Issue-125323: ICE non-ADT in struct pattern when long time constant evaluation is in for loop by Shunpoco · Pull Request #138679 · rust-lang/rust (original) (raw)

This PR fixes #125323

Context

According to the issue, the ICE happens since #121206.
In the PR, some error methods were reorganized. For example, has_errors() was renamed to has_errors_exclude_lint_errors(). However, some codes which used the original has_errors() were not switched to has_errors_exclude_lint_errors(). I finally found that report_error() in writeback.rs causes this ICE. Currently the method uses tainted_by_errors() to get guar (ErrorGuaranteed), but originally it used dcx().has_errors() but it wasn't changed to has_errors_exclude_lint_errors() when changes in #121206 were merged. I don't think I fully understand how an error is propagated, but I suppose that the error from long time constant evaluation is unexpectedly propagated other parts (in this ICE, for loop), then cause the non-ADT in struct pattern ICE.

Change

• Fix report_error() in writeback.rs: use dcx().has_errors_exclude_lint_errors() instead of tainted_by_errors() to prevent error propagation from constant evaluation.
• Add test for the ICE
• Modify some tests to align the change: Due to this fix, E0282 error happens (or not happen anymore) in some tests.

NOTE

The 4th commit aims to revert the fix in #123516 because I confirmed that the ICE solved by the PR doesn't happen if I modify report_error(). I think the root cause of that ICE is the same as #125323 . But I can discard this commit since we can fix #125323 without it.