Support unnamed extension trait

[taiki-e]

This allows to elide the trait name. Note that in this case, #[ext] assigns a random name, so you cannot import/export the generated trait.

use easy_ext::ext;
#[ext]
impl<T, E> Result<T, E> {
    fn err_into<U>(self) -> Result<T, U>
    where
        E: Into<U>,
    {
        self.map_err(Into::into)
    }
}

[taiki-e]

See taiki-e/auto_enums#60 for reasons to use the hash value of the input AST.

[taiki-e]

bors r+

[bors]

Build succeeded

• style (clippy)
• test (nightly)
• style (rustdoc)
• test (1.31.0)
• test (stable)
• style (rustfmt)
• test (beta)