How to see Rust source code when debugging WebAssembly in a browser?

Question

I am testing a simple todo app in Rust using the YEW framework. When I get an error, the browser console (Devmode) shows JavaScript or assembler (I tried both Chrome and Firefox). How can I get the Rust code? Do I have to setup source maps somewhere?

Firefox Nightly's Javascript debugger now supports debugging and source maps for Rust compiled to WASM from last year Mozilla All Hands Austin, but I couldn't find any information about it. — dilvan
– dilvan, Commented Jun 6, 2018 at 13:59
OMG @FirefoxNightly's JavaScript Debugger supports debugging & source maps for @rustlang in #WebAssemby-compiled web code!‏ @slsoftworks 14 Dec 2017 afaict you just just emscripten (not the direct rustc wasm backend) and it just works. /cc @yurydelendik @jasonlaster11 @kripken` — dilvan
– dilvan, Commented Jun 6, 2018 at 15:42
The example in the OP's cross-posted question shows that it is already possible: the webpage here, source repo here. — ShreevatsaR
– ShreevatsaR, Commented Apr 29, 2022 at 16:27

ColinE · Accepted Answer · 2018-06-06 17:20:43Z

8

To achieve this you’d need WebAssembly to support sourcemaps. This is something that is being considered for future tooling, but I don’t think much progress has been made yet.

There is also an open issue for Rust sourcemap support

edited Jun 6, 2018 at 17:20

answered Jun 6, 2018 at 16:58

ColinE

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2 Comments

Shepmaster Over a year ago

In OPs cross-posted question, they claim that it's already possible.

joe Over a year ago

Seems that the issue you linked has been closed. Relevant/related links: github.com/WebAssembly/debugging | medium.com/oasislabs/webassembly-debugging-bec0aa93f8c6 | github.com/rustwasm/team/issues/26

Timmmm · Accepted Answer · 2022-03-11 14:46:33Z

3

This is possible now for C++. See this post. You need to install this extension and pass -g to generate debug info when compiling the C++.

Unfortunately it doesn't work in Rust yet (at least if you're using wasm-bindgen which you probably are) because wasm-bindgen discards all the DWARF info. See this post and this linked issue.

answered Mar 11, 2022 at 14:46

Timmmm

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