Using a bare pack name where a runtime value is required was silent garbage
(f(xs)/return xs produced a stray pointer). Now a clear, context-tailored
compile error: isPackName + diagPackAsValue, caught at lowerVarDecl (storage),
lowerReturn (return), lowerFor (iterate), and an identifier-arm catch-all for
call/other. Storage binds a placeholder so there is no cascade error.
Suggestions point at WORKING fixes -- materialize (..xs), or declare the slice
form ..xs: []P for runtime use. The plan category-B "spread ..xs" is broken
(spreading a comptime pack into a []Any param crashes the LLVM verifier; filed
issue 0053), so the diagnostics steer to the slice-of-protocol variadic instead.
Repurposed examples/162-pack-bare-args.sx (was an aspirational bare-$args->[]Any
auto-materialise, contradicting Decision 1) into the slice-form forward
(..args: []Any). examples/203 is the four-category negative test. specs.md "Pack
as value" updated. 238 examples + unit green.
Lock-ins for follow-ups #3 (bare `args` reference) and #4
(`args[<runtime_int>]`) from step 2b. Both share the same root
cause: the pack-mono does not materialise an `[]Any` slice
value for the pack name, so any body that needs `args` as a
value at runtime fails.
`examples/162-pack-bare-args.sx` — pack-fn body forwards `args`
to a `[]Any`-typed helper. Today: "unresolved 'args' (in
... fn forward__pack_s64_string_f64)".
`examples/163-pack-runtime-index.sx` — pack-fn body indexes
`args[i]` with a runtime `i`. Today: LLVM verifier crash —
"GEP base pointer is not a vector or a vector of pointers" —
because `args` resolves to a junk Ref via the scope-lookup
fall-through, and the slice-indexing path emits a GEP off
that.
Next commit materialises an `[]Any` slice on demand inside the
mono: each pack param is boxed into Any, stored in a stack
[N x Any] array, and the slice {data_ptr, len} is bound to the
pack name. `args` then resolves as a runtime value the same way
the pre-2b inline path used to. `args[i]` runtime indexing goes
through the standard slice index path; element type is `Any`
(lossy on per-position types — inherent to runtime indexing
into a heterogeneous pack).
202/202 example tests + `zig build test` green.
