Allow refinements that refine already refined types. #243
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Previously, a double definition errorfor `T` was produced in a case like this:
type T1 = C { T <: A }
type T2 = T1 { T <: B }
This was caused by the way T1 was treated in the refinement class
that is used to typecheck the type. Desugaring of T2 with `refinedTypeToClass`
would give
trait <refinement> extends T1 { type T <: B }
and `normalizeToClassRefs` would transform this to:
trait <refinement> extends C { type T <: A; type T <: B }
Hence the double definition. The new scheme desugars the rhs of `T2` to:
trait <refinement> extends C { this: T1 => type T <: B }
which avoids the problem.
Also, added tests that scala#232 (fix/boundsPropagation) indeed considers all refinements
together when comparing refined types.
|
The new test in neg had a wrongly capitalized name: refinedSubTyping instead of refinedSubtyping. |
tgodzik
added a commit
to tgodzik/scala3
that referenced
this pull request
Apr 29, 2025
Backport "fix: Only fallback to the definition of a synthetic valdef if it is zero extent" to 3.3 LTS
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Previously, a double definition errorfor
Twas produced in a case like this:This was caused by the way T1 was treated in the refinement class
that is used to typecheck the type. Desugaring of T2 with
refinedTypeToClasswould give
and
normalizeToClassRefswould transform this to:Hence the double definition. The new scheme desugars the rhs of
T2to:which avoids the problem.
Also, added tests that #232 (fix/boundsPropagation) indeed considers all refinements
together when comparing refined types.
Review by @retronym please.