4daa263e0b
Currently you can get a list of lints and lint groups by running `rustc -Whelp`. This prints an additional line at the end: ``` Compiler plugins can provide additional lints and lint groups. To see a listing of these, re-run `rustc -W help` with a crate filename. ``` Clippy is such a "compiler plugin", that provides additional lints. Running `clippy-driver -Whelp` (`rustc` wrapper) still only prints the rustc lints with the above message at the end. But when running `clippy-driver -Whelp main.rs`, where `main.rs` is any rust file, it also prints Clippy lints. I don't think this is a good approach from a UX perspective: Why is a random file necessary to print a help message? This commit changes this behavior: Whenever a compiler callback registers lints, it is assumed that these lints come from a plugin and are printed without having to specify a Rust source file.
The driver crate is effectively the "main" function for the rust
compiler. It orchestrates the compilation process and "knits together"
the code from the other crates within rustc. This crate itself does
not contain any of the "main logic" of the compiler (though it does
have some code related to pretty printing or other minor compiler
options).
For more information about how the driver works, see the rustc dev guide.