diff options
| -rw-r--r-- | src/dotty/tools/dotc/typer/Typer.scala | 5 | ||||
| -rw-r--r-- | tests/neg/singletons.scala | 4 |
2 files changed, 8 insertions, 1 deletions
diff --git a/src/dotty/tools/dotc/typer/Typer.scala b/src/dotty/tools/dotc/typer/Typer.scala index 33ec156a1..4441adcfb 100644 --- a/src/dotty/tools/dotc/typer/Typer.scala +++ b/src/dotty/tools/dotc/typer/Typer.scala @@ -782,7 +782,10 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit def typedSingletonTypeTree(tree: untpd.SingletonTypeTree)(implicit ctx: Context): SingletonTypeTree = track("typedSingletonTypeTree") { val ref1 = typedExpr(tree.ref) - checkStable(ref1.tpe, tree.pos) + val illegal = Set[Symbol](defn.NullClass, defn.SymbolClass) + val refSym = ref1.tpe.widen.typeSymbol + if (illegal contains refSym) ctx.error(i"$refSym is not a legal singleton constant type", tree.pos) + else checkStable(ref1.tpe, tree.pos) assignType(cpy.SingletonTypeTree(tree)(ref1), ref1) } diff --git a/tests/neg/singletons.scala b/tests/neg/singletons.scala index 3bf7ee050..e4c6db060 100644 --- a/tests/neg/singletons.scala +++ b/tests/neg/singletons.scala @@ -2,4 +2,8 @@ object Test { val a: 42 = 43 // error: different constant val x = 42 val z: 42 = x // error: x is not final + + val n: null = null // error: Null is not a legal singleton type + + val sym: 'sym = 'sym // error: Symbol is a legal singleton type } |