From 8130c32734c0008b664780a708f25d0cda6a6ed6 Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Tue, 13 Jul 2021 17:49:30 +0200
Subject: [PATCH 1/2] Handle overloaded members when generating Java varargs
 bridges

Fixes #13043
---
 .../tools/dotc/transform/ElimRepeated.scala   | 25 ++++++++++++++++---
 tests/pos/i13043/Impl.scala                   |  5 ++++
 tests/pos/i13043/Intf.java                    |  5 ++++
 3 files changed, 32 insertions(+), 3 deletions(-)
 create mode 100644 tests/pos/i13043/Impl.scala
 create mode 100644 tests/pos/i13043/Intf.java

diff --git a/compiler/src/dotty/tools/dotc/transform/ElimRepeated.scala b/compiler/src/dotty/tools/dotc/transform/ElimRepeated.scala
index 8068e88bf874..6e2c260e9f5d 100644
--- a/compiler/src/dotty/tools/dotc/transform/ElimRepeated.scala
+++ b/compiler/src/dotty/tools/dotc/transform/ElimRepeated.scala
@@ -1,4 +1,5 @@
-package dotty.tools.dotc
+package dotty.tools
+package dotc
 package transform
 
 import core._
@@ -76,7 +77,23 @@ class ElimRepeated extends MiniPhase with InfoTransformer { thisPhase =>
 
   override def infoMayChange(sym: Symbol)(using Context): Boolean = sym.is(Method)
 
-  private def overridesJava(sym: Symbol)(using Context) = sym.allOverriddenSymbols.exists(_.is(JavaDefined))
+  /** Does `sym` override a symbol defined in a Java class? One might think that
+   *  this can be expressed as
+   *
+   *      sym.allOverriddenSymbols.exists(_.is(JavaDefined))
+   *
+   *  but that does not work, since `allOverriddenSymbols` gets confused because the
+   *  signatures of a Java varargs method and a Scala varargs override are not the same.
+   */
+  private def overridesJava(sym: Symbol)(using Context) =
+    sym.owner.info.baseClasses.drop(1).exists { bc =>
+      bc.is(JavaDefined) && {
+        val other = bc.info.nonPrivateDecl(sym.name)
+        other.hasAltWith { alt =>
+          sym.owner.thisType.memberInfo(alt.symbol).matchesLoosely(sym.info)
+        }
+      }
+    }
 
   private def hasVarargsAnnotation(sym: Symbol)(using Context) = sym.hasAnnotation(defn.VarargsAnnot)
 
@@ -85,7 +102,8 @@ class ElimRepeated extends MiniPhase with InfoTransformer { thisPhase =>
   private def isVarargsMethod(sym: Symbol)(using Context) =
     hasVarargsAnnotation(sym) ||
       hasRepeatedParams(sym) &&
-      (sym.allOverriddenSymbols.exists(s => s.is(JavaDefined) || hasVarargsAnnotation(s)))
+        overridesJava(sym)
+        || sym.allOverriddenSymbols.exists(hasVarargsAnnotation)
 
   /** Eliminate repeated parameters from method types. */
   private def elimRepeated(tp: Type, isJava: Boolean)(using Context): Type = tp.stripTypeVar match
@@ -292,6 +310,7 @@ class ElimRepeated extends MiniPhase with InfoTransformer { thisPhase =>
         report.error(s"$src produces a forwarder method that conflicts with ${conflict.showDcl}", original.srcPos)
       case Nil =>
         forwarder.enteredAfter(thisPhase)
+  end addVarArgsForwarder
 
   /** Convert type from Scala to Java varargs method */
   private def toJavaVarArgs(tp: Type)(using Context): Type = tp match
diff --git a/tests/pos/i13043/Impl.scala b/tests/pos/i13043/Impl.scala
new file mode 100644
index 000000000000..7db75ee99d89
--- /dev/null
+++ b/tests/pos/i13043/Impl.scala
@@ -0,0 +1,5 @@
+class Impl extends Intf {
+  override def thing(x: Int) = ???
+  override def thing(y: String*) = ???
+  override def thing2(y: String*) = ???
+}
\ No newline at end of file
diff --git a/tests/pos/i13043/Intf.java b/tests/pos/i13043/Intf.java
new file mode 100644
index 000000000000..8b845bdca146
--- /dev/null
+++ b/tests/pos/i13043/Intf.java
@@ -0,0 +1,5 @@
+interface Intf {
+    public void thing(int x);
+    public void thing(String... y);
+    public void thing2(String... y);
+}
\ No newline at end of file

From abf4b45f4735664249fc85e95d38915515e0ac5e Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Thu, 15 Jul 2021 12:29:20 +0200
Subject: [PATCH 2/2] Add missing parens

---
 compiler/src/dotty/tools/dotc/transform/ElimRepeated.scala | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/compiler/src/dotty/tools/dotc/transform/ElimRepeated.scala b/compiler/src/dotty/tools/dotc/transform/ElimRepeated.scala
index 6e2c260e9f5d..429c0e7445b2 100644
--- a/compiler/src/dotty/tools/dotc/transform/ElimRepeated.scala
+++ b/compiler/src/dotty/tools/dotc/transform/ElimRepeated.scala
@@ -100,10 +100,9 @@ class ElimRepeated extends MiniPhase with InfoTransformer { thisPhase =>
   private def parentHasVarargsAnnotation(sym: Symbol)(using Context) = sym.allOverriddenSymbols.exists(hasVarargsAnnotation)
 
   private def isVarargsMethod(sym: Symbol)(using Context) =
-    hasVarargsAnnotation(sym) ||
-      hasRepeatedParams(sym) &&
-        overridesJava(sym)
-        || sym.allOverriddenSymbols.exists(hasVarargsAnnotation)
+    hasVarargsAnnotation(sym)
+    || hasRepeatedParams(sym)
+        && (overridesJava(sym) || sym.allOverriddenSymbols.exists(hasVarargsAnnotation))
 
   /** Eliminate repeated parameters from method types. */
   private def elimRepeated(tp: Type, isJava: Boolean)(using Context): Type = tp.stripTypeVar match