Want to know which part of the rust repo handle command line arguments

i like know about the rust repo, how it is organized especially the cli interface

Start here:

Clap is particularly powerful, and also has a macro option. You can define subcommands with it like a true champ.

https://crates.io/crates/clap

This, however, doesn't answer the OP, since rustc itself uses not clap, but getopts.

Getops is not as pretty as clap, but perhaps I misunderstood the question. I assumed the question was about what crate can handle command line arguments.