rand with stdweb feature is not compatible with wasm32-unkown-emscripten target or --nodejs in wasm32-unkown-unknown target

[huangjj27]

Hi, everyon! I was trying to use rand in wasm32-unknown-unknown target, so I added the stdweb features in cargo.toml:

[dependencies]
# ...

# FIXME: after the 0.5 version of rand is released on crates.io, lock the version.
rand = { git = "https://github.com/rust-lang-nursery/rand", features = ["stdweb"] }

and it did work fine with the target.

However, in this build, it fails me with such given error:

Testing for wasm32-unknown-emscripten...

# ...many irrelevant logs reduced

   Compiling rand v0.5.0-pre.1 (https://github.com/rust-lang-nursery/rand#b1c35856)
error[E0463]: can't find crate for `stdweb`
   --> /home/travis/.cargo/git/checkouts/rand-02690058d91f0548/b1c3585/src/lib.rs:193:1
    |
193 | extern crate stdweb;
    | ^^^^^^^^^^^^^^^^^^^^ can't find crate
error: aborting due to previous error
For more information about this error, try `rustc --explain E0463`.
error: Could not compile `rand`.

Is it a compatiblity issue between these 2 wasm target?

[huangjj27]

I found the stdweb crate will be included when using wasm32-* target:

// lib.rs: 191-193 
#[cfg(all(target_arch = "wasm32", feature = "stdweb"))]
#[macro_use]
extern crate stdweb;

So I think this is a compatiblity bug

[pitdicker]

@huangjj27 Thank you for opening the issue. I think one problem is that we have this in cargo.toml:

[target.wasm32-unknown-unknown.dependencies]
stdweb = { version = "0.4", optional = true }

Also OsRng contained a line to not use stdweb in combination with emscripten.

I have tried a fix in https://github.com/pitdicker/rand/tree/emscripten, but have trouble testing it out locally. Can you give it a try?

[huangjj27]

@pitdicker I'm sorry I don't have emscripten locally neither. maybe you can make a PR to check the test? I just make a PR #444 . Let's see if we can fix the problem

[huangjj27]

It seen fix the problem, but causing another.