// A protocol-method impl with the right NAME but a mismatched RETURN type (or
// parameter type) is a hard error, not a silent miscompile. Regression (issue
// 0178): the issue-0176 conformance gate is name-based, so an `impl P for T`
// whose method returns `bool` where the protocol method returns `i64` passed
// the gate and built a wrong-ABI thunk — dispatch through the erased protocol
// silently returned the wrong value (exit 0, no diagnostic). The conformance
// gate now validates each impl method's signature (arity after `self`, each
// parameter type, and the return type) against the protocol declaration, with
// `Self` substituted to the concrete type (so the REQUIRED `*T` / `T` impl form
// is NOT flagged). A clear type mismatch reports at the erasure site, exit 1.

#import "modules/std.sx";

P :: protocol { val :: (self: *Self) -> i64; }
T :: struct { n: i64 = 7; }
impl P for T { val :: (self: *T) -> bool { return true; } }   // return bool != i64

main :: () {
  t := T.{ n = 7 };
  p : P = t;                  // <- 'T' does not implement 'P' (return type)
  print("{}\n", p.val());
}