The help message when an invalid calling convention is specified is getting a little unwieldy

[nagisa]

After #93561 misspelling a calling convention will output the following note:

LL | extern "路濫狼á́́" fn foo() {}
   |        ^^^^^^^^^ invalid ABI
   |
   = help: valid ABIs: Rust, C, C-unwind, cdecl, cdecl-unwind, stdcall, stdcall-unwind, fastcall, fastcall-unwind, vectorcall, vectorcall-unwind, thiscall, thiscall-unwind, aapcs, aapcs-unwind, win64, win64-unwind, sysv64, sysv64-unwind, ptx-kernel, msp430-interrupt, x86-interrupt, amdgpu-kernel, efiapi, avr-interrupt, avr-non-blocking-interrupt, C-cmse-nonsecure-call, wasm, system, system-unwind, rust-intrinsic, rust-call, platform-intrinsic, unadjusted

This is getting pretty hard to read!

There are a couple of improvements we could make:

1. Invoke Levenshtein magic and only suggest some calling conventions that are close, if any (covers mis-spellings);
   • This could be a MachineApplicable::MaybeIncorrect rustfix!
2. Suggest at most a couple of the most common ABIs (possibly a target-specific list?);
3. Do not suggest CCs that cannot be used due to them being unstable and feature not being enabled; and finally
4. Explain where to find a full list (may involve adding CLI surface to rustc).

With these suggestions in place the message could look like:

LL | extern "wni64" fn foo() {}
   |        ^^^^^^^ invalid ABI
   |
   = help: did you mean `win64`?
   = note: invoke `rustc --print=calling-conventions` for a full list of supported calling conventions

or

LL | extern "路濫狼á́́" fn foo() {}
   |        ^^^^^^^^^ invalid ABI
   |
   = help: commonly used calling conventions include: `C`, `system`, `sysv64`, `win64` and `wasm`
   = note: invoke `rustc --print=calling-conventions` for a full list of supported calling conventions

[ritobanrc]

I'd be interested in tackling this, though it would be my first contribution, so I'll probably need some additional guidance.

[ritobanrc]

@rustbot claim

[khyperia]

Hey, are you still working on this? If not, I'm going to take a shot at it 🙂

[ritobanrc]

Nope, something came up, feel free to take it. @rustbot release-assignment

…

On Sat, Aug 13, 2022, 02:23 Ashley Hauck ***@***.***> wrote: Hey, are you still working on this? If not, I'm going to take a shot at it 🙂 — Reply to this email directly, view it on GitHub <#93601 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ADIVSOIRCPR46O36PWNFR5LVY5SQTANCNFSM5NNEVHKQ> . You are receiving this because you were assigned.Message ID: ***@***.***>