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
This PR makes the arity reduction pass in the new code generator match
the old one when it comes to the behavior of decls with no used
parameters. This is important, because otherwise we might create a
top-level decl with no params that contains unreachable code, which
would get evaluated unconditionally during initialization. This actually
happens when initializing Init.Core built with the new code generator.
This PR modifies LCNF.toMonoType to use a more refined type erasure
scheme, which distinguishes between irrelevant/erased information
(represented by lcErased) and erased type dependencies (represented by
lcAny). This corresponds to the irrelevant/object distinction in the old
code generator.
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.)
