48 lines
1.4 KiB
Rust
48 lines
1.4 KiB
Rust
use std::env;
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use std::io::Write;
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use std::process::{Command, Stdio};
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fn main() {
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if probe("fn main() { 0i128; }") {
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println!("cargo:rustc-cfg=has_i128");
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} else if env::var_os("CARGO_FEATURE_I128").is_some() {
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panic!("i128 support was not detected!");
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}
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// Verbose probe to ensure we can blanket impl associated const traits.
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// Early versions of associated consts prohibited this due to a restriction
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// of const expressions to non-Drop types.
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if probe("fn main() {
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trait Const { const CONST: Self; }
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impl<T: Const> Const for Option<T> {
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const CONST: Option<T> = Some(T::CONST);
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}
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}") {
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println!("cargo:rustc-cfg=has_associated_consts");
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}
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}
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/// Test if a code snippet can be compiled
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fn probe(code: &str) -> bool {
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let rustc = env::var_os("RUSTC").unwrap_or_else(|| "rustc".into());
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let out_dir = env::var_os("OUT_DIR").expect("environment variable OUT_DIR");
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let mut child = Command::new(rustc)
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.arg("--out-dir")
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.arg(out_dir)
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.arg("--emit=obj")
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.arg("-")
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.stdin(Stdio::piped())
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.spawn()
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.expect("rustc probe");
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child
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.stdin
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.as_mut()
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.expect("rustc stdin")
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.write_all(code.as_bytes())
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.expect("write rustc stdin");
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child.wait().expect("rustc probe").success()
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}
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