From a5e24768f26bb2d28c7610ff5a184b0c65f56c55 Mon Sep 17 00:00:00 2001
From: Jason Zaugg <jzaugg@gmail.com>
Date: Wed, 13 Nov 2013 10:24:15 +0100
Subject: SI-7967 Account for type aliases in self-type checks

These eluded the check for "illegal inheritance; self-type does not
conform" as AliasTypeRef doesn't forward `typeOfThis`.

This commit dealiases before calling `typeOfThis`. That seems to be
the most localised change.

Without the dealias, we had:

    parent.tpe            = TypeRef(pre, sym = AliasTypeSymbol("CC"), Nil)
    parent.tpe.typeOfThis = parent.tpe.transform(sym.typeOfThis) = CC

After:

    parent.tpe.dealias            = TypeRef(pre, sym = ClassSymbol("C"), Nil)
    parent.tpe.dealias.typeOfThis = C with B
---
 src/compiler/scala/tools/nsc/typechecker/Typers.scala | 5 +++--
 test/files/neg/t7967.check                            | 9 +++++++++
 test/files/neg/t7967.scala                            | 9 +++++++++
 3 files changed, 21 insertions(+), 2 deletions(-)
 create mode 100644 test/files/neg/t7967.check
 create mode 100644 test/files/neg/t7967.scala

diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index a9bb81c691..f90c6f1d86 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -1698,15 +1698,16 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
               psym addChild context.owner
             else
               pending += ParentSealedInheritanceError(parent, psym)
+          val parentTypeOfThis = parent.tpe.dealias.typeOfThis
 
-          if (!(selfType <:< parent.tpe.typeOfThis) &&
+          if (!(selfType <:< parentTypeOfThis) &&
               !phase.erasedTypes &&
               !context.owner.isSynthetic &&   // don't check synthetic concrete classes for virtuals (part of DEVIRTUALIZE)
               !selfType.isErroneous &&
               !parent.tpe.isErroneous)
           {
             pending += ParentSelfTypeConformanceError(parent, selfType)
-            if (settings.explaintypes) explainTypes(selfType, parent.tpe.typeOfThis)
+            if (settings.explaintypes) explainTypes(selfType, parentTypeOfThis)
           }
 
           if (parents exists (p => p != parent && p.tpe.typeSymbol == psym && !psym.isError))
diff --git a/test/files/neg/t7967.check b/test/files/neg/t7967.check
new file mode 100644
index 0000000000..cde950dcdf
--- /dev/null
+++ b/test/files/neg/t7967.check
@@ -0,0 +1,9 @@
+t7967.scala:6: error: illegal inheritance;
+ self-type C does not conform to C's selftype C with B
+  new C {} // fails
+      ^
+t7967.scala:8: error: illegal inheritance;
+ self-type Test.CC does not conform to Test.CC's selftype Test.CC
+  new CC {} // should fail, doesn't
+      ^
+two errors found
diff --git a/test/files/neg/t7967.scala b/test/files/neg/t7967.scala
new file mode 100644
index 0000000000..4f13347948
--- /dev/null
+++ b/test/files/neg/t7967.scala
@@ -0,0 +1,9 @@
+
+trait B
+trait C {self: B =>}
+
+object Test {
+  new C {} // fails
+  type CC = C
+  new CC {} // should fail, doesn't
+}
-- 
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