Fix libcore build

library/stdarch/ci/dox.sh

@@ -22,19 +22,24 @@ dox() {
   rm -rf "target/doc/${arch}"
   mkdir "target/doc/${arch}"
 
+  export RUSTFLAGS="--cfg core_arch_docs"
+  export RUSTDOCFLAGS="--cfg core_arch_docs"
+
   cargo build --verbose --target "${target}" --manifest-path crates/core_arch/Cargo.toml
   cargo build --verbose --target "${target}" --manifest-path crates/std_detect/Cargo.toml
 
   rustdoc --verbose --target "${target}" \
           -o "target/doc/${arch}" crates/core_arch/src/lib.rs \
           --crate-name core_arch \
-          --library-path "target/${target}/debug/deps"
+          --library-path "target/${target}/debug/deps" \
+          --cfg core_arch_docs
   rustdoc --verbose --target "${target}" \
           -o "target/doc/${arch}" crates/std_detect/src/lib.rs \
           --crate-name std_detect \
           --library-path "target/${target}/debug/deps" \
           --extern cfg_if="$(ls target/"${target}"/debug/deps/libcfg_if-*.rlib)" \
-          --extern libc="$(ls target/"${target}"/debug/deps/liblibc-*.rlib)"
+          --extern libc="$(ls target/"${target}"/debug/deps/liblibc-*.rlib)" \
+          --cfg core_arch_docs
 }
 
 dox i686 i686-unknown-linux-gnu

library/stdarch/crates/core_arch/Cargo.toml

@@ -14,6 +14,7 @@ readme = "README.md"
 keywords = ["core", "simd", "arch", "intrinsics"]
 categories = ["hardware-support", "no-std"]
 license = "MIT/Apache-2.0"
+build = "build.rs"
 
 [badges]
 travis-ci = { repository = "rust-lang-nursery/stdsimd" }

library/stdarch/crates/core_arch/build.rs

@@ -1,6 +1,3 @@
-use std::env;
-
 fn main() {
-    println!("cargo:rustc-env=TARGET={}", env::var("TARGET").unwrap());
-    println!("cargo:rerurn-if-changed=build.rs");
+    println!("cargo:rustc-cfg=core_arch_docs");
 }

library/stdarch/crates/core_arch/src/mod.rs

@@ -5,7 +5,11 @@
 
 mod simd;
 
-#[doc(include = "core_arch_docs.md")]
+#[cfg_attr(
+    not(core_arch_docs),
+    doc(include = "../stdsimd/crates/core_arch/src/core_arch_docs.md")
+)]
+#[cfg_attr(core_arch_docs, doc(include = "core_arch_docs.md"))]
 #[stable(feature = "simd_arch", since = "1.27.0")]
 pub mod arch {
     /// Platform-specific intrinsics for the `x86` platform.