libstdc++: Use __builtin_unreachable for constexpr assertions [PR 100676]
The current implementation of compile-time precondition checks causes compilation to fail by calling a non-constexpr function declared at block scope. This breaks the CUDA compiler, which wraps some libstdc++ headers in a pragma that declares everything as a __host__ __device__ function, but others are not wrapped and so everything is a __host__ function. The local declaration thus gets redeclared as two different types of function, which doesn't work. Just use __builtin_unreachable to make constant evaluation fail, instead of the local function declaration. Also simplify the assertion macros, which has the side effect of giving simpler compilation errors when using Clang. libstdc++-v3/ChangeLog: PR libstdc++/100676 * include/bits/c++config (__glibcxx_assert_1): Rename to ... (__glibcxx_constexpr_assert): ... this. (__glibcxx_assert_impl): Use __glibcxx_constexpr_assert. (__glibcxx_assert): Define as either __glibcxx_constexpr_assert or __glibcxx_assert_impl. (__glibcxx_assert_2): Remove * include/debug/macros.h (_GLIBCXX_DEBUG_VERIFY_AT_F): Use __glibcxx_constexpr_assert instead of __glibcxx_assert_1. * testsuite/21_strings/basic_string_view/element_access/char/back_constexpr_neg.cc: Adjust expected error. * testsuite/21_strings/basic_string_view/element_access/char/constexpr_neg.cc: Likewise. * testsuite/21_strings/basic_string_view/element_access/char/front_constexpr_neg.cc: Likewise. Likewise. * testsuite/21_strings/basic_string_view/element_access/wchar_t/back_constexpr_neg.cc: Likewise. * testsuite/21_strings/basic_string_view/element_access/wchar_t/constexpr_neg.cc: Likewise. * testsuite/21_strings/basic_string_view/element_access/wchar_t/front_constexpr_neg.cc: Likewise. * testsuite/23_containers/span/back_neg.cc: Likewise. * testsuite/23_containers/span/front_neg.cc: Likewise. * testsuite/23_containers/span/index_op_neg.cc: Likewise.
This commit is contained in:
Jonathan Wakely
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ee336ecb2a
commit
6b42b5a8a2
@ -487,6 +487,16 @@ namespace std
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# define _GLIBCXX_EXTERN_TEMPLATE -1
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#endif
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#if __has_builtin(__builtin_is_constant_evaluated)
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# define __glibcxx_constexpr_assert(cond) \
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if (__builtin_is_constant_evaluated() && !bool(cond)) \
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__builtin_unreachable() /* precondition violation detected! */
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#else
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# define __glibcxx_constexpr_assert(unevaluated)
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#endif
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// Assert.
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#if defined(_GLIBCXX_ASSERTIONS) \
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|| defined(_GLIBCXX_PARALLEL) || defined(_GLIBCXX_PARALLEL_ASSERTIONS)
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@ -506,14 +516,19 @@ namespace std
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}
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#define __glibcxx_assert_impl(_Condition) \
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if (__builtin_expect(!bool(_Condition), false)) \
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{ \
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__glibcxx_constexpr_assert(_Condition); \
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std::__replacement_assert(__FILE__, __LINE__, __PRETTY_FUNCTION__, \
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#_Condition)
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#_Condition); \
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}
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#endif
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#if defined(_GLIBCXX_ASSERTIONS)
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# define __glibcxx_assert_2(_Condition) __glibcxx_assert_impl(_Condition)
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# define __glibcxx_assert(cond) \
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do { __glibcxx_assert_impl(cond); } while (false)
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#else
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# define __glibcxx_assert_2(_Condition)
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# define __glibcxx_assert(cond) \
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do { __glibcxx_constexpr_assert(cond); } while (false)
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#endif
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// Macros for race detectors.
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@ -736,25 +751,6 @@ namespace std
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#undef _GLIBCXX_HAS_BUILTIN
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#if _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED && __cplusplus >= 201402L
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# define __glibcxx_assert_1(_Condition) \
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if (__builtin_is_constant_evaluated()) \
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{ \
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void __failed_assertion(); \
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if (!bool(_Condition)) \
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__failed_assertion(); \
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} \
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else
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#else
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# define __glibcxx_assert_1(_Condition)
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#endif
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# define __glibcxx_assert(_Condition) \
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do { \
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__glibcxx_assert_1(_Condition) \
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{ __glibcxx_assert_2(_Condition); } \
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} while (false)
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// PSTL configuration
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@ -45,8 +45,8 @@
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#define _GLIBCXX_DEBUG_VERIFY_AT_F(_Cond,_ErrMsg,_File,_Line,_Func) \
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do { \
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__glibcxx_assert_1(_Cond) \
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{ _GLIBCXX_DEBUG_VERIFY_COND_AT(_Cond,_ErrMsg,_File,_Line,_Func); } \
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__glibcxx_constexpr_assert(_Cond); \
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_GLIBCXX_DEBUG_VERIFY_COND_AT(_Cond,_ErrMsg,_File,_Line,_Func); \
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} while (false)
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#define _GLIBCXX_DEBUG_VERIFY_AT(_Cond,_ErrMsg,_File,_Line) \
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@ -32,4 +32,4 @@ back()
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static_assert(back() != 'a'); // { dg-error "non-constant condition" }
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// { dg-prune-output "in 'constexpr' expansion" }
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// { dg-prune-output "failed_assertion" }
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// { dg-prune-output "unreachable" }
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@ -31,4 +31,4 @@ test()
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static_assert(test() == 0); // { dg-error "non-constant condition" }
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// { dg-prune-output "in 'constexpr' expansion" }
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// { dg-prune-output "failed_assertion" }
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// { dg-prune-output "unreachable" }
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@ -32,4 +32,4 @@ front()
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static_assert(front() != 'a'); // { dg-error "non-constant condition" }
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// { dg-prune-output "in 'constexpr' expansion" }
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// { dg-prune-output "failed_assertion" }
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// { dg-prune-output "unreachable" }
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@ -32,4 +32,4 @@ back()
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static_assert(back() != L'a'); // { dg-error "non-constant condition" }
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// { dg-prune-output "in 'constexpr' expansion" }
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// { dg-prune-output "failed_assertion" }
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// { dg-prune-output "unreachable" }
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@ -31,4 +31,4 @@ test()
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static_assert(test() == 0); // { dg-error "non-constant condition" }
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// { dg-prune-output "in 'constexpr' expansion" }
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// { dg-prune-output "failed_assertion" }
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// { dg-prune-output "unreachable" }
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@ -32,4 +32,4 @@ front()
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static_assert(front() != L'a'); // { dg-error "non-constant condition" }
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// { dg-prune-output "in 'constexpr' expansion" }
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// { dg-prune-output "failed_assertion" }
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// { dg-prune-output "unreachable" }
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@ -31,5 +31,5 @@ test01(bool b)
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static_assert(test01(false));
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static_assert(test01(true)); // { dg-error "non-constant" }
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// { dg-error "assert" "" { target *-*-* } 0 }
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// { dg-error "unreachable" "" { target *-*-* } 0 }
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// { dg-prune-output "in 'constexpr' expansion" }
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@ -31,5 +31,5 @@ test01(bool b)
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static_assert(test01(false));
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static_assert(test01(true)); // { dg-error "non-constant" }
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// { dg-error "assert" "" { target *-*-* } 0 }
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// { dg-error "unreachable" "" { target *-*-* } 0 }
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// { dg-prune-output "in 'constexpr' expansion" }
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@ -31,5 +31,5 @@ test01(bool b)
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static_assert(test01(false));
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static_assert(test01(true)); // { dg-error "non-constant" }
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// { dg-error "assert" "" { target *-*-* } 0 }
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// { dg-error "unreachable" "" { target *-*-* } 0 }
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// { dg-prune-output "in 'constexpr' expansion" }
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