I know little about it and I'm not sure that it works. It might.
I do know that for regular std-using programs, std has its own panic strategy that it was compiled with, so even if you set your own code's panic strategy to abort, it still ends up pulling in unwind-related code from libstd. The solution to that is to also recompile libstd with the same parameters as your own code, which is what `-Z build-std` does.
I don't know if the same thing applies even to libcore, ie for no_std programs. FWIW, coincidentally I spent yesterday making a no_std panic=abort program for a custom freestanding target, and the only missing symbols it needed from me were memcpy and memcmp, even though the code does do panicking things like slice indexing. That program requires `-Z build-std=core` since it's for a custom freestanding target.
I do know that for regular std-using programs, std has its own panic strategy that it was compiled with, so even if you set your own code's panic strategy to abort, it still ends up pulling in unwind-related code from libstd. The solution to that is to also recompile libstd with the same parameters as your own code, which is what `-Z build-std` does.
I don't know if the same thing applies even to libcore, ie for no_std programs. FWIW, coincidentally I spent yesterday making a no_std panic=abort program for a custom freestanding target, and the only missing symbols it needed from me were memcpy and memcmp, even though the code does do panicking things like slice indexing. That program requires `-Z build-std=core` since it's for a custom freestanding target.