fmt: warn if glob matches nothing

[kevinkassimo]

Closes #3915

$ ./target/debug/deno fmt fdsafdasf.ts
Warning: 'fdsafdasf.ts' does not match any files
Formatted 0 files in 817ns

[hayd]

In a script (which is the only time exit code really matters) running 0 tests is always going to be a bug and so IMO it should exit(1).

[kevinkassimo]

@hayd I believe this might be debatable? We can add a flag to turn this warning into an error, or if more people think it is a good default, invert the flag to turn error (default) into warning

[hayd]

What's the counter-argument?

[nayeemrmn]

@hayd The warnings are applied per-glob here. It would be too strict to give a non-zero exit code for any glob that didn't match anything. That said, I would prefer if it matched the test runner.

Maybe alongside the per-glob warnings, if no provided glob matched anything then we can exit(1)?

[dplewis]

@hayd I agree with you on zero tests but the PR is about formatting files.

[ry]

I’m not sure why we need to be expanding globs at all in Deno... Isn’t this taken care of by the shell?

[nayeemrmn]

@ry Things like default globs, directory expansion, a useful --exclude flag will require internal glob handling. This particular usage aside, having no good way to expand globs within cli is too crippling to get away with. I worry that #3865 will be more than a short-term regression when I hear justifications for not needing this capability.

[ry]

Thanks Kevin, I was about to merge this, but as I was fixing the conflicts I noticed some other things and ended up doing a whole refactor.

#3988