Use unions and const size_of only if the Rust version supports them

Author: gnzlbg

.travis.yml

@@ -49,9 +49,7 @@ matrix:
     - env: TARGET=sparc64-unknown-linux-gnu
     - env: TARGET=asmjs-unknown-emscripten
     - env: TARGET=wasm32-unknown-emscripten
-    - env: TARGET=wasm32-unknown-unknown
-      install: rustup target add $TARGET
-      script: cargo build --no-default-features --target $TARGET --release
+    - env: TARGET=wasm32-unknown-unknown BUILD_ONLY=1
 
   allow_failures:
       # FIXME: https://github.com/rust-lang/libc/issues/1226
@@ -62,10 +60,16 @@ install:
   - rustup install beta
   - rustup install stable
   - rustup install 1.13.0
+  - rustup install 1.19.0
+  - rustup install 1.24.0
+  - rustup install 1.30.0
   - rustup target add $TARGET || true
   - rustup target add $TARGET --toolchain beta || true
   - rustup target add $TARGET --toolchain stable || true
   - rustup target add $TARGET --toolchain 1.13.0 || true
+  - rustup target add $TARGET --toolchain 1.19.0 || true
+  - rustup target add $TARGET --toolchain 1.24.0 || true
+  - rustup target add $TARGET --toolchain 1.30.0 || true
 
 script:
   - cargo generate-lockfile --manifest-path libc-test/Cargo.toml

build.rs

@@ -3,11 +3,22 @@ use std::process::Command;
 use std::str;
 
 fn main() {
-    /*
-     * If `core::ffi::c_void` exists, libc can just re-export it. Otherwise, it
-     * must define an incompatible type to retain backwards-compatibility.
-     */
-    if rustc_minor_version().expect("Failed to get rustc version") >= 30 {
+
+    let rustc_minor_ver = rustc_minor_version().expect("Failed to get rustc version");
+
+    // Rust >= 1.19 supports unions:
+    if rustc_minor_ver >= 19 {
+        println!("cargo:rustc-cfg=libc_union");
+    }
+
+    // Rust >= 1.24 supports const mem::size_of:
+    if rustc_minor_ver >= 24 {
+        println!("cargo:rustc-cfg=libc_const_size_of");
+    }
+
+    // If `core::ffi::c_void` exists, libc can just re-export it. Otherwise, it
+    // must define an incompatible type to retain backwards-compatibility.
+    if rustc_minor_ver >= 30 {
         println!("cargo:rustc-cfg=core_cvoid");
     }
 }

ci/run-docker.sh

@@ -28,6 +28,7 @@ run() {
       --volume "$(pwd)":/checkout:ro \
       --volume "$(pwd)"/target:/checkout/target \
       --env CARGO_TARGET_DIR=/checkout/target \
+      --env BUILD_ONLY="$BUILD_ONLY" \
       --workdir /checkout \
       libc \
       ci/run.sh "${1}"

ci/run.sh

@@ -80,13 +80,14 @@ if [ "$QEMU" != "" ]; then
   exec grep "^PASSED .* tests" "${CARGO_TARGET_DIR}/out.log"
 fi
 
-build_types="+nightly +beta +stable +1.13.0"
+build_types="+nightly +beta +stable +1.13.0 +1.19.0 +1.24.0 +1.30.0"
 for build_type in $build_types;
 do
-
     opt=
     if [ "$TARGET" = "x86_64-unknown-linux-gnux32" ]; then
-        # FIXME: x86_64-unknown-linux-gnux32 fail to compile without --release
+        # FIXME: x86_64-unknown-linux-gnux32 fail to compile without
+        # --release
+        #
         # See https://github.com/rust-lang/rust/issues/45417
         opt="--release"
 
@@ -96,21 +97,36 @@ do
         fi
     fi
 
-    # Building with --no-default-features is currently broken on rumprun because we
-    # need cfg(target_vendor), which is currently unstable.
-    if [ "$TARGET" != "x86_64-rumprun-netbsd" ]; then
-        cargo "$build_type" test $opt --no-default-features --manifest-path libc-test/Cargo.toml --target "${TARGET}"
-    fi
+    if [ "$BUILD_ONLY" = "1" ]; then
+        cargo "$build_type" build $opt --target "${TARGET}"
+    else
+        # Building with --no-default-features is currently broken on rumprun
+        # because we need cfg(target_vendor), which is currently unstable.
+        if [ "$TARGET" != "x86_64-rumprun-netbsd" ]; then
+            cargo "$build_type" test $opt \
+                  --no-default-features \
+                  --manifest-path libc-test/Cargo.toml \
+                  --target "${TARGET}"
+        fi
 
-    # Test the #[repr(align(x))] feature; requires Rust >= 1.25.0
-    if [ "$build_type" != "+1.13.0" ]; then
-        cargo "$build_type" test $opt --features align --manifest-path libc-test/Cargo.toml --target "${TARGET}"
-    fi
+        # Test the #[repr(align(x))] feature; requires Rust >= 1.25.0
+        if [ "$build_type" != "+1.13.0" ]; then
+            cargo "$build_type" test $opt \
+                  --features align \
+                  --manifest-path libc-test/Cargo.toml \
+                  --target "${TARGET}"
+        fi
 
-    # Test the `extra_traits` feature; requires Rust >= 1.25.0
-    if [ "$build_type" != "+1.13.0" ]; then
-        cargo "$build_type" test $opt --features extra_traits --manifest-path libc-test/Cargo.toml --target "${TARGET}"
-    fi
+        # Test the `extra_traits` feature; requires Rust >= 1.25.0
+        if [ "$build_type" != "+1.13.0" ]; then
+            cargo "$build_type" test $opt \
+                  --features extra_traits \
+                  --manifest-path libc-test/Cargo.toml \
+                  --target "${TARGET}"
+        fi
 
-    exec cargo "$build_type" test $opt --manifest-path libc-test/Cargo.toml --target "${TARGET}"
+        cargo "$build_type" test $opt \
+             --manifest-path libc-test/Cargo.toml \
+             --target "${TARGET}"
+    fi
 done

src/unix/bsd/apple/mod.rs

@@ -513,12 +513,6 @@ s! {
 }
 
 s_no_extra_traits!{
-    pub union semun {
-        pub val: ::c_int,
-        pub buf: *mut semid_ds,
-        pub array: *mut ::c_ushort,
-    }
-
     pub struct proc_threadinfo {
         pub pth_user_time: u64,
         pub pth_system_time: u64,
@@ -596,28 +590,41 @@ s_no_extra_traits!{
     }
 }
 
-#[cfg(feature = "extra_traits")]
-impl PartialEq for semun {
-    fn eq(&self, other: &semun) -> bool {
-        unsafe { self.val == other.val }
-    }
-}
-#[cfg(feature = "extra_traits")]
-impl Eq for semun {}
-#[cfg(feature = "extra_traits")]
-impl std::fmt::Debug for semun {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
-        f.debug_struct("semun")
-            .field("val", unsafe { &self.val })
-            .finish()
-    }
-}
-#[cfg(feature = "extra_traits")]
-impl std::hash::Hash for semun {
-    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
-        unsafe { self.val.hash(state) };
+cfg_if! {
+    if #[cfg(libc_union)] {
+        s_no_extra_traits! {
+            pub union semun {
+                pub val: ::c_int,
+                pub buf: *mut semid_ds,
+                pub array: *mut ::c_ushort,
+            }
+        }
+
+        cfg_if! {
+            if #[cfg(feature = "extra_traits")] {
+                impl PartialEq for semun {
+                    fn eq(&self, other: &semun) -> bool {
+                        unsafe { self.val == other.val }
+                    }
+                }
+                impl Eq for semun {}
+                impl std::fmt::Debug for semun {
+                    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+                        f.debug_struct("semun")
+                            .field("val", unsafe { &self.val })
+                            .finish()
+                    }
+                }
+                impl std::hash::Hash for semun {
+                    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
+                        unsafe { self.val.hash(state) };
+                    }
+                }
+            }
+        }
     }
 }
+
 #[cfg(feature = "extra_traits")]
 impl PartialEq for proc_threadinfo {
     fn eq(&self, other: &proc_threadinfo) -> bool {
@@ -2765,11 +2772,18 @@ pub const SF_IMMUTABLE:     ::c_uint = 0x00020000;
 pub const SF_APPEND:        ::c_uint = 0x00040000;
 pub const UF_HIDDEN:        ::c_uint = 0x00008000;
 
+#[cfg(libc_const_size_of)]
 fn __DARWIN_ALIGN32(p: usize) -> usize {
     const __DARWIN_ALIGNBYTES32: usize = mem::size_of::<u32>() - 1;
     p + __DARWIN_ALIGNBYTES32 & !__DARWIN_ALIGNBYTES32
 }
 
+#[cfg(not(libc_const_size_of))]
+fn __DARWIN_ALIGN32(p: usize) -> usize {
+    let __DARWIN_ALIGNBYTES32: usize = mem::size_of::<u32>() - 1;
+    p + __DARWIN_ALIGNBYTES32 & !__DARWIN_ALIGNBYTES32
+}
+
 f! {
     pub fn CMSG_NXTHDR(mhdr: *const ::msghdr,
                        cmsg: *const ::cmsghdr) -> *mut ::cmsghdr {

src/unix/bsd/netbsdlike/openbsdlike/openbsd/mod.rs

@@ -51,6 +51,7 @@ s! {
         pub mount_info: mount_info,
     }
 
+    #[cfg(libc_union)]
     pub union mount_info {
         pub ufs_args: ufs_args,
         pub mfs_args: mfs_args,