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Don't generate Mirror.Sum for simple enum cases #14525

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Merged
merged 4 commits into from
Mar 14, 2022
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Don't generate Mirror.Sum for simple enum cases #14525

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d25fc49
Don't generate Mirror.Sum for simple enum cases
andrzejressel Feb 20, 2022
d317135
Disallow Sum with enum or discointed class
andrzejressel Mar 2, 2022
74eeebd
Use strict classSymbol equality to block bad unions
dwijnand Mar 9, 2022
e80dcba
add checks for HK and annots
bishabosha Mar 14, 2022
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2 changes: 1 addition & 1 deletion compiler/src/dotty/tools/dotc/typer/Synthesizer.scala
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Expand Up @@ -273,7 +273,7 @@ class Synthesizer(typer: Typer)(using @constructorOnly c: Context):
val cls = mirroredType.classSymbol
val useCompanion = cls.useCompanionAsSumMirror

if cls.isGenericSum(if useCompanion then cls.linkedClass else ctx.owner) then
if (!mirroredType.termSymbol.isEnumCase && (cls.isGenericSum(if useCompanion then cls.linkedClass else ctx.owner))) then
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isGenericSum is used in one more place and I wonder if it should be modified as well.

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@andrzejressel andrzejressel Feb 22, 2022 •
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In SyntheticMembers::addMirrorSupport? It's not an issue, because this method will never be called: as far as I understand branch else if (impl.removeAttachment(ExtendsSingletonMirror).isDefined) will be invoked.

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@bishabosha bishabosha Feb 22, 2022 •
edited
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it's fine to keep isGenericSum implementation unchanged, it should only be called on a class symbol, perhaps it could be more informative to rename to isGenericSumClass, along with isGenericProduct to isGenericProductClass

val elemLabels = cls.children.map(c => ConstantType(Constant(c.name.toString)))

def solve(sym: Symbol): Type = sym match
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15 changes: 15 additions & 0 deletions tests/neg/scala_enum_testing.scala
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Original file line number Diff line number Diff line change
@@ -0,0 +1,15 @@
import scala.util.NotGiven
import scala.compiletime.*
import scala.deriving.Mirror

enum Color:
case Red, Green, Blue
end Color

object Test {

def main(args: Array[String]): Unit = {
summon[Mirror.ProductOf[Color]] // error
summon[Mirror.SumOf[Color.Red.type]] // error
}
}
17 changes: 17 additions & 0 deletions tests/run/scala_enum_testing.scala
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@@ -0,0 +1,17 @@
import scala.util.NotGiven
import scala.compiletime.*
import scala.deriving.Mirror

enum Color:
case Red, Green, Blue
end Color

object Test {

def main(args: Array[String]): Unit = {
summon[Mirror.Of[Color.Red.type]]
summon[Mirror.Of[Color]]
summon[Mirror.ProductOf[Color.Red.type]]
summon[Mirror.SumOf[Color]]
}
}