[trollbridge]

I've found it's terrible at digesting a few codebases I've needed to deal with (to wit, 2007-era C# which used lots of libraries which were popular then, and 1993-era Visual Basic which also used from third party library that no LLM seems to understand the first thing about).

[simonw]

I had great results recently with ~22 year old PHP: https://simonwillison.net/2025/Jul/1/mid-2000s/

It even guessed the vintage correctly!

> This appears to be a custom template system from the mid-2000s era, designed to separate presentation logic from PHP code while maintaining database connectivity for dynamic content generation.

[dotancohen]

That's great. Just yesterday I spoke with a developer who refutes Rector on old codebases, instead having an LLM simply refactor his PHP 5.6 to 8.(3 I think). He doesn't even check in Rector anymore. These are all bespoke business scripts that his team have been nursing for two decades. He even updated the Codeigniter framework it's all running on.

[nl]

I suspect the problem with VB is that VB 4 and 5 (which I think was that era) were so closely tied to the IDE it is difficult to work out what is going on without it.

(I did Delphi back when VB6 was the other option so remember this problem well)