Tracking issue for formatting with a radix

[alexcrichton]

This is a tracking issue for the unstable fmt_radix feature in the standard library. These functions provide the ability to format a number in an arbitrary radix. Note that base 2, 8, and 10, and 16 are already supported via various formatting flags.

Needs a decision about whether this functionality should even be in the standard library, and it will perhaps want a different interface as well.

[steveklabnik]

#18301 was an open issue related to an older version of this code.

[alexcrichton]

Nominating for removal

[alexcrichton]

🔔 This issue is now entering its final comment period for deprecation 🔔

[alexcrichton]

The libs team discussed this in triage recently and the decision was to deprecate