Fix another ICE in rustdoc scrape_examples

[fee1-dead]

This has occurred to me when documenting a crate with the arguments. Not sure what could have caused it.

r? @willcrichton

[jyn514]

@fee1-dead can you please add a test for this?

[willcrichton]

Thanks @fee1-dead !!

One request. Can you add a trace! call for these two early returns? Just like I'm introducing in this other PR: https://github.com/rust-lang/rust/pull/90583/files#diff-77f9ef3a3f7e3637167a2856739a2fbb33946a33c1bccb328119dfaaa801a02dR187

[fee1-dead]

I found the percent_encoding crate was causing it. I was able to reproduce with the file, but I don't know the root cause of the ICE, so I'm just going to use the file as a ui test.

The file is available to download from here

[camelid]

Please try to make the test case an MCVE too. I don't think we should have a 500 line test case if we can avoid it.

[jyn514]

@fee1-dead if you like, I know that https://github.com/chengniansun/perses is a tool for trying to reduce test cases, it may or may not be easier than trying to reduce this manually.

[fee1-dead]

Thanks @jyn514! Perses is a very powerful tool and it reduced it to use core; which shocked me.

[jyn514]

Hmm, that doesn't actually give me a lot of confidence that we know how this crash happens ... but I guess it's not super important as long as it's fixed and we have a test it won't regress.

@bors r=jyn514,willcrichton

[bors]

📌 Commit 9c14d82 has been approved by jyn514,willcrichton

[petrochenkov]

@fee1-dead
The added test writes the t.calls file right to the root of the repository (at least if you run x.py from it).

$ git status
On branch master
Your branch is up to date with 'origin/master'.

Untracked files:
  (use "git add <file>..." to include in what will be committed)
        t.calls

All test outputs should be limited to the build directory.

[jyn514]

I think you can just remove output-path here.

[fee1-dead]

Don't think so, it will error if either of the two options are unset. Perhaps it should point to build/tmp/?

[jyn514]

it will error if either of the two options are unset.

well that's odd ... @willcrichton is there a reason you made that a hard error instead of giving it a default value?

anyway, in the meantime, try {{build-base}}/t.calls: https://rustc-dev-guide.rust-lang.org/tests/adding.html#input-normalization

[willcrichton]

There isn't an obvious default value IMO. Eg doing {crate_name}.calls isn't desirable due to the many conflicting crate names in a workspace.

[jyn514]

We could do {crate_name}-{crate_type} maybe. I don't think it has to be amazing, just some reasonable default to match --output-format json.

[jyn514]

Any tool that cares about conflicts should be using output-path like you suggested.

[jyn514]

All test outputs should be limited to the build directory.

Maybe it would be useful to write a tidy check for this?