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// force-host
// no-prefer-dynamic
#![crate_type = "proc-macro"]
extern crate proc_macro;
use proc_macro::{TokenStream, TokenTree as Tt};
use std::str::FromStr;
// String containing the current version number of the tip, i.e. "1.41.2"
static VERSION_NUMBER: &str = include_str!("../../../../../src/version");
#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
struct Version {
major: i16,
minor: i16,
patch: i16,
}
fn parse_version(s: &str) -> Option<Version> {
let mut digits = s.splitn(3, '.');
let major = digits.next()?.parse().ok()?;
let minor = digits.next()?.parse().ok()?;
let patch = digits.next().unwrap_or("0").trim().parse().ok()?;
Some(Version { major, minor, patch })
}
#[proc_macro_attribute]
/// Emits a #[cfg(version)] relative to the current one, so passing
/// -1 as argument on compiler 1.50 will emit #[cfg(version("1.49.0"))],
/// while 1 will emit #[cfg(version("1.51.0"))]
pub fn ver_cfg_rel(attr: TokenStream, input: TokenStream) -> TokenStream {
let mut v_rel = None;
for a in attr.into_iter() {
match a {
Tt::Literal(l) => {
let mut s = l.to_string();
let s = s.trim_matches('"');
let v: i16 = s.parse().unwrap();
v_rel = Some(v);
break;
},
_ => panic!("{:?}", a),
}
}
let v_rel = v_rel.unwrap();
let mut v = parse_version(VERSION_NUMBER).unwrap();
v.minor += v_rel;
let attr_str = format!("#[cfg(version(\"{}.{}.{}\"))]", v.major, v.minor, v.patch);
let mut res = Vec::<Tt>::new();
res.extend(TokenStream::from_str(&attr_str).unwrap().into_iter());
res.extend(input.into_iter());
res.into_iter().collect()
}
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