Access Field.attname and Field.column directly

[Adam Johnson]

Many field references call Field.get_attname_column() or Field.get_attname(), despite the attname and column attributes containing the computed results (after contribute_to_class()). Updating those call sites to plain attribute access eliminates some function calls, a worthy small speedup.

From a profile of system checks on a smaller project, there were ~2k calls between the versions of each method:

• 630 for Field.get_attname_column()
• 208 for ForeignKey.get_attname_column()
• 666 for Field.get_attname()
• 431 for ForeignKey.get_attname()

All of these are eliminated by moving to attribute access.

[Mariusz Felisiak]

I'm pretty sure this will break some 3rd party packages, e.g.​django-joinfield. I don't think it's worth doing.

[Adam Johnson]

I think it has very little chance to break things. There are hundreds of pre-existing uses of .attname and .column, the PR only updates a handful. Also, non-deterministic attname would be somewhat meaningless, as nothing would reattach the field’s descriptor with a different attribute name.

[Mariusz Felisiak]

I'm always preoccupied with such cleanups as more often than not they cause regressions, but agreed, let's give it a chance.

[Mariusz Felisiak <felisiak.mariusz@…>]

In 31314980:

Fixed #35236 -- Used Field.attname/column attributes instead of get_attname()/get_attname_column().