Macro impl_from

macro_rules! impl_from {
    ($($variant:ident $(($($sub_variant:ident),*))?),* for $enum:ident) => { ... };
    ($($variant:ident$(<$V:ident>)?),* for $enum:ident) => { ... };
}

Generates From impls for Enum E { Foo(Foo), Bar(Bar) } enums

Example

impl_from!(Struct, Union, Enum for Adt);