# Attribute Macro rustc_macros::extension

source ·

    #[extension]

Expand description

Derive an extension trait for a given impl block. The trait name goes into the parenthesized args of the macro, for greppability. For example:

    use rustc_macros::extension;
    #[extension(pub trait Foo)]
    impl i32 { fn hello() {} }

expands to:

    pub trait Foo { fn hello(); }
    impl Foo for i32 { fn hello() {} }