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.)
The issue is only going to be properly fixed when we rewrite `csimp`
in Lean. The `csimp` performs transformations that do not preserve
typability, but it also uses the kernel `infer_type` which assumes the
input is type correct. In the new `csimp`, we must have a different
`infer_type` which returns an `Any` type in this kind of situation.
The workaround in this commit simply disables optimizations when
`infer_type` fails. It does not fix all occurrences of this problem,
but the two places that issue #1030 triggered.
closes#1030
