1 files changed, 127 insertions, 0 deletions
diff --git a/third_party/rust/serde/build.rs b/third_party/rust/serde/build.rs
new file mode 100644
index 0000000000..613760811c
--- /dev/null
+++ b/third_party/rust/serde/build.rs
@@ -0,0 +1,127 @@
+use std::env;
+use std::process::Command;
+use std::str::{self, FromStr};
+
+// 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 minor = match rustc_minor_version() {
+        Some(minor) => minor,
+        None => return,
+    };
+
+    let target = env::var("TARGET").unwrap();
+    let emscripten = target == "asmjs-unknown-emscripten" || target == "wasm32-unknown-emscripten";
+
+    // std::collections::Bound was stabilized in Rust 1.17
+    // but it was moved to core::ops later in Rust 1.26:
+    // https://doc.rust-lang.org/core/ops/enum.Bound.html
+    if minor >= 26 {
+        println!("cargo:rustc-cfg=ops_bound");
+    } else if minor >= 17 && cfg!(feature = "std") {
+        println!("cargo:rustc-cfg=collections_bound");
+    }
+
+    // core::cmp::Reverse stabilized in Rust 1.19:
+    // https://doc.rust-lang.org/stable/core/cmp/struct.Reverse.html
+    if minor >= 19 {
+        println!("cargo:rustc-cfg=core_reverse");
+    }
+
+    // CString::into_boxed_c_str and PathBuf::into_boxed_path stabilized in Rust 1.20:
+    // https://doc.rust-lang.org/std/ffi/struct.CString.html#method.into_boxed_c_str
+    // https://doc.rust-lang.org/std/path/struct.PathBuf.html#method.into_boxed_path
+    if minor >= 20 {
+        println!("cargo:rustc-cfg=de_boxed_c_str");
+        println!("cargo:rustc-cfg=de_boxed_path");
+    }
+
+    // From<Box<T>> for Rc<T> / Arc<T> stabilized in Rust 1.21:
+    // https://doc.rust-lang.org/std/rc/struct.Rc.html#impl-From<Box<T>>
+    // https://doc.rust-lang.org/std/sync/struct.Arc.html#impl-From<Box<T>>
+    if minor >= 21 {
+        println!("cargo:rustc-cfg=de_rc_dst");
+    }
+
+    // Duration available in core since Rust 1.25:
+    // https://blog.rust-lang.org/2018/03/29/Rust-1.25.html#library-stabilizations
+    if minor >= 25 {
+        println!("cargo:rustc-cfg=core_duration");
+    }
+
+    // 128-bit integers stabilized in Rust 1.26:
+    // https://blog.rust-lang.org/2018/05/10/Rust-1.26.html
+    //
+    // Disabled on Emscripten targets as Emscripten doesn't
+    // currently support integers larger than 64 bits.
+    if minor >= 26 && !emscripten {
+        println!("cargo:rustc-cfg=integer128");
+    }
+
+    // Inclusive ranges methods stabilized in Rust 1.27:
+    // https://github.com/rust-lang/rust/pull/50758
+    if minor >= 27 {
+        println!("cargo:rustc-cfg=range_inclusive");
+    }
+
+    // Non-zero integers stabilized in Rust 1.28:
+    // https://blog.rust-lang.org/2018/08/02/Rust-1.28.html#library-stabilizations
+    if minor >= 28 {
+        println!("cargo:rustc-cfg=num_nonzero");
+    }
+
+    // TryFrom, Atomic types, and non-zero signed integers stabilized in Rust 1.34:
+    // https://blog.rust-lang.org/2019/04/11/Rust-1.34.0.html#tryfrom-and-tryinto
+    // https://blog.rust-lang.org/2019/04/11/Rust-1.34.0.html#library-stabilizations
+    if minor >= 34 {
+        println!("cargo:rustc-cfg=core_try_from");
+        println!("cargo:rustc-cfg=num_nonzero_signed");
+
+        // Whitelist of archs that support std::sync::atomic module. Ideally we
+        // would use #[cfg(target_has_atomic = "...")] but it is not stable yet.
+        // Instead this is based on rustc's src/librustc_target/spec/*.rs.
+        let has_atomic64 = target.starts_with("x86_64")
+            || target.starts_with("i686")
+            || target.starts_with("aarch64")
+            || target.starts_with("powerpc64")
+            || target.starts_with("sparc64")
+            || target.starts_with("mips64el");
+        let has_atomic32 = has_atomic64 || emscripten;
+        if has_atomic64 {
+            println!("cargo:rustc-cfg=std_atomic64");
+        }
+        if has_atomic32 {
+            println!("cargo:rustc-cfg=std_atomic");
+        }
+    }
+}
+
+fn rustc_minor_version() -> Option<u32> {
+    let rustc = match env::var_os("RUSTC") {
+        Some(rustc) => rustc,
+        None => return None,
+    };
+
+    let output = match Command::new(rustc).arg("--version").output() {
+        Ok(output) => output,
+        Err(_) => return None,
+    };
+
+    let version = match str::from_utf8(&output.stdout) {
+        Ok(version) => version,
+        Err(_) => return None,
+    };
+
+    let mut pieces = version.split('.');
+    if pieces.next() != Some("rustc 1") {
+        return None;
+    }
+
+    let next = match pieces.next() {
+        Some(next) => next,
+        None => return None,
+    };
+
+    u32::from_str(next).ok()
+}