Remove autoSeedVar, use Boolean to distinguish suggested or autoSeed

[jackkoenig]

Contributor Checklist

• Did you add Scaladoc to every public function/method?
• Did you add at least one test demonstrating the PR?
• Did you delete any extraneous printlns/debugging code?
• Did you specify the type of improvement?
• Did you add appropriate documentation in docs/src?
• Did you request a desired merge strategy?
• Did you add text to be included in the Release Notes for this change?

Type of Improvement

• Performance improvement

Desired Merge Strategy

• Squash

Release Notes

• Combined with Micro-optimize Direction #4251, reduces the memory use of a typical bound UInt from 64 bytes shallow, 120 bytes retained, to 56 bytes shallow, 112 bytes retained.

Reviewer Checklist (only modified by reviewer)

• Did you add the appropriate labels? (Select the most appropriate one based on the "Type of Improvement")
• Did you mark the proper milestone (Bug fix: 3.6.x, 5.x, or 6.x depending on impact, API modification or big change: 7.0)?
• Did you review?
• Did you check whether all relevant Contributor checkboxes have been checked?
• Did you do one of the following when ready to merge:
  • Squash: You/ the contributor Enable auto-merge (squash), clean up the commit message, and label with Please Merge.
  • Merge: Ensure that contributor has cleaned up their commit history, then merge with Create a merge commit.

[debs-sifive]

lgtm! Would it be worthwhile to add a warning if someone calls autoSeed when suggestSeed is already set? Or would that be too noisy/not actually helpful?

[jackkoenig]

Would it be worthwhile to add a warning if someone calls autoSeed when suggestSeed is already set? Or would that be too noisy/not actually helpful?

I think some work in that direction would be good. People have requested in the past that suggestSeed that has no effect should be a warning or error. We could do something similar for autoSeed or whatever replaces it (IMO we should move towards a more immutable style API rather than the mutation of suggestSeed and autoSeed, but that's a separate discussion as well).