From d9f070dad733f0de450ae55c991e603b4db80549 Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Thu, 9 Dec 2021 17:45:31 +0100
Subject: [PATCH 1/3] Make outer references Java-synthetic

Fixes #14083

I verified manually that the puter accessors are now ACC_SYNHETIC. If someone wants to add a bytecode test, this would be good. I don't know how to make one.
---
 compiler/src/dotty/tools/dotc/transform/ExplicitOuter.scala | 2 +-
 tests/pos/i14083.scala                                      | 3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)
 create mode 100644 tests/pos/i14083.scala

diff --git a/compiler/src/dotty/tools/dotc/transform/ExplicitOuter.scala b/compiler/src/dotty/tools/dotc/transform/ExplicitOuter.scala
index a6a6b2736b1b..9c50e3c2f114 100644
--- a/compiler/src/dotty/tools/dotc/transform/ExplicitOuter.scala
+++ b/compiler/src/dotty/tools/dotc/transform/ExplicitOuter.scala
@@ -177,7 +177,7 @@ object ExplicitOuter {
           else prefix.widen)
     val info = if (flags.is(Method)) ExprType(target) else target
     atPhaseNoEarlier(explicitOuterPhase.next) { // outer accessors are entered at explicitOuter + 1, should not be defined before.
-      newSymbol(owner, name, Synthetic | flags, info, coord = cls.coord)
+      newSymbol(owner, name, SyntheticArtifact | flags, info, coord = cls.coord)
     }
   }
 
diff --git a/tests/pos/i14083.scala b/tests/pos/i14083.scala
new file mode 100644
index 000000000000..542640e96bf1
--- /dev/null
+++ b/tests/pos/i14083.scala
@@ -0,0 +1,3 @@
+class Outer {
+  class Inner
+}
\ No newline at end of file

From 185f09e15be9760c013b353571305d2ad9a36e9a Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Thu, 9 Dec 2021 18:13:04 +0100
Subject: [PATCH 2/3] Make it a proper test

---
 tests/pos/i14083.scala | 3 ---
 tests/run/i14083.scala | 9 +++++++++
 2 files changed, 9 insertions(+), 3 deletions(-)
 delete mode 100644 tests/pos/i14083.scala
 create mode 100644 tests/run/i14083.scala

diff --git a/tests/pos/i14083.scala b/tests/pos/i14083.scala
deleted file mode 100644
index 542640e96bf1..000000000000
--- a/tests/pos/i14083.scala
+++ /dev/null
@@ -1,3 +0,0 @@
-class Outer {
-  class Inner
-}
\ No newline at end of file
diff --git a/tests/run/i14083.scala b/tests/run/i14083.scala
new file mode 100644
index 000000000000..7c4d7f4da4dc
--- /dev/null
+++ b/tests/run/i14083.scala
@@ -0,0 +1,9 @@
+class Outer {
+  class Inner
+}
+@main def Test =
+  assert(
+    classOf[Outer#Inner]
+      .getDeclaredFields
+      .filter(_.getName == "$outer")
+      .exists(_.isSynthetic))

From da5b3d89cc081c7ff2baed4fe5b29112a12b8947 Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Thu, 9 Dec 2021 18:23:59 +0100
Subject: [PATCH 3/3] Make constructor parameter $outer also Java synthetic

This does not work yet, since the backend does not issue a ACC_SYNTHETIC for
parameters labeled Artifact.
---
 compiler/src/dotty/tools/backend/jvm/BCodeHelpers.scala | 1 +
 compiler/src/dotty/tools/dotc/transform/Erasure.scala   | 2 +-
 tests/run/i14083.scala                                  | 4 ++++
 3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/compiler/src/dotty/tools/backend/jvm/BCodeHelpers.scala b/compiler/src/dotty/tools/backend/jvm/BCodeHelpers.scala
index 03d5ac13665b..4085d87ad7ca 100644
--- a/compiler/src/dotty/tools/backend/jvm/BCodeHelpers.scala
+++ b/compiler/src/dotty/tools/backend/jvm/BCodeHelpers.scala
@@ -343,6 +343,7 @@ trait BCodeHelpers extends BCodeIdiomatic with BytecodeWriters {
     def emitParamNames(jmethod: asm.MethodVisitor, params: List[Symbol]) =
       for param <- params do
         var access = asm.Opcodes.ACC_FINAL
+        if param.is(Artifact) then access |= asm.Opcodes.ACC_SYNTHETIC
         jmethod.visitParameter(param.name.mangledString, access)
 
     /*
diff --git a/compiler/src/dotty/tools/dotc/transform/Erasure.scala b/compiler/src/dotty/tools/dotc/transform/Erasure.scala
index ab6f00dfc575..7a89a819677f 100644
--- a/compiler/src/dotty/tools/dotc/transform/Erasure.scala
+++ b/compiler/src/dotty/tools/dotc/transform/Erasure.scala
@@ -929,7 +929,7 @@ object Erasure {
       if constr.isConstructor && needsOuterParam(constr.owner.asClass) then
         constr.info match
           case MethodTpe(outerName :: _, outerType :: _, _) =>
-            val outerSym = newSymbol(constr, outerName, Flags.Param, outerType)
+            val outerSym = newSymbol(constr, outerName, Flags.Param | Flags.SyntheticArtifact, outerType)
             ValDef(outerSym) :: Nil
           case _ =>
             // There's a possible race condition that a constructor was looked at
diff --git a/tests/run/i14083.scala b/tests/run/i14083.scala
index 7c4d7f4da4dc..4014e474ad45 100644
--- a/tests/run/i14083.scala
+++ b/tests/run/i14083.scala
@@ -2,6 +2,10 @@ class Outer {
   class Inner
 }
 @main def Test =
+  assert(classOf[Outer#Inner]
+    .getConstructors.head
+    .getParameters.head
+    .isSynthetic)
   assert(
     classOf[Outer#Inner]
       .getDeclaredFields