Files
sx/issues/0053-comptime-pack-spread-into-any-slice.md
agra d8076b9333 lang: rename signed integer types sN -> iN
Surface rename of the signed integer family: s1..s64 become i1..i64
(u1..u64, usize, isize unchanged). 'string' keeps the s-prefix arm in
name classification; width parsing moves to the i-prefix arm next to
isize.

Internal TypeId tags follow the surface (.s8/.s16/.s32/.s64 ->
.i8/.i16/.i32/.i64), as do mono-key mangle fragments (ptr_i64,
tu_i64_bool) and all display/diagnostic formatting (i{d}).

Migrated in the same sweep: stdlib + examples + issue repros + FFI C
companions (shared symbol names like ffi_id_i64), expected
stdout/stderr/ir snapshots, specs.md, readme.md, CLAUDE.md/AGENTS.md,
implementation_plan.md, docs/, issue writeups. Vendored stb_image and
historical flow state left untouched.

zig build test: 426/426; examples suite: 595/595.
2026-06-12 09:31:53 +03:00

74 lines
2.9 KiB
Markdown

**FIXED** via the `xx <pack>` bridge (the preferred fix below), not by changing
the `..args` spread. `xx args` with a slice target now materializes the pack
into a runtime `[]Any`/`[]P` — see [examples/204-pack-xx-to-slice.sx](../examples/204-pack-xx-to-slice.sx).
`lowerXX`/the unary-op arm intercepts `xx <pack>` before the pack-as-value
check and calls the new `lowerPackToSlice` ([src/ir/lower.zig](../src/ir/lower.zig)).
The bare `..args` spread into a non-variadic `[]Any` param is still unsupported
(use `xx args`); left as-is.
# Symptom
Spreading a comptime pack `..$args` into a `[]Any` parameter — `f(..args)` where
`f` takes `items: []Any` — fails LLVM verification:
```
LLVM verification failed: Incorrect number of arguments passed to called function!
%call = call i64 @log_count(ptr %0, { ptr, i64 }, { ptr, i64 }, double ...)
```
The spread passes the pack's N elements as N separate positional args instead of
materialising a single `[]Any` slice for the one `items` parameter.
# Reproduction
```sx
#import "modules/std.sx";
log_count :: (items: []Any) -> i64 { return items.len; }
forward :: (..$args) -> i64 { return log_count(..args); }
main :: () -> i32 { print("{}\n", forward(1, "hi", 2.5)); return 0; }
```
Expected: `3` (the pack spreads into the `[]Any` slice, like calling
`log_count(1, "hi", 2.5)` against a `[]Any` variadic would).
# Preferred fix — `xx args` (pack → slice materialization)
Rather than make the splat-y `..args` spread collapse into a single slice arg,
the cleaner spelling is an **`xx` cast**, which already means "erase/convert to
the expected type":
```sx
forward :: (..$args) -> i64 { return log_count(xx args); } // target: []Any
```
`xx args` (target-typed) should materialize the pack into the expected slice:
- target `[]Any` → box each pack element to `Any`, build `[N]Any``[]Any`;
- target `[]P``xx`-erase each element to the protocol `P`, build `[N]P`
`[]P` (reuse the slice-of-protocol erasure landed in `packVariadicCallArgs`,
issue 0052).
This reuses the existing `xx`/protocol machinery, reads naturally, and keeps
`..xs` reserved for true spreads into pack/variadic callees.
**Currently `xx args` errors** ("pack 'args' has no runtime value") because the
Step 2.7 pack-as-value check fires on the bare `args` operand before `xx` is
considered. The fix: in `xx` (unary_op `.xx`) lowering, intercept a pack operand
*before* the pack-as-value diagnostic and, when the target type is a slice,
materialize as above.
# Workaround today
Declare the forwarder as the **slice** variadic instead of a pack — then it's
already a runtime `[]Any` and forwards directly:
```sx
forward :: (..args: []Any) -> i64 { return log_count(args); } // works -> 3
```
This is what `examples/162-pack-bare-args.sx` demonstrates.
# Verification
After the fix, `log_count(xx args)` (and the original `..args` form, if also
fixed) should print `3` and pass `sx ir` LLVM verification.