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>
24 lines
658 B
Text
24 lines
658 B
Text
--
|
|
|
|
set_option trace.Meta.Tactic.subst true
|
|
|
|
theorem tst1 (x y z : Nat) : y = z → x = x → x = y → x = z := by
|
|
intro h1 h2 h3
|
|
subst x
|
|
assumption
|
|
|
|
theorem tst2 (x y z : Nat) : y = z → x = z + y → x = z + z := by
|
|
intro h1 h2
|
|
subst h1
|
|
subst h2
|
|
exact rfl
|
|
|
|
def BV (n : Nat) : Type := { a : Array Bool // a.size = n }
|
|
|
|
theorem tst3 (n m : Nat) (v : BV n) (w : BV m) (h1 : n = m) (h2 : forall (v1 v2 : BV n), v1 = v2) : v = cast (congrArg BV h1.symm) w := by
|
|
subst h1
|
|
apply h2
|
|
|
|
theorem tst4 (n m : Nat) (v : BV n) (w : BV m) (h1 : n = m) (h2 : forall (v1 v2 : BV n), v1 = v2) : v = cast (congrArg BV h1.symm) w := by
|
|
subst n
|
|
apply h2
|