3 Commits

Author SHA1 Message Date
Brummel 76b21c00eb feat(lang): eliminate the Implicit ownership default — totality + the drop-soundness it demasks (#55)
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
2026-06-02 00:03:46 +02:00
Brummel 07f080256c iter remove-mut-var-assign.1: atomic removal of mut/var/assign
mut/var/assign removed from AILang entirely and atomically. Deleted:
Term::Mut/Term::Assign/struct MutVar; the three Form-A keywords +
parse_mut/parse_assign + grammar EBNF; the 4 mut CheckError variants;
the mut_scope_stack synth threading (param dropped from synth + every
internal/external/test caller); the two lower_term arms; and every
exhaustive no-_ Term::Mut/Term::Assign match arm across 17 source
files — cut in lockstep with DESIGN.md, fixtures, the drift trio,
carve-out and roadmap so the schema is honest at every commit. No
catch-all wildcard introduced (verified). loop/recur + let/if are
the surviving forms.

The shared codegen alloca machinery survives (loop reuses it):
mut_var_allocas renamed binder_allocas (representation-only, loop
codegen byte-identical) and the shared Term::Lam escape guard
simplified to !loop_stack.is_empty() with the loop half
(LoopBinderCapturedByLambda) byte-equivalent. Feature-acceptance
applied inverted: the removed feature fails clause 2 (redundant)
and clause 3 (IS the iterated-mutable-state bug class).

Behaviour preservation is executable: mut_counter/mut_sum_floats
still print 55 after the faithful let/if rewrite. The removal is
made executable by the new mut_removed_pin.rs (4 must-fail pins).
Independent verification: cargo test --workspace 605/0, zero
residual mut symbols in any crate source, loop/recur non-regression
all green (55 / 500000500000 / infinite-compiles / the
lambda_capturing_loop_binder pin), roundtrip_cli PASS.

One DONE_WITH_CONCERNS: a 4th recurrence of the recon-undercount
class (in-source mod tests + a drift-pin fn + 5 orphaned mut
.ail.json carve-outs + a non-enumerated E0599); all resolved within
implementer remit, no behaviour change. Milestone-close audit then
fieldtest remain.

spec docs/specs/2026-05-18-remove-mut-var-assign.md (grounding PASS)
plan docs/plans/remove-mut-var-assign.1.md
2026-05-18 11:06:17 +02:00
Brummel 1faee673f7 fieldtest: mut-local — 6 examples (4 positive + 2 negative probes), 0 bugs / 3 friction / 1 spec_gap
Boss-dispatched fieldtest after audit-mut-local closed. Six AIL
Surface (.ail) fixtures under examples/fieldtest/ exercise the
shipped mut-local surface from a downstream-LLM-author's perspective
(no compiler-source access; DESIGN.md + public examples only).

Positive fixtures all run end-to-end first-try:
- mut-local_1_factorial.ail: straight-line Int accumulator
  unroll (5!), prints 120.
- mut-local_2_classify_temp.ail: nested-if assigns into a Unit-
  typed mut block, prints classification code.
- mut-local_3_horner.ail: Float mut accumulator for polynomial
  evaluation, prints 18.
- mut-local_4_has_small_factor.ail: Bool mut flag via four
  if-then-assign checks, prints true.

Negative probes confirm diagnostics fire as documented:
- mut-local_5_lambda_capture_probe.ail: [mut-var-captured-by-lambda].
- mut-local_6_diag_probe.ail: [mut-var-unsupported-type].

Findings:

[friction] F1 — mut without iteration: the accumulator-over-an-
iteration shape never materializes. Without while/for, the LLM-
author still writes a tail-recursive helper (the very pattern
the milestone Goal said mut would replace). examples/mut_counter.ail
illustrates the degeneration. Routing: planner for a while/for
iteration OR tighten DESIGN.md to name the gap honestly.

[friction] F2 — all four mut-related diagnostics emit their
bracketed [code] twice ('error: [code] fn-name: [code] message').
Mechanical bug: the #[error('[code] ...')] Display attributes I
authored in mut.2/mut.4-tidy include the bracketed prefix in the
message body, and the cli-diag-human formatter adds another from
CheckError::code(). Routing: debug (mechanical message-body
cleanup).

[friction] F3 — no surface form to call a zero-arg fn ('(app f)'
rejected at parse with 'expected at least one argument').
Orthogonal to mut-local but surfaced building the closure-factory
probe. Routing: planner for a small tidy iter.

[spec_gap] F4 — DESIGN.md does not name the 'use a tail-rec
helper instead' workaround for the iteration-over-accumulator
shape that mut alone cannot express. Routing: ratify in DESIGN.md
alongside F1's resolution.

[working] W1/W2/W3 — surface reachable on first read; diagnostics
pinpoint cause (mut-assign-out-of-scope even lists available
vars); composes cleanly with if + lambda-without-capture +
final-expression position.

Spec: docs/specs/2026-05-15-fieldtest-mut-local.md (333 lines).

Refs: docs/specs/2026-05-15-mut-local.md, audit-mut-local close
at 8685e96.
2026-05-15 09:52:43 +02:00