1 files changed, 37 insertions, 6 deletions

diff --git a/libc/build.rs b/libc/build.rs
index efc95b6..f447c0e 100644
--- a/libc/build.rs
+++ b/libc/build.rs
@@ -3,11 +3,12 @@ use std::process::Command;
 use std::str;
 
 fn main() {
-    let rustc_minor_ver =
-        rustc_minor_version().expect("Failed to get rustc version");
+    let (rustc_minor_ver, is_nightly) =
+        rustc_minor_nightly().expect("Failed to get rustc version");
     let rustc_dep_of_std = env::var("CARGO_FEATURE_RUSTC_DEP_OF_STD").is_ok();
     let align_cargo_feature = env::var("CARGO_FEATURE_ALIGN").is_ok();
-    #[allow(unused)]
+    let const_extern_fn_cargo_feature =
+        env::var("CARGO_FEATURE_CONST_EXTERN_FN").is_ok();
     let libc_ci = env::var("LIBC_CI").is_ok();
 
     if env::var("CARGO_FEATURE_USE_STD").is_ok() {
@@ -17,17 +18,26 @@ fn main() {
         );
     }
 
-    // The ABI of libc is backward compatible with FreeBSD 11.
+    // The ABI of libc used by libstd is backward compatible with FreeBSD 10.
+    // The ABI of libc from crates.io is backward compatible with FreeBSD 11.
     //
     // On CI, we detect the actual FreeBSD version and match its ABI exactly,
     // running tests to ensure that the ABI is correct.
     match which_freebsd() {
+        Some(10) if libc_ci || rustc_dep_of_std => {
+            println!("cargo:rustc-cfg=freebsd10")
+        }
         Some(11) if libc_ci => println!("cargo:rustc-cfg=freebsd11"),
         Some(12) if libc_ci => println!("cargo:rustc-cfg=freebsd12"),
         Some(13) if libc_ci => println!("cargo:rustc-cfg=freebsd13"),
         Some(_) | None => println!("cargo:rustc-cfg=freebsd11"),
     }
 
+    // On CI: deny all warnings
+    if libc_ci {
+        println!("cargo:rustc-cfg=libc_deny_warnings");
+    }
+
     // Rust >= 1.15 supports private module use:
     if rustc_minor_ver >= 15 || rustc_dep_of_std {
         println!("cargo:rustc-cfg=libc_priv_mod_use");
@@ -64,9 +74,16 @@ fn main() {
     if rustc_dep_of_std {
         println!("cargo:rustc-cfg=libc_thread_local");
     }
+
+    if const_extern_fn_cargo_feature {
+        if !is_nightly || rustc_minor_ver < 40 {
+            panic!("const-extern-fn requires a nightly compiler >= 1.40")
+        }
+        println!("cargo:rustc-cfg=libc_const_extern_fn");
+    }
 }
 
-fn rustc_minor_version() -> Option<u32> {
+fn rustc_minor_nightly() -> Option<(u32, bool)> {
     macro_rules! otry {
         ($e:expr) => {
             match $e {
@@ -85,7 +102,20 @@ fn rustc_minor_version() -> Option<u32> {
         return None;
     }
 
-    otry!(pieces.next()).parse().ok()
+    let minor = pieces.next();
+
+    // If `rustc` was built from a tarball, its version string
+    // will have neither a git hash nor a commit date
+    // (e.g. "rustc 1.39.0"). Treat this case as non-nightly,
+    // since a nightly build should either come from CI
+    // or a git checkout
+    let nightly_raw = otry!(pieces.next()).split('-').nth(1);
+    let nightly = nightly_raw
+        .map(|raw| raw.starts_with("dev") || raw.starts_with("nightly"))
+        .unwrap_or(false);
+    let minor = otry!(otry!(minor).parse().ok());
+
+    Some((minor, nightly))
 }
 
 fn which_freebsd() -> Option<i32> {
@@ -105,6 +135,7 @@ fn which_freebsd() -> Option<i32> {
     let stdout = stdout.unwrap();
 
     match &stdout {
+        s if s.starts_with("10") => Some(10),
         s if s.starts_with("11") => Some(11),
         s if s.starts_with("12") => Some(12),
         s if s.starts_with("13") => Some(13),