add HermitCore support even if it doesn't have a UNIX interface

ci/build.sh

@@ -167,7 +167,9 @@ done
 # FIXME: https://github.com/rust-lang/rust/issues/58564
 # sparc-unknown-linux-gnu
 RUST_LINUX_NO_CORE_TARGETS="\
+x86_64-unknown-hermit \
 x86_64-unknown-dragonfly \
+aarch64-unknown-hermit \
 aarch64-pc-windows-msvc \
 aarch64-unknown-cloudabi \
 armebv7r-none-eabi \

src/hermit/aarch64.rs

@@ -0,0 +1,2 @@
+pub type c_char = u8;
+pub type wchar_t = u32;

src/hermit/mod.rs

@@ -0,0 +1,83 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// libc port for HermitCore (https://hermitcore.org)
+//
+// Ported by Colin Fink <[email protected]>
+//       and Stefan Lankes <[email protected]>
+
+pub type int8_t = i8;
+pub type int16_t = i16;
+pub type int32_t = i32;
+pub type int64_t = i64;
+pub type uint8_t = u8;
+pub type uint16_t = u16;
+pub type uint32_t = u32;
+pub type uint64_t = u64;
+
+pub type c_schar = i8;
+pub type c_uchar = u8;
+pub type c_short = i16;
+pub type c_ushort = u16;
+pub type c_int = i32;
+pub type c_uint = u32;
+pub type c_float = f32;
+pub type c_double = f64;
+pub type c_longlong = i64;
+pub type c_ulonglong = u64;
+pub type intmax_t = i64;
+pub type uintmax_t = u64;
+
+pub type size_t = usize;
+pub type ptrdiff_t = isize;
+pub type intptr_t = isize;
+pub type uintptr_t = usize;
+pub type ssize_t = isize;
+
+pub type c_long = i64;
+pub type c_ulong = u64;
+
+pub type wint_t = u32;
+pub type wctype_t = i64;
+
+pub type regoff_t = size_t;
+pub type off_t = c_long;
+
+cfg_if! {
+    if #[cfg(target_arch = "aarch64")] {
+        mod aarch64;
+        pub use self::aarch64::*;
+    } else if #[cfg(target_arch = "x86_64")] {
+        mod x86_64;
+        pub use self::x86_64::*;
+    } else {
+        // Unknown target_arch
+    }
+}
+
+cfg_if! {
+    if #[cfg(libc_core_cvoid)] {
+        pub use ::ffi::c_void;
+    } else {
+        // Use repr(u8) as LLVM expects `void*` to be the same as `i8*` to help
+        // enable more optimization opportunities around it recognizing things
+        // like malloc/free.
+        #[repr(u8)]
+        #[allow(missing_copy_implementations)]
+        #[allow(missing_debug_implementations)]
+        pub enum c_void {
+            // Two dummy variants so the #[repr] attribute can be used.
+            #[doc(hidden)]
+            __variant1,
+            #[doc(hidden)]
+            __variant2,
+        }
+    }
+}

src/hermit/x86_64.rs

@@ -0,0 +1,2 @@
+pub type c_char = i8;
+pub type wchar_t = i32;

src/lib.rs

@@ -106,6 +106,9 @@ cfg_if! {
     } else if #[cfg(unix)] {
         mod unix;
         pub use unix::*;
+    } else if #[cfg(target_os = "hermit")] {
+        mod hermit;
+        pub use hermit::*;
     } else if #[cfg(target_env = "sgx")] {
         mod sgx;
         pub use sgx::*;