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Fix #7748: Don't allow case classes to be defined in universal traits #7772

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Merged
merged 3 commits into from
Dec 17, 2019
Merged

Fix #7748: Don't allow case classes to be defined in universal traits #7772

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a05ffad
Fix #7748: Don't allow classes to be defined in universal traits
odersky Dec 15, 2019
7d0ab6f
Disallow only case classes
odersky Dec 15, 2019
3d69d05
Adopt review suggestions
odersky Dec 16, 2019
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7 changes: 7 additions & 0 deletions compiler/src/dotty/tools/dotc/typer/Typer.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -1810,6 +1810,13 @@ class Typer extends Namer
// check value class constraints
checkDerivedValueClass(cls, body1)

val effectiveOwner = cls.owner.skipWeakOwner
if !cls.isRefinementClass
&& !cls.isAllOf(PrivateLocal)
&& effectiveOwner.is(Trait)
&& !effectiveOwner.derivesFrom(defn.ObjectClass)
ctx.error(i"$cls cannot be defined in universal $effectiveOwner", cdef.sourcePos)

// Temporarily set the typed class def as root tree so that we have at least some
// information in the IDE in case we never reach `SetRootTree`.
if (ctx.mode.is(Mode.Interactive) && ctx.settings.YretainTrees.value)
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11 changes: 11 additions & 0 deletions tests/neg/i7748.scala
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Original file line number Diff line number Diff line change
@@ -0,0 +1,11 @@
trait A extends Any {
case class B() // error
val x = {
case class C() // error
1
}
def f = {
case class C() // ok
1
}
}