End of Life Ruby 3.1 has reached end of life and gets no more fixes. Switch to Ruby 4.0 →

instance method

Date#iso8601

d.iso8601 → string

static VALUE
d_lite_iso8601(VALUE self)
{
    return strftimev("%Y-%m-%d", self, set_tmx);
}

This method is equivalent to strftime(‘%F’).

See also .iso8601 #inspect_raw #italy #inspect also in 4.1 · 4.0 · 3.4 · 3.3 · 3.2 · 3.0