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ffi issue-0048: lazyLowerFunction isolates pack-fn mono state

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`lazyLowerFunction` now saves and nulls `pack_arg_nodes`,
`pack_param_count`, `pack_arg_types`, and `inline_return_target`
before lowering the callee's body, then restores them via defer.

Same shape as the save/restore already in `createComptimeFunction`
(issue-0046 fix). Without this, a lazily lowered regular fn called
from inside a pack-fn mono inherited the outer pack maps, and the
`<pack_name>.len` intercept in `lowerFieldAccess` constant-folded
the callee's same-named param to the outer mono's arity.

`examples/173-pack-bare-args-cross-call.sx` now passes; previously-
green tests untouched. 213/213.
This commit is contained in:
agra
2026-05-27 21:09:56 +03:00
parent 8fcf352de8
commit 0ede0973f4
2 changed files with 35 additions and 1 deletions
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14
current/CHECKPOINT-FFI.md
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@@ -852,7 +852,19 @@ plus 2 codegen fixes surfaced along the way.**
## Current state
- 212/212 example tests pass; `zig build test` green.
- 213/213 example tests pass; `zig build test` green.
- issue-0048 (bare `$args` slice loses `.len` across function-
call boundary — root cause: `lazyLowerFunction` did not save/
restore `pack_arg_nodes` / `pack_param_count` / `pack_arg_types`
/ `inline_return_target`, so a lazily lowered callee inside a
pack-fn mono inherited the outer pack maps and `lowerFieldAccess`'s
`<pack_name>.len` intercept folded the callee's same-named param
to the outer mono's arity). FIXED — defer-restore block added to
`lazyLowerFunction`; regression locked in at
`examples/173-pack-bare-args-cross-call.sx`.
- Step 5.0 probe done — nested `() -> Ret callconv(.c) { body }`
parses, `@inner` address-of binds to a fn-pointer, indirect call
works. The trampoline emission pattern is unblocked.
- Phase 3.0/3.1/3.2 + M1.0–M1.3 + M2.1–M2.3 + M3 + M4.0 + M4.A all landed.
- Pack feature step 1 done (1c.A → 1d.B; commits bb6eca6 → 08feb60).
- Pack feature step 2 done — typed `args[$i]` at literal indices

22
src/ir/lower.zig
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@@ -1011,6 +1011,28 @@ pub const Lowering = struct {
const saved_jni_env_base = self.jni_env_stack_base;
self.jni_env_stack_base = self.jni_env_stack.items.len;
defer self.jni_env_stack_base = saved_jni_env_base;
// Pack-fn mono state is lexical to the pack-fn body. A lazily
// lowered callee may share a param NAME with the active pack
// (e.g. `walk(args: []Any)` called from `probe(..$args)`); without
// isolation, `lowerFieldAccess`'s `<pack_name>.len` intercept
// folds the callee's `args.len` to the outer mono's arity and
// bakes the constant into the IR. Same shape for the AST-node
// and per-element-type maps. Null out for the duration of the
// body lowering and restore on exit.
const saved_pan = self.pack_arg_nodes;
const saved_ppc = self.pack_param_count;
const saved_pat = self.pack_arg_types;
const saved_iri = self.inline_return_target;
self.pack_arg_nodes = null;
self.pack_param_count = null;
self.pack_arg_types = null;
self.inline_return_target = null;
defer {
self.pack_arg_nodes = saved_pan;
self.pack_param_count = saved_ppc;
self.pack_arg_types = saved_pat;
self.inline_return_target = saved_iri;
}
self.func_defer_base = self.defer_stack.items.len;
self.block_terminated = false;
self.force_block_value = false;