Fix `--message-format JSON` when rustc emits non-JSON warnings by fmdkdd · Pull Request #3410 · rust-lang/cargo

fmdkdd · 2016-12-15T23:15:58Z

The --message-format JSON flag parses all the stderr output of rustc to JSON,
but rustc can emit non-JSON lines to stderr (e.g., for warning about the
unstable -Z flag on the stable channel), causing cargo to fail reporting
compilation errors when using --message-format JSON.

This commit adds a check to look for lines beginning with { to only parse
these lines as JSON. Other lines from rustc are forwarded to the stderr of
cargo.

Fixes #3390.

The `--message-format JSON` flag parses all the stderr output of rustc to JSON, but rustc can emit non-JSON lines to stderr (e.g., for warning about the unstable `-Z` flag on the stable channel), causing cargo to fail reporting compilation errors when using `--message-format JSON`. This commit adds a check to look for lines beginning with `{` to only parse these lines as JSON. Other lines from rustc are forwarded to the stderr of cargo. Fixes rust-lang#3390.

rust-highfive · 2016-12-15T23:16:10Z

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @brson (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

Please see the contribution instructions for more information.

fmdkdd · 2016-12-15T23:22:57Z

@matklad To forward the output to stderr, using cx.config.shell().err() as you suggested caused a bunch of errors of this sort:

260 |     return Ok(Work::new(move |state| {
    |               ^^^^^^^^^ trait `std::cell::RefCell<core::shell::MultiShell>: std::marker::Sync` not satisfied
    |
    = note: `std::cell::RefCell<core::shell::MultiShell>` cannot be shared between threads safely
    = note: required because it appears within the type `util::config::Config`
   [...]

I used io::stderr() directly, which works (errors from rustc are correctly forwarded). But I'm not sure if it's the right solution for that one.

Please let me know if I should change it (and hint at the correct way to do it, since I haven't looked much at dealing with threads in Rust).

alexcrichton · 2016-12-16T00:23:30Z

This looks good to me, thanks! Could you also add a test for this?

fmdkdd · 2016-12-16T13:20:40Z

@alexcrichton Done. I've added to make sure that JSON errors are emitted, and that stderr is forwarded.

The test is skipped with a nightly rustc, since the warning for -Z won't appear there, and I didn't know how to trigger a warning for all versions.

alexcrichton · 2016-12-16T17:45:34Z

@bors: r+

Thanks!

bors · 2016-12-16T17:45:35Z

📌 Commit 3e32503 has been approved by alexcrichton

bors · 2016-12-16T17:50:33Z

⌛ Testing commit 3e32503 with merge c07ecb0...

…alexcrichton Fix `--message-format JSON` when rustc emits non-JSON warnings The `--message-format JSON` flag parses all the stderr output of rustc to JSON, but rustc can emit non-JSON lines to stderr (e.g., for warning about the unstable `-Z` flag on the stable channel), causing cargo to fail reporting compilation errors when using `--message-format JSON`. This commit adds a check to look for lines beginning with `{` to only parse these lines as JSON. Other lines from rustc are forwarded to the stderr of cargo. Fixes #3390.

bors · 2016-12-16T18:25:00Z

💔 Test failed - status-appveyor

alexcrichton · 2016-12-16T18:27:39Z

Oh that looks like rust-lang/rust#38177 which was fixed in rust-lang/rust#38357 which should be in the next nightly, I'll r+ then.

alexcrichton · 2016-12-19T17:03:56Z

@bors: retry

bors · 2016-12-19T17:04:01Z

⌛ Testing commit 3e32503 with merge 109d9c5...

…alexcrichton Fix `--message-format JSON` when rustc emits non-JSON warnings The `--message-format JSON` flag parses all the stderr output of rustc to JSON, but rustc can emit non-JSON lines to stderr (e.g., for warning about the unstable `-Z` flag on the stable channel), causing cargo to fail reporting compilation errors when using `--message-format JSON`. This commit adds a check to look for lines beginning with `{` to only parse these lines as JSON. Other lines from rustc are forwarded to the stderr of cargo. Fixes #3390.

bors · 2016-12-19T18:18:52Z

☀️ Test successful - status-appveyor, status-travis
Approved by: alexcrichton
Pushing 109d9c5 to master...

rust-highfive assigned brson Dec 15, 2016

Add a test for --message-format parsing the mixed output of rustc

3e32503

fmdkdd force-pushed the fix-3390-message-format-parse-stderr branch from 397ac0d to 3e32503 Compare December 16, 2016 13:46

matklad mentioned this pull request Dec 19, 2016

Make some aspects of check/build available as an API. #3427

Merged

bors merged commit 3e32503 into rust-lang:master Dec 19, 2016

fmdkdd deleted the fix-3390-message-format-parse-stderr branch December 20, 2016 10:30

ehuss added this to the 1.15.0 milestone Feb 6, 2022

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