Guidance on what counts as a non-user visable change

[oxinabox]

I think it might be useful to define what a non-user visible change is.
Possibly with reference to making releases.
In a sense perhaps a non-user visible change is a 3rd category, like bug-fix or feature.

When I say non-user-visible change I mean one of:

• Refactoring to change internal structure (but not the public API)
• Updating a comment
• renaming a variable
• Fixing a mistake in the tests

Some things sound similar like:

• Performance improvements
• updating documentation.

But are not.

Was reminded of this in
JuliaDiff/ChainRules.jl#296 (comment)

[ChrisRackauckas]

Yes, good point. I'd also add a big one: changes to arguments in non-public APIs. It's really the definition of non-public: you can break it at will, and it's not a breaking change.

[oxinabox]

Yep, basically a special case of refactoring that is worth calling out to be clear.