Note that "asSeenFrom" (aka asf) is used by SymDenotation#findMember,
which is used by TypeComparer's "hasMatchingMember", as a part of
"compareRefinedSlow".
Previously (using the minimisation in i17222.8.scala) summonOne is
inlined during the "inlining" phase, while "summonInline" is inlined
during typing. The result is that during inlining we fail to find
Reader[BC, Int] because we incorrectly consider A{type F = Int} as
stable.
Note that "asSeenFrom" (aka asf) is used by SymDenotation#findMember, which is used by TypeComparer's "hasMatchingMember", as a part of "compareRefinedSlow".
Previously (using the minimisation in i17222.8.scala)
summonOneis inlined during the "inlining" phase, while "summonInline" is inlined during typing. The result is that during inlining we fail to findReader[BC, Int]because we incorrectly considerA{type F = Int}as stable.Fixes #17222