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odersky opened this issue Jan 9, 2023 · 0 comments · Fixed by #16644
Closed

Over-eager Cyclic References when compiling Opaque Types #16642

odersky opened this issue Jan 9, 2023 · 0 comments · Fixed by #16644
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@odersky
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area:opaque-types itype:bug
Milestone
3.3.0

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@odersky
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odersky commented Jan 9, 2023 •
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Compiler version

All 3.x versions

Minimized example

object Syms:
  import SymDs.*
  opaque type Symbol <: AnyRef  // compiles OK if <: AnyRef is missing
    = SymDenotation

object SymDs:
  import Syms.*
  class SymDenotation(sym: Symbol)

Output

3 |  opaque type Symbol <: AnyRef
  |              ^
  |              Cyclic reference involving type Symbol
  |
  | longer explanation available when compiling with `-explain`

Expectation

Should compile in the same way as when <: AnyRef is missing.
@odersky odersky added the stat:needs triage Every issue needs to have an "area" and "itype" label label Jan 9, 2023
@odersky odersky self-assigned this Jan 9, 2023
@odersky odersky added area:typer area:opaque-types itype:bug and removed area:typer stat:needs triage Every issue needs to have an "area" and "itype" label labels Jan 9, 2023
odersky added a commit to dotty-staging/dotty that referenced this issue Jan 9, 2023
@odersky
Delay opaque alias checking until PostTyper
8bf5b49 
When we have a TypeBounds tree that also has an alias, we checked
that the alias is within bounds at Typer. This could provoke a
CyclicReference when processing opaque type aliases where
the type has a bound and also the alias refers back to the type.
We avoid the problem by performing the check at PostTyper, analogous
to other bounds checks.

Fixes scala#16642
odersky added a commit to dotty-staging/dotty that referenced this issue Jan 9, 2023
@odersky
Delay opaque alias checking until PostTyper
a7035c2 
When we have a TypeBounds tree that also has an alias, we checked
that the alias is within bounds at Typer. This could provoke a
CyclicReference when processing opaque type aliases where
the type has a bound and also the alias refers back to the type.
We avoid the problem by performing the check at PostTyper, analogous
to other bounds checks.

Fixes scala#16642
This was referenced Jan 9, 2023
Merged
Closed
odersky added a commit that referenced this issue Jan 10, 2023
@odersky
Delay opaque alias checking until PostTyper (#16644)
4fa0715 
When we have a TypeBounds tree that also has an alias, we checked that
the alias is within bounds at Typer. This could provoke a
CyclicReference when processing opaque type aliases where the type has a
bound and also the alias refers back to the type. We avoid the problem
by performing the check at PostTyper, analogous to other bounds checks.

Fixes #16642
odersky added a commit to dotty-staging/dotty that referenced this issue Jan 11, 2023
@odersky
Delay opaque alias checking until PostTyper
15b136a 
When we have a TypeBounds tree that also has an alias, we checked
that the alias is within bounds at Typer. This could provoke a
CyclicReference when processing opaque type aliases where
the type has a bound and also the alias refers back to the type.
We avoid the problem by performing the check at PostTyper, analogous
to other bounds checks.

Fixes scala#16642
little-inferno pushed a commit to little-inferno/dotty that referenced this issue Jan 25, 2023
@odersky @little-inferno
Delay opaque alias checking until PostTyper
0951d43 
When we have a TypeBounds tree that also has an alias, we checked
that the alias is within bounds at Typer. This could provoke a
CyclicReference when processing opaque type aliases where
the type has a bound and also the alias refers back to the type.
We avoid the problem by performing the check at PostTyper, analogous
to other bounds checks.

Fixes scala#16642
@Kordyjan Kordyjan added this to the 3.3.0 milestone Aug 1, 2023
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Delay opaque alias checking until PostTyper dotty-staging/dotty
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@odersky @Kordyjan