"wasm32-unknown-unknown target is not supported"-error while integrating try-runtime

Question

Using this guide to integrate try-runtime on my node i get the error about get random not building for wasm.

  error: the wasm32-unknown-unknown target is not supported by default, you may need to enable the "js" feature. For more information see: https://docs.rs/getrandom/#webassembly-support
     --> /home/simson/.cargo/registry/src/github.com-1ecc6299db9ec823/getrandom-0.2.3/src/lib.rs:219:9
      |
  219 | /         compile_error!("the wasm32-unknown-unknown target is not supported by \
  220 | |                         default, you may need to enable the \"js\" feature. \
  221 | |                         For more information see: \
  222 | |                         https://docs.rs/getrandom/#webassembly-support");
      | |________________________________________________________________________^

  error[E0433]: failed to resolve: use of undeclared crate or module `imp`
     --> /home/simson/.cargo/registry/src/github.com-1ecc6299db9ec823/getrandom-0.2.3/src/lib.rs:246:5
      |
  246 |     imp::getrandom_inner(dest)
      |     ^^^ use of undeclared crate or module `imp`

I get this error when I enable frame-try-runtime on the second line below (In [features] section of runtime/Cargo.toml)

try-runtime = [
    "frame-executive/try-runtime",
    "frame-try-runtime",
    "frame-system/try-runtime",
]

I suspect the root cause of this is not related to wasm but rather that some dependency is leaking std code into the wasm build. What kind of miss-configuration should I be looking for to find this problem?

Answer 1

It looks like the latest Rust nightly has broken our Wasm builds.

There have been other reports of this issue here:

https://github.com/paritytech/substrate/issues/10767

And the fix is coming in here:

https://github.com/paritytech/substrate/pull/10837