The r16-6177-g866bc8a9214b1d introduced type-constraint on _Urbg template
parameter in __glibcxx_concepts, which make the mangled inconsistient.
This lead to the missing symbol errors in tests, from
__gnu_cxx::random_condition::throw_conditionally.
libstdc++-v3/ChangeLog:
* include/bits/random.tcc (generate_canonical)
[!_GLIBCXX_USE_OLD_GENERATE_CANONICAL]: Use static_assert
instead of type-constraint on template parameter.
---
I have not yet determined what is causing pre-C++20 version of
__gnu_cxx::random_condition::throw_conditionally to be linked against
post-C++20 version. I am concerned about it, because if we call
generate_canonical from libstdc++ shared library, then
_GLIBCXX_USE_OLD_GENERATE_CANONICAL
flag will not properly restore old behavior. Posting anyway to
aknowledge the issue.
libstdc++-v3/include/bits/random.tcc | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)
diff --git a/libstdc++-v3/include/bits/random.tcc
b/libstdc++-v3/include/bits/random.tcc
index 38e8645c88c..29d50d553e2 100644
--- a/libstdc++-v3/include/bits/random.tcc
+++ b/libstdc++-v3/include/bits/random.tcc
@@ -3619,12 +3619,6 @@ namespace __detail
template <> const bool __is_rand_dist_float_v<long double> = true;
#endif
-#ifdef __glibcxx_concepts
-# define _Uniform_random_bit_generator uniform_random_bit_generator
-#else
-# define _Uniform_random_bit_generator typename
-#endif
-
// Note, this works even when (__range + 1) overflows:
template <typename _Rng>
constexpr bool __is_power_of_2_less_1(_Rng __range)
@@ -3646,10 +3640,13 @@ namespace __detail
* @since C++11
*/
template<typename _RealT, size_t __digits,
- _Uniform_random_bit_generator _Urbg>
+ typename _Urbg>
_RealT
generate_canonical(_Urbg& __urng)
{
+#ifdef __glibcxx_concepts
+ static_assert(uniform_random_bit_generator<_Ubrg>);
+#endif
static_assert(__is_rand_dist_float_v<_RealT>,
"template argument must be floating point");
static_assert(__digits != 0 && _Urbg::max() > _Urbg::min(),
--
2.52.0
