No More Printf: Interactive Debugging Wasm for web and server

Ralph Squillace - Microsoft / Natalia Venditto - Microsoft / Till Schneidereit - Fermyon

Last year, WebAssembly debugging, particularly for components, was bad but “could be made to work”. This year, it actually works! But better doesn’t mean it’s still not a pain. But you can do it! This update will show you how.

Debugging WebAssembly systematically front end to back end remains a total pain. Most usage in the browser focuses on features enabled in F12, which assumes a JavaScript engine is hosting the assembly and, often but not always, the Chrome Debugging Protocol. And that’s the front end; outside the browser, there’s no standard debugger API (yet), protocols between languages vary widely, and not all languages treat debug symbols the same way.

But there’s hope! We’ll tour using debugging from front end to back end using open source debuggers and using core modules and WebAssembly components in the same solution to give you interactive step-through debugging – the thing you want. We’ll wrap up with the debugging UX issues yet to be solved and more importantly where you can dive in and contribute.