Seven-task plan for adding str_concat : (borrow Str, borrow Str) -> Str
as a runtime + checker + codegen primitive in the four-site-lockstep
pattern established by str_clone / int_to_str / bool_to_str (iter
24.1).
T1: RED — new fixture examples/show_user_adt_with_label.ail
(LLM-natural Show body using str_concat) + E2E test
crates/ail/tests/str_concat_e2e.rs.
T2: runtime/str.c — append ailang_str_concat C helper after the
existing ailang_str_clone implementation (slab-alloc, memcpy
twice, terminate).
T3: ailang-check/src/builtins.rs — install + list() + new unit test
install_str_concat_signature; type is Fn { 2x Str borrow -> Str own,
effects empty }.
T4: ailang-codegen/src/lib.rs — extern declare ptr @ailang_str_concat
(ptr, ptr); lower_app arm after str_clone arm; extend
is_builtin_callable match list; append IR-pin unit test
str_concat_emits_call_to_ailang_str_concat.
T5: lockstep collision repair — rename str_concat -> format_label in
examples/bug_unbound_in_instance_method.ail and the corresponding
pin test (the fixture currently uses str_concat as the unbound
symbol because that was the literal fieldtester repro; after
shipping the builtin it would silently become a builtin call and
the pin would fail; format_label preserves the pin's intent under
an LLM-author-realistic name that will never become a builtin).
T6: DESIGN.md new §"Heap-Str primitives" subsection between the
milestone-24 amend block and the Primitive output paragraph,
cataloguing all 5 primitives (int_to_str, bool_to_str, float_to_str,
str_clone, str_concat) with one-line signatures + descriptions and
cross-references to runtime/str.c.
T7: verification + roadmap [x] strike entry.
Open questions resolved Boss-side ahead of dispatch:
- DESIGN.md anchor: new §"Heap-Str primitives" subsection (option (b)
in recon report) — the existing milestone-24 Show-backer enumeration
stays unchanged; the new section gives the heap-Str-primitive
category an explicit home.
- bug-fixture collision: rename to format_label (option (a) in recon
report) — LLM-author-realistic, preserves regression coverage.
Expected net delta: +3 tests from baseline (559 -> 562 green).
Brummel
679572a92d