// Regression test for issue-0025 path B.
//
// When a fn-pointer's type is spelled with `callconv(.c)`, the indirect
// call must apply the same C-ABI byval coercion that direct C-ABI calls
// do at the call site (path A): >16-byte non-HFA aggregates are passed
// as `ptr byval(<T>)`. Without the fix, the indirect call site builds
// an LLVM function type whose param slot is the raw struct, which the
// AArch64/x86_64 backend tries to lay out across registers + stack in
// ways that don't match the byval-attributed callee signature — the
// callee then reads garbage out of the wrong machine-state slots.
//
// The opt-in is the `callconv(.c)` on the fn-pointer type spelling.
// Pure-sx fn-pointer casts (no callconv suffix) keep their default
// calling convention — verified by examples/87-fnptr-cast-large-aggregate.sx.

#import "modules/std.sx";

Wide :: struct {
    a: i64;
    b: i64;
    c: i64;
    d: i64;
}

accept_c :: (w: Wide) -> i64 callconv(.c) {
    w.a + w.b + w.c + w.d
}

main :: () -> i32 {
    w := Wide.{ a = 1, b = 10, c = 100, d = 1000 };
    if accept_c(w) != 1111 { return 1; }

    fn_ptr : (Wide) -> i64 callconv(.c) = xx accept_c;
    if fn_ptr(w) != 1111 { return 2; }

    0
}