Use cargo fmt instead of rustfmt

[vmalloc]

For Rust 2018, rustfmt does not work correctly (e.g. removes leading :: from use statements. The fact that rust-mode runs it instead of cargo fmt makes it problematic for writing 2018 code...

It would be nice to have this mode use the recommended cargo fmt command instead of rustfmt.

Thanks in advance!

[das-sein]

Could you provide a code snippet that it's formatting incorrectly? I'm not experiencing this issue myself, but am wondering if using rustfmt is actually the issue here. While playing with replacing the rustfmt calls, I found that cargo fmt itself will pass arguments to rustfmt given the -- argument.

[vmalloc]

I stumbled upon it as a part of the Rust 2018 changes - where rustfmt did not respect the "Edition" directive in cargo.toml. I guess this is no longer the case so the priority of this should not be that critical IMO

[agrover]

Certainly still seems to be the case for me. See rust-lang/rustfmt#3724

[topecongiro]

rustfmt does not respect Cargo.toml because it is intended for a stand-alone tool, even without cargo. You could still pass --edition 2018 to rustfmt to let it understand that the files being passed use edition 2018.