9e76a83f69
Generic `Into(Block) for Closure(string) -> void` (step 5.2) emits
a trampoline whose `callconv(.c)` param type collapses through
`abiCoerceParamType`'s `string → ptr` heuristic — the libc
"char *" convention. The caller side (typed fn-pointer cast +
indirect call through `b.invoke`) keeps the full `{ptr, i64}`
slice. Result on AArch64: caller passes 16 bytes in x0+x1,
trampoline reads 8 bytes from x0 only, the slice len is lost or
mis-tracked, and the trampoline's `memcpy` from the half-formed
string segfaults.
`examples/188-block-string-arg.sx` pins the post-fix behaviour
("got: <hello>"). Today's run segfaults inside the trampoline's
first read. The next commit splits `abiCoerceParamType` into a
foreign-only path (extern decls keep the libc collapse) and a
preserve-slice path (sx-internal `callconv(.c)`).
29 lines
1.1 KiB
Plaintext
29 lines
1.1 KiB
Plaintext
// Generic `Into(Block)` impl with a `string`-typed arg in the
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// closure signature. The block trampoline declares the param with
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// callconv(.c); without the abi-collapse fix, sx `string` got
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// silently collapsed to `ptr` (the libc `char *` heuristic) and
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// the caller's 16-byte `{ptr, len}` value mismatched the
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// trampoline's 8-byte `ptr` slot. Result: segfault inside the
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// trampoline's first read.
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//
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// The fix lives in `abiCoerceParamTypeEx`: the `string`/`slice` →
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// `ptr` collapse only applies to `is_extern` foreign decls (libc
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// interop). sx-internal `callconv(.c)` keeps the full slice
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// shape, which lands as `[2 x i64]` at the LLVM signature site
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// and matches the caller's two-register pass on AArch64.
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#import "modules/std.sx";
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#import "modules/std/objc_block.sx";
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g_s: string = "";
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main :: () -> s32 {
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cl := (s: string) => { g_s = s; };
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b : Block = xx cl;
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invoke_fn : (*Block, string) -> void callconv(.c) = xx b.invoke;
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invoke_fn(@b, "hello");
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if g_s.len == 0 { print("FAIL: empty\n"); return 1; }
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print("got: <{}>\n", g_s);
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0;
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}
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