Tracking issue for 0.2.0

[josephlr]

In the process of addressing #94, we realized that some of the changes we want to do would require breaking backwards compatibility. If we are going to release a version 0.2, we should consider other changes to getrandom.

A potential list is below. @dhardy and @newpavlov feel free to edit this to include your own ideas.

• Only expose the std traits if the std feature is enabled (see trait impl disappeared without bumping major version #94 and Add back in std-only trait definitions #96)
  • This is needed for Use getrandom crate rust-lang/rust#62082
• Think about having default features
  • What should these be?
• Rename features to allow for grouping of dependencies
  • wasm-bindgen -> bindgen, would make it much easier to use js_sys or web_sys.
  • Moot, now that Add support for Custom RNGs #109 removed those features.
• The default behavior for wasm32-unknown-unknown (with no explicit features). Options are:
  • Always fail (current implementation)
  • Compile error (current 0.2 behavior, see Feature for using CPU-based RNG #84)
  • Default to bindgen
• Cleanup wasm32 error codes
  • Implemented in wasm32: Unify error codes and implementations #146
• Custom Randomness (embedded source compatibility #4)
  • Can we make a solution that does not require unsafe code for users?
• Feature for CPU randomness (Feature for using CPU-based RNG #84)
  • If we add this, then it might make sense to remove explicit support for hermit, l4re, and uefi and just use this feature instead, as these platforms (especially UEFI) have multiple ways to get randomness.
• Minimum Rust Version
  • Minor Cleanups for 0.2 #136 increases the MSRV to 1.33
  • Do we want to increase this further? Bumping to 1.34 would let us use TryInto, which could be useful.
  • Update MSRV to 1.34 #159 Bumped to 1.34
• Documentation
  • Implementation at Update docs for 0.2 Release  #135

If you have suggestions, please comment!

[newpavlov]

Unfortunately we probably still can't use compilation error by default for wasm32-unknown-unknown, since it would require bumping rand/rand_core versions (i.e. breaking change leaks downstream in this case).

I like the idea of replacing support for hermit, l4re, and uefi with rdrand flag, but I am bit unsure about implications for rand, since again strictly speaking it can be considered a breaking change. :/

wasm-bindgen -> bindgen, would make it much easier to use js_sys or web_sys.

I am still not sure why would we want to use web_sys instead of wasm-bindgen directly.

[josephlr]

Unfortunately we probably still can't use compilation error by default for wasm32-unknown-unknown, since it would require bumping rand/rand_core versions (i.e. breaking change leaks downstream in this case).

Hmm, that would be true. We could consider dividing the issues into "things that would require rand 0.8" and "things we could make work with rand 0.7".

I like the idea of replacing support for hermit, l4re, and uefi with rdrand flag, but I am bit unsure about implications for rand, since again strictly speaking it can be considered a breaking change. :/

I mean we could always cop out and say those platforms weren't officially supported by rand yet and so it's not a breaking change (as all of these are new-ish targets, it might be fine).

wasm-bindgen -> bindgen, would make it much easier to use js_sys or web_sys.

I am still not sure why would we want to use web_sys instead of wasm-bindgen directly.

A fair point, I guess what I meant here is that if we want to do something like this, we should rename the feature. I'll try to see if the code would be any better using js_sys. I think this would be easier to talk about with actual code.

[dhardy]

(i.e. breaking change leaks downstream in this case)

We could use a feature-flag to re-enable (perhaps dummy-wasm32-unknown). But I don't recall any reason we shouldn't keep this behaviour as the default for wasm32-unknown-unknown; as @newpavlov has said a couple of times it's a not-quite-standardised target that can hopefully be dropped at some point.

Custom Randomness (#4)

IMO this is not an urgent issue (at least, I've seen very little demand for it). There is already a safe alternative: a Cargo patch to replace the crate.

Feature for CPU randomness (#84)

There are multiple aspects to this:

• Does it do anything on targets with good alternative sources?
• If so, does it replace that source or does it get used as a fallback (where failure is possible)?
• Do we, as suggested, drop support for targets like UEFI and SGX where CPU randomness is our only option anyway?

[josephlr]

I've created a 0.2 branch to track breaking changes to getrandom. PRs that make breaking changes should be submitted/merged against that branch.

[newpavlov]

Maybe we also should remove the log feature? IIRC it was mostly useful for WASM backends and I haven't seen anyone to enable this feature directly and it's not cascaded from the rand crates.

[CryZe]

Both cargo and the wasm target are still way too broken to remove the dummy implementation for rand / getrandom's wasm32-unknown-unknown support.

[josephlr]

Both cargo and the wasm target are still way too broken to remove the dummy implementation for rand / getrandom's wasm32-unknown-unknown support.

@CryZe what do you mean? Our plan (see #109) is to give users of rand/getrandom a way to set a custom RNG source (similar to how Custom Allocators work) on unsupported targets (which would include wasm32-unknown-unknown). Is there a reason that wouldn't work for your use-case?

Having the dummy impl makes debugging issues very hard, as the dummy impl fails at runtime as opposed to compile time.

[CryZe]

Ah, I think that would work then.

[josephlr]

@newpavlov I think dropping the log feature is also a good idea. We should focus on getting any relevant error info into the Error structure itself.