[gentoo-dev] Rationalizing USE flags by narrowing the scope of them.

[Piotr Karbowski]

Hi,

I'd like to get some insight how others see the concept of narrowing the 
scope of USE flags in Gentoo.

Taking a quote from devmanual:

   > USE flags are to control optional dependencies and settings which 
the user may reasonably want to select.

I'd like to focus on the 'reasonably want' here. While it is commonly 
agreed on that we interface as USE flags only things that make sense to 
be togglable, it is not always the case. It is not uncommon to see 
packages that puts every possible option as USE flag which hardly 
benefit anyone in some cases.

It creates artificial choice of USE flag that makes as much sense as 
building and trying to use solar-powered night vision googles. Possible 
to be engineered, but makes absolute no sense to exist, yet, there will 
be someone who will go with it and then things will not work in desired 
way, bugs will be reported, effort will be wasted on investigation and 
patching things up.

As example I'd like to use 'ipv6' USE flag, at the moment of writing 
this email there's 351 ebuilds in tree that expose ipv6 as USE flag, 
allow it to be disabled.

The thing is, it's 2022, and it does not make any sense to *not* support 
IPv6, even if one does not connect to any network with IPv6, there's no 
harm to just have it there.

While I am all for choice, I am for choice on things that do make sense. 
For instance, Linux kernel can be built with CONFIG_MULTIUSER=n, someone 
could argue that since Linux kernel, that is user-configured in Gentoo, 
can be built without support for other than UID 0, then Gentoo should 
support it. One of the extreme examples of not supporting something that 
does not make sense to be supported.

Beside 'ipv6', there are other USE flags that I have on mind. 'pam' 
being another of them.

Whats your view on it?

-- Piotr.