This PR fixes an issue when including a hard line break in a `Format`
that caused subsequent (ordinary) line breaks to be erroneously
flattened to spaces.
This issue is especially important for displaying notes and hints in
error messages, as these components could appear garbled due to improper
line-break rendering.
This PR makes `#guard_msgs` to treat `trace` messages separate from
`info`, `warning` and `error`. It also introduce the ability to say
`#guard_msgs (pass info`, like `(drop info)` so far, and also adds
`(check info)` as the explicit form of `(info)`, for completeness.
Fixes#8266
so that the pretty-printed origin is clickable, and avoid the
unnecessary `@`.
Particularly nice is this fix:
```diff
/--
-info: [Meta.Tactic.simp.discharge] @bar discharge ✅
+info: [Meta.Tactic.simp.discharge] bar discharge ✅
autoParam T _auto✝
- [Meta.Tactic.simp.rewrite] { }:1000, T ==> True
-[Meta.Tactic.simp.rewrite] @bar:1000, U ==> True
+ [Meta.Tactic.simp.rewrite] T.mk:1000, T ==> True
+[Meta.Tactic.simp.rewrite] bar:1000, U ==> True
-/
```
Many of our tests in `tests/lean/run/` produce output from `#eval` (or
`#check`) statements, that is then ignored.
This PR tries to capture all the useful output using `#guard_msgs`. I've
only done a cursory check that the output is still sane --- there is a
chance that some "unchecked" tests have already accumulated regressions
and this just cements them!
In the other direction, I did identify two rotten tests:
* a minor one in `setStructInstNotation.lean`, where a comment says `Set
Nat`, but `#check` actually prints `?_`. Weird?
* `CompilerProbe.lean` is generating empty output, apparently indicating
that something is broken, but I don't know the signficance of this file.
In any case, I'll ask about these elsewhere.
(This started by noticing that a recent `grind` test file had an
untested `trace_state`, and then got carried away.)
When updating Std, be careful that not every lemma has been upstreamed,
so we need to be careful to only delete things that have already been
declared.
