d1174e10e6
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
12 lines
413 B
Text
12 lines
413 B
Text
mutwf1.lean:21:2-21:6: error: unsolved goals
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case h.a
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n : Nat
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h : n ≠ 0
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⊢ n.sub 0 ≠ 0
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mutwf1.lean:31:22-31:29: error: failed to prove termination, possible solutions:
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- Use `have`-expressions to prove the remaining goals
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- Use `termination_by` to specify a different well-founded relation
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- Use `decreasing_by` to specify your own tactic for discharging this kind of goal
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case h
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n : Nat
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⊢ n + 1 < n
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