fix: tactics in terms in tactics may break incremental reporting #4436
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A pending tactic mvar managed to escape into an unexpected context in specific circumstances. ```lean example : True := by · rw [show 0 = 0 by rfl] ``` * Term elaboration of the `show` creates a pending mvar for the `by rfl` proof * `rw` fails with an exception because the pattern does not occur in the target * `cdot` catches the exception and admits the goal * `Term.runTactic` [synthesizes all pending mvars from the tactic's execution](https://github.com/leanprover/lean4/blob/5f9dedfe5ee9972acdebd669f228f487844a6156/src/Lean/Elab/SyntheticMVars.lean#L350), including the `by rfl` proof. But this would not have happened without `cdot` as the exception would have skipped that invocation! * Now incrementality is confused because the nested `by rfl` proof is unexpectedly run in the same context as the top-level proof, writing to the wrong promise, and the error message is lost Solution: disable incrementality for these pending mvars (cherry picked from commit 8d3be96)
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A pending tactic mvar managed to escape into an unexpected context in specific circumstances. ```lean example : True := by · rw [show 0 = 0 by rfl] ``` * Term elaboration of the `show` creates a pending mvar for the `by rfl` proof * `rw` fails with an exception because the pattern does not occur in the target * `cdot` catches the exception and admits the goal * `Term.runTactic` [synthesizes all pending mvars from the tactic's execution](https://github.com/leanprover/lean4/blob/5f9dedfe5ee9972acdebd669f228f487844a6156/src/Lean/Elab/SyntheticMVars.lean#L350), including the `by rfl` proof. But this would not have happened without `cdot` as the exception would have skipped that invocation! * Now incrementality is confused because the nested `by rfl` proof is unexpectedly run in the same context as the top-level proof, writing to the wrong promise, and the error message is lost Solution: disable incrementality for these pending mvars (cherry picked from commit 8d3be96)
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A pending tactic mvar managed to escape into an unexpected context in specific circumstances.
showcreates a pending mvar for theby rflproofrwfails with an exception because the pattern does not occur in the targetcdotcatches the exception and admits the goalTerm.runTacticsynthesizes all pending mvars from the tactic's execution, including theby rflproof. But this would not have happened withoutcdotas the exception would have skipped that invocation!by rflproof is unexpectedly run in the same context as the top-level proof, writing to the wrong promise, and the error message is lostSolution: disable incrementality for these pending mvars