Closes fieldtest-form-a friction finding #4. `str_concat : (borrow Str,
borrow Str) -> Str` ships in the four-site-lockstep pattern established
by `str_clone` / `int_to_str` / `bool_to_str` (iter 24.1). The
LLM-natural Show-MyType body
`(app str_concat "label=" (app int_to_str x))` now parses, checks,
builds, and runs end-to-end.
Sites touched (lockstep):
- runtime/str.c — `ailang_str_concat(a, b)` slab-allocates and
memcpys both source payloads into a new heap-Str.
- ailang-check/src/builtins.rs — `env.globals.insert("str_concat",
Fn { 2x Str borrow, ret Str own, effects [] })` + `list()` row +
`install_str_concat_signature` unit test.
- ailang-codegen/src/lib.rs — `declare ptr @ailang_str_concat(ptr,
ptr)` extern + `lower_app` arm after str_clone + `is_builtin_callable`
extension + IR-pin unit test `str_concat_emits_call_to_ailang_str_concat`.
- examples/show_user_adt_with_label.ail (new) + crates/ail/tests/
str_concat_e2e.rs (new) — corpus fixture exercising the LLM-natural
Show body shape + E2E pin asserting check + build + run produce
`Item 42\n`.
Lockstep collision repaired: examples/bug_unbound_in_instance_method.ail
used `str_concat` as its UNBOUND name (because that was the literal
fieldtester repro). Renamed to `format_label` (LLM-author-realistic
helper name that will never become a builtin) and updated the pin test
`crates/ail/tests/unbound_in_instance_method_pin.rs` accordingly,
preserving the regression guard's intent (instance-method-body walked
through unbound-var check).
DESIGN.md amended: new §"Heap-Str primitives" subsection between the
milestone-24 Show-backer enumeration and the existing
`Primitive output goes through ...` paragraph, cataloguing all five
heap-Str primitives (`int_to_str`, `bool_to_str`, `float_to_str`,
`str_clone`, `str_concat`) with signatures, iter origins, and the
user-visible-vs-prelude-internal distinction. Show-backer block
unchanged.
IR snapshots regenerated (hello, list, max3, sum, ws_main) to absorb
the new `declare ptr @ailang_str_concat(ptr, ptr)` line in the
unconditional extern header — same upkeep pattern as hs.4 which
regenerated the same 5 snapshots for the same reason
(unconditional declares dead-stripped by clang -O2 when unused).
Tests: 559 + 3 = 562 green (E2E pin + builtin-signature test + IR-pin
test). Zero re-loops across all 7 tasks.
First iter of milestone 24 (Show + print rewire). Wires two new
heap-Str-producing primitives parallel to hs.4's int_to_str /
float_to_str:
- runtime/str.c gains ailang_bool_to_str(bool) → heap-Str "true" /
"false" and ailang_str_clone(const char *) → memcpy'd heap-Str
copy. Both use the existing str_alloc slab helper.
- builtins.rs + synth.rs install the two signatures lockstep with
ret_mode: Own; str_clone carries param_modes: [Borrow].
- IR-header preamble gains two unconditional `declare ptr @...`
lines; Emitter::lower_app gets two new arms; is_static_callee
whitelist extends with the two names.
- Five IR snapshots regenerate for the two new declares.
- Pre-existing-drift fix: int_to_str row added to builtins.rs::list()
(hs.4 installed env.globals entry but missed the list() row).
Substantive deviation flagged by orchestrator (DONE_WITH_CONCERNS):
builtin signatures registered in uniqueness.rs::infer_module and
linearity.rs::check_module_with_visible (8 LOC × 2 files), symmetric
to iter 23.4-prep's class-method registration in the same globals
maps. Without this fix str_clone's param_modes: [Borrow] is invisible
to the App-arg walker, src_heap walks as Position::Consume, the
scope-close ailang_rc_dec is gated off, and the
str_clone_cross_realisation_uniform_abi test's plan-literal
`frees == 3` assertion does not hold. The fix is the substantively
correct repair, not a design departure.
9 new tests: 2 builtins-install unit, 2 IR-shape unit pins, 5 E2E
(2 RC-stats, 2 stdout-smoke for both Bool branches, 1 cross-
realisation). 4 new .ail.json fixtures.
Full cargo test --workspace: 513 passed, 0 failed.
bench/compile_check.py: 24/24 stable. bench/cross_lang.py: 25/25
stable.
Append three new symbols to runtime/str.c: a private str_alloc(uint64_t)
slab helper that allocates [rc_header | len | bytes... | NUL] via
ailang_rc_alloc and writes the len prefix, plus two extern formatters
ailang_int_to_str(int64_t) and ailang_float_to_str(double) that compose
str_alloc with snprintf("%lld") / snprintf("%g"). Defensive abort() on
truncation; 64-byte stack buffer comfortably oversized for either
formatter.
The extern declaration of ailang_rc_alloc carries __attribute__((weak)).
First regression sweep without it surfaced 11 e2e link failures under
--alloc=gc and --alloc=bump: public T-visible symbols (int_to_str /
float_to_str) pull their transitive callees (rc_alloc) into every
binary's symbol set, but rc.c is not linked under gc/bump in hs.3.
The weak attribute makes the cross-allocator link safe in isolation;
under rc the strong definition wins as usual. Retained after hs.4
(when rc.c becomes unconditionally linked) as a no-op that keeps
str.c link-safe in isolation.
No IR-side caller wired yet — hs.4 lands the IR-header declare lines,
the int_to_str/float_to_str codegen lowering, the checker install,
and the unconditional rc.c link.
cargo test --workspace + cross_lang.py + compile_check.py + check.py
all green on re-sweep.
Brummel