[committed] libstdc++: Remove unused alias template in std::optional

[Jonathan Wakely]

Tested x86_64-linux. Pushed to trunk.

-- >8 --

I added this __is_bool alias template in r15-2309-g6d86486292acbe but
it isn't actually used so can be removed.

libstdc++-v3/ChangeLog:

        * include/std/optional (__is_bool): Remove.
---
 libstdc++-v3/include/std/optional | 2 --
 1 file changed, 2 deletions(-)

diff --git a/libstdc++-v3/include/std/optional 
b/libstdc++-v3/include/std/optional
index 933a5b15e56..6a8e76f60e3 100644
--- a/libstdc++-v3/include/std/optional
+++ b/libstdc++-v3/include/std/optional
@@ -850,8 +850,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        using __not_self = __not_<is_same<optional, __remove_cvref_t<_Up>>>;
       template<typename _Up>
        using __not_tag = __not_<is_same<in_place_t, __remove_cvref_t<_Up>>>;
-      template<typename _Up>
-       using __is_bool = is_same<remove_cv_t<_Up>, bool>;
       template<typename... _Cond>
        using _Requires = enable_if_t<__and_v<_Cond...>, bool>;
 #endif
-- 
2.46.0