2 releases
Uses old Rust 2015
0.2.2 | Feb 21, 2018 |
---|---|
0.2.1 | Feb 21, 2018 |
#1370 in Rust patterns
68 downloads per month
67KB
2K
SLoC
proc-macro2
A small shim over the proc_macro
crate in the compiler intended to multiplex
the current stable interface (as of 2017-07-05) and the upcoming richer
interface.
The upcoming support has features like:
- Span information on tokens
- No need to go in/out through strings
- Structured input/output
The hope is that libraries ported to proc_macro2
will be trivial to port to
the real proc_macro
crate once the support on nightly is stabilize.
Usage
This crate by default compiles on the stable version of the compiler. It only
uses the stable surface area of the proc_macro
crate upstream in the compiler
itself. Usage is done via:
[dependencies]
proc-macro2 = "0.2"
followed by
extern crate proc_macro;
extern crate proc_macro2;
#[proc_macro_derive(MyDerive)]
pub fn my_derive(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
let input: proc_macro2::TokenStream = input.into();
let output: proc_macro2::TokenStream = {
/* transform input */
};
output.into()
}
If you'd like you can enable the nightly
feature in this crate. This will
cause it to compile against the unstable and nightly-only features of the
proc_macro
crate. This in turn requires a nightly compiler. This should help
preserve span information, however, coming in from the compiler itself.
You can enable this feature via:
[dependencies]
proc-macro2 = { version = "0.2", features = ["nightly"] }
Unstable Features
proc-macro2
supports exporting some methods from proc_macro
which are
currently highly unstable, and may not be stabilized in the first pass of
proc_macro
stabilizations. These features are not exported by default. Minor
versions of proc-macro2
may make breaking changes to them at any time.
To enable these features, the procmacro2_semver_exempt
config flag must be
passed to rustc.
RUSTFLAGS='--cfg procmacro2_semver_exempt' cargo build
Note that this must not only be done for your crate, but for any crate that depends on your crate. This infectious nature is intentional, as it serves as a reminder that you are outside of the normal semver guarantees.
License
This project is licensed under either of
- Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
- MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)
at your option.
Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in Serde by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.
Dependencies
~3MB
~55K SLoC