Multiple identical extern functions with different types causes panic in wasm_bindgen

[hansihe]

Steps to Reproduce

Run wasm-pack test --node on the following crate:

Cargo.toml:

[package]
name = "reprod"
version = "0.0.0"
authors = []
edition = "2018"

[lib]
crate-type = ["cdylib"]

[dependencies]
js-sys = "0.3"
wasm-bindgen = "0.2"

[dev-dependencies]
wasm-bindgen-test = "0.2"

lib.rs:

mod a {
    use wasm_bindgen::prelude::*;

    #[wasm_bindgen]
    extern "C" {
        #[wasm_bindgen(js_namespace = console)]
        fn log(s: &str);
    }

}

mod b {

    use wasm_bindgen::prelude::*;
    use wasm_bindgen_test::*;
    use js_sys::{JsString};

    #[wasm_bindgen]
    extern "C" {
        #[wasm_bindgen(js_namespace = console)]
        fn log(s: &JsString);
    }

    #[wasm_bindgen_test]
    fn aa() {
        let string = JsString::from_char_code(&[]);
        log(&string);
    }

}

If applicable, add a link to a test case (as a zip file or link to a repository we can clone).

Expected Behavior

Either:

1. An error message describing what I'm doing wrong
2. No panic

Actual Behavior

hansihe@hansihe-XPS-13-9370:~/proj/rust/bindgen_run_reprod$ wasm-pack test --node
[INFO]: Checking for the Wasm target...
   Compiling screeps_anathema v0.0.0 (/home/hansihe/proj/rust/bindgen_run_reprod)
    Finished dev [unoptimized + debuginfo] target(s) in 0.78s
[INFO]: Installing wasm-bindgen...
    Finished dev [unoptimized + debuginfo] target(s) in 0.07s
     Running target/wasm32-unknown-unknown/debug/deps/screeps_anathema-c294c97529e4fd68.wasm
thread 'main' panicked at 'assertion failed: iter.next().is_none()', crates/cli-support/src/webidl/bindings.rs:227:5
stack backtrace:
   0: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
   1: core::fmt::write
   2: std::io::Write::write_fmt
   3: std::panicking::default_hook::{{closure}}
   4: std::panicking::default_hook
   5: std::panicking::rust_panic_with_hook
   6: std::panicking::begin_panic
   7: wasm_bindgen_cli_support::webidl::bindings::assert_signature_match
   8: wasm_bindgen_cli_support::webidl::bindings::register_import
   9: wasm_bindgen_cli_support::webidl::Context::program
  10: wasm_bindgen_cli_support::webidl::process
  11: wasm_bindgen_cli_support::Bindgen::generate_output
  12: wasm_bindgen_cli_support::Bindgen::generate
  13: wasm_bindgen_test_runner::main
  14: std::rt::lang_start::{{closure}}
  15: std::panicking::try::do_call
  16: __rust_maybe_catch_panic
  17: std::rt::lang_start_internal
  18: main
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
error: test failed, to rerun pass '--lib'         
Error: Running Wasm tests with wasm-bindgen-test failed
Caused by: failed to execute `cargo test`: exited with exit code: 101
hansihe@hansihe-XPS-13-9370:~/proj/rust/bindgen_run_reprod$ 

[alexcrichton]

Sorry for the delay in commenting on this, but thanks for the report!

I think this is a bug in the CLI where it's a panic, instead a first-class error should likely be reported. I unfortunately won't have time to get around to this for some time, but it's good to have this logged!