rust toolchain example is incompatible with MacOS / M1

[dfee]

Describe the bug builds fail with error:

  = note: ld: library not found for -liconv
          collect2: error: ld returned 1 exit status

error: could not compile `thiserror` due to previous error

To Reproduce

• checkout the repo
• enter into a nix shell
• cd examples/toolchains/rust
• bazel build :hello
• get a build failure: note: ld: library not found for -liconv

Expected behavior the build to suceed

Environment

• OS name + version: Apple M1 Max / Ventura 13.4
• Version of the code: current main

[benradf]

Thanks for reporting this @dfee. I don't have access to a Mac right now to reproduce this myself, but hopefully later this week I'll be able to. In the meantime, if you try running with --verbose_failures, you should be able to see the full command that produces this linker error. That might provide some clues about why it's failing to find iconv.