This patch defines _GLIBCXX_HAS_BUILTIN_TRAIT, which will be used as a
flag to toggle built-in traits in the type_traits header. Through this
macro function and _GLIBCXX_NO_BUILTIN_TRAITS macro, we can switch the
use of built-in traits without needing to modify the source code.
libstdc++-v3/ChangeLog:
* include/bits/c++config (_GLIBCXX_HAS_BUILTIN_TRAIT): Define.
Signed-off-by: Ken Matsui <kmat...@gcc.gnu.org>
---
libstdc++-v3/include/bits/c++config | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/libstdc++-v3/include/bits/c++config
b/libstdc++-v3/include/bits/c++config
index dd47f274d5f..de13f61db71 100644
--- a/libstdc++-v3/include/bits/c++config
+++ b/libstdc++-v3/include/bits/c++config
@@ -854,7 +854,11 @@ namespace __gnu_cxx
# define _GLIBCXX_HAVE_BUILTIN_LAUNDER 1
#endif
-#undef _GLIBCXX_HAS_BUILTIN
+// Returns true if _GLIBCXX_NO_BUILTIN_TRAITS is not defined and the compiler
+// has a corresponding built-in type trait. _GLIBCXX_NO_BUILTIN_TRAITS is
+// defined to disable the use of built-in traits.
+#define _GLIBCXX_HAS_BUILTIN_TRAIT(BT) \
+ (!defined(_GLIBCXX_NO_BUILTIN_TRAITS) && _GLIBCXX_HAS_BUILTIN(BT))
// Mark code that should be ignored by the compiler, but seen by Doxygen.
#define _GLIBCXX_DOXYGEN_ONLY(X)
--
2.41.0
