cli panics with out of bounds error

[kuviman]

Describe the Bug

Trying to just compile my project to the web, I stumbled upon this panic message.
I think this may happen because of version mismatch between the cli app and the dependency.
After running cargo update everything works fine.

Steps to Reproduce

I can not really show the code. I may try to provide a simplified example if needed

OS: Windows
Rust version: rustc 1.55.0 (c8dfcfe04 2021-09-06)
wasm-bindgen-cli version: 0.2.77
wasm-bindgen dependency version: 0.2.76

Running command: wasm-bindgen --target=web --no-typescript --out-dir tmp target/wasm32-unknown-unknown/release/theproject.wasm

Expected Behavior

wasm-bindgen does its magic without any errors

Actual Behavior

wasm-bindgen panics with following message:

thread 'main' panicked at 'index out of bounds: the len is 0 but the index is 0', C:\Users\myusername\.cargo\registry\src\github.aaakk.us.kg-1ecc6299db9ec823\wasm-bindgen-cli-support-0.2.77\src\descriptor.rs:205:15

Additional Context

As I said, looks like problems with different versions. I remember wasm-bindgen would just panic instantly with message saying that versions should match. I guess it is not the case anymore? So this took me a while to even think about running cargo update

[alexcrichton]

Yes recently the version-match was removed because it was hoped to get caught by other things and/or not change much. I believe that's the cause of this.

[chinedufn]

Uh oh!

Yeah I worked on this in #2546 with the hope of removing this requirement.

It looks like something is going wrong.. Alex if you already know the issue definitely let me know and I can get it fixed it.

Otherwise I can take a look into this later tonight and figure out what's going wrong!

IIRC this should have actually worked in theory.. so it's probably a minor oversight or something.. hopefully..!

[alexcrichton]

Oh I'm not sure what actually caused this, I'd assume that something about the schema probably changed and the version number of the schema was forgotten to get bumped, but I would have to track things down to be sure.

[chinedufn]

Ahh got it.

Yeah, just checked and this test is failing:

wasm-bindgen/crates/shared/src/schema_hash_approval.rs

Lines 13 to 16 in 7236748

	#[test]
	fn schema_version() {
	assert_eq!(env!("SCHEMA_FILE_HASH"), APPROVED_SCHEMA_FILE_HASH)
	}

Seems like we just need to start running it in CI.

[chinedufn]

I'm on it one sec.

[chinedufn]

@kuviman (and anyone else that comes here) sorry about this.

In short.. we currently need to manually change the schema version whenever one of wasm-bindgen's internal data structures changes.

This is used to ensure that you get a nice error when trying to use two versions of wasm-bindgen with different schemas.

There's a test that fails when we forget to change this schema version.

But this test wasn't running in CI so no one noticed / remembered to change the schema version.

#2680 runs this test in CI so we shouldn't forget again!

In the future.. we could automatic this entirely using a proc macro that hashes the tokens and generated the schema version variable or something.. but since the schema doesn't change often we probably won't need to go that route.

Sorry!