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
84 lines
3.0 KiB
Plaintext
84 lines
3.0 KiB
Plaintext
; Axis: a small streaming-feel state machine threading MORE THAN
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; ONE piece of state, updating only a SUBSET per branch.
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;
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; Scan a token stream (a recursive Int list; 1 = '(', 2 = ')',
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; 0 = any other token) and decide if the brackets are balanced.
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;
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; Imperative instinct (exactly what `mut` would invite):
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; depth = 0
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; ok = true
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; for t in stream:
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; if t == 1: depth = depth + 1 ; only depth changes
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; elif t == 2:
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; if depth == 0: ok = false ; only ok changes
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; else: depth = depth - 1 ; only depth changes
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; ; t == 0 -> neither changes
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; return ok && depth == 0
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;
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; Surviving-surface shape: a recursive scanner fn threading
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; (rest, depth, ok) — `loop`/`recur` cannot walk an ADT (it rebinds
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; positionally, there is no structural pattern in a recur), so the
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; stream traversal is ordinary tail recursion; the per-branch
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; "update a subset of the state" becomes "pass the unchanged values
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; through unchanged". This is the task that most stresses the
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; removal: an imperative author updates one variable and leaves the
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; others implicitly alone; here every recur must restate all three.
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;
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; balanced "(()())" -> true ; stream 1 1 2 1 2 2
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; balanced ")(" -> false ; stream 2 1
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; Expected stdout (per line): true, false
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(module remove-mut_4_bracket_scanner
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(data TokStream
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(doc "1='(' , 2=')' , 0=other.")
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(ctor Nil)
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(ctor Cons (con Int) (con TokStream)))
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(fn scan
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(doc "Thread (rest, depth, ok). Each arm updates a subset of state; the unchanged components must be restated in every tail call.")
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(type
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(fn-type
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(params (own (con TokStream)) (own (con Int)) (own (con Bool)))
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(ret (own (con Bool)))))
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(params rest depth ok)
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(body
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(match rest
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(case (pat-ctor Nil)
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(if ok (app eq depth 0) false))
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(case (pat-ctor Cons t more)
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(match t
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(case (pat-lit 1)
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(tail-app scan more (app + depth 1) ok))
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(case (pat-lit 2)
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(if (app eq depth 0)
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(tail-app scan more depth false)
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(tail-app scan more (app - depth 1) ok)))
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(case _
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(tail-app scan more depth ok)))))))
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(fn balanced
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(type (fn-type (params (own (con TokStream))) (ret (own (con Bool)))))
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(params s)
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(body (app scan s 0 true)))
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(fn main
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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
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(app print
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(app balanced
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(term-ctor TokStream Cons 1
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(term-ctor TokStream Cons 1
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(term-ctor TokStream Cons 2
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(term-ctor TokStream Cons 1
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(term-ctor TokStream Cons 2
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(term-ctor TokStream Cons 2
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(term-ctor TokStream Nil)))))))))
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(app print
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(app balanced
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(term-ctor TokStream Cons 2
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(term-ctor TokStream Cons 1
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(term-ctor TokStream Nil)))))))))
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