lean4-htt/tests/lean/issue2981.lean.expected.out
Joachim Breitner d1174e10e6
feat: always run clean_wf, even before decreasing_by (#5016)
Previously, the tactic state shown at `decreasing_by` would leak lots of
details about the translation, and mention `invImage`, `PSigma` etc.
This is not nice.
  
So this introduces `clean_wf`, which is like `simp_wf` but using
`simp`'s `only` mode, and runs this unconditionally. This should clean
up the goal to a reasonable extent.
  
Previously `simp_wf` was an unrestricted `simp […]` call, but we
probably don’t want arbitrary simplification to happen at this point, so
this now became `simp only` call. For backwards compatibility,
`decreasing_with` begins with `try simp`. The `simp_wf` tactic
is still available to not break too much existing code; it’s docstring
suggests to no longer use it.

With `set_option cleanDecreasingByGoal false` one can disable the use of
`clean_wf`. I hope this is only needed for debugging and understanding.
  
Migration advise: If your `decreasing_by` proof begins with `simp_wf`,
either remove that (if the proof still goes through), or replace with
`simp`.
  
I am a bit anxious about running even `simp only` unconditionally here,
as it may do more than some user might want, e.g. because of options
like `zetaDelta := true`. We'll see if we need to reign in this tactic
some more.

I wonder if in corner cases the `simp_wf` tactic might be able to close
the goal, and if that is a problem. If so, we may have to promote simp’s
internal `mayCloseGoal` parameter to a simp configuration option and use
that here.
  
fixes #4928
2024-08-15 14:42:15 +00:00

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Tactic is run (ideally only once)
Tactic is run (ideally only twice)
Tactic is run (ideally only twice)
Tactic is run (ideally only once, in most general context)
n : Nat
⊢ n < n.succ
Tactic is run (ideally only twice, in most general context)
Tactic is run (ideally only twice, in most general context)
n : Nat
⊢ n < n.succ
n m : Nat ⊢ n < n.succ