Enhance UI test output handling for runtime errors

[AMS21]

When a UI test runs a compiled binary and an error/forbid pattern check fails, the failure message previously only showed compiler output, hiding the executed programs stdout/stderr. This makes it harder to see near-miss or unexpected runtime lines.

Fixed #141531
Supersedes #141977

[rustbot]

r? @Kobzol

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[rustbot]

Some changes occurred in src/tools/compiletest

cc @jieyouxu

[Kobzol]

Makes sense to me. It would be nicer to return a tuple (String, ProcRes) from the if condition, but that would require cloning a ProcRes for all non-executed UI tests, which could add up a bit.

I'll let @jieyouxu leave comments, since you reviewed the previous variant of this PR.

[AMS21]

Makes sense to me. It would be nicer to return a tuple (String, ProcRes) from the if condition, but that would require cloning a ProcRes for all non-executed UI tests, which could add up a bit.

Yes, avoiding the clone was the exact reason I implemented it this way.

[jieyouxu]

Seems fine, thanks. Just a tiny naming nit

[jieyouxu]

@bors r+ rollup

[bors]

📌 Commit dbd5add has been approved by jieyouxu

It is now in the queue for this repository.