Is your idea related to a problem? Please describe.
From a certain point of view everything is a problem. So no and yes ;P
Describe the solution you'd like
With a pig iron tool killing a pig should repair the tool by 1 (or more)
Describe alternatives you've considered
Not killing a pig to repair it? Killing a cow to repair it? Repairing it normally?
Additional context
Add any other context or screenshots about the feature request here.

mDiyo said so
Versions:

• Minecraft:1.16.5
• Forge: 36.1.16
• Mantle: 1.6.9.2
• Tinkers Construct: 3.0.3.144

Confirm below that this enhancement is not covered on the roadmap or "Whats New?"
As of 10:08am EST it is not on either.

This feature exists indirectly. Pig iron killing pigs gives a chance to drop bacon, and that bacon can be used to repair pig iron tools. In my opinion, that is sufficient for this idea.