internal error: unexpected way of calling JS shims

[BafDyce]

Yesterday I upgraded rust-nightly (last install was ~1-2 weeks old), now I get the following compilation error with cargo-web (latest version):

$ RUST_BACKTRACE=1 cargo web build --bin ce-ui --features ui
warning: debug builds on the wasm32-unknown-unknown are currently totally broken
         forcing a release build
    Finished release [optimized] target(s) in 0.09s
    Garbage collecting "ce-ui.wasm"...
    Processing "ce-ui.wasm"...
thread 'main' panicked at 'internal error: unexpected way of calling JS shims; please report this!', src/wasm_inline_js.rs:75:38
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
             at src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:39
   1: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:70
   2: std::panicking::default_hook::{{closure}}
             at src/libstd/sys_common/backtrace.rs:58
             at src/libstd/panicking.rs:200
   3: std::panicking::default_hook
             at src/libstd/panicking.rs:215
   4: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:478
   5: std::panicking::begin_panic
   6: cargo_web::wasm_inline_js::process_and_extract
   7: core::ops::function::impls::<impl core::ops::function::FnMut<A> for &mut F>::call_mut
   8: cargo_web::cargo_shim::BuildConfig::build_internal
   9: cargo_web::cargo_shim::BuildConfig::build
  10: cargo_web::build::Project::build_or_check
  11: cargo_web::cmd_build::command_build_or_check
  12: cargo_web::main
  13: std::rt::lang_start::{{closure}}
  14: std::panicking::try::do_call
             at src/libstd/rt.rs:49
             at src/libstd/panicking.rs:297
  15: __rust_maybe_catch_panic
             at src/libpanic_unwind/lib.rs:87
  16: std::rt::lang_start_internal
             at src/libstd/panicking.rs:276
             at src/libstd/panic.rs:388
             at src/libstd/rt.rs:48
  17: main
  18: __libc_start_main
  19: _start

Content of my Web.toml:

default-target="wasm32-unknown-unknown"

[cargo-web]
minimum-version = "0.6.9"

As my project is quite large and I haven't done any source code changes since the last successful compilation, I do not know how I would create a minimal example for this.

[koute]

This is interesting! Unfortunately I'm not really sure how I could reproduce it.

Could you try a few of these things?

• Nuke the whole target directory and do a clean rebuild.
• Try to build with the Emscripten targets and see if it works.
• Try to maybe bisect from which nightly exactly it stopped working? (If it's only two weeks worth of nightlies this should only take a few tries.)
• Send me (in private if you don't want to share it) the .wasm file generated by the nightly on which this problem reproduce.

[dsander]

Hi,

I am seeing the same error on my project. I manually bisected the nightly versions and it first broke with 1.33.0-nightly (20c2cba61 2019-01-26) the previous nightly rustc 1.33.0-nightly (bf669d1e3 2019-01-25) works fine.

Here are the rustc changes: https://github.com/rust-lang/rust/compare/bf669d1e3...20c2cba61

If you like I can send you my .wasm via email.

[koute]

It looks like there were some LLVM updates between those commits, which makes sense.

Yes, @dsander if you can I'd appreciate if you could send me a .wasm file from a project on which this reproduces.

[koute]

Thanks for the .wasm file @dsander.

Okay, I know what's the issue here. @dsander it looks like you're using an old version of stdweb (0.4.10) which still uses the non-procedural version of the js! macro. The implementation of that was a little hacky, which made it somewhat brittle and it didn't really support non-release builds. Since stdweb 0.4.11 a new version of the js! macro was introduced which shouldn't have this problem.

Could you delete the Cargo.lock in your project and try to rebuild?

[dsander]

Sorry for the delay and thanks @koute!

Going from stdweb 0.4.10 to 0.4.15 fixed the issue for me.