+// rustc-cfg emitted by the build script:
+//
+// "u128"
+// Include u128 and i128 constructors for proc_macro2::Literal. Enabled on
+// any compiler 1.26+.
+//
+// "use_proc_macro"
+// Link to extern crate proc_macro. Available on any compiler and any target
+// except wasm32. Requires "proc-macro" Cargo cfg to be enabled (default is
+// enabled). On wasm32 we never link to proc_macro even if "proc-macro" cfg
+// is enabled.
+//
+// "wrap_proc_macro"
+// Wrap types from libproc_macro rather than polyfilling the whole API.
+// Enabled on rustc 1.29+ as long as procmacro2_semver_exempt is not set,
+// because we can't emulate the unstable API without emulating everything
+// else. Also enabled unconditionally on nightly, in which case the
+// procmacro2_semver_exempt surface area is implemented by using the
+// nightly-only proc_macro API.
+//
+// "slow_extend"
+// Fallback when `impl Extend for TokenStream` is not available. These impls
+// were added one version later than the rest of the proc_macro token API.
+// Enabled on rustc 1.29 only.
+//
+// "nightly"
+// Enable the Span::unwrap method. This is to support proc_macro_span and
+// proc_macro_diagnostic use on the nightly channel without requiring the
+// semver exemption opt-in. Enabled when building with nightly.
+//
+// "super_unstable"
+// Implement the semver exempt API in terms of the nightly-only proc_macro
+// API. Enabled when using procmacro2_semver_exempt on a nightly compiler.
+//
+// "span_locations"
+// Provide methods Span::start and Span::end which give the line/column
+// location of a token. Enabled by procmacro2_semver_exempt or the
+// "span-locations" Cargo cfg. This is behind a cfg because tracking
+// location inside spans is a performance hit.
+
use std::env;
use std::process::Command;
use std::str;
let target = env::var("TARGET").unwrap();
- let minor = match rustc_minor_version() {
- Some(n) => n,
+ let version = match rustc_version() {
+ Some(version) => version,
None => return,
};
- if minor >= 26 {
+ if version.minor >= 26 {
println!("cargo:rustc-cfg=u128");
}
+ let semver_exempt = cfg!(procmacro2_semver_exempt);
+ if semver_exempt {
+ // https://github.com/alexcrichton/proc-macro2/issues/147
+ println!("cargo:rustc-cfg=procmacro2_semver_exempt");
+ }
+
+ if semver_exempt || cfg!(feature = "span-locations") {
+ println!("cargo:rustc-cfg=span_locations");
+ }
+
if !enable_use_proc_macro(&target) {
return;
}
+
println!("cargo:rustc-cfg=use_proc_macro");
// Rust 1.29 stabilized the necessary APIs in the `proc_macro` crate
- if (minor >= 29 && !cfg!(procmacro2_semver_exempt)) || cfg!(feature = "nightly") {
+ if version.nightly || version.minor >= 29 && !semver_exempt {
println!("cargo:rustc-cfg=wrap_proc_macro");
-
- if cfg!(procmacro2_semver_exempt) {
- println!("cargo:rustc-cfg=super_unstable");
- // https://github.com/alexcrichton/proc-macro2/issues/147
- println!("cargo:rustc-cfg=procmacro2_semver_exempt");
- }
}
- if minor == 29 {
+ if version.minor == 29 {
println!("cargo:rustc-cfg=slow_extend");
}
+
+ if version.nightly {
+ println!("cargo:rustc-cfg=nightly");
+ }
+
+ if semver_exempt && version.nightly {
+ println!("cargo:rustc-cfg=super_unstable");
+ }
}
fn enable_use_proc_macro(target: &str) -> bool {
cfg!(feature = "proc-macro")
}
-fn rustc_minor_version() -> Option<u32> {
+struct RustcVersion {
+ minor: u32,
+ nightly: bool,
+}
+
+fn rustc_version() -> Option<RustcVersion> {
macro_rules! otry {
($e:expr) => {
match $e {
}
};
}
+
let rustc = otry!(env::var_os("RUSTC"));
let output = otry!(Command::new(rustc).arg("--version").output().ok());
let version = otry!(str::from_utf8(&output.stdout).ok());
+ let nightly = version.contains("nightly");
let mut pieces = version.split('.');
if pieces.next() != Some("rustc 1") {
return None;
}
- otry!(pieces.next()).parse().ok()
+ let minor = otry!(pieces.next());
+ let minor = otry!(minor.parse().ok());
+
+ Some(RustcVersion {
+ minor: minor,
+ nightly: nightly,
+ })
}