Latest git not building for wasm

[singalen]

I have this in my cargo.lock:

version = "0.8.1"
source = "git+https://github.com/thebracket/bracket-lib.git#2c52c1b96de26dac4d669657937167cf25afc46f"
dependencies = [
...
 "ctrlc",

When I try to build for wasm, I get:

$ cargo build --release --target wasm32-unknown-unknown
   Compiling ctrlc v3.1.7
   Compiling paste v1.0.4
   Compiling downcast-rs v1.2.0
   Compiling ucd-trie v0.1.3
   Compiling unicode-segmentation v1.7.1
   Compiling proc-macro2 v1.0.24
   Compiling syn v1.0.60
   Compiling log v0.4.14
error[E0432]: unresolved import `platform::Signal`
  --> /Users/vsergiienko/.cargo/registry/src/github.com-1ecc6299db9ec823/ctrlc-3.1.7/src/lib.rs:53:9
   |
53 | pub use platform::Signal;
   |         ^^^^^^^^^^^^^^^^ no `Signal` in `platform`

error[E0412]: cannot find type `Error` in module `platform`
  --> /Users/vsergiienko/.cargo/registry/src/github.com-1ecc6299db9ec823/ctrlc-3.1.7/src/error.rs:25:23
   |
25 | impl From<::platform::Error> for Error {
   |                       ^^^^^ not found in `platform`
   |
help: consider importing one of these items
   |
1  | use Error;
   |
1  | use error::fmt::Error;
   |
1  | use std::error::Error;
   |
1  | use std::io::Error;
   |

...and a bunch of other errors.

MacOS,

$ rustc --version
rustc 1.50.0 (cb75ad5db 2021-02-10)

[justinbowes]

I have the same issue with 0.8.0 and 0.8.1. If I borrow dependencies from amethyst/rustrogueliketutorial@3792f07 I can get it to work.

This implies

1. using bracket-terminal 0.8.1 which does not rely on ctrlc
2. using bracket-random 0.8.0 and rand 0.7.3; newer rand has a transitive dependency through rand_core on getrandom > 0.2.0, see Comment on WASM targets where getrandom should never work rust-random/getrandom#152 , and therefore rolling back to bracket-noise 0.8.1

[vks]

To fix the build failure with Rand, you might have to enable the js feature for getrandom 0.2 if you are using the wasm32-unknown-unknown target. Alternatively, you can use the wasm32-unknown-emscripten or wasm32-wasi target.

[justinbowes]

Right. So the rand requires js feature issue might properly go against https://github.com/amethyst/rustrogueliketutorial/blob/master/book/src/webbuild.md

The dependency on ctrlc would however block in any case.

[singalen]

Looks like rand can be built without getrandom. Who needs a hardware random seeds in a roguelike game?
ctrlc probably needs to be a bracket-terminal option.

[vks]

You need getrandom to initialize your RNG. It's not about hardware support.

[thebracket]

Starting work on this now.

[singalen]

You need getrandom to initialize your RNG. It's not about hardware support.

https://crates.io/crates/getrandom:

A Rust library for retrieving random data from (operating) system source. It is assumed that system always provides high-quality cryptographically secure random data, ideally backed by hardware entropy sources.

While that's what it does, what we get as a package is too much and is outright harmful. This is how node.js dependencies turn into a supermassive black hole.
I hope this case can be dealt with through a careful use of crate features and platform-specific dependencies .

[thebracket]

The wasm_fix branch has code that works now. I'm looking to see how much pain it will be to use getrandom in normal builds and just use the seconds since epoch in wasm builds. Having some odd behavior trying to just change default-features based on an arch tag in cargo.

[thebracket]

Apparently, I'm going to have some pain with having rand in two platforms with different feature sets. The new "resolver" fixes it, but makes bracket-random nightly only at present; I don't want to do that, so I'll stick with the seconds-since-epoch approach. It really shouldn't be a problem if a game seed isn't crypto-sound.

[thebracket]

Ok, I've confirmed that all tests and examples build on wasm32 and native on my system. I'll mark this issue "pending confirmation" if someone else would like to test for me. Then I'll close it/push a crate version bump. Thanks!

[justinbowes]

I'm a Rust neophyte, but:

cargo clean
rm Cargo.lock

# Set dependency: 
# [dependencies] 
# rltk = { git = "https://github.com/amethyst/bracket-lib" }

cargo build --release --target wasm32-unknown-unknown
wasm-bindgen ...

The build completes successfully. 🥇

However, running it, I get a panic in the web console:

Uncaught (in promise) RuntimeError: unreachable
    at __rust_start_panic (http://localhost:8080/rltktut_bg.wasm:wasm-function[1622]:0x82f9f)
    at rust_panic (http://localhost:8080/rltktut_bg.wasm:wasm-function[1190]:0x80ee6)
    at std::panicking::rust_panic_with_hook::h4f753dc70b771d8e (http://localhost:8080/rltktut_bg.wasm:wasm-function[733]:0x75179)
    at std::panicking::begin_panic::{{closure}}::hce5f3f65f96f2f2a (http://localhost:8080/rltktut_bg.wasm:wasm-function[1177]:0x80ce1)
    at std::sys_common::backtrace::__rust_end_short_backtrace::h706c23cb5ca53ba5 (http://localhost:8080/rltktut_bg.wasm:wasm-function[1138]:0x80629)
    at std::panicking::begin_panic::h500a2937ff20cfd7 (http://localhost:8080/rltktut_bg.wasm:wasm-function[1176]:0x80cb4)
    at std::sys::wasm::time::SystemTime::now::h780c8e91d0f652ad (http://localhost:8080/rltktut_bg.wasm:wasm-function[1449]:0x827da)
    at std::time::SystemTime::now::h92037ca9d5c1afb7 (http://localhost:8080/rltktut_bg.wasm:wasm-function[1563]:0x82d16)
    at bracket_random::random::RandomNumberGenerator::new::hf0a76cba565441ab (http://localhost:8080/rltktut_bg.wasm:wasm-function[744]:0x75a2d)
    at rltktut::map::Map::new_map_rooms_and_corridors::h1d98ee7f801ac015 (http://localhost:8080/rltktut_bg.wasm:wasm-function[144]:0x1fcde)

[justinbowes]

This may be relevant: rust-lang/rust#48564 (comment)

((I'll be happy to contribute with PRs once I get my head around Rust a little more. Trying to help however I can at the moment.)

[thebracket]

I'll dig into it some more, my testing didn't quite get that far (which was why I'd left it open). It's hard to believe that SystemTime::now breaks on WASM, but I guess there's a sandboxing/security problem with just exposing it. I'm pretty sure that the issue you linked will help me resolve that. Thanks!

[thebracket]

The patch I just committed is now working for me. The results of a WASM build: http://bfnightly.bracketproductions.com/sprites-23-02-2021/ (sprite movement is random via bracket-random).

[justinbowes]

Confirming your findings: wasm32-unknown-unknown builds and runs my project successfully for me against current master, aabfa49. Since I intend to get there eventually, I rebuilt https://github.com/amethyst/rustrogueliketutorial and tried out chapter 74, assuming that it exercises more features. That was also fine.

Excellent! Thank you.

[vks]

@thebracket Why don't you enable the getrandom/js feature instead?

[singalen]

Removing a whole target system, and reducing the module portability because of implementation convenience, is not a responsible behavior towards community.

[thebracket]

I think I have some ideas to find a middle-ground here. (With that said, I will give the warning that if you really need crypto-strength randomness, this library may not be a good choice for you - xorshift has lots of nice properties, but I'm really not qualified to judge its entropy scores). I'm also not a huge fan of renaming the crossterm feature, but I think I should have done that one anyway - Cargo gets pretty limiting when your feature name matches a dependency.

So I'll keep this issue open and not push a crate version until I have a somewhat better solution in place.

[thebracket]

Ok, I've updated this again (hopefully the last one before I do a crate upload):

• The cross_term feature is still crossterm is you use RLTK or bracket-lib directly. You only need to change the feature name if you are using bracket-terminal directly. That should minimize the impact of the feature change.
• On a non-WASM ("native") build, bracket-random first tries to use getrandom. If for some reason your platform doesn't provide a good answer, it falls back to the time since startup. If you don't have a clock OR an RNG, it can't help you - use the with_seed call.
• On a WASM build, it uses some code from getrandom (not getrandom itself, there's difficulties pulling in a crate with different feature flags by target at this time). It tries to detect if you are using Node, and uses Node's crypto system to get a seed. If that isn't available, it looks to see if your browser can provide a good seed - and uses that. If your browser isn't providing that either, it falls back to JS time. Again, if none of those can help you - use with_seed and provide one!

It works on my test builds (the tutorial, and http://bfnightly.bracketproductions.com/sprites-23-02-2021/ ). If anyone could give it a whirl before I publish, I'd appreciate it.

[justinbowes]

On 927d229 in my project, all of the following now build and run. I lack a test environment for other combinations.

• rltk/default
  • wasm32
  • x86_64-pc-windows-msvc
• rltk/crossterm
  • x86_64-pc-windows-msvc
  • x86_64-unknown-linux-musl
• rltk/curses
  • x86_64-pc-windows-msvc
  • x86_64-unknown-linux-musl
• rltk/amethyst_engine_vulkan
  • x86_64-pc-windows-msvc

[thebracket]

I forgot to close this one - it's working on everything I've test it with.