driver: print rustc --version --verbose on "clippy-driver rustc --version"

[matthiaskrgr]

Fixes #5159

changelog: make "clippy-driver rustc --version" print "rustc --version --verbose" output.

[flip1995]

Looking at #5167, I think we should rethink the output of clippy, when called with --version/-V/.... I think adding a rustc --version doesn't really solve this problem.

Maybe we could add clippy-driver rustc ... which just forwards every flag to rustc (maybe even disables clippy completely and just runs plain rustc on the code)

[matthiaskrgr]

Yeah that sounds like a good solution.

[jsgf]

No, there's no guarantee that there's a rustc in the path, or that if there is, it has anything to do with the version of clippy-driver we're running.

[jsgf]

@flip1995 Yes, I think making clippy-driver rustc ... pass all options through to the linked-in rustc makes sense, but it should still keep the clippy functionality. clippy-driver is already a functionally complete rustc, aside from the handful of options it intercepts early.

If we could go back in time, I'd suggest that all clippy-specific options should be of the form --clippy-X - --clippy-version etc - so that all other options can be passed directly through to rustc. But using clippy-driver rustc as a way of quoting them seems like a reasonable workaround now.

[flip1995]

but it should still keep the clippy functionality.

Yeah, I also think this would be the better behavior. Just in case this should be way harder to implement, I'd also be good with just having clippy-driver rustc == rustc-linked-with-clippy.

I'd suggest that all clippy-specific options should be of the form --clippy-X

I think I would have disagreed with this, but let's not bikeshed something we would have to go back in time to change 😄

[jsgf]

Yeah, I also think this would be the better behavior. Just in case this should be way harder to implement, I'd also be good with just having clippy-driver rustc == rustc-linked-with-clippy.

In addition, if filename(argv[0]) == "rustc", then behave as rustc (so you can either execve it as rustc, or symlink rustc -> clippy-driver).

[flip1995]

ping @matthiaskrgr Are you interested in implementing this? Otherwise I'd close this PR, because just adding rustc --version doesn't really adds much IMHO, since something similar can already be achieved by just -Vv (accidentally).

[matthiaskrgr]

I posted a different attempt where clippy-driver rustc --foo just execs rustc --foo: #5178

[jsgf]

@matthiaskrgr That's basically what this PR does, and it has the same problem (I commented on your PR as well as here).

[flip1995]

Closing in favor of #5178