Oooh! C++20 has std::format that would allow me to easily format file modification times from std::filesystem/chrono.
Oh, allegedly it does in MSVC and Clang, but not in the C++20 support with the GCC that’s part of Mint 21.3 or the versions of Ubuntu/Debian on which it is based (which I thought was supposed to fully support C++20).
I found a workaround by using libfmt as a drop-in replacement. Unfortunately the version shipped with Mint 21.3 has a bug that means it doesn’t work for the way I want to use it — I get a compiler error. It’s fixed in a later release, but I really don’t want to get into carrying third-party libraries around.
Irritation factor eleven, Mr. Sulu. I guess I’ll have to do it the hard way then.