Note: this error code is no longer emitted by the compiler.

The pub keyword was used inside a public enum.

Erroneous code example:

pub enum Foo {
    pub Bar, // error: unnecessary `pub` visibility
}

Since the enum is already public, adding pub on one its elements is unnecessary. Example:

enum Foo {
    pub Bar, // not ok!
}

This is the correct syntax:

pub enum Foo {
    Bar, // ok!
}