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regression 1.52 - proc-macro-hack panic #84136
Description
proc-macro-hack is panicking[1] on beta 1.52 in some cases where it wasn't before:
My guess is this might have something to do with the usize-suffixed tuple indices, but I'm not sure. It seems to be new behavior on beta; I don't know whether this is caused by any of the recently landed macro-related patches, but it seems not impossible.
[1]: This is my belief, as it's the only repository in the dependency tree to contain the 'source.starts_with(prefix)' string in its source code (based on cargo vendor).
cc @Aaron1011 @petrochenkov @dtolnay
edit - some more cases:
- https://crater-reports.s3.amazonaws.com/beta-1.52-1/beta-2021-03-27/gh/bryanburgers.connectbot/log.txt
- https://crater-reports.s3.amazonaws.com/beta-1.52-1/beta-2021-03-27/gh/guillepb10.performance_test_rust/log.txt
- https://crater-reports.s3.amazonaws.com/beta-1.52-1/beta-2021-03-27/gh/marekm1844.user-tower/log.txt
- https://crater-reports.s3.amazonaws.com/beta-1.52-1/beta-2021-03-27/gh/mindriot101.gitlab-hook-deploy/log.txt
- https://crater-reports.s3.amazonaws.com/beta-1.52-1/beta-2021-03-27/gh/victorinno.tower_web_dummy_service/log.txt
- https://crater-reports.s3.amazonaws.com/beta-1.52-1/beta-2021-03-27/gh/vizitiuRoman.notifier-service/log.txt
- https://crater-reports.s3.amazonaws.com/beta-1.52-1/beta-2021-03-27/gh/vizitiuRoman.rust-notification-service/log.txt
- https://crater-reports.s3.amazonaws.com/beta-1.52-1/beta-2021-03-27/reg/tower-web-protobuf-0.1.0/log.txt
- https://crater-reports.s3.amazonaws.com/beta-1.52-1/beta-2021-03-27/reg/rustiful-0.1.0/log.txt
Activity
Aaron1011 commentedon Apr 12, 2021
It looks like the pretty-printing assumptions made by an older version of
proc-macro-backhave stopped holding. Runningcargo update -p proc-macro-hackin one of the failing crates fixed the panic for me.Mark-Simulacrum commentedon Apr 12, 2021
This seems pretty widespread (edit: 57 cases, of which 10 are crates.io crates) - I found at least 5-6 more repositories in crater, though not too many actual crates. Is there an easy way for us to continue having the same pretty printing? I know we don't generally guarantee stability there, and it looks like there's a pretty easy upgrade path, so if not that seems OK (but we'll want to mention it in release notes).
dtolnay commentedon Apr 12, 2021
dtolnay/proc-macro-hack@4df5a94 fixed the whitespace sensitivity for 0.4.3. I have not looked at the build logs but it sounds like the failures are things pinned to an old patch version of 0.4? If so, I would be inclined to close this.
Mark-Simulacrum commentedon Apr 12, 2021
Yeah, things using 0.4.1 - 57 repositories is not small, and most of these are just tiny self-projects I suspect, so I agree that we can likely close if there's not a trivial fix (probably not, based on the scope of the breakage).
petrochenkov commentedon Apr 12, 2021
I remember fixing this in the past by tweaking pretty-printing (#63897), not sure what change caused pretty-printing to change again.
apiraino commentedon Apr 14, 2021
Removing I-prioritize as these panics seems to be solved by upgrading the library (but in case it helps, let's assign a priority).
@rustbot label -I-prioritize
emilyalbini commentedon May 4, 2021
This regression will unfortunately be included in 1.52.0 stable. Updating the labels.
Mark-Simulacrum commentedon May 4, 2021
Closing as "expected breakage"; I don't think we plan to take further action here.
rust: Update to 1.52.0.
Update lang/rust to version 1.52.1.
Update lang/rust to version 1.52.1.
Update lang/rust to version 1.52.1.
Update lang/rust to version 1.52.1.