From 7be5bfbb547f9d9980138f9602b927d210f85294 Mon Sep 17 00:00:00 2001
From: Hamza Remmal <hamza@remmal.net>
Date: Thu, 6 Feb 2025 10:57:58 +0100
Subject: [PATCH] chore: recover scala 2's semantics for AnyVal under
 Ycompile-scala2-library

---
 .../dotc/transform/SyntheticMembers.scala     |  8 +++++-
 .../tools/dotc/printing/PrintingTest.scala    |  3 +++
 ...Scala2LibraryBootstrappedMiMaFilters.scala | 17 +++++++++++--
 tests/printing/posttyper/i22533.check         | 25 +++++++++++++++++++
 tests/printing/posttyper/i22533.flags         |  1 +
 tests/printing/posttyper/i22533.scala         |  7 ++++++
 6 files changed, 58 insertions(+), 3 deletions(-)
 create mode 100644 tests/printing/posttyper/i22533.check
 create mode 100644 tests/printing/posttyper/i22533.flags
 create mode 100644 tests/printing/posttyper/i22533.scala

diff --git a/compiler/src/dotty/tools/dotc/transform/SyntheticMembers.scala b/compiler/src/dotty/tools/dotc/transform/SyntheticMembers.scala
index 45606b0dbef5..376e43b3982d 100644
--- a/compiler/src/dotty/tools/dotc/transform/SyntheticMembers.scala
+++ b/compiler/src/dotty/tools/dotc/transform/SyntheticMembers.scala
@@ -78,7 +78,13 @@ class SyntheticMembers(thisPhase: DenotTransformer) {
 
   private def existingDef(sym: Symbol, clazz: ClassSymbol)(using Context): Symbol =
     val existing = sym.matchingMember(clazz.thisType)
-    if existing != sym && !existing.is(Deferred) then existing else NoSymbol
+    if ctx.settings.YcompileScala2Library.value && clazz.isValueClass && (sym == defn.Any_equals || sym == defn.Any_hashCode) then
+      NoSymbol
+    else if existing != sym && !existing.is(Deferred) then 
+      existing 
+    else 
+      NoSymbol
+  end existingDef
 
   private def synthesizeDef(sym: TermSymbol, rhsFn: List[List[Tree]] => Context ?=> Tree)(using Context): Tree =
     DefDef(sym, rhsFn(_)(using ctx.withOwner(sym))).withSpan(ctx.owner.span.focus)
diff --git a/compiler/test/dotty/tools/dotc/printing/PrintingTest.scala b/compiler/test/dotty/tools/dotc/printing/PrintingTest.scala
index 8a80a6978bdb..15522d61e31f 100644
--- a/compiler/test/dotty/tools/dotc/printing/PrintingTest.scala
+++ b/compiler/test/dotty/tools/dotc/printing/PrintingTest.scala
@@ -69,6 +69,9 @@ class PrintingTest {
   @Test
   def printing: Unit = testIn("tests/printing", "typer")
 
+  @Test
+  def posttyper: Unit = testIn("tests/printing/posttyper", "posttyper")
+
   @Test
   def untypedPrinting: Unit = testIn("tests/printing/untyped", "parser")
 
diff --git a/project/Scala2LibraryBootstrappedMiMaFilters.scala b/project/Scala2LibraryBootstrappedMiMaFilters.scala
index 102a2a50e9d4..65d24bcd96ca 100644
--- a/project/Scala2LibraryBootstrappedMiMaFilters.scala
+++ b/project/Scala2LibraryBootstrappedMiMaFilters.scala
@@ -18,8 +18,21 @@ object Scala2LibraryBootstrappedMiMaFilters {
         // trait $init$
         ProblemFilters.exclude[DirectMissingMethodProblem]("scala.*.$init$"),
 
-        // Value class extension methods
-        ProblemFilters.exclude[DirectMissingMethodProblem]("scala.*$extension"),
+        // Issue: https://github.com/scala/scala3/issues/22495
+        ProblemFilters.exclude[DirectMissingMethodProblem]("scala.collection.ArrayOps.scala$collection$ArrayOps$$elemTag$extension"),
+        ProblemFilters.exclude[DirectMissingMethodProblem]("scala.collection.ArrayOps.iterateUntilEmpty$extension"),
+        ProblemFilters.exclude[DirectMissingMethodProblem]("scala.collection.StringOps.isLineBreak$extension"),
+        ProblemFilters.exclude[DirectMissingMethodProblem]("scala.collection.StringOps.isLineBreak2$extension"),
+        ProblemFilters.exclude[DirectMissingMethodProblem]("scala.collection.StringOps.linesSeparated$extension"),
+        ProblemFilters.exclude[DirectMissingMethodProblem]("scala.collection.StringOps.escape$extension"),
+        ProblemFilters.exclude[DirectMissingMethodProblem]("scala.collection.StringOps.toBooleanImpl$extension"),
+        ProblemFilters.exclude[DirectMissingMethodProblem]("scala.collection.StringOps.unwrapArg$extension"),
+        ProblemFilters.exclude[DirectMissingMethodProblem]("scala.collection.StringOps.iterateUntilEmpty$extension"),
+        ProblemFilters.exclude[DirectMissingMethodProblem]("scala.runtime.Tuple2Zipped.coll1$extension"),
+        ProblemFilters.exclude[DirectMissingMethodProblem]("scala.runtime.Tuple2Zipped.coll2$extension"),
+        ProblemFilters.exclude[DirectMissingMethodProblem]("scala.runtime.Tuple3Zipped.coll1$extension"),
+        ProblemFilters.exclude[DirectMissingMethodProblem]("scala.runtime.Tuple3Zipped.coll2$extension"),
+        ProblemFilters.exclude[DirectMissingMethodProblem]("scala.runtime.Tuple3Zipped.coll3$extension"),
 
         // Companion module class
         ProblemFilters.exclude[FinalClassProblem]("scala.*$"),
diff --git a/tests/printing/posttyper/i22533.check b/tests/printing/posttyper/i22533.check
new file mode 100644
index 000000000000..33c023d94a74
--- /dev/null
+++ b/tests/printing/posttyper/i22533.check
@@ -0,0 +1,25 @@
+[[syntax trees at end of                 posttyper]] // tests/printing/posttyper/i22533.scala
+package <empty> {
+  @SourceFile("tests/printing/posttyper/i22533.scala") trait A() extends Any {
+    override def equals(x: Any): Boolean = ???
+    override def hashCode(): Int = ???
+  }
+  @SourceFile("tests/printing/posttyper/i22533.scala") final class Foo(u: Int)
+     extends AnyVal(), A {
+    override def hashCode(): Int = Foo.this.u.hashCode()
+    override def equals(x$0: Any): Boolean =
+      x$0 match
+        {
+          case x$0 @ _:Foo @unchecked => this.u.==(x$0.u)
+          case _ => false
+        }
+    private[this] val u: Int
+  }
+  final lazy module val Foo: Foo = new Foo()
+  @SourceFile("tests/printing/posttyper/i22533.scala") final module class Foo()
+     extends AnyRef() { this: Foo.type =>
+    private def writeReplace(): AnyRef =
+      new scala.runtime.ModuleSerializationProxy(classOf[Foo.type])
+  }
+}
+
diff --git a/tests/printing/posttyper/i22533.flags b/tests/printing/posttyper/i22533.flags
new file mode 100644
index 000000000000..21379f85d52a
--- /dev/null
+++ b/tests/printing/posttyper/i22533.flags
@@ -0,0 +1 @@
+-Ycompile-scala2-library
diff --git a/tests/printing/posttyper/i22533.scala b/tests/printing/posttyper/i22533.scala
new file mode 100644
index 000000000000..07e9e1c4c011
--- /dev/null
+++ b/tests/printing/posttyper/i22533.scala
@@ -0,0 +1,7 @@
+//> using options -Ycompile-scala2-library
+
+trait A extends Any:
+    override def equals(x: Any): Boolean = ???
+    override def hashCode(): Int = ???
+
+class Foo(u: Int) extends AnyVal, A
\ No newline at end of file