Make it possible to not import specific generators

[dbdr]

Background

I'm using rand for numerical simulations where cryptographic security is not required, while runtime speed and binary size are important. SmallRng is appropriate for my use. My issue is that chacha and hc are still downloaded and compiled even though I don't use them, wasting time and space. It would be useful if it was possible to use SmallRng with rand without pulling the other generators.

Feature request

Make chacha and hc optional features (they can be enabled by default if that's deemed desirable for most users).

[dhardy]

This is a duplicate of #938 and already fixed by #948, so it should already happen with rand 0.8 (with --no-default-features).

[dbdr]

Oh, wonderful, thanks @dhardy. I searched for an existing issue, but not in closed issues, as is the default search. That's one argument for keeping issues open until the fix is released. Is there a stronger reason to close them?

I'll try 0.8 from git and report if I find any issue.

[vks]

I think most projects close issues that are fixed on master. This is consistent with GitHub automatically closing issues when "Fixes #..." is mentioned in the pull request. It seems prudent to search closed issues when a version older than the current master is used.

[dbdr]

Isn't a released version always older than master, unless nothing has been committed since release? :)
Anyways, that make sense, thanks for the explanation. Closing.

[dhardy]

Some projects use separate development and master branches. We don't, and it seems neither do most Rust projects, so master is where it happens.