Visualize and debug Rust programs with a new lens
41 comments
·May 25, 2025orsenthil
This is very good. Excellent user-interface too. Reminded me of Pythontutor that I use.
waschl
That looks very impressive! Would give it a spin but as far as I can tell I can’t use it with my Rust os kernel running inside qemu
tonyhart7
would love to do this with database instead, inspect query and so on
anyone know the tool name??? I know it exist but forget it while ago
hencoappel
Something like the SQL Server Management Studio execution plan view?
https://learn.microsoft.com/en-us/sql/relational-databases/p...
artogahr
Dequery might be what you're looking for: https://dequery.io
forrestthewoods
Please show me this being used to debug a real program. Toy examples that don’t do any real work isn’t interesting. My confidence that this work for an actual program is approximately zero percent.
spencerflem
Cool, reminds me somewhat of Glamorous Toolkit [1], another project I just found out about. Excited to give it a try, I love these sort of "explain a program as it's running" type tools.
quotemstr
From a debugger's point of view, Rust is just another native code language. DWARF tells you how to get stacks, find variables, and interpret chunks of memory as data structures. Anyone trying to pitch you a debugger specifically for Rust is trying to ride a hype wave or just plain bamboozle you.
vvern
While that’s sort of true, there’s a lot of language specific things that go into making the UX of a debugger pleasant (think container abstractions, coroutines, vtables and interfaces). Specifically async rust and Tokio gets pretty interesting for a debugger to deal with.
Also, there’s usually some language (and compiler) specific garbage that makes the dwarf hard to use and requires special treatment.
RealityVoid
Sure, I agree, but in my experience, probe-rs for example has much better ability to step and identifies the variables much better than GDB did. Not sure if it's how it handles the name mangling or what, but GDB couldn't interpret a lot of context.
khuey
It appears to rely on source instrumentation so it really is language specific.
yencabulator
Where do you see source instrumentation? I see Rust-specific details so for sure it's language-specific, but I didn't see any mention of altering the source code.
khuey
I didn't look at it very closely but it seems like you need to add fire::dbg! macros to your code if you want anything beyond function parameters/return values.
quotemstr
Oh. When I read the section on instrumenting function returns, I thought they were going for something more general, since they talk about analyzing assembly. Now I see they're looking at individual Box and Rc instances and have special cases for stdlib data structures. Async support is also a to-do item.
I can't see this approach working for very long. Tracing at the binary level, whether you do it as RR does with performance counting or whether you do it via instrumentation like Undo and iDNA, works for the general case because it records execution at the lowest level available to a process and therefore captures everything, without special cases.
If these guys want to make a fancy time travel debugger data explorer, that's great. They could in principle make one on top of existing tracing technology without having to simultaneously reinvent both the debugger core and the GUI.
khuey
From https://firedbg.sea-ql.org/blog/2023-12-11-architecture-of-f... it seems more like lldb automation than what "time travel debugger" brings to mind.
mdaniel
relevant: DWARF as a Shared Reverse Engineering Format - https://news.ycombinator.com/item?id=44113026 - May, 2025 (17 comments)
lpapez
This is true in the same way that Dropbox is just a wrapper around rsync.
Rust-Trends
Nice project! I’ll be highlighting it in the next edition of the https://Rust-Trends.com newsletter.
Veserv
This is just a trace viewer. Except the trace visualization is vastly less dense than any standard trace viewer and seems to provide no meaningful execution time information.
Compare to chrome://tracing
https://www.chromium.org/developers/how-tos/trace-event-prof...
I am not sure if trace visualizers were invented 20 years ago for the original time travel debuggers, but they have certainly been used for time travel debugging visualization since at least 20 years ago.
sureglymop
It's definitely a little more than just a trace viewer.
As the page reads, it is a time traveling debugger. You can jump back and forth between different snapshots of time during the execution of your program. It's neat because for compiled languages like rust doing something like this is more advanced.
Veserv
That is exactly how trace viewers have been used with time travel debuggers for literally, and I do mean literally, over 20 years.
You click a point in the trace, you jump to that point in time. That has been the standard integration for decades.
sureglymop
I was under the impression that with a trace viewer you would do that after the execution of the program has finished. Learned something!
null
quotemstr
It's both. It is a trace viewer, but they instrument native code to emit logs of its operation, e.g. calls and returns, similar to what the recent non-performance-counter rr branch does. Except for some reason it's coupled to a specific GUI and a specific language instead of being a general purpose tool like RR is.
The tech industry is getting stupider and hype-ier as it implodes.
null
levkk
I want to use this right now, but two issues:
- Bash script from Internet requiring sudo, no way
- VSCode plugin? I don't use VSCode. I'm not switching from Zed (literally built in Rust for Rust development)
Help me out, what can I do to try this?
leoh
They're just trying to offer an easy way to try things out and unsafe code from Firefox would be insanely harmful for their brand. Of course, if you take a moment to merely download the bash script and inspect it. It's truly not dissimilar from downloading a repository from GitHub and building it. In general, certainly, yes, you don't want to run arbitrary programs.
mdaniel
Depending on where your "Internet" boundary starts, you can clone the repo and run its install.sh although I think it's for really lazy people since it just downloads the GitHub release artifact anyway https://github.com/SeaQL/FireDBG.for.Rust/blob/1.81.0/instal...
I don't see that VSCode is required, they have a section dedicated to CLI usage https://github.com/SeaQL/FireDBG.for.Rust#firedbg-command-li... and even the "firedbg open" seems to just be a convenience method for file globbing https://github.com/SeaQL/FireDBG.for.Rust/blob/1.81.0/comman...
I'm a little with you that it is sus that they don't seem to have any .ts nor package.json file in that repo which would allow one to (a) see what the extension does (b) build the .vsix themselves
null
mickey475778
[dead]
sahil_sharma0
[dead]
“Simple things should be simple. Complex things should be possible.” - Alan Kay
Rust really embodies this imo. I think it will be a few more years, but we're going to be seeing a lot more Rust -- and for good reason.