// Erasing a concrete type to a protocol it does NOT `impl`-ement is a hard
// error, not a silent SIGABRT. Regression (issue 0176): a plain free function
// `speak :: (self: *Dog)` with a matching receiver does NOT satisfy the
// protocol — protocol erasure is impl-driven, not structural (specs.md
// §"Storage and protocol conformance"). Before the fix, erasure built a vtable
// of unreachable thunks and `h.s.speak()` aborted with exit 133 and no output;
// now it reports a clear diagnostic at the erasure site and exits 1.

#import "modules/std.sx";

Speaker :: protocol { speak :: (self: *Self) -> i64; }
Dog :: struct { n: i64 = 0; }
speak :: (self: *Dog) -> i64 { return self.n; }   // free fn — NOT an impl
Holder :: struct { s: Speaker; b: i64 = 0; }

main :: () {
  d := Dog.{ n = 42 };
  h : Holder = .{ s = d, b = 5 };   // <- 'Dog' does not implement 'Speaker'
  print("{}\n", h.s.speak());
}