1 files changed, 65 insertions, 0 deletions
diff --git a/third_party/rust/camino/build.rs b/third_party/rust/camino/build.rs
new file mode 100644
index 0000000000..7f5cbdf9b6
--- /dev/null
+++ b/third_party/rust/camino/build.rs
@@ -0,0 +1,65 @@
+// Copyright (c) The camino Contributors
+// SPDX-License-Identifier: MIT OR Apache-2.0
+
+//! Adapted from
+//! https://github.com/dtolnay/syn/blob/a54fb0098c6679f1312113ae2eec0305c51c7390/build.rs.
+
+use std::{env, process::Command, str};
+
+// The rustc-cfg strings below are *not* public API. Please let us know by
+// opening a GitHub issue if your build environment requires some way to enable
+// these cfgs other than by executing our build script.
+fn main() {
+    let compiler = match rustc_version() {
+        Some(compiler) => compiler,
+        None => return,
+    };
+
+    // NOTE:
+    // Adding a new cfg gated by Rust version MUST be accompanied by an addition to the matrix in
+    // .github/workflows/ci.yml.
+    if compiler.minor >= 44 {
+        println!("cargo:rustc-cfg=path_buf_capacity");
+    }
+    if compiler.minor >= 56 {
+        println!("cargo:rustc-cfg=shrink_to");
+    }
+    // Stable and beta 1.63 have a stable try_reserve_2.
+    if (compiler.minor >= 63
+        && (compiler.channel == ReleaseChannel::Stable || compiler.channel == ReleaseChannel::Beta))
+        || compiler.minor >= 64
+    {
+        println!("cargo:rustc-cfg=try_reserve_2");
+    }
+}
+
+struct Compiler {
+    minor: u32,
+    channel: ReleaseChannel,
+}
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+enum ReleaseChannel {
+    Stable,
+    Beta,
+    Nightly,
+}
+
+fn rustc_version() -> Option<Compiler> {
+    let rustc = env::var_os("RUSTC")?;
+    let output = Command::new(rustc).arg("--version").output().ok()?;
+    let version = str::from_utf8(&output.stdout).ok()?;
+    let mut pieces = version.split('.');
+    if pieces.next() != Some("rustc 1") {
+        return None;
+    }
+    let minor = pieces.next()?.parse().ok()?;
+    let channel = if version.contains("nightly") {
+        ReleaseChannel::Nightly
+    } else if version.contains("beta") {
+        ReleaseChannel::Beta
+    } else {
+        ReleaseChannel::Stable
+    };
+    Some(Compiler { minor, channel })
+}