07f25689ff
Reconsidered the M5.A.2 cleanup. The compiler-synthesised trampoline
path was hidden behaviour — a user reading their code couldn't tell
how `xx my_closure : Block` worked without reading lower.zig. That's
exactly the kind of magic sx's design has been pushing against.
New design (strict mode):
1. Stdlib's modules/std/objc_block.sx hand-rolls
`__block_invoke_void` + `Into(Block) for Closure() -> void` and
the same pair for `Closure(bool) -> void` (restored from M5.A.2).
These are readable reference implementations of the bridge ABI.
2. The compiler intercept fires NO synthesis — instead, when
`tryUserConversion` can't find a reachable `Into(Block)` impl for
the closure's signature, it emits a focused diagnostic:
"no `Into(Block) for <Closure-sig>` 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"
3. Per-signature declarations live in stdlib (for common signatures)
or in user code (for app-specific ones). 96-objc-block-multi-arg
now demonstrates the user-side pattern in-file — it declares its
own `__block_invoke_void_s32_p` + `Into(Block) for Closure(s32,
*void) -> void` impl alongside its main().
Net effect:
- Every block bridge is source-visible. No hidden compiler magic.
- Users see exactly how the Apple ABI shape is constructed in sx
source — stdlib serves as the reference implementation.
- Compiler enforces the discipline: missing impl → clear diagnostic
pointing at the template.
- Coverage for arbitrary signatures requires conscious user opt-in,
not silent fallthrough.
Removed from lower.zig: `tryClosureToBlockConversion`,
`emitBlockInvokeTrampoline`, `mangleClosureSigForBlock`,
`mangleTypeForBlock`, and the `block_invoke_trampolines` dedup
state field. Net: the synthesis machinery is gone; only the
detection helper `isClosureToBlockCast` remains, used by the
diagnostic.
190/190 example tests pass; chess on iOS-sim green.
62 lines
2.1 KiB
Plaintext
62 lines
2.1 KiB
Plaintext
// `xx closure : Block` for an arbitrary closure signature.
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//
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// The stdlib (modules/std/objc_block.sx) declares hand-rolled
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// `Into(Block) for Closure() -> void` and `Closure(bool) -> void`
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// impls — the two most common Apple block shapes. Other signatures
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// need a per-shape `__block_invoke_<sig>` trampoline + `Into(Block)`
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// impl declared somewhere reachable (stdlib if shared, in-file if
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// app-specific).
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//
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// This test exercises the user-declared variant: signature
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// `Closure(s32, *void) -> void` (a two-arg block — not in stdlib).
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// If the impl is missing, the compiler emits a focused diagnostic
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// pointing at modules/std/objc_block.sx as the template.
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#import "modules/std.sx";
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#import "modules/std/objc_block.sx";
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// Trampoline matching `void (^)(int, void*)` — the C ABI Apple's
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// runtime calls. Forwards through to the sx closure with the
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// standard `(__sx_ctx, env, ...args)` shape.
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__block_invoke_void_s32_p :: (block_self: *Block, arg0: s32, arg1: *void) callconv(.c) {
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typed_fn : (*void, s32, *void) -> void = xx block_self.sx_fn;
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typed_fn(block_self.sx_env, arg0, arg1);
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}
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impl Into(Block) for Closure(s32, *void) -> void {
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convert :: (self: Closure(s32, *void) -> void) -> 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 = xx @__block_invoke_void_s32_p,
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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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// Side-effect capture so we can observe both args reached the
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// closure body.
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g_sum: s32 = 0;
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g_tag: *void = null;
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main :: () -> s32 {
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cl := (n: s32, tag: *void) => {
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g_sum = n + 1;
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g_tag = tag;
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};
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b : Block = xx cl;
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invoke_fn : (*Block, s32, *void) -> void callconv(.c) = xx b.invoke;
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sentinel: s32 = 42;
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invoke_fn(@b, 41, xx @sentinel);
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if g_sum != 42 { print("FAIL: g_sum expected 42, got {}\n", g_sum); return 1; }
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if g_tag == null { print("FAIL: g_tag null\n"); return 1; }
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print("block multi-arg ok: sum={}\n", g_sum);
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0;
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}
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