Reduce code bloat from `FlagContainer`s

KeithBauerANZ commented 1 year ago

📒 Description

A few hundred flags in some nested groups could easily generate a few MB of code for their init/deinit/copy functions. By reducing the stored properties in Flag/FlagGroup to a minimum, we can reduce this bloat to a minimum. By inlining Decorator, the number of heap allocations can remain constant.

🔍 Detailed Design

Entirely API-compatible change (though IMO it could be improved by making some more Flag/FlagGroup properties read-only, and avoiding the need for isKnownUniquelyReferenced)

📓 Documentation Plan

Entirely API-compatible change

🗳 Test Plan

Entirely API-compatible change. Existing tests pass.

🧯 Source Impact

None

✅ Checklist

[x] I've added at least one test that validates that my change is working, if appropriate

(doesn't seem necessary)
[x] I've followed the code style of the rest of the project

(I hope 🤦‍♀️ )
[x] I've read the Contribution Guidelines
[x] I've updated the documentation if necessary

(doesn't seem necessary)