Comment on the empty cases in notNullInfoFromCases.

bracevac · Dec 10, 2024 · 200c038 · 200c038
1 parent 00430c0
commit 200c038
Showing 1 changed file with 5 additions and 3 deletions.
diff --git a/compiler/src/dotty/tools/dotc/typer/Typer.scala b/compiler/src/dotty/tools/dotc/typer/Typer.scala
@@ -2147,9 +2147,11 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
   }
 
   private def notNullInfoFromCases(initInfo: NotNullInfo, cases: List[CaseDef])(using Context): NotNullInfo =
-    if cases.nonEmpty then
-      initInfo.seq(cases.map(_.notNullInfo).reduce(_.alt(_)))
-    else initInfo
+    if cases.isEmpty then
+      // Empty cases is not allowed for match tree in the source code,
+      // but it can be generated by inlining: `tests/pos/i19198.scala`.
+      initInfo
+    else cases.map(_.notNullInfo).reduce(_.alt(_))
 
   def typedCases(cases: List[untpd.CaseDef], sel: Tree, wideSelType0: Type, pt: Type)(using Context): List[CaseDef] =
     var caseCtx = ctx