Brummel
caefcf996a
Three sibling sites previously fell back to shallow `ailang_rc_dec` when a binder had non-empty `moved_slots` and a dynamic runtime ctor tag: Iter B Own-param dec at fn-return (lib.rs), Iter A arm-close pattern-binder dec (match_lower.rs), and emit_inlined_partial_drop's non-Ctor branch (drop.rs). Shallow freed the outer cell but did not walk the unmoved ptr fields — silent leak. Adds `emit_partial_drop_fn_for_type`: a per-ADT helper structurally parallel to `emit_drop_fn_for_type` but taking an i64 moved-slots bitmask. Each ptr-field's dec is gated on the corresponding mask bit; the outer box is dec'd at join. Emitted alongside the per-type drop fn for every ADT under --alloc=rc. Three call sites rewritten to resolve the partial_drop symbol from the binder's static type and build the mask from `moved_slots`. Three RED-then-GREEN fixtures (rc_own_param_/rc_match_arm_/ rc_app_let_partial_drop_leak) pin the carve-outs in regression coverage; live cell counts go from 3/1/3 (pre-fix) to 0/0/0. e2e count: 66 → 69. The pre-existing `alloc_rc_own_param_dec_at_fn_return` IR-shape assertion is widened to accept `partial_drop_<m>_<T>(%arg_xs, i64 mask)` as a third valid drop shape (the canonical fu2 case). Closes the JOURNAL queue's only remaining iter; the "wait for organic fixture" stance from the 18g tidy is retracted — known leaks are bugs, CLAUDE.md's TDD rule covers them autonomously.
72 lines
2.2 KiB
Plaintext
72 lines
2.2 KiB
Plaintext
; Iter 18g.tidy.fu2 RED-test fixture 2/3: dynamic-tag partial-drop
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; carve-out at outer-arm-close pattern-binder dec
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; (Iter A / match_lower.rs:839).
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;
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; Shape:
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; - `Pair` carries two `Cell` fields; `Cell` carries two `Wrap`
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; fields. (Same types as fixture 1.)
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; - `use_first` takes `(own Pair)` and the OUTER match binds both
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; slots: `MkPair a b`.
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; - The arm body INNER-matches `a` as `MkCell w1 _` — slot 0 of
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; a is bound, slot 1 is wildcarded.
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; - Inner arm-close drops `w1` properly via `drop_<m>_Wrap`.
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; Inner match adds slot 0 to `moved_slots[a]`.
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; - Outer arm-close drops `a` and `b`. `a` has `moves={0}`
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; (non-empty) and `consume_count==0` (only Borrow use as
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; scrutinee of inner match) → Iter A's dynamic-tag carve-out
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; fires: shallow `ailang_rc_dec(a)`. a's outer Cell is freed,
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; but slot 1 (the unbound MkWrap(2) cell) leaks.
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; - `b` has `moves={}` and `consume_count==0` → routes through
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; `drop_<m>_Cell(b)` which cascades through both Wraps. No
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; leak from b.
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; - At fn return, `p`'s `moves={0,1}` (both slots bound) → Iter
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; B carve-out fires too, but with all slots moved, the shallow
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; dec is correct (no additional leak from p).
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;
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; Pre-fix: live = 1 (the unbound MkWrap(2) cell in slot 1 of a).
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; Post-fix: live = 0.
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(module rc_match_arm_partial_drop_leak
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(data Wrap
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(ctor MkWrap (con Int)))
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(data Cell
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(ctor MkCell (con Wrap) (con Wrap)))
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(data Pair
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(ctor MkPair (con Cell) (con Cell)))
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(fn build_pair
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(type
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(fn-type
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(params (con Int))
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(ret (own (con Pair)))))
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(params n)
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(body
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(term-ctor Pair MkPair
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(term-ctor Cell MkCell
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(term-ctor Wrap MkWrap n)
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(term-ctor Wrap MkWrap 2))
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(term-ctor Cell MkCell
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(term-ctor Wrap MkWrap 3)
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(term-ctor Wrap MkWrap 4)))))
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(fn use_first
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(type
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(fn-type
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(params (own (con Pair)))
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(ret (con Int))))
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(params p)
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(body
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(match p
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(case (pat-ctor MkPair a b)
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(match a
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(case (pat-ctor MkCell w1 _) 1))))))
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(fn main
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(type (fn-type (params) (ret (con Unit)) (effects IO)))
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(params)
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(body
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(do io/print_int (app use_first (app build_pair 1))))))
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