fixup! Use compUnitInfo in mirrorSupportsDefaultArguments

Author: EugeneFlesselle

compiler/src/dotty/tools/dotc/typer/Synthesizer.scala

@@ -411,8 +411,8 @@ class Synthesizer(typer: Typer)(using @constructorOnly c: Context):
       val elemLabels = accessors.map(acc => ConstantType(Constant(acc.name.toString)))
       val elemsLabels = TypeOps.nestedPairs(elemLabels)
 
-      val elemHasDefaults = accessors.map(acc => 
-        ConstantType(Constant(cls.mirrorSupportsDefaultArguments && acc.is(HasDefault))))
+      val supportsDefaults = cls.mirrorSupportsDefaultArguments
+      val elemHasDefaults = accessors.map(acc => ConstantType(Constant(supportsDefaults && acc.is(HasDefault))))
       val elemsHasDefaults = TypeOps.nestedPairs(elemHasDefaults)
 
       val typeElems = tps.getOrElse(accessors.map(mirroredType.resultType.memberInfo(_).widenExpr))