949cf69246
This PR changes the "declaration uses 'sorry'" warning to use backticks instead of single quotes, consistent with Lean's conventions for formatting code identifiers in diagnostic messages.
46 lines
1.2 KiB
Text
46 lines
1.2 KiB
Text
/-!
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# Issue 3922
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The `apply?` tactic would apply `symm` to every hypothesis in the local context,
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leading to these new hypotheses being included in the term even if they weren't used.
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They also created unelaboratable terms such as `?_ (id (r.symm h₂))`.
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-/
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set_option linter.unusedVariables false
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-- set up a binary relation
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axiom r : Nat → Nat → Prop
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-- that is symmetric
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axiom r.symm {a b : Nat} : r a b → r b a
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-- and has some other property
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axiom r.trans {a b c : Nat} : r a b → r b c → r a c
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/--
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info: Try this:
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[apply] refine r.symm ?_
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-- Remaining subgoals:
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-- ⊢ r a c
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---
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info: found a partial proof, but the corresponding tactic failed:
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(expose_names; refine r.trans ?_ ?_)
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It may be possible to correct this proof by adding type annotations, explicitly specifying implicit arguments, or eliminating unnecessary function abstractions.
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---
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warning: declaration uses `sorry`
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-/
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#guard_msgs (ordering := sorted) in
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example (a b c : Nat) (h₁ : r b a) (h₂ : r b c) : r c a := by
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apply?
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-- now attach the `symm` attribute to `r.symm`
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attribute [symm] r.symm
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/--
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info: Try this:
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[apply] exact r.trans (id (r.symm h₂)) h₁
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-/
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#guard_msgs in
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example (a b c : Nat) (h₁ : r b a) (h₂ : r b c) : r c a := by
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apply?
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