[clang] [libcxx] Allow string to use SSO in constant evaluation. (PR #66576)

[James Y Knight via cfe-commits]

================
@@ -1746,26 +1747,8 @@ private:
 #endif // _LIBCPP_STD_VER >= 20
     }
 
-    _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __default_init() {
-        __r_.first() = __rep();
-        if (__libcpp_is_constant_evaluated()) {
-            size_type __sz = __recommend(0) + 1;
-            pointer __ptr = __alloc_traits::allocate(__alloc(), __sz);
-            __begin_lifetime(__ptr, __sz);
-            __set_long_pointer(__ptr);
-            __set_long_cap(__sz);
-            __set_long_size(0);
-        }
-    }
-
-    _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __deallocate_constexpr() {
-        if (__libcpp_is_constant_evaluated() && __get_pointer() != nullptr)
-            __alloc_traits::deallocate(__alloc(), __get_pointer(), __get_long_cap());
-    }
-
     _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI static bool __fits_in_sso(size_type __sz) {
-        // SSO is disabled during constant evaluation because `__is_long` isn't constexpr friendly
-        return !__libcpp_is_constant_evaluated() && (__sz < __min_cap);
+        return (__sz < __min_cap);
----------------
jyknight wrote:

Done.

https://github.com/llvm/llvm-project/pull/66576