SI-5877 Support implicit classes in package objects

This used to crash, as both the package and the package object
had the synthetic method in `decls`, and the typer tried to add
the tree to both places.

Now, synthetics in the package object are excluded from the pacakge
itself.

3 files changed, 31 insertions, 1 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index 5714c2c109..9af72c1c00 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -2828,7 +2828,10 @@ trait Typers extends Modes with Adaptations with Tags {
         var moreToAdd = true
         while (moreToAdd) {
           val initElems = scope.elems
-          for (sym <- scope)
+          // SI-5877 The decls of a package include decls of the package object. But we don't want to add
+          //         the corresponding synthetics to the package itself.
+          def isPackageObjectSym(sym: Symbol) = sym.owner.isPackageObjectClass && context.owner.isPackage
+          for (sym <- scope if !isPackageObjectSym(sym))
             for (tree <- context.unit.synthetics get sym) {
               newStats += typedStat(tree) // might add even more synthetics to the scope
               context.unit.synthetics -= sym
diff --git a/test/files/pos/t5877.scala b/test/files/pos/t5877.scala
new file mode 100644
index 0000000000..c7827df99f
--- /dev/null
+++ b/test/files/pos/t5877.scala
@@ -0,0 +1,14 @@
+package foo {
+  class Foo
+
+  object Test {
+    new Foo().huzzah
+  }
+}
+
+package object foo {
+  // Crasher: No synthetics for method PimpedFoo2: synthetics contains
+  implicit class PimpedFoo2(value: Foo) {
+    def huzzah = ""
+  }
+}
diff --git a/test/files/pos/t5877b.scala b/test/files/pos/t5877b.scala
new file mode 100644
index 0000000000..6b8cbd473e
--- /dev/null
+++ b/test/files/pos/t5877b.scala
@@ -0,0 +1,13 @@
+package foo
+
+class Foo
+
+object Test {
+  new Foo().huzzah
+}
+
+object `package` {
+  implicit class PimpedFoo2(value: Foo) {
+    def huzzah = ""
+  }
+}