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 modifies `all_goals` so that in recovery mode it commits changes
to the state only for those goals for which the tactic succeeds (while
preserving the new message log state). Before, we were trusting that
failing tactics left things in a reasonable state, but now we roll back
and admit the goal. The changes also fixes a bug where we were rolling
back only the metacontext state and not the tactic state, leading to an
inconsistent state (a goal list with metavariables not in the
metacontext). Closes#7883
Alternatively we could stop on the first error, however it is helpful to
see what the tactic did to each goal while interactively writing a
tactic script. There is some non-monotonicity here though since tactics
can solve for metavariables that appear in successive goals, and
conceivably a later goal succeeds only if a previous one does. Given
that the non-monotonicity is limited to recovery mode (which is for
example the RHS and not the LHS of the `<;>` combinator), we think this
is acceptable.
Another justification for the change to roll back the state on each
failure is that we need to admit goals in the failing cases. When a
tactic throws an error, we cannot assume the goal list is meaningful.
Rolling back lets us admit just the goal the tactic started with,
without needing to try to work out which new metavariables should be
admitted in the error state, allowing the tactic to continue trying the
tactic on the next goal.
This PR enables the elaboration of theorem bodies, i.e. proofs, to
happen in parallel to each other as well as to other elaboration tasks.
Specifically, to be eligible for parallel proof elaboration,
* the theorem must not be in a `mutual` block
* `deprecated.oldSectionVars` must not be set
* `Elab.async` must be set (currently defaults to `true` in the language
server, `false` on the cmdline)
To be activated for downstream projects (i.e. in stage 1) pending
further Mathlib validation.
New behavior: when in recovery mode, if any tactic fails in `all_goals`
then the metacontext is restored and all goals are admitted.
Without this, it can leave partially-solved metavariables and incomplete
goal lists.
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.)
@Kha It has a few advantages over `<or>` (`<|>`).
- It is not an infix operator.
- It takes tactic sequences instead of tactics as arguments
For example, we can write
```
first
| apply h1; assumption
| exact y; exact h3; assumption
```
or
```
first apply h1; assumption | exact y; exact h3; assumption
```
instead of
```
(apply h1; assumption) <|> (exact y; exact h3; assumption)
```
