A small shim over the
proc_macro crate in the compiler intended to multiplex
the stable interface as of 1.15.0 and the interface as of 1.30.0.
New features added in Rust 1.30.0 include:
- Span information on tokens
- No need to go in/out through strings
- Structured input/output
Libraries ported to
proc_macro2 can retain support for older compilers while
continuing to get all the nice benefits of using a 1.30.0+ compiler.
This crate compiles on all 1.15.0+ stable compilers and usage looks like:
 = "0.4"
extern crate proc_macro; extern crate proc_macro2;
The 1.30.0 compiler is automatically detected and its interfaces are used when available.
proc-macro2 supports exporting some methods from
proc_macro which are
currently highly unstable, and are not stabilized in the first pass of
proc_macro stabilizations. These features are not exported by default. Minor
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.
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.
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.