ProtoTypes#wildApprox: fix LazyRef approximation #1107
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Before this commit, the output of `wildApprox(A)` where `A <: Sys[LazyRef(A)]` was `? <: Sys[LazyRef(() => wildApprox(A))]`. This lead to infinite subtyping checks. This is fixed by always approximating a LazyRef by an unbounded wildcard. Since we only create LazyRefs when we encounter a cycle, this should be safe. Fix scala#1103.
odersky
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Feb 19, 2016
ProtoTypes#wildApprox: fix LazyRef approximation
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Before this commit, the output of
wildApprox(A)whereA <: Sys[LazyRef(A)]was? <: Sys[LazyRef(() => wildApprox(A))]. This lead to infinitesubtyping checks.
This is fixed by always approximating a LazyRef by an unbounded
wildcard. Since we only create LazyRefs when we encounter a cycle, this
should be safe.
Fix #1103.
Review by @odersky