Brummel
76b21c00eb
Deletes `ParamMode::Implicit`. `ParamMode` is now `{Own, Borrow}`:
every fn-type slot on every signature carries an explicit `own` or
`borrow`, no defaulted position survives anywhere (model 0008 §2,
spec 0062). The parser rejects a bare fn-type slot; `borrow-return`
and `borrow-over-value` reject at the signature; the corpus is
migrated to minimal-ownership modes (consumed ⇒ own, read-only-heap
⇒ borrow, value ⇒ trivial-own). The documented `Implicit`-ret-mode
leak is fixed: an owned heap return now drops exactly once (live=0,
acceptance criterion 5).
This was the easy half. Removing the default ACTIVATED a family of
drop paths that `Implicit` had silently skipped — the pre-cutover
language was leaking (and in places mis-dropping) here rather than
crashing, because an Implicit scrutinee turned the drop off. Making
the modes explicit (Own) turned those paths on and exposed two
latent-bug clusters, all fixed RED-first as part of this cutover:
Drop-soundness family (four legs):
A. lit-sub-pattern double-free — the desugar re-matched the same
owned scrutinee in the lit fall-through; fixed by grouping
consecutive same-ctor arms into one match (bind fields once),
in ailang-core desugar.
B. Cons-husk leak on non-tail arm bodies — the lit-sub-pattern
desugar rebound the owned scrutinee via `Let $mp = xs`, which
bumped consume_count and suppressed the existing fn-return
partial_drop. Fixed by not rebinding a bare-Var scrutinee
(one husk-freeing mechanism, not two).
C. polymorphic `drop_<T>` rc_dec'd monomorphised value fields —
the per-ADT drop fn was emitted once from the polymorphic
TypeDef, defaulting type-var fields to ptr and rc_dec'ing
inline Ints (segfault). Fixed with per-monomorph drop
functions (new ailang-codegen::dropmono): the drop set is
collected from the lowered MIR, value-type fields are skipped,
heap fields still freed once; monomorphic-concrete ADTs keep
their byte-identical un-suffixed drop symbol.
D. static Str literal passed to an `(own Str)` param — the
literal lowers to a header-less rodata constant; the callee's
now-active rc_dec read its length field as a refcount and
freed a static address (segfault). Fixed with the missing
fourth StrRep::Static→Heap promotion in lower_to_mir's App arm,
gated on Own mode (borrow args stay static, no regression).
over-strict-mode lint over-fired: it suggested `(borrow V)` for
value-typed params (which `borrow-over-value` rejects — own is the
only legal mode there) and fired on `(intrinsic)` bodies (whose
consumption the linearity walk cannot observe). Tightened to skip
both; contract 0008 updated to the narrowed firing scope.
Irreversible step — canonical-form hash reset (model 0008 §6,
acceptance criterion 6). Every signature now carries explicit modes,
so the hashable canonical JSON changed for every module. RATIFY:
the corpus-wide hash-pin reset (hash_pin, prelude_module_hash_pin,
mono_hash_stability, eq_ord_e2e, embed_export_hash_stable, the
ct4/iter*/loop_recur schema-extension pins) and the list ir_snapshot
golden were regenerated once, deliberately, as the intended one-time
consequence of removing the mode elision from the canonical form —
not a regression. Each regenerated hash verified deterministic across
two runs.
Also fixes a pre-existing latent failure surfaced by the verification
gate, unrelated to this cutover: the `every_contract_names_a_resolvable_
ratifying_test` resolver (design_index_pin) could not resolve the
" + " dual-link ratifying-test form (`uniqueness.rs + linearity.rs`)
that the #57 audit-close (dfdc65f) introduced — it shipped red on that
commit. Resolver taught the dual-link form, mirroring its sibling.
Verification: cargo test --workspace = 731 passed, 0 failed (twice,
stable); e2e 102 passed, no binary exits non-zero (corpus crash-free);
grep-clean for Implicit/fn_implicit/mode_eq across crates; every drop
fix confirmed via emitted IR + AILANG_RC_STATS balance on the head==K,
head!=K, and Nil paths. Three BLOCKEDs en route (the unsound first
husk-dec attempt, the over-strict derivation premise, the leg-B fix
direction) were each treated as a real design/spec gap and rediagnosed,
not patched over.
Supersedes #54 (return-position-only leak patch). Precondition #57
(linearity hardening) was already met. Spec docs/specs/0062, plan
docs/plans/0121.
closes #55
60 lines
2.6 KiB
Plaintext
60 lines
2.6 KiB
Plaintext
; Iter 16b.4 — LetRec captures of match-arm pattern bindings.
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; `count_below(p)` takes a `Pair Int Int` (threshold, n), pattern-
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; matches on `(MkPair threshold n)`, and inside that match arm runs
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; a recursive helper `loop` that captures BOTH match-arm bindings
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; (`threshold` and `n`) and counts how many integers in 1..=n are
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; strictly less than `threshold`.
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;
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; The 16b.2/16b.3 desugar passes cannot lift this LetRec — both
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; `threshold` and `n` are bound by a `Pattern::Ctor` Var sub-
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; pattern (`ScopeEntry::MatchArm`). Before 16b.4 this panicked at
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; desugar time. Now the desugar pass leaves the LetRec in place;
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; the post-typecheck `lift_letrecs` pass walks the enclosing match,
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; resolves each pattern binding's type via constructor-field
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; substitution against the matched ctor's declared field types
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; (here: `Pair Int Int`'s ctor `MkPair` has fields `[Int, Int]`,
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; and the scrutinee's `Type::Con.args` are also `[Int, Int]`, so
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; substitution is a no-op and both bindings get type `Int`), and
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; lifts to `loop$lr_0(i: Int, threshold: Int, n: Int) -> Int`.
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;
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; The match has a single ctor and no catch-all; the chain machinery
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; treats the only arm as default-dominating since there's no `_`
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; arm needed for an exhaustive single-ctor ADT (Pair has one ctor).
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;
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; Expected stdout (one per line):
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; count_below(MkPair 10 0) = 0
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; count_below(MkPair 10 5) = 5 (1..=5 all below 10)
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; count_below(MkPair 10 15) = 9 (1..=9 below 10, 10..=15 not)
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(module local_rec_match_capture
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(data Pair (vars a b)
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(ctor MkPair a b))
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(fn count_below
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(doc "Match-arm captures `threshold` and `n`; inner LetRec captures both.")
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(type (fn-type (params (own (con Pair (con Int) (con Int)))) (ret (own (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 threshold n)
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(let-rec loop
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(params i)
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(type (fn-type (params (own (con Int))) (ret (own (con Int)))))
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(body
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(if (app gt i n)
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0
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(if (app lt i threshold)
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(app + 1 (app loop (app + i 1)))
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(app loop (app + i 1)))))
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(in (app loop 1)))))))
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(fn main
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(doc "Drive count_below at MkPair 10 {0,5,15}. Expected: 0, 5, 9.")
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(type (fn-type (params) (ret (own (con Unit))) (effects IO)))
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(params)
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(body
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(seq (seq (app print (app count_below (term-ctor Pair MkPair 10 0))) (do io/print_str "\n"))
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(seq (seq (app print (app count_below (term-ctor Pair MkPair 10 5))) (do io/print_str "\n"))
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(seq (app print (app count_below (term-ctor Pair MkPair 10 15))) (do io/print_str "\n")))))))
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