// Rejection counterpart to 1046 (ERR step E1.8). Reading a failable's value slot
// where its error is NOT proven absent is a compile error. Two unproven shapes:
//
//   (A) reading the value inside the `if err { … }` error path itself
//   (B) reading the value after a bare tag-compare (`if err == error.X`), which
//       narrows the tag but proves nothing about absence
//
// Each read is rejected with the E1.8 diagnostic; the program never runs (exit 1).

#import "modules/std.sx";

E :: error { Bad }

parse :: (n: i32) -> (i32, !E) {
    if n < 0 { raise error.Bad; }
    return n * 10;
}

// (A) the read sits on the error path — `err` is present here, not absent.
bad_a :: () -> i32 {
    v, err := parse(5);
    if err { return v; }                  // REJECTED: err present on this path
    return 0;
}

// (B) a tag-compare narrows which error, but does not prove there is none.
bad_b :: () -> i32 {
    v, err := parse(5);
    if err == error.Bad { return 1; }
    return v;                             // REJECTED: err not proven absent
}

main :: () -> i32 {
    return bad_a() + bad_b();
}