Support wasm32-unknown-emscripten

Author: pitdicker

Cargo.toml

@@ -50,6 +50,10 @@ fuchsia-zircon = { version = "0.3.2", optional = true }
 # use with `--target wasm32-unknown-unknown --features=stdweb`
 stdweb = { version = "0.4", optional = true }
 
+[target.wasm32-unknown-emscripten.dependencies]
+# use with `--target wasm32-unknown-unknown --features=stdweb`
+stdweb = { version = "0.4", optional = true }
+
 [dev-dependencies]
 # This is for testing serde, unfortunately we can't specify feature-gated dev
 # deps yet, see: https://github.com/rust-lang/cargo/issues/1596

src/rngs/os.rs

@@ -147,6 +147,7 @@ impl RngCore for OsRng {
 
 #[cfg(all(unix,
           not(target_os = "cloudabi"),
+          not(all(target_os = "emscripten", feature = "stdweb")),
           not(target_os = "freebsd"),
           not(target_os = "fuchsia"),
           not(target_os = "ios"),
@@ -660,8 +661,7 @@ mod imp {
 }
 
 #[cfg(all(target_arch = "wasm32",
-          not(target_os = "emscripten"),
-          not(feature = "stdweb")))]
+          not(any(target_os = "emscripten", feature = "stdweb"))))]
 mod imp {
     use {Error, ErrorKind};
 
@@ -681,9 +681,7 @@ mod imp {
     }
 }
 
-#[cfg(all(target_arch = "wasm32",
-          not(target_os = "emscripten"),
-          feature = "stdweb"))]
+#[cfg(all(target_arch = "wasm32", feature = "stdweb"))]
 mod imp {
     use std::mem;
     use stdweb::unstable::TryInto;