// Error-tag `{}` interpolation (ERR step E3 — tag-name table). Formatting an
// error-set value with `{}` renders the tag NAME (`BadDigit`), not the raw id,
// reusing the `any_to_string` dispatch (new `error_set` category → the
// `error_tag_name` builtin → the always-linked tag-name table indexed by global
// tag id). Works for a bound tag, a re-raised/caught tag, and inside text.

#import "modules/std.sx";

E :: error { BadDigit, Empty, Overflow }

parse :: (n: s32) -> (s32, !E) {
    if n < 0  { raise error.BadDigit; }
    if n == 0 { raise error.Empty; }
    return n * 2;
}

main :: () -> s32 {
    a : E = error.BadDigit;
    b : E = error.Overflow;
    print("a={} b={}\n", a, b);              // a=BadDigit b=Overflow

    // A tag bound by `catch` interpolates too (diverging handler).
    v := parse(0) catch (e) {
        print("parse failed with {}\n", e);   // parse failed with Empty
        return 0;
    };
    print("v={}\n", v);                       // not reached (parse(0) raises Empty)
    return 0;
}