Clang has this weird behavior of setting __GNUC__ to 4, hence clang will always take the if branch. This is suboptimal because std::is_trivially_copyable has almost always been in clang.
starting with clang 15 a warning is raised for the current implementation:
warning: builtin __has_trivial_copy is deprecated; use __is_trivially_copyable instead [-Wdeprecated-builtins]
Since we are using -Werror, we should fix this.
When compiled with new toolchain that implements std::format_to, it become
ambiguous on which one should be called. Due to argument-dependent lookup, even
if we are not `using namespace std;` the std version is still considered. So
let's add fmt:: to avoid ambiguous compilation error.
