IndexMap build error on yew v0.17.4

[hube12]

Compiling yew v0.17.4 from trunk serve give this error

bad status returned from cargo build:    Compiling yew v0.17.4
error[E0107]: wrong number of type arguments: expected 2, found 1
  --> C:\Users\r1\.cargo\registry\src\github.com-1ecc6299db9ec823\yew-0.17.4\src\virtual_dom\mod.rs:69:10
   |
69 |     set: IndexSet<String>,
   |          ^^^^^^^^^^^^^^^^ expected 2 type arguments

error: aborting due to previous error

For more information about this error, try `rustc --explain E0107`.

Steps To Reproduce
Steps to reproduce the behavior:

cargo install trunk ... rust add....
git clone https://github.com/yewstack/yew
cd examples/boids
trunk serve --release

clone the boid web app, install wasm dependencies and trunk, run trunk serve, get error

Expected behavior
Mod.rs should not have that kind of error

[thedodd]

@hube12 if you build your app outside of trunk using cargo build --release --target wasm32-unknown-unknown do you still get the same error? I ask because technically that is all Trunk does at the end of the day — other than the processing of the non-Rust assets (html, sass, css, &c).

[hube12]

@hube12 if you build your app outside of trunk using cargo build --release --target wasm32-unknown-unknown do you still get the same error? I ask because technically that is all Trunk does at the end of the day — other than the processing of the non-Rust assets (html, sass, css, &c).

cargo build --release --target wasm32-unknown-unknown
   Compiling yew v0.17.4
error[E0107]: wrong number of type arguments: expected 2, found 1
  --> C:\Users\r1\.cargo\registry\src\github.com-1ecc6299db9ec823\yew-0.17.4\src\virtual_dom\mod.rs:69:10
   |
69 |     set: IndexSet<String>,
   |          ^^^^^^^^^^^^^^^^ expected 2 type arguments

error: aborting due to previous error

For more information about this error, try `rustc --explain E0107`.
error: could not compile `yew`

To learn more, run the command again with --verbose.

[thedodd]

@hube12 that's about what I expected. Looks like this doesn't really have anything to do with Trunk :). I hereby yield to the maintainers (@siku2 @jstarry & others).

[siku2]

As mentioned on Discord, this error looks like indexmap thinks it's being built without the standard library. In that case IndexMap no longer defaults to the RandomState hasher from std but instead requires a custom one through a type argument, thus the error.
I don't know why it thinks there's no standard library though, there's likely something special about your setup that causes it.

indexmap detects the presence of std in the build script using autocfg::new().emit_sysroot_crate("std") which uses some interesting hacks to detect it (it involves invoking rustc on a small code snippet to see if it compiles). You can look into that to find out more. Try setting the CARGO_FEATURE_STD variable (which is can be used to explicitly set it) to see if this detection is indeed the problem. This requires indexmap 1.6.1 so make sure you have the latest version using cargo update.