split generates wrong wasm files

[johansmitsnl]

When you run cargo leptos build --split is generates html where it requests pkg/web-app_bg.wasm. But if you look in the pkg dir there is no such file with the extention _bg.wasm. Only pkg/web-app.wasm.

Is this just a naming error of the file of is the _bg a different file that was not generated?

Now the UI is not functional due to the load failure.

[johansmitsnl]

It looks like the rename is not working?

Edit, I also found this in leptos hydration pushing the name with the _bg in it if the env LEPTOS_OUTPUT_NAME was not set.

[gbj]

These issues (this and leptos-rs/leptos#4347) give me the impression that there is something happening in your setup that I cannot reproduce and that other users have not encountered.

I'm also a little unclear on what you mean: cargo leptos build --split doesn't generate HTML at all, so I'm not sure how it would generate HTML that requests the wrong WASM file.

Could you provide some steps to reproduce the problem? Because it does not occur in the general case.

[johansmitsnl]

I'm trying to debug what was happening (still in progress but a state update), this is what I found until now:

1. cargo leptos build --split builds the wasm file pkg/web-app_bg.wasm but does a rename to pkg/web-app.wasm for backwards compatibility. I don't know (lack of knowledge) what this backwards compatibility is. To me it should be if the LEPTOS_OUTPUT_NAME env variable was not set. See point 5.
2. The binary is shipped to another location (away from finding the Cargo.toml)
3. The leptos_config is initialized from leptos::config::get_config_from_env()
4. Running the app in a different location requires a LEPTOS_OUTPUT_NAME=web-app env variable to be set.
5. Setting the variable should NOT extend the filename with _bg according to this code

I did set the LEPTOS_OUTPUT_NAME but the HydrationScripts was generating the file with _bg.

I'm using Rust 1.91.0-beta.4 for the other reason (leptos-rs/leptos#4347) that split didn't work.

I have a dev set-up of Leptos + my deployment in a state where I can now simply start debugging the code. But can you explain what the backwards compatibility here means and should this still be present and the whole _bg manipulation can be removed? Because I could not find in the code how cargo-leptos can leave the file un-renamed. Or don't rename it at all and keep the _bg convention on both projects.

[johansmitsnl]

@gbj a new update hopefully gives it more insight where it might be wrong.

I have made it reproducible with the example repo I made leptos-ssr-lazy (this is now updated)

1. rustup override set beta
2. Build the module: cargo leptos build --split without cross and build.
   When running the app is does not contain the _bg.wasm reference.
   <link rel="preload" href="/pkg/leptos-ssr-lazy.wasm" as="fetch" type="application/wasm" crossorigin="MJes6yjL5EkRnfIaztw3jQ">
3. Build the module: cargo leptos build --split with cross and build.
   When running the app is does contain the _bg.wasm reference.
   <link rel="preload" href="/pkg/leptos-ssr-lazy_bg.wasm" as="fetch" type="application/wasm" crossorigin="iViOaXIyluJBzyOdfeOM3Q">

Since my dev machine is a x86_64 machine and the target is a arm64 machine I need to use cross. That is the reason why I get this. To check if the architecture was the issue I did a test only on x86_64 with and without cross.

To reproduce the issue it does not matter if you use cargo leptos watch --split. You must run it outside the project directory. I run it like this:

1. cd /tmp
2. env RUST_LOG=info LEPTOS_OUTPUT_NAME=leptos-ssr-lazy $CARGO_HOME/target/x86_64-unknown-linux-gnu/debug/leptos-ssr-lazy.

running it outside the project dir it is missing the site assets. The UI is not working due to missing files. I check using the curl command like this: curl http://127.0.0.1:3000 |grep wasm.

In both runs you see it print that is was compiled the same way: rustc 1.91.0-beta.4 [beta] on x86_64-unknown-linux-gnu (aa7859c0dec2de6c9cab34b03028bcef7b1fc25d).

So the question now is why cross builds are different then native builds?

[johansmitsnl]

@gbj I found the problem and solution!

When you are building with cross not all variables are passed through to the build environment for sane default reason.

The solution is to add the Cargo.toml with content:

[build.env]
passthrough = [
    "LEPTOS_OUTPUT_NAME",
    "LEPTOS_SITE_ROOT",
    "LEPTOS_SITE_PKG_DIR",
    "LEPTOS_SITE_ADDR",
    "LEPTOS_RELOAD_PORT",
    "LEPTOS_LIB_DIR",
    "LEPTOS_BIN_DIR",
    "LEPTOS_JS_MINIFY",
    "LEPTOS_HASH_FILES",
    "RUSTFLAGS",
]

Once these variables are allowed the build goes fine. I think that more information on the documentation part is needed that when you change the bin-cargo-command the sub process needs to accept/allow/passthrough these variables. Because there are some compile time env variables that are baked into the final bin that matter if they are absent.

I don't know the code sufficient to check where this happens and if this is really necessary.

So the problem is not cargo-leptos related with the _bg issue, but it would need a documentation update on the env variables that are set during the bin build. Please verify my findings and I can provide a PR with a documentation update on this part.

[gbj]

Go ahead and make a PR — I have zero experience with cross (literally zero, I have never used it and didn't add the feature to be able to call it from cargo-leptos) but if that's the config that's missing and it fixes your use case, then I am sure it will fix it for others as well.

[johansmitsnl]

Created a PR #576

[johansmitsnl]

I'm able to reproduce the error. Not sure it is because I'm doing something stupid.
This is with the new PR on wasm split (leptos-rs/leptos#4369 and #578) but I have not reverted it with just your code but the error is the same.

Make sure you are on this commit: johansmitsnl/leptos-ssr-lazy@642ff16

You have to hit click me for it to happen.

The code what broke it is and that is the usage of (use_event_listener):

    view! {
      <h1>"Welcome to Leptos!"</h1>
      <button on:click={on_click}>"Click Me: " {count}</button>
      {move || {
        (count.get() == 1)
          .then(|| {
            let cleanup = use_event_listener(
              document().body(),
              leptos::ev::keydown,
              move |evt: KeyboardEvent| {
                debug_warn!("Modal keypress of {} ", &evt.key());
                if Some(evt.key()) == Some(String::from("a")) {
                  debug_warn!("Modal key pressed, performing action closing modal");
                }
              },
            );
            on_cleanup(cleanup);
          })
      }}
    }

In my code I'm using it similar in my modals that are open and depending on the modal bind to certain key events. Those are rendered in the view and then the use_event_listener is created/attached.