ce3c2fe7bd
Step 1d lock-in test pinning today's matching behaviour. `registerParamImpl` records every impl in `param_impl_map` keyed by `"Proto\x00<arg_mangled>\x00<src_mangled>"`. For a pack impl `Into(Block) for Closure(..$args) -> $R` the key contains the pack-shaped closure's mangle (interns with `pack_start = Some(0)` after 1c.B). At the `xx cl : *Block` site the lookup mangles the concrete `Closure(s32, bool) -> bool` source and finds nothing — the existing focused diagnostic fires: no `Into(Block) for cl_s32_bool__bool` impl — add a per-signature `__block_invoke_<sig>` trampoline + Into impl alongside the existing ones in modules/std/objc_block.sx, or declare it in your own code The pack impl is reachable in the file but never considered. Next commit (1d.B): - New `param_impl_pack_map` keyed by `"Proto\x00<arg_mangled>"` (no src) — populated by `registerParamImpl` when the source is pack-shaped. - `tryUserConversion` walks the pack map on concrete-key miss. Pack shape matches when the impl's fixed prefix equals the source's matching prefix; the remainder binds to `$args` and the source's return type binds to `$R`. Concrete impls win over pack impls (specificity). - `resolveTypeWithBindings` learns the closure_type_expr path so the impl body's `self: Closure(..$args) -> $R` substitutes to the concrete source closure during monomorphisation. The `Closure(s32, bool) -> bool` shape is not covered by stdlib or 96-block-multi-arg's hand-rolled impls, so the pack impl is the only candidate post-1d.B. 193/193 example tests + `zig build test` green.
47 lines
1.6 KiB
Plaintext
47 lines
1.6 KiB
Plaintext
// Variadic heterogeneous type packs — `..$args` — impl matching
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// lock-in.
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//
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// Step 1d slice for the pack feature (see
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// ~/.claude/plans/lets-see-options-for-merry-dijkstra.md). Pins
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// today's concrete-only impl-matching behaviour: a user-declared
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// `impl Into(Block) for Closure(..$args) -> $R` does NOT match
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// any concrete closure source type. The xx cast site hits the
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// existing "no `Into(Block) for <src>` impl" diagnostic even
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// though the pack impl is reachable.
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//
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// Next commit (1d.B) teaches `tryUserConversion` /
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// `registerParamImpl` to walk a second `param_impl_pack_map`
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// when the concrete-key miss happens. Pack impls bind their
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// `$args` and `$R` to the concrete source closure's tail types
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// and return; monomorphisation proceeds against those bindings.
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//
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// The `Closure(s32, bool) -> bool` shape is not covered by
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// stdlib's hand-rolled impls (only `Closure() -> void` and
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// `Closure(bool) -> void`) and not covered by 96-block-multi-arg's
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// `Closure(s32, *void) -> void` impl, so the pack impl is the
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// only candidate.
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#import "modules/std.sx";
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#import "modules/std/objc_block.sx";
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impl Into(Block) for Closure(..$args) -> $R {
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convert :: (self: Closure(..$args) -> $R) -> Block {
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.{
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isa = @_NSConcreteStackBlock,
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flags = 0,
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reserved = 0,
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invoke = null,
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descriptor = xx @__sx_block_descriptor,
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sx_env = self.env,
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sx_fn = self.fn_ptr,
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};
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}
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}
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main :: () -> s32 {
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cl := (a: s32, b: bool) => true;
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b : *Block = xx cl;
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print("pack impl match ok\n");
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return 0;
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}
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