#size #monomorphization #monomorphizing #share-generics #code-bloat

macro mono-macro

Force monomorphizing on functions with share-generics to minimalize binary size

4 releases

0.1.3 Aug 8, 2023
0.1.2 Aug 8, 2023
0.1.1 Mar 7, 2022
0.1.0 Mar 6, 2022

#302 in Procedural macros

MIT/Apache

10KB
103 lines

Mono macro

This crate provides the #[mono] macro to force a generic function to be monomorphizied with given types.

Pair with share-generics mode in rustc, this can result less code, for details see https://github.com/rust-lang/rust/pull/48779.

[dependencies]
mono-macro = "0.1"

Usage

Since we are monomorphizing ourselves, you are required to spell out the static dispatch manually:

In a bare function case,

#[mono(T = i32, U = i64)]
fn func<T, U>(t: T, u: U) {
    ...
}

it will be expanded to:

pub const _: *const () = (&foo::<i32, i64>) as *const _ as _;
fn func<T, U>(t: T, u: U) {
    ...
}

For more complicated case, use mono_macro! instead:

trait Tr<T> {
    fn foo(&self, _t: T) {}
}

struct Foo<'a> {
    t: &'a str,
}

impl<'a, T> Tr<T> for Foo<'a> {
    fn foo(&self, _t: T) {}
}

mono_macro!(<Foo<'static> as Tr<i32>>::foo);

this will expand to:

trait Tr<T> {
    fn foo(&self, _t: T) {}
}

struct Foo<'a> {
    t: &'a str,
}

impl<'a, T> Tr<T> for Foo<'a> {
    fn foo(&self, _t: T) {}
}

pub const _: *const () = (&<Foo<'static> as Tr<i32>>::foo) as *const _ as _;

License

Licensed under either of Apache License, Version 2.0 or MIT license at your option.
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this crate by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

Dependencies

~1.5MB
~34K SLoC