Add make_indirect and make_polymorphic extensions

[jbcoe]

@Quuxplusone @Ukilele this may be of interest to you both.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.60%. Comparing base (f5cb1b3) to head (1968bc1).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #546   +/-   ##
=======================================
  Coverage   99.59%   99.60%           
=======================================
  Files          11       11           
  Lines         748      760   +12     
  Branches       76       76           
=======================================
+ Hits          745      757   +12     
  Misses          3        3           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[Quuxplusone]

Awesome. Are you proposing these for the Standard? did LEWG/LWG ask for them?

[Twon]

Nice, I'm in favour of the added consistency these bring.

[jbcoe]

These have not been asked for. They'd need adding as a NB comment, a library defect or as part of C++29.

I'd want collaborators on the standardisation effort.

[Quuxplusone]

These have not been asked for. They'd need adding as a NB comment, a library defect or as part of C++29.

I'd want collaborators on the standardisation effort.

I'm certainly happy to help craft wording and/or coauthor (or not). I'd like to see these get in, too. Procedurally, as a design issue, this would not be a defect/LWG-issue; but as a kind of "bugfix" to new-in-C++26 material (from the original authors no less), the paper should have no trouble getting seen in LEWG in a timely fashion.

[Ukilele]

LGTM :)

[jbcoe]

@Quuxplusone @Ukilele this PR is looking for an owner who's willing or able (ideally both) to write a paper/issue for C++26.