bug#51577: [External] : Re: bug#51577: 27.2; Regression: reproducible hang with face functions

[Drew Adams]

> evalling a circular face definition should signal an error.

No.  The inheritance that causes the infloop
should just not be done (ignored.)  That sane
behavior is exactly what was broken, in the
case cited.

Whether you want to try to ambitiously deal
with nested inheritance etc. causing loops
is something else.  That's not what this bug
(regression) report is about.

Inheritance of a face by itself should be
ignored, silently.  Emacs should at least be
smart enough to do that.  (It used to be.)