06fb4bec52
This PR wraps the top-level command parser with `withPosition` to enforce indentation in `by` blocks, combined with an empty-by fallback for better error messages. This subsumes #3215 (which introduced `withPosition commandParser` but without the empty-by fallback). It is also related to #9524, which explores elaboration with empty tactic sequences — this PR reuses that idea for the empty-by fallback, so that a `by` not followed by an indented tactic produces an elaboration error (unsolved goals) rather than a parse error. **Changes:** - `topLevelCommandParserFn` now uses `(withPosition commandParser).fn`, setting the saved position at the start of each top-level command - `tacticSeqIndentGt` gains an empty tactic sequence fallback (`pushNone`) so that missing indentation produces an elaboration error (unsolved goals) instead of a parse error - `isEmptyBy` in `goalsAt?` removed: with strict `by` indentation, empty `by` blocks parse successfully via `pushNone` (producing empty nodes) rather than producing `.missing` syntax, making the `isEmptyBy` check dead code. The `isEmpty` helper in `isSyntheticTacticCompletion` continues to work correctly because it handles both `.missing` and empty nodes from `pushNone` (via the vacuously-true `args.all isEmpty` on `#[]`) - Test files updated to indent `by` blocks and expression continuations that were previously at column 0 **Behavior:** - Top-level `by` blocks now require indentation (column > 0 for commands at column 0) - Commands indented inside `section` require proofs to be indented past the command's column - `#guard_msgs in example : True := by` works because tactic indentation is checked against the outermost command's column - Expression continuations (not just `by`) must also be indented past the command, which is slightly more strict but more consistent - `have : True := by` followed by a dedent now correctly puts `this` in scope in the outer tactic block (the `have` is structurally complete with an unsolved-goal error, rather than a parse error) **Code changes observed in practice (lean4 test suite + Mathlib):** - `by` blocks: top-level `theorem ... := by` / `decreasing_by` followed by tactics at column 0 must be indented - `variable` continuations: `variable {A : Type*} [Foo A]\n{B : Type*}` where the second line starts at column 0 must be indented (most common category in Mathlib) - Expression continuations: `def f : T :=\nexpr` or `#synth Foo\n[args]` where the body/arguments start at column 0 - Structure literals: `.symm\n{ toFun := ...` where the struct literal starts at column 0 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com> --------- Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
52 lines
1.4 KiB
Text
52 lines
1.4 KiB
Text
--
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set_option tactic.hygienic false in
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theorem ex1 {a p q r : Prop} : p → (p → q) → (q → r) → r := by
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intro _ h1 h2;
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apply h2;
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apply h1;
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exact a_1 -- Bad practice, using name generated by `intro`.
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theorem ex2 {a p q r : Prop} : p → (p → q) → (q → r) → r := by
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intro _ h1 h2;
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apply h2;
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apply h1;
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exact a_1 -- error "unknown identifier"
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theorem ex3 {a p q r : Prop} : p → (p → q) → (q → r) → r := by
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intro _ h1 h2;
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apply h2;
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apply h1;
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assumption
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example {p q : Prop} (h₁ : p → q) (h₂ : p ∨ q) : q := by
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cases h₂;
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{ apply h₁; exact h }; -- error "unknown identifier"
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exact h
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set_option tactic.hygienic false in
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example {p q : Prop} (h₁ : p → q) (h₂ : p ∨ q) : q := by
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cases h₂;
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{ apply h₁; exact h }; -- hygiene is disabled
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exact h
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-- Hygienic versions
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example {p q : Prop} (h₁ : p → q) (h₂ : p ∨ q) : q := by
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cases h₂ with
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| inl h => apply h₁; exact h
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| inr h => exact h
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example {p q : Prop} (h₁ : p → q) (h₂ : p ∨ q) : q := by
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cases h₂;
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{ apply h₁; assumption };
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assumption
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example {p q : Prop} (h₁ : p → q) (h₂ : p ∨ q) : q := by
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match h₂ with
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| Or.inl _ => apply h₁; assumption
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| Or.inr h => exact h
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example {p q : Prop} (h₁ : p → q) (h₂ : p ∨ q) : q := by unhygienic
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cases h₂
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{ apply h₁; exact h } -- hygiene is disabled
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exact h
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