Add Serialize to companions of serializable classes in stdlib-bootsrapped

Author: nicolasstucki

compiler/src/dotty/tools/dotc/transform/PostTyper.scala

@@ -425,7 +425,7 @@ class PostTyper extends MacroTransform with IdentityDenotTransformer { thisPhase
                 if sym.isOpaqueAlias then
                   VarianceChecker.checkLambda(rhs, TypeBounds.upper(sym.opaqueAlias))
               case _ =>
-          processMemberDef(super.transform(tree))
+          processMemberDef(super.transform(scala2LibPatch(tree)))
         case tree: Bind =>
           if tree.symbol.isType && !tree.symbol.name.is(WildcardParamName) then
             Checking.checkGoodBounds(tree.symbol)
@@ -534,5 +534,21 @@ class PostTyper extends MacroTransform with IdentityDenotTransformer { thisPhase
         sym.addAnnotation(Annotation(defn.ExperimentalAnnot, sym.span))
         sym.companionModule.addAnnotation(Annotation(defn.ExperimentalAnnot, sym.span))
 
+    private def scala2LibPatch(tree: TypeDef)(using Context) =
+      val sym = tree.symbol
+      if ctx.settings.Yscala2Stdlib.value
+        && sym.isClass && sym.is(Module) && !sym.derivesFrom(defn.SerializableClass)
+        && sym.companionClass.derivesFrom(defn.SerializableClass)
+      then
+        // Add Serializable to companion objects of serializable classes
+        sym.info = sym.info match
+          case info: ClassInfo =>
+            info.derivedClassInfo(declaredParents = info.parents :+ defn.SerializableType)
+        tree.rhs match
+          case impl: Template =>
+            val parents1 = impl.parents :+ TypeTree(defn.SerializableType)
+            val impl1 = cpy.Template(impl)(parents = parents1)
+            cpy.TypeDef(tree)(rhs = impl1)
+      else tree
   }
 }

project/MiMaFilters.scala

@@ -51,7 +51,11 @@ object MiMaFilters {
 
         // Companion module class
         ProblemFilters.exclude[FinalClassProblem]("scala.*$"),
-        ProblemFilters.exclude[MissingTypesProblem]("scala.*$"),
+
+        // Missing types {scala.runtime.AbstractFunction1}
+        ProblemFilters.exclude[MissingTypesProblem]("scala.ScalaReflectionException$"),
+        ProblemFilters.exclude[MissingTypesProblem]("scala.UninitializedFieldError$"),
+        ProblemFilters.exclude[MissingTypesProblem]("scala.collection.StringView$"),
 
         // Tuples
         ProblemFilters.exclude[FinalClassProblem]("scala.Tuple1"),

project/TastyMiMaFilters.scala

@@ -76,7 +76,15 @@ object TastyMiMaFilters {
     ProblemMatcher.make(ProblemKind.MissingTermMember, "scala.*$default$*"), // To check (semantic names vs mangled name?)
 
     // Problem: Missing Serializable in companions of serializable classes
-    ProblemMatcher.make(ProblemKind.MissingParent, "scala.*$"),
+    ProblemMatcher.make(ProblemKind.MissingParent, "scala.collection.Searching.Found$"),
+    ProblemMatcher.make(ProblemKind.MissingParent, "scala.collection.Searching.InsertionPoint$"),
+    ProblemMatcher.make(ProblemKind.MissingParent, "scala.jdk.FunctionWrappers.AsJava*$"),
+    ProblemMatcher.make(ProblemKind.MissingParent, "scala.jdk.FunctionWrappers.FromJava*$"),
+
+    // Missing types {scala.runtime.AbstractFunction1}
+    ProblemMatcher.make(ProblemKind.MissingParent, "scala.ScalaReflectionException$"),
+    ProblemMatcher.make(ProblemKind.MissingParent, "scala.UninitializedFieldError$"),
+    ProblemMatcher.make(ProblemKind.MissingParent, "scala.collection.StringView$"),
 
     // Problem: Class[T] or ClassTag[T] return type
     ProblemMatcher.make(ProblemKind.IncompatibleTypeChange, "scala.*.getClass"),