Failed to write main executable: invalid code after misc prefix

[brianmay]

Somehow in the latest nixos 24.11 and 25.05 something changed, and now I am getting this error:

  48.170s  INFO Bundling app...
  48.170s  INFO Running wasm-bindgen...
  48.371s  INFO Running optimization with wasm-opt...
  48.451s ERROR err=Other(Failed to write main executable

Caused by:
    0: Failed to read module
    1: [parse exception: invalid code after misc prefix: 17 (at 0:3354470)])
  48.452s ERROR err=Other(Failed to write main executable

Caused by:
    0: Failed to read module
    1: [parse exception: invalid code after misc prefix: 17 (at 0:3354470)])

Any ideas?

Am using 0.2.100 of wasm-bindgen-cli, that hasn't changed. Assuming dx is correctly using the installed version still.

[brianmay]

Could be connected to rust-lang/rust#141048

So far the suggested work around of modifying Cargo.toml isn't helping.

[brianmay]

Problem only happens in release mode.

[brianmay]

I suspect the problem is that dx runs wasm-opt, but isn't parsing the required arguments, and cannot be configured to parse the required arguments (people say --enable-bulk-memory is important)

dioxus/packages/cli/src/wasm_opt.rs

Lines 28 to 66 in ad8c869

	async fn run_locally(input_path: &Path, output_path: &Path, cfg: &WasmOptConfig) -> Result<()> {
	let mut args = vec![
	// needed by wasm-bindgen
	"--enable-reference-types",
	];
	if cfg.memory_packing {
	// needed for our current approach to bundle splitting to work properly
	// todo(jon): emit the main module's data section in chunks instead of all at once
	args.push("--memory-packing");
	}
	if !cfg.debug {
	args.push("--strip-debug");
	} else {
	args.push("--debuginfo");
	}
	let level = match cfg.level {
	WasmOptLevel::Z => "-Oz",
	WasmOptLevel::S => "-Os",
	WasmOptLevel::Zero => "-O0",
	WasmOptLevel::One => "-O1",
	WasmOptLevel::Two => "-O2",
	WasmOptLevel::Three => "-O3",
	WasmOptLevel::Four => "-O4",
	};
	tokio::process::Command::new("wasm-opt")
	.arg(input_path)
	.arg(level)
	.arg("-o")
	.arg(output_path)
	.args(args)
	.output()
	.await?;
	Ok(())
	}

[brianmay]

I think I got the code reference wrong, think the run_from_lib is used by default.

dioxus/packages/cli/src/wasm_opt.rs

Lines 12 to 26 in ad8c869

	#[allow(unreachable_code)]
	pub async fn optimize(input_path: &Path, output_path: &Path, cfg: &WasmOptConfig) -> Result<()> {
	#[cfg(feature = "optimizations")]
	return run_from_lib(input_path, output_path, cfg).await;
	// It's okay not to run wasm-opt but we should *really* try it
	if which::which("wasm-opt").is_err() {
	tracing::warn!("wasm-opt not found and CLI is compiled without optimizations. Skipping optimization for {}", input_path.display());
	return Ok(());
	}
	run_locally(input_path, output_path, cfg).await?;
	Ok(())
	}

dioxus/packages/cli/src/wasm_opt.rs

Lines 69 to 93 in ad8c869

	#[cfg(feature = "optimizations")]
	async fn run_from_lib(
	input_path: &Path,
	output_path: &Path,
	options: &WasmOptConfig,
	) -> Result<()> {
	let mut level = match options.level {
	WasmOptLevel::Z => wasm_opt::OptimizationOptions::new_optimize_for_size_aggressively(),
	WasmOptLevel::S => wasm_opt::OptimizationOptions::new_optimize_for_size(),
	WasmOptLevel::Zero => wasm_opt::OptimizationOptions::new_opt_level_0(),
	WasmOptLevel::One => wasm_opt::OptimizationOptions::new_opt_level_1(),
	WasmOptLevel::Two => wasm_opt::OptimizationOptions::new_opt_level_2(),
	WasmOptLevel::Three => wasm_opt::OptimizationOptions::new_opt_level_3(),
	WasmOptLevel::Four => wasm_opt::OptimizationOptions::new_opt_level_4(),
	};
	level
	.enable_feature(wasm_opt::Feature::ReferenceTypes)
	.add_pass(wasm_opt::Pass::MemoryPacking)
	.debug_info(options.debug)
	.run(input_path, output_path)
	.map_err(|err| crate::Error::Other(anyhow::anyhow!(err)))?;
	Ok(())
	}

[brianmay]

Work around for now seems to be to stick to rust 1.86, and not to upgrade to 1.87.

[jkelleyrtp]

thanks for doing the sleuthing! saved us a bunch of hassle.

issue here: #4186
pr here: #4187

should now let you customize the flags in the event we don't have them enabled by default, as well as enables bulk-memory by default