forked from abdul124/rust-core_io
103 lines
3.1 KiB
Rust
103 lines
3.1 KiB
Rust
extern crate rustc_version;
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use std::env;
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use std::fs::File;
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use std::io::Write;
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use std::path::PathBuf;
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struct Mapping(&'static str,&'static str);
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fn parse_mappings(mut mappings: &'static str) -> Vec<Mapping> {
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// FIXME: The format used here used to be parsed directly by rustc, which
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// is why it's kind of weird. It should be changed to a saner format.
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const P1: &'static str = r#"-Mapping(""#;
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const P2: &'static str = r#"",""#; ;
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const P3: &'static str = "\")\n";
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trait TakePrefix: Sized {
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fn take_prefix(&mut self, mid: usize) -> Self;
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}
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impl<'a> TakePrefix for &'a str {
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fn take_prefix(&mut self, mid: usize) -> Self {
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let prefix = &self[..mid];
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*self = &self[mid..];
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prefix
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}
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}
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let mut result = Vec::with_capacity( mappings.len() / (P1.len()+40+P2.len()+40+P3.len()) );
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while mappings.len() != 0 {
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match (
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mappings.take_prefix(P1.len()),
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mappings.take_prefix(40),
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mappings.take_prefix(P2.len()),
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mappings.take_prefix(40),
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mappings.take_prefix(P3.len()),
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) {
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(P1, hash1, P2, hash2, P3) => result.push(Mapping(hash1, hash2)),
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_ => panic!("Invalid input in mappings"),
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}
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}
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result
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}
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type Cfg = Option<&'static str>;
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type Date = &'static str;
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/// A `ConditionalCfg` is basically a list of optional feature names
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/// (`Cfg`s) separated by `Date`s. The dates specify ranges of compiler
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/// versions for which to enable particular features.
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type ConditionalCfg = (Cfg, &'static [(Date, Cfg)]);
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const CONDITIONAL_CFGS: &'static [ConditionalCfg] = &[
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(None, &[("2019-02-24", Some("pattern_guards"))]),
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(None, &[("2018-08-14", Some("non_exhaustive"))]),
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(Some("unicode"), &[("2018-08-13", None)]),
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(None, &[("2018-01-01", Some("core_memchr"))]),
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(None, &[("2017-06-15", Some("no_collections"))]),
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(Some("rustc_unicode"), &[("2016-12-15", Some("std_unicode")), ("2017-03-03", None)]),
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];
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fn main() {
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let ver=rustc_version::version_meta();
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let io_commit=match env::var("CORE_IO_COMMIT") {
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Ok(c) => c,
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Err(env::VarError::NotUnicode(_)) => panic!("Invalid commit specified in CORE_IO_COMMIT"),
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Err(env::VarError::NotPresent) => {
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let mappings=parse_mappings(include_str!("mapping.rs"));
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let compiler=ver.commit_hash.expect("Couldn't determine compiler version");
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mappings.iter().find(|&&Mapping(elem,_)|elem==compiler).expect("Unknown compiler version, upgrade core_io?").1.to_owned()
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}
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};
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for &(mut curcfg, rest) in CONDITIONAL_CFGS {
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for &(date, nextcfg) in rest {
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// if no commit_date is provided, assume compiler is current
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if ver.commit_date.as_ref().map_or(false,|d| &**d<date) {
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break;
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}
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curcfg = nextcfg;
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}
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if let Some(cfg) = curcfg {
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println!("cargo:rustc-cfg={}", cfg);
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}
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}
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let mut dest_path=PathBuf::from(env::var_os("OUT_DIR").unwrap());
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dest_path.push("io.rs");
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let mut f=File::create(&dest_path).unwrap();
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let mut target_path=PathBuf::from(env::var_os("CARGO_MANIFEST_DIR").unwrap());
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target_path.push("src");
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target_path.push(io_commit);
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target_path.push("mod.rs");
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f.write_all(br#"#[path=""#).unwrap();
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f.write_all(target_path.into_os_string().into_string().unwrap().replace("\\", "\\\\").as_bytes()).unwrap();
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f.write_all(br#""] mod io;"#).unwrap();
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}
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