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.
ail check returns ok for a program that references an unbound
identifier inside an instance method's lambda body. The error
surfaces later at ail build as a degraded mono-pass diagnostic
(monomorphise_workspace: unknown identifier) without source
location, symbol kind, or "did you mean" candidates.
Cause: check_def at crates/ailang-check/src/lib.rs:1593 early-
returns Ok(()) for Def::Instance without walking method bodies.
The arm's comment promises instance-body typechecking from iter
22b.2; that wiring was never implemented. Only the workspace-
load coherence checks (Orphan/Duplicate/MissingMethod) touch
instance defs, and they inspect schema only, not the method-
body identifier graph.
This commit lands RED only. GREEN follows via implement mini-
mode.
Fixture: examples/bug_unbound_in_instance_method.ail
RED test: crates/ail/tests/unbound_in_instance_method_pin.rs
- check_fires_unbound_var_for_str_concat_in_instance_method_body
- check_json_unbound_var_in_instance_method_body
Brummel