Anything that needs an "obstacle course" or a "downhill slalom" to modify? Examples:

- Compilers/IDEs that only exist on single machines (expensive mainframes, single user VMs, SSH hosts)

- Compilers/IDES that must be air-gapped for any security reason (including CVEs and expired support, not just PII/PCI/confidential-quarantine reasons)

Things start to feel impossible when you have to use a Windows XP VM because it was the last OS Microsoft officially supported the VB6 IDE, who knows how to install and license the ActiveX controls anymore for development (some of the vendors don't even exist anymore to ask), the VM is intentionally air-gapped/quarantined from internet traffic because it is an XP VM so there's now some fun extra steps with virtual folder redirects and worktree-less clones as remotes to get git changes in/out. (If your VM stopped supporting basic copy/paste from the host machine you feel you might go mad. Trying to grep VB6 code in VSCode to make navigation feel somewhat more sane due to scroll delays in the VM feels like its own growing madness as VSCode believes you to be insane using such an arcane language that looks but does not smell like VB.NET.)

Uh, not that that resembles my current situation or anything.

There are similar horror stories from say COBOL devs with airgapped mainframes.

What do you mean?

Technically speaking, you can build software on an outdated and unsupported framework, sure. But why on earth would you, for example, continue building your software on PHP 5.6 (EOL Jan 2019) when anytime a CVE is identified, you're basically SOL in being able to patch it.

Sure, you shouldn't just stick with the old and add features. You should focus an incremental rewrite to bring you closer to a switch to something supported early (e.g. dumping dependencies that won't migrate with you, preparing the code base for a quick conversion of incompatible language features, ...). Only few technologies are such dead-ends that isn't possible.

But once it's too late no migration strategy rids you of the old codebase and it's environment now. With the full rewrite you need to maintain and run it until that's done. With the strangler the old code still runs until it is replaced.

I'm so confused. What are you suggesting that's any different from what I said?

Apologies, then I must have misunderstood your original comment.

All good!