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rjbwork

"Imagine"... I've been doing it in Visual Studio for years.

Step 1. Find problematic code

Step 2. Step back to before problematic statement

Step 3. Change problematic data value and/or code to hypothesized good one (while debugger is active and paused)

Step 4. Continue execution and observe if output is as desired

Step 5. Write test case.

Easy peasy. I'm glad to see the Rust community doing something similar, as the benefits of ease of development are not to be discounted, and Rust seems like a pretty nifty language.

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That seems to describe memory editing plus "edit and continue", which is distinct from record&replay and reverse execution.

Also, rr has nothing to do with Rust in particular, although this article shows how to use it with Rust.

> "That seems to describe memory editing plus "edit and continue", which is distinct from record&replay and reverse execution."

Sounds more like IntelliTrace to me (if you're not familiar with it, it's worth mentioning it's only available in Visual Studio Ultimate).

https://msdn.microsoft.com/en-us/library/dd572114.aspx

Step 2 was explicitly stepping backwards i thought. The rest was just a continuation of what the ability gives you and what I often do after stepping backwards to observe the execution.

rr works for C++/C code too?

Yes.

To expand on the monosyllabic sibling answer, rr is completely language agnostic because it works at the level of machine code, (ab)using platform features like performance counters to do its thing. It should basically work for every x86 and x86-64 program you can debug with gdb, no matter which language(s) it was compiled with.

This sounds exciting so I thought I'd look it up: http://stackoverflow.com/questions/26431737/can-i-get-revers...

"Visual Studio (2010, 2012, 2013 Ultimate only .. does not support C++"

You can still move the program counter and modify arbitrary data in memory. It's not the same but I wanted to mention that as it comes in handy for me frequently.

And you can do all that stuff in gdb too. rr is really quite innovative.

Yeah, for sure; as I say in "Removing the rose-coloured glasses", rr is definitely not the first tool to do this, it's just the first one I've been lucky enough to use. I've not done much development on Windows, so haven't had an opportunity to use/enjoy Visual Studio.

Also, I'm sure there's a large chunk of people like me, who don't use debuggers much and have no idea what a good one is capable of.

Too bad this sometimes moves your focus from the problem you are solving and makes you an output matching machine.

HAH! True, but it's just one tool in a vast array of problem solving tools.

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