Build error: specializing std::is_pointer is not allowed (libc++ with _LIBCPP_NO_SPECIALIZATIONS )

[yunyi1201]

Problem

Building with Apple Clang 21.0.0 (clang-2100.1.1.101) on macOS fails because include/ylt/util/ff_ptr.hpp specializes std::is_pointer , which is now prohibited by libc++.

Error Message

include/ylt/util/ff_ptr.hpp:523:8: error: 'is_pointer' cannot be  specialized:  Users are not allowed to specialize this standard library entity [-Winvalid-specialization]                                                     
struct is_pointer<ylt::util::ff_ptr<T>> : public std::true_type {};                                                   

Environment

• Compiler: Apple Clang 21.0.0 (clang-2100.1.1.101)
• OS: macOS

[poor-circle]

I will remove those code later.