make individual errors in a failed test more clearly visible

[RalfJung]

In large errors I feel it is easy to miss when somewhere at the top it also says "got exit status: 0, but expected 1", or so.

Ideally all errors would do this consistently, e.g. start with a underlined title and then perhaps have more details. However that doesn't really work for the errors that show a span... but maybe ut's worth doing that at least for these two otherwise-easy-to-miss errors?

[oli-obk]

We could also use the snippets logic we use for spanned errors, so you'd get it in the same format and style (red error followed by the message)

[RalfJung]

Yeah that would be the other option I guess. We need to be careful to make this still clearly "smaller" than the separator that introduces the messages for each test failure:

tests/fail/function_pointers/abi_mismatch_simple.rs FAILED:

Maybe if it looks like this that is enough?

<underline><bold><red>FAILED TEST:</red> tests/fail/function_pointers/abi_mismatch_simple.rs</bold></underline>

<bold><red>error:</red> bad exit status</bold>

<bold><red>error:</red> substring not found</bold>
{span printed}

<bold><red>error:</red> unmatched diagnostics</bold>
{span printed}

The all-caps and the underline then hopefully clearly separate multiple failed tests.

[oli-obk]

Yea that sounds good to me.

[RalfJung]

This looks better I think, but it's not entirely the same tone of red somehow...

[RalfJung]

Though rustc and cargo are not consistent either.^^

Anyway I made it all bright_red, now it is consistent within ui_test. I left diff at red though, not sure which one git diff uses.

[RalfJung]

I think git diff uses the darker red.

[RalfJung]

Updated screenshot:

[oli-obk]

I love it, thanks!

[RalfJung]

Yeah I'm quite happy with it. Can't wait to see it in Miri. Just needs a release now. nudge wink ;)

[oli-obk]

I can do releases from gha, I just can't do the version bump from it 😃

I'll do both tomorrow

[RalfJung]

No worries, not urgent at all. :)