3 //! will accept them, rather than hard-coding specific version support.
11 //! [build-dependencies]
16 //! example, to test for 128-bit integer support, it might look like:
33 //! If the type test succeeds, this will write a `cargo:rustc-cfg=has_i128` line
34 //! for Cargo, which translates to Rust arguments `--cfg has_i128`.  Then in the
100 /// This looks like: `cargo:rustc-cfg=CFG`
102 /// Cargo will use this in arguments to rustc, like `--cfg CFG`.
105 /// so the compiler my generate an [`unexpected_cfgs` warning][check-cfg-flags].
108 /// [check-cfg-flags]: https://blog.rust-lang.org/2024/05/06/check-cfg.html
110     println!("cargo:rustc-cfg={}", cfg);  in emit()
115 /// This looks like: `cargo:rerun-if-changed=PATH`
120     println!("cargo:rerun-if-changed={}", path);  in rerun_path()
126 /// This looks like: `cargo:rerun-if-env-changed=VAR`
131     println!("cargo:rerun-if-env-changed={}", var);  in rerun_env()
134 …tes to rustc that a config flag should not generate an [`unexpected_cfgs` warning][check-cfg-flags]
136 /// This looks like `cargo:rustc-check-cfg=cfg(VAR)`
138 /// As of rust 1.80, the compiler does [automatic checking of cfgs at compile time][check-cfg-flags…
146 /// If this is not desired, see [the blog post][check-cfg].
148 /// [check-cfg-flags]: https://blog.rust-lang.org/2024/05/06/check-cfg.html
150     println!("cargo:rustc-check-cfg=cfg({})", cfg);  in emit_possibility()
158 pub fn new() -> AutoCfg {  in new()
167     /// - `rustc` can't be executed, from `RUSTC` or in the `PATH`.
168     /// - The version output from `rustc` can't be parsed.
169     /// - `OUT_DIR` is not set in the environment, or is not a writable directory.
171     pub fn new() -> Result<Self, Error> {  in new()
182     /// - `rustc` can't be executed, from `RUSTC` or in the `PATH`.
183     /// - The version output from `rustc` can't be parsed.
184     /// - `dir` is not a writable directory.
186     pub fn with_dir<T: Into<PathBuf>>(dir: T) -> Result<Self, Error> {  in with_dir()
224     /// This is automatically detected during construction -- if an empty probe
233     /// like floating-point trigonometry and slice sorting.
237     /// [prelude]: https://doc.rust-lang.org/reference/names/preludes.html#the-no_std-attribute
238     pub fn no_std(&self) -> bool {  in no_std()
251     pub fn probe_rustc_version(&self, major: usize, minor: usize) -> bool {  in probe_rustc_version()
266     fn new_crate_name(&self) -> String {  in new_crate_name()
274     fn probe_fmt<'a>(&self, source: Arguments<'a>) -> Result<(), Error> {  in probe_fmt()
277             .arg("--crate-name")  in probe_fmt()
279             .arg("--crate-type=lib")  in probe_fmt()
280             .arg("--out-dir")  in probe_fmt()
282             .arg("--emit=llvm-ir");  in probe_fmt()
285             command.arg("--target").arg(target);  in probe_fmt()
290         command.arg("-").stdin(Stdio::piped());  in probe_fmt()
291         let mut child = try!(command.spawn().map_err(error::from_io));  in probe_fmt()
304     fn probe<'a>(&self, code: Arguments<'a>) -> bool {  in probe()
317     /// The code is passed to the compiler exactly as-is, notably not even
334     /// Rust nightly features could be tested as well -- ideally including a
349     ///     pub fn probe(slice: &[i32]) -> impl Iterator<Item = &[i32]> {
357     pub fn probe_raw(&self, code: &str) -> Result<(), Error> {  in probe_raw()
368     pub fn probe_sysroot_crate(&self, name: &str) -> bool {  in probe_sysroot_crate()
389     pub fn probe_path(&self, path: &str) -> bool {  in probe_path()
395     /// Any non-identifier characters in the `path` will be replaced with
416     pub fn probe_trait(&self, name: &str) -> bool {  in probe_trait()
422     /// Any non-identifier characters in the trait `name` will be replaced with
443     pub fn probe_type(&self, name: &str) -> bool {  in probe_type()
449     /// Any non-identifier characters in the type `name` will be replaced with
470     pub fn probe_expression(&self, expr: &str) -> bool {  in probe_expression()
489     pub fn probe_constant(&self, expr: &str) -> bool {  in probe_constant()
502 fn mangle(s: &str) -> String {  in mangle()
515 ) -> bool {  in dir_contains_target()
533 fn rustflags(target: &Option<OsString>, dir: &Path) -> Vec<String> {  in rustflags()
534     // Starting with rust-lang/cargo#9601, shipped in Rust 1.55, Cargo always sets  in rustflags()
551     // cross-compilation environment. Sadly, we don't have a way to detect  in rustflags()
552     // when we're building HOST artifact in a cross-compilation environment,  in rustflags()
553     // so for now we only apply RUSTFLAGS when cross-compiling an artifact.  in rustflags()
555     // See https://github.com/cuviper/autocfg/pull/10#issuecomment-527575030.  in rustflags()
561 …://github.com/rust-lang/cargo/blob/69aea5b6f69add7c51cca939a79644080c0b0ba0/src/cargo/core/compile…  in rustflags()
577 fn new_uuid() -> u64 {  in new_uuid()
584     // Feed the `HashSet`-shuffled order into FNV-1a.  in new_uuid()