3 files changed, 41 insertions, 0 deletions
diff --git a/src/dotty/tools/dotc/typer/RefChecks.scala b/src/dotty/tools/dotc/typer/RefChecks.scala
index 9b14fffc0..6a1f3652b 100644
--- a/src/dotty/tools/dotc/typer/RefChecks.scala
+++ b/src/dotty/tools/dotc/typer/RefChecks.scala
@@ -71,6 +71,17 @@ object RefChecks {
     }
   }
 
+  /** Check that self type of this class conforms to self types of parents */
+  private def checkSelfType(clazz: Symbol)(implicit ctx: Context): Unit = clazz.info match {
+    case cinfo: ClassInfo =>
+      for (parent <- cinfo.classParents) {
+        val pself = parent.givenSelfType.asSeenFrom(clazz.thisType, parent.classSymbol)
+        if (pself.exists && !(cinfo.selfType <:< pself))
+          ctx.error(d"illegal inheritance: self type ${cinfo.selfType} of $clazz does not conform to self type $pself of parent ${parent.classSymbol}", clazz.pos)
+      }
+    case _ =>
+  }
+
   // Override checking ------------------------------------------------------------
 
   /** 1. Check all members of class `clazz` for overriding conditions.
@@ -770,6 +781,7 @@ class RefChecks extends MiniPhase with SymTransformer { thisTransformer =>
     override def transformTemplate(tree: Template)(implicit ctx: Context, info: TransformerInfo) = {
       val cls = ctx.owner
       checkOverloadedRestrictions(cls)
+      checkSelfType(cls)
       checkAllOverrides(cls)
       checkAnyValSubclass(cls)
       tree
diff --git a/test/dotc/tests.scala b/test/dotc/tests.scala
index a015b9efe..c3f501a52 100644
--- a/test/dotc/tests.scala
+++ b/test/dotc/tests.scala
@@ -126,6 +126,7 @@ class tests extends CompilerTest {
   @Test def neg_i0281 = compileFile(negDir, "i0281-null-primitive-conforms", xerrors = 3)
   @Test def neg_moduleSubtyping = compileFile(negDir, "moduleSubtyping", xerrors = 4)
   @Test def neg_escapingRefs = compileFile(negDir, "escapingRefs", xerrors = 2)
+  @Test def neg_selfInheritance = compileFile(negDir, "selfInheritance", xerrors = 5)
 
   @Test def dotc = compileDir(dotcDir + "tools/dotc", failedOther)(allowDeepSubtypes ++ twice) // see dotc_core
   @Test def dotc_ast = compileDir(dotcDir + "tools/dotc/ast", failedOther ++ twice)
diff --git a/tests/neg/selfInheritance.scala b/tests/neg/selfInheritance.scala
new file mode 100644
index 000000000..5f61c5bbb
--- /dev/null
+++ b/tests/neg/selfInheritance.scala
@@ -0,0 +1,28 @@
+trait T { self: B => }
+
+abstract class A { self: B =>
+
+}
+
+class B extends A with T {
+}
+
+class C { self: B =>
+
+}
+
+class D extends A      // error
+
+class E extends T      // error
+
+object Test {
+
+  new B() {}
+
+  new A() {}   // error
+
+  object O extends A  // error
+
+  object M extends C // error
+
+}