From 4f9d7c81e4fdbfaa0b6b57e8497849bd8394abd9 Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Thu, 24 Dec 2020 11:13:47 +0100
Subject: [PATCH 1/2] Avoid NPE when duplicating symbols

Fixes #10542
---
 .../src/dotty/tools/dotc/core/Symbols.scala   |  6 ++--
 tests/pos/i10542.scala                        | 29 +++++++++++++++++++
 2 files changed, 33 insertions(+), 2 deletions(-)
 create mode 100644 tests/pos/i10542.scala

diff --git a/compiler/src/dotty/tools/dotc/core/Symbols.scala b/compiler/src/dotty/tools/dotc/core/Symbols.scala
index a9baa4d65802..b1939261084f 100644
--- a/compiler/src/dotty/tools/dotc/core/Symbols.scala
+++ b/compiler/src/dotty/tools/dotc/core/Symbols.scala
@@ -835,8 +835,10 @@ object Symbols {
           info = completer,
           privateWithin = ttmap1.mapOwner(odenot.privateWithin), // since this refers to outer symbols, need not include copies (from->to) in ownermap here.
           annotations = odenot.annotations)
-        copy.registeredCompanion =
-          copy.registeredCompanion.subst(originals, copies)
+        copy.denot match
+          case cd: ClassDenotation =>
+            cd.registeredCompanion = cd.unforcedRegisteredCompanion.subst(originals, copies)
+          case _ =>
       }
 
       copies.foreach(_.ensureCompleted()) // avoid memory leak
diff --git a/tests/pos/i10542.scala b/tests/pos/i10542.scala
new file mode 100644
index 000000000000..21e0e2a50748
--- /dev/null
+++ b/tests/pos/i10542.scala
@@ -0,0 +1,29 @@
+package test1:
+
+  trait Foo {
+    inline def foo[A](t: => A): Unit = ()
+  }
+
+  object Bar extends Foo
+
+  object Test {
+    Bar.foo {
+      sealed trait T1
+      case object S1 extends T1
+    }
+  }
+/*
+package test2:
+
+  trait Foo {
+    inline def foo[A](t: => A): Unit = ()
+  }
+
+  object Bar extends Foo
+
+  object Test {
+    Bar.foo {
+      trait T1
+      val array = Array(new T1 {})
+    }
+  }*/
\ No newline at end of file

From 20a4652c5ea0198050d21a6ef1d06c8ae6be4408 Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Thu, 24 Dec 2020 11:27:05 +0100
Subject: [PATCH 2/2] Properly map type constants in TreeTypeMap

---
 .../src/dotty/tools/dotc/ast/TreeTypeMap.scala  |  4 +++-
 tests/pos/i10542.scala                          | 17 +++++++++++++----
 2 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/compiler/src/dotty/tools/dotc/ast/TreeTypeMap.scala b/compiler/src/dotty/tools/dotc/ast/TreeTypeMap.scala
index 6bbf253d3b80..a3c1484d4e62 100644
--- a/compiler/src/dotty/tools/dotc/ast/TreeTypeMap.scala
+++ b/compiler/src/dotty/tools/dotc/ast/TreeTypeMap.scala
@@ -4,7 +4,7 @@ package ast
 
 import core._
 import Types._, Contexts._
-import Symbols._, Annotations._, Trees._, Symbols._
+import Symbols._, Annotations._, Trees._, Symbols._, Constants.Constant
 import Decorators._
 import dotty.tools.dotc.transform.SymUtils._
 import core.tasty.TreePickler.Hole
@@ -124,6 +124,8 @@ class TreeTypeMap(
           cpy.Labeled(labeled)(bind1, expr1)
         case Hole(isTermHole, n, args) =>
           Hole(isTermHole, n, args.mapConserve(transform)).withSpan(tree.span).withType(mapType(tree.tpe))
+        case lit @ Literal(Constant(tpe: Type)) =>
+          cpy.Literal(lit)(Constant(mapType(tpe)))
         case tree1 =>
           super.transform(tree1)
       }
diff --git a/tests/pos/i10542.scala b/tests/pos/i10542.scala
index 21e0e2a50748..f6c759ef4769 100644
--- a/tests/pos/i10542.scala
+++ b/tests/pos/i10542.scala
@@ -1,4 +1,4 @@
-package test1:
+package test_10542:
 
   trait Foo {
     inline def foo[A](t: => A): Unit = ()
@@ -12,8 +12,8 @@ package test1:
       case object S1 extends T1
     }
   }
-/*
-package test2:
+
+package test_10540:
 
   trait Foo {
     inline def foo[A](t: => A): Unit = ()
@@ -26,4 +26,13 @@ package test2:
       trait T1
       val array = Array(new T1 {})
     }
-  }*/
\ No newline at end of file
+  }
+
+package test_9655:
+
+  inline def foo[T](inline body: T): T = body
+
+  def test = foo {
+    sealed trait Status
+    object Active extends Status
+  }