`createComptimeFunction` wraps a comptime expression into a
fresh fn that the interp executes in isolation. The wrapper
must not inherit the enclosing call's lowering state — any
leaked slot, binding, or scope flag corrupts the wrapper's
own lowering.
Pre-fix, only `func` / `current_block` / `inst_counter` /
`scope` / `current_ctx_ref` were saved. Specifically NOT
saved:
- `inline_return_target` — set by `lowerComptimeCall` for an
outer comptime body with `return X;`. The wrapper's body
was lowering through this slot, routing the wrapper's
`ret` into a basic block from a different function.
- `pack_arg_nodes`, `pack_param_count`, `pack_arg_types` —
active during a pack-fn mono's body lowering. (Pack-fn
face of 0046 was already fixed by step 2b moving pack-fn
calls off the inline path; these saves close a latent
cross-contamination if any future pack-mono body invokes
the comptime interp.)
- `comptime_param_nodes` — active during an outer
`lowerComptimeCall` to bind `$fmt`-style substitutions.
- `block_terminated`, `target_type`, `func_defer_base` — fn-
local flags that the wrapper's lowering needs fresh.
All eight now save/restore in `createComptimeFunction`. The
wrapper runs in a clean state.
`examples/issue-0046.sx` flips from the
non-deterministic interp panic to "inside\n" + "n=42\n".
204/204 example tests + `zig build test` green. Issue file
marked FIXED with a pointer to the regression test.
Comptime fn body containing BOTH a nested comptime call
(`print(...)`) AND a `return X;` fails in one of two shapes
depending on the comptime-param flavour: a `storeAtRawPtr`
panic in the interp (plain `$x: s32` comptime) or "unresolved
'result'" at compile time (pack-fn `..$args`).
Same root: my issue-0045 fix's `inline_return_target` slot
setup interacts badly with the recursive comptime-call path
that invokes `#insert build_format(fmt)` → interpreter →
parse-and-lower of `result := ...` statements.
Pre-issue-0045-fix the pattern crashed at the LLVM verifier
("Terminator found in the middle of a basic block") so the
recursive path never ran. The fix exposed the deeper bug; it
didn't create it.
Not blocking the next pack-feature slices:
- Step 2a tests use arrow-form bodies with no nested print.
- Steps 2b/3 don't inherently require nested comptime calls —
builders run inside `#insert` contexts, not inside public
pack-fn bodies.
- Will bite when step 5 refactors stdlib's `print`/`format` to
`..$args` or when user code writes a pack-fn with both
`print` debug output and an early `return`.
Investigation prompt in the issue file points at
`createComptimeFunction`'s saved/restored state list (missing
`inline_return_target`, `pack_arg_nodes`,
`comptime_param_nodes`) as the most likely angle.
