Remove mach dependency

src/libstd/Cargo.toml

@@ -53,9 +53,6 @@ rustc_tsan = { path = "../librustc_tsan" }
 [target.'cfg(any(all(target_arch = "wasm32", not(target_os = "emscripten")), all(target_vendor = "fortanix", target_env = "sgx")))'.dependencies]
 dlmalloc = { version = "0.1", features = ['rustc-dep-of-std'] }
 
-[target.'cfg(any(target_os = "macos", target_os = "ios"))'.dependencies]
-mach = { version = "0.3.2", default-features = false, features = ['rustc-dep-of-std'] }
-
 [target.x86_64-fortanix-unknown-sgx.dependencies]
 fortanix-sgx-abi = { version = "0.3.2", features = ['rustc-dep-of-std'] }
 

src/libstd/lib.rs

@@ -338,10 +338,6 @@ extern crate alloc as alloc_crate;
 #[allow(unused_extern_crates)]
 extern crate libc;
 
-#[cfg(any(target_os = "macos", target_os = "ios"))]
-#[allow(unused_extern_crates)]
-extern crate mach;
-
 // We always need an unwinder currently for backtraces
 #[doc(masked)]
 #[allow(unused_extern_crates)]

src/libstd/sys/unix/time.rs

@@ -137,9 +137,21 @@ mod inner {
         t: Timespec::zero(),
     };
 
+    #[repr(C)]
+    #[derive(Copy, Clone)]
+    struct mach_timebase_info {
+        numer: u32,
+        denom: u32,
+    }
+    type mach_timebase_info_t = *mut mach_timebase_info;
+    type kern_return_t = libc::c_int;
+
     impl Instant {
         pub fn now() -> Instant {
-            Instant { t: unsafe { mach::mach_time::mach_absolute_time() } }
+            extern "C" {
+                fn mach_absolute_time() -> u64;
+            }
+            Instant { t: unsafe { mach_absolute_time() } }
         }
 
         pub const fn zero() -> Instant {
@@ -230,9 +242,8 @@ mod inner {
         Some(mul_div_u64(nanos, info.denom as u64, info.numer as u64))
     }
 
-    fn info() -> mach::mach_time::mach_timebase_info {
-        static mut INFO: mach::mach_time::mach_timebase_info
-            = mach::mach_time::mach_timebase_info {
+    fn info() -> mach_timebase_info {
+        static mut INFO: mach_timebase_info = mach_timebase_info {
             numer: 0,
             denom: 0,
         };
@@ -246,7 +257,12 @@ mod inner {
 
             // ... otherwise learn for ourselves ...
             let mut info = mem::zeroed();
-            mach::mach_time::mach_timebase_info(&mut info);
+            extern "C" {
+                fn mach_timebase_info(info: mach_timebase_info_t)
+                                      -> kern_return_t;
+            }
+
+            mach_timebase_info(&mut info);
 
             // ... and attempt to be the one thread that stores it globally for
             // all other threads

src/tools/tidy/src/deps.rs

@@ -48,11 +48,12 @@ const EXCEPTIONS: &[&str] = &[
     "bytesize",           // Apache-2.0, cargo
     "im-rc",              // MPL-2.0+, cargo
     "adler32",            // BSD-3-Clause AND Zlib, cargo dep that isn't used
-    "fortanix-sgx-abi",   // MPL-2.0+, libstd but only for `sgx` target
     "constant_time_eq",   // CC0-1.0, rustfmt
     "utf8parse",          // Apache-2.0 OR MIT, cargo via strip-ansi-escapes
     "vte",                // Apache-2.0 OR MIT, cargo via strip-ansi-escapes
     "sized-chunks",       // MPL-2.0+, cargo via im-rc
+    // FIXME: this dependency violates the documentation comment above:
+    "fortanix-sgx-abi",   // MPL-2.0+, libstd but only for `sgx` target
 ];
 
 /// Which crates to check against the whitelist?