Error on S-interpolator usage for assert, assume and printf

[adkian-sifive]

This is to be backported to 3.5.x as a warning instead of an error

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 state the API impact?
• Did you specify the code generation impact?
• Did you request a desired merge strategy?
• Did you add text to be included in the Release Notes for this change?

Type of Improvement

• updated feature/API

API Impact

Current assert, assume and printf APIs allow the Scala s-interpolator for formatting messages. This often leads to user errors where the Scala object is printed instead of the Chisel object, which leads to the messages being generally unhelpful.

After this update, using s-interpolators will throw an error about deprecation.

Backend Code Generation Impact

N/A

Desired Merge Strategy

• Squash: The PR will be squashed and merged (choose this if you have no preference.

Release Notes

Using Scala s-interpolators now throws an error recommending a shift to the cf interpolator.

Reviewer Checklist (only modified by reviewer)

• Did you add the appropriate labels?
• Did you mark the proper milestone (Bug fix: 3.4.x, [small] API extension: 3.5.x, API modification or big change: 3.6.0)?
• 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.

[mwachs5]

I think this requires some fixes to the printable docs? Or can we say something there to show people the warning/error they will get if they try to printf(s"...")?

[jackkoenig]

This is not marked with Milestone 3.5.x because we do not want it to be backported and automerged, instead after merging we will do a manual backport and change the behavior to be just a warning.

[mwachs5]

Nice :)