[libc++] Add GCC workaround in std::char_traits<char>::length()
GCC currently does not allow `__builtin_strlen()` during constant evaluation. This PR adds a workaround in `std::char_traits<char>::length()`
Reviewed By: Quuxplusone, ldionne, #libc, Mordante
Spies: Mordante, libcxx-commits
Differential Revision: https://reviews.llvm.org/D115795
NOKEYCHECK=True
GitOrigin-RevId: 148ef80f895297975b95800f6fa989674767c5a2
diff --git a/include/__string b/include/__string
index e3fd0c2..2840819 100644
--- a/include/__string
+++ b/include/__string
@@ -337,8 +337,21 @@
static _LIBCPP_CONSTEXPR_AFTER_CXX14
int compare(const char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT;
- static inline size_t _LIBCPP_CONSTEXPR_AFTER_CXX14
- length(const char_type* __s) _NOEXCEPT {return __builtin_strlen(__s);}
+
+ static inline size_t _LIBCPP_CONSTEXPR_AFTER_CXX14 length(const char_type* __s) _NOEXCEPT {
+ // GCC currently does not support __builtin_strlen during constant evaluation.
+ // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70816
+#ifdef _LIBCPP_COMPILER_GCC
+ if (__libcpp_is_constant_evaluated()) {
+ size_t __i = 0;
+ for (; __s[__i] != char_type('\0'); ++__i)
+ ;
+ return __i;
+ }
+#endif
+ return __builtin_strlen(__s);
+ }
+
static _LIBCPP_CONSTEXPR_AFTER_CXX14
const char_type* find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT;
static inline _LIBCPP_CONSTEXPR_AFTER_CXX17