - if (b >= 0) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> + if (0 >= b)
> + return 0;
> + if (b > 0)
> return 0;
> if (0 <= b) // expected-warning {{comparison of 0 <= unsigned enum expression is always true}}
> return 0;
> + if (b <= 0)
> + return 0;
> if (0 > b) // expected-warning {{comparison of 0 > unsigned enum expression is always false}}
> return 0;
> + if (b >= 0) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> + return 0;
> + if (0 < b)
> + return 0;
> +
> if (b < 0U) // expected-warning {{comparison of unsigned enum expression < 0 is always false}}
> return 0;
> - if (b >= 0U) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> + if (0U >= b)
> + return 0;
> + if (b > 0U)
> return 0;
> if (0U <= b) // expected-warning {{comparison of 0 <= unsigned enum expression is always true}}
> return 0;
> + if (b <= 0U)
> + return 0;
> if (0U > b) // expected-warning {{comparison of 0 > unsigned enum expression is always false}}
> return 0;
> + if (b >= 0U) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> + return 0;
> + if (0U < b)
> + return 0;
>
> - if (c < 0) // ok
> + if (c < 0)
> return 0;
> - if (c >= 0) // ok
> + if (0 >= c) // expected-warning {{comparison 0 >= 'enum C' is always true}}
> return 0;
> - if (0 <= c) // ok
> + if (c > 0) // expected-warning {{comparison 'enum C' > 0 is always false}}
> + return 0;
> + if (0 <= c)
> return 0;
> - if (0 > c) // ok
> + if (c <= 0) // expected-warning {{comparison 'enum C' <= 0 is always true}}
> + return 0;
> + if (0 > c)
> + return 0;
> + if (c >= 0)
> return 0;
> + if (0 < c) // expected-warning {{0 < 'enum C' is always false}}
> + return 0;
> +
> if (c < 0U) // expected-warning {{comparison of unsigned enum expression < 0 is always false}}
> return 0;
> - if (c >= 0U) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> + if (0U >= c)
> + return 0;
> + if (c > 0U)
> return 0;
> if (0U <= c) // expected-warning {{comparison of 0 <= unsigned enum expression is always true}}
> return 0;
> + if (c <= 0U)
> + return 0;
> if (0U > c) // expected-warning {{comparison of 0 > unsigned enum expression is always false}}
> return 0;
> + if (c >= 0U) // expected-warning {{comparison of unsigned enum expression >= 0 is always true}}
> + return 0;
> + if (0U < c)
> + return 0;
> #else
> - // expected-no-diagnostics
> if (a < 0)
> return 0;
> - if (a >= 0)
> + if (0 >= a) // expected-warning {{comparison 0 >= 'enum A' is always true}}
> + return 0;
> + if (a > 0) // expected-warning {{comparison 'enum A' > 0 is always false}}
> return 0;
> if (0 <= a)
> return 0;
> + if (a <= 0) // expected-warning {{comparison 'enum A' <= 0 is always true}}
> + return 0;
> if (0 > a)
> return 0;
> + if (a >= 0)
> + return 0;
> + if (0 < a) // expected-warning {{comparison 0 < 'enum A' is always false}}
> + return 0;
> +
> if (a < 0U)
> return 0;
> - if (a >= 0U)
> + if (0U >= a)
> + return 0;
> + if (a > 0U)
> return 0;
> if (0U <= a)
> return 0;
> + if (a <= 0U)
> + return 0;
> if (0U > a)
> return 0;
> + if (a >= 0U)
> + return 0;
> + if (0U < a)
> + return 0;
>
> if (b < 0)
> return 0;
> - if (b >= 0)
> + if (0 >= b)
> + return 0;
> + if (b > 0)
> return 0;
> if (0 <= b)
> return 0;
> + if (b <= 0)
> + return 0;
> if (0 > b)
> return 0;
> + if (b >= 0)
> + return 0;
> + if (0 < b)
> + return 0;
> +
> if (b < 0U)
> return 0;
> - if (b >= 0U)
> + if (0U >= b)
> + return 0;
> + if (b > 0U)
> return 0;
> if (0U <= b)
> return 0;
> + if (b <= 0U)
> + return 0;
> if (0U > b)
> return 0;
> + if (b >= 0U)
> + return 0;
> + if (0U < b)
> + return 0;
>
> if (c < 0)
> return 0;
> - if (c >= 0)
> + if (0 >= c) // expected-warning {{comparison 0 >= 'enum C' is always true}}
> + return 0;
> + if (c > 0) // expected-warning {{comparison 'enum C' > 0 is always false}}
> return 0;
> if (0 <= c)
> return 0;
> + if (c <= 0) // expected-warning {{comparison 'enum C' <= 0 is always true}}
> + return 0;
> if (0 > c)
> return 0;
> + if (c >= 0)
> + return 0;
> + if (0 < c) // expected-warning {{0 < 'enum C' is always false}}
> + return 0;
> +
> if (c < 0U)
> return 0;
> - if (c >= 0U)
> + if (0U >= c)
> + return 0;
> + if (c > 0U)
> return 0;
> if (0U <= c)
> return 0;
> + if (c <= 0U)
> + return 0;
> if (0U > c)
> return 0;
> + if (c >= 0U)
> + return 0;
> + if (0U < c)
> + return 0;
> +#endif
> +
> + return 1;
> +}
> +
> +namespace crash_enum_zero_width {
> +int test() {
> + enum A : unsigned {
> + A_foo = 0
> + };
> + enum A a;
> +
> + // used to crash in llvm::APSInt::getMaxValue()
> +#ifndef SILENCE
> + if (a < 0) // expected-warning {{comparison of unsigned enum expression < 0 is always false}}
> +#else
> + if (a > 0)
> #endif
> + return 0;
>
> return 1;
> }
> +} // namespace crash_enum_zero_width
>
>
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