libstdc++: Fix std::numeric_limits::lowest() test for strict modes

This test uses std::is_integral to decide whether we are testing an
integral or floating-point type. But that fails for __int128 because
is_integral<__int128> is false in strict modes. By using
numeric_limits::is_integer instead we get the right answer for all types
that have a numeric_limits specialization.

We can also simplify the test by removing the unnecessary tag
dispatching.

libstdc++-v3/ChangeLog:

	* testsuite/18_support/numeric_limits/lowest.cc: Use
	numeric_limits<T>::is_integer instead of is_integral<T>::value.

(cherry picked from commit 45ba5426c1)
This commit is contained in:
Jonathan Wakely 2021-10-11 13:28:32 +01:00
parent 00967465fe
commit 60c20a314d

View File

@ -23,30 +23,20 @@
// 18.2.1.1 template class numeric_limits
#include <limits>
#include <type_traits>
#include <testsuite_hooks.h>
template<typename T>
void
do_test(std::true_type)
do_test()
{
T limits_min = std::numeric_limits<T>::min();
VERIFY( std::numeric_limits<T>::lowest() == limits_min );
}
template<typename T>
void
do_test(std::false_type)
{
T limits_max = std::numeric_limits<T>::max();
if (std::numeric_limits<T>::is_integer)
VERIFY( std::numeric_limits<T>::lowest() == limits_min );
else
VERIFY( std::numeric_limits<T>::lowest() == -limits_max );
}
template<typename Tp>
void
do_test()
{ do_test<Tp>(typename std::is_integral<Tp>::type()); }
void test01()
{
do_test<char>();