compile-time internal error on passing &Function to js

[limira]

I encountered internal error: entered unreachable code with wasm-bindgen when I tried the git master version at merge of #1353 (and still there at the merge of #1372, not sure how far ago when the bug appear. But the bug is not in 0.2.39 release)

You can see the minimal code that produce the error here. In words, I have a library wb-lib that wraps around Foo in foo.js. Foo is a JS class that need a callback that the Rust code will pass a &js_sys::Function to it. An app wb-app depends on wb-lib, it initialize a Foo object.

Compile the provided repo (using a matched version of wasm-bindgen-cli) will cause the compile time error as shown in the backtrace file (also in repo). Note that I run wasm-bindgen --web.

No error if arguments not include a js_sys::Function. No error with v0.2.39.

[alexcrichton]

Thanks for the report and for the reproduction! I think this should be "fixed" in #1377 where "fixed" here means "produces a better error message". The real fix though for this is to add [patch] annotations for web-sys in addition to wasm-bindgen because the problem was that too many crates showed up in the crate graph, confusing the CLI!