Auto merge of #41913 - nikomatsakis:issue-41849-variance-cycle, r=eddyb

do not fetch variance for items when equating

Fixes #41849. Problem was that evaluating the constant expression
required evaluating a trait, which would equate types, which would
request variance information, which it would then discard. However,
computing the variance information would require determining the type of
a field, which would evaluate the constant expression.

(This problem will potentially arise *later* as we move to more sophisticated
constants, however, where we need to check subtyping. We can tackle that
when we come to it.)

r? @eddyb

0 files changed, 0 insertions, 0 deletions