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
45 lines
1.7 KiB
Plaintext
45 lines
1.7 KiB
Plaintext
; RED-pin fixture for leg (C) of the drop-soundness bug family the
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; Implicit-cutover (#55) surfaced: a polymorphic ctor's drop fn
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; rc_dec's a type-parameter field even when that field is
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; monomorphised at a value type (Int).
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;
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; `Box a` is the minimal single-field box. `unbox` takes the box by
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; `own` and matches it, extracting the inner value `x` and returning
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; it. The match consumes the box husk, so codegen emits the
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; scope-close drop `drop_drop_value_field_no_segfault_pin_Box(box)`.
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; That drop fn is emitted ONCE from the polymorphic declaration; the
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; field type is the type-var `a`, which `llvm_type` cannot lower, so
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; drop.rs's `.unwrap_or_else(|_| "ptr")` treats it as a boxed pointer
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; and emits `ailang_rc_dec` on it.
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;
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; At the `Box Int` monomorph the field holds the raw i64 `7` stored
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; inline (offset 8), NOT a heap pointer. `ailang_rc_dec(7)`
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; dereferences address 7 -> SIGSEGV. Expected post-fix: prints `7`,
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; exits 0, AILANG_RC_STATS reports `allocs == frees && live == 0`
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; (the one Box slab is freed exactly once; no spurious dec of the
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; inline value field).
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(module drop_value_field_no_segfault_pin
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(data Box (vars a)
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(doc "Single-field polymorphic box.")
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(ctor MkBox a))
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(fn unbox
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(doc "Consume the box by own, return its inner value. The match drops the box husk.")
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(type
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(forall (vars a)
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(fn-type
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(params (own (con Box a)))
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(ret (own a)))))
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(params b)
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(body
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(match b
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(case (pat-ctor MkBox x) x))))
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(fn main
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(doc "Build MkBox 7 at Int, unbox it (drops the Box husk), print the result.")
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(type (fn-type (params) (ret (own (con Unit))) (effects IO)))
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(params)
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(body (app print (app unbox (term-ctor Box MkBox 7))))))
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