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
34 lines
1.7 KiB
Plaintext
34 lines
1.7 KiB
Plaintext
(module loop_recur_str_binder_no_leak_pin
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; RED for bug #49 (Str leg): a heap-Str loop binder that `recur`
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; REPLACES with a fresh heap value each iteration. The seed is the
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; static literal "x"; each `recur` rebinds `acc` to a FRESH heap slab
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; returned by `str_concat`. Codegen's Term::Recur arm
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; (crates/ailang-codegen/src/lib.rs) decs the superseded prior binder
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; value only under the gate `is_ptr && !is_str`; the `!is_str` clause
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; excludes a Str binder entirely, so the plain `store` overwrites the
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; prior str_concat slab without RC-dec'ing it, leaking it every
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; iteration.
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;
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; The companion ADT fixture (loop_recur_heap_binder_no_leak_pin.ail,
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; commit f488d31) is the SAME leak class WITH the dec emitted; the only
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; difference is the `!is_str` clause. The Str exclusion was a
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; conservatism about the static seed literal: the seed "x" may be a
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; constexpr-GEP into a static global with no rc_header, so an
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; unconditional dec on iteration 1 would be UB. But the intermediate
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; str_concat results ARE heap slabs that must be dec'd.
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;
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; allocs: three str_concat results (acc="xy","xyy","xyyy") = 3 heap
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; slabs (the seed "x" is a static literal, not counted as an alloc).
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; The loop returns acc="xyyy"; that FINAL result is consumed by print.
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; The two superseded heap results ("xy", "xyy") plus the final "xyyy"
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; after print must all be freed. Pre-fix: live=3. Post-fix: live=0.
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; Expected stdout: xyyy.
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(fn main (type (fn-type (params) (ret (own (con Unit))) (effects IO))) (params)
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(body
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(let s
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(loop (acc (con Str) "x") (i (con Int) 0)
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(if (app ge i 3)
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acc
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(recur (app str_concat acc "y") (app + i 1))))
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(app print s)))))
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