rust-lang / rust-lang/rust

Audit `run-fail` ui tests to see if they need *exact* run stderr/stdout

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A-testsuite C-cleanup E-medium E-tedious T-compiler
Dominant language
Rust
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Description

compiletest triage: I'm not convinced switching error-pattern run-fail ui tests to use only the current form of check-run-results is an improvement over error-pattern unconditionally. If anything, it would be a regression to flaky tests in many cases that are sensitive to exact run stdout/stderr (line numbers, backtraces that can depend on platform-specific unwind mechanism, concrete addresses, version numbers, etc.).

I would be in favor of auditing some of these run-fail tests and sparingly add check-run-results if the exact run stderr/stdout is critical for the intention of the test, but not in a blanket fashion. As such, I'm going to close this issue in favor of a more concrete audit issue.

Originally posted by @jieyouxu in #65865

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Research direction

Start by auditing the Rust compiletest run-fail UI tests that use error-pattern, comparing their intended checks with the current check-run-results behavior. Identify tests where exact run stdout or stderr is essential, especially cases involving line numbers, backtraces, addresses, or version numbers; done means selectively updating only those tests and preserving platform-stable expectations.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
compilers, testing-qa
Issue type
Refactor
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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