65e5053008
This PR fixes false-positive "unused variable" warnings for mutable variables reassigned inside `try`/`catch` blocks with the new do elaborator. The root cause was that `ControlStack.stateT.runInBase` packed mutable variables into a state tuple without calling `Term.addTermInfo'`, so the unused variable linter could not see that the variables were used. The fix mirrors how the `for` loop elaborator handles the same pattern in `useLoopMutVars`. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
44 lines
1.1 KiB
Text
44 lines
1.1 KiB
Text
module
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import Init.Control.Do
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/-!
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Regression test: the new do elaborator should not produce false-positive
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"unused variable" warnings for mutable variables reassigned inside `try`/`catch`.
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The root cause was that `ControlStack.stateT.runInBase` packed mutable variables
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into a state tuple without adding `TermInfo`, so the linter could not see that
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the variables were used.
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-/
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set_option linter.unusedVariables true
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set_option backward.do.legacy false
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-- Mut in try/catch with branching reassignment
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def test_mut_try_catch : IO Nat := do
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let mut params := 0
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for p in #[1, 2, 3] do
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try
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if p > 2 then
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params ← pure (params + 10)
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else
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params ← pure (params + p)
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catch _ =>
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pure ()
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return params
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-- Mut with try reassign, catch returns
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def test_mut_try_reassign (f : Nat → IO Nat) : IO Nat := do
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let mut proof ← f 0
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try proof ← f proof
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catch _ => return 0
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return proof
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-- Tuple pattern mut reassign in for+try
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def test_pat_reassign_try : IO Nat := do
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let mut g' := 0
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for x in #[1, 2, 3] do
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try
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(_, g') ← pure (x, g' + x)
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catch _ => g' ← pure g'
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return g'
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