// A bodiless `#builtin` carrying a `$T: Type` parameter, whose name the
// compiler does not recognize, must fail LOUDLY with an "unknown #builtin"
// diagnostic — not silently evaluate to 0 (the CLAUDE.md silent-fallback
// pattern). The generic monomorphization path (monomorphizeFunction's
// builtin-body branch) now diagnoses an unresolved builtin name instead of
// falling through to `ensureTerminator`'s `constInt(0)`.
//
// Regression (issue 0144).
#import "modules/std.sx";

// `mystery` is not a recognized builtin.
mystery :: ($T: Type, x: T) -> T #builtin;

main :: () {
    print("mystery(42) = {}\n", mystery(i64, 42));
}