i64tos / u64tos / f64tos return a fresh owned str (caller frees via
os.free) instead of writing into a caller-supplied [N]u8. Adds typed
variants (i32tos / i16tos / i8tos and u32 / u16 / u8) and the missing
base parameter on stoi64 / stou64 + typed parse wrappers.
Base values are exported as plain-i32 `def`s (strconv.DEC,
strconv.HEX_UPPER, ...) rather than a `base` enum: cross-module
`strconv.base.DEC` chains miscompile in the cstage cgen — it emits a
memory load through `base(SB)` rather than inlining the constant.
The Sdef path resolves correctly, so callers say `strconv.DEC` and
both cgens lower to an immediate.
Also renames strings.byteindex / rbyteindex to strings.indexbyte /
rindexbyte, matching bytes.indexbyte and reserving the Hare name
`byteindex` for the future `(str | rune)`-needle shape.
fmt drops printint / printlnint / fprintint — those were stand-ins
for variadic `fmt::println(42)`; with the owned-str graduation the
substitute is one call: `fmt.println(strconv.i64tos(42, strconv.DEC))`.
strerror is sketched in a comment but not shipped — match arms over
the wider `error = !(invalid | overflow)` union still expose a
cstage-vs-wwstage spill divergence.
Replaces the -1 sentinel return on indexbyte/byteindex/rbyteindex/
index with Hare's optional-shaped tagged union. Callers `match` on
the result and bind the index from the i32 variant.
Two cgen fixes were needed first:
1. resolve_type for N_TTAGGED rounded value payload up to an 8-byte
multiple. (i32 | void) was sized 12 — tag (8) + payload (4) —
which made the reg-passing ABI compute size/8 = 1 word and drop
the value word.
2. The call-arg push path special-cased struct and slice args but
not tagged-return calls. A nested `f(g())` where g returns a
tagged union pushed only AX (tag); the matching pop loaded a
stale DX/SI for the value. Now pushes AX/DX[/CX] in order so
the pop side drains tag → arg-reg[0], value(s) → arg-reg[1..].
strings.contains rewritten to match on the new tagged result. No
other callers existed in lib/ — bufio/io still use their own
shapes.
