Not gonna argue for or against IDEs; I try to use VSCode but recompiling several (or several hundred) files before I even save a one-line change has been getting on my nerves due to ElixirLS being so aggressive that it manages to slow down a moderately impressive desktop machine (and a quite strong MacBook Pro as well).

I find myself cycling between a very vanilla Emacs setup and VSCode+ElixirLS depending on mood and/or scope of the task ahead.

Outside of that, I would recommend the mix xref task to OP. I always use it before refactoring.

How often do you actually do this?

On a big project lasting for years refactoring is not just normal, it is mandatory to fight technical debt. It was just one example, but such situations happen regularly.

Sounds like an issue with your workflow if you’re regularly renaming functions.

One day you rename something, another - move to other module, the other day you decided to rename the module. The point is - any change that requires understanding of the language is pain with text editor.
Reducing pain and raising productivity during development is the task for tools.

You are more productive with IDE than with text editor. Sorry but I don’t want to prove it in this particular topic.

Yup, the compiler will tell you where they all are.

Yes, generally it helps.
Or not. Even in statically typed language some usual refactorings does not bring syntactic errors.
Or it will, but errors would be terrible to understand.
Compiler must be exceptionally good to aid in such situations and even if it is, errors directly in code are easier and faster to understand and fix.

Lots of languages have become hugely successful before getting a proper IDE. JS, Ruby, Python, PHP, Go.

Ruby, Python, PHP became popular decades ago. Programming is different today and languages market is different too. JS became popular by single reason - it is the only language available in browsers. Not sure about how Goers do their everyday work tho.

I don’t want to offend you, but I have to ask: what is your long-term commercial development experience? Maybe it’s something wrong with me.

I just use VIM not an IDE. I don’t use any of the elixir plugins either except for the colors. I should probably get an autocomplete plugin working eventually but it hasn’t been a priority.

imagine you decided to rename a named function after a couple of years.

How often do you actually do this? Even with regular refactoring actually renaming functions is something I never do in my work after like the first day or two while I’m hashing ideas out. Sounds like an issue with your workflow if you’re regularly renaming functions.

So you will introduce errors just with simple renaming.

Yup, the compiler will tell you where they all are.

This look to be essential for success of a practical language.

I don’t think this is true at all. Lots of languages have become hugely successful before getting a proper IDE. JS, Ruby, Python, PHP, Go.