How do you debug rust code on the web?

[rookboom]

Firstly, thanks for this package! What is the best practice to debug rust code?
It doesn't look like breakpoints work nor println! statements.

Is there a trick to log debug info in rust to be output somewhere?
I've tried returning a UTF8 string in the Rust response, but it the bytes field seems to be always empty on the Dart side if the response is not successful.

rustc 1.72.0 (5680fa18f 2023-08-23)
libprotoc 24.3
[✓] Xcode - develop for iOS and macOS (Xcode 14.3.1)
[✓] Chrome - develop for the web
[!] Android Studio (not installed)
[✓] VS Code (version 1.81.1)
[✓] Connected device (3 available)
[✓] Network resources

! Doctor found issues in 2 categories.

[temeddix]

Hello @rookboom

Breakpoints won't work because Flutter is building and running Rust, not the IDE.

Are you running the app in the web browser? If so, println!() won't work at all, because web browsers need JavaScript's console.log() . The recommended way to print messages in this framework is using crate::print!() macro, located in ./native/hub/src/web_alias.rs. You can see the usage examples at ./native/hub/src/sample_functions.rs.

Please let me know if anything is not clear yet :)

[rookboom]

I'm actually targeting iOS and test with the iPhone simulator.
On web I run into the CORS header problem which prevents my app from starting at all:

Error: Buffers cannot be shared due to missing cross-origin headers.
Make sure your web server responds with the following headers:
- cross-origin-opener-policy: same-origin
- cross-origin-embedder-policy: credentialless OR require-corp

I tried disabeling web security like this:
flutter run -d chrome --web-browser-flag "--disable-web-security"

Still getting the same error though.

[temeddix]

@rookboom

That's strange, I've been testing things on the web and everything seems to work fine.

Have you built the webassembly module with the command below, as written here? This not only builds webassembly but also adds cross-origin related headers to the Flutter web server.

rifs wasm

[rookboom]

Ah, I skipped this step before since I was not thinking about running it in a browser. It is working now.