Two flags occupy the same bit

Why this fires¶

Two single-bit flags in the same @flags enum resolved to the same bit — usually because both were given the same explicit value.

@flags
enum Perm: u8 {
    Read  = 1,
    Write = 1,
    //      ^ error[TE122]: flags `Perm::Read` and `Perm::Write` occupy the same bit 1
}

Fix it¶

Give each single-bit flag a distinct power of two, or drop the explicit values and let them auto-increment:

@flags
enum Perm: u8 {
    Read,                     // 1
    Write,                    // 2
}

See also¶

• TE120 — a flag value isn't a power of two or a known composite.
• TE121 — a flag value doesn't fit the backing type.
• /docs/data-structures#enums — @flags bit-flag enums.