Rewrite mutable.Set/Map no longer have a + operation

Author: MasseGuillaume

scalafix/input/src/main/scala/fix/MutSetMapSrc.scala

@@ -0,0 +1,11 @@
+/*
+rule = "scala:fix.Scalacollectioncompat_newcollections"
+ */
+package fix
+
+import scala.collection.mutable
+
+class MutSetMapSrc(map: mutable.Map[Int, Int], set: mutable.Set[Int]) {
+  set + 2
+  map + (2 -> 3)
+}

scalafix/output/src/main/scala/fix/MutSetMapSrc.scala

@@ -0,0 +1,11 @@
+
+
+
+package fix
+
+import scala.collection.mutable
+
+class MutSetMapSrc(map: mutable.Map[Int, Int], set: mutable.Set[Int]) {
+  set.clone() += 2
+  map.clone() += (2 -> 3)
+}

scalafix/rules/src/main/scala/fix/Scalacollectioncompat_newcollections.scala

@@ -29,6 +29,12 @@ case class Scalacollectioncompat_newcollections(index: SemanticdbIndex)
     Symbol("_root_.scala.runtime.Tuple2Zipped.Ops.zipped."),
     Symbol("_root_.scala.runtime.Tuple3Zipped.Ops.zipped.")
   )
+  val mutSetPlus = SymbolMatcher.exact(
+    Symbol("_root_.scala.collection.mutable.SetLike#`+`(Ljava/lang/Object;)Lscala/collection/mutable/Set;.")
+  )
+  val mutMapPlus = SymbolMatcher.exact(
+    Symbol("_root_.scala.collection.mutable.MapLike#`+`(Lscala/Tuple2;)Lscala/collection/mutable/Map;.")
+  )
   def foldSymbol(isLeft: Boolean): SymbolMatcher = {
     val op = 
       if (isLeft) "/:"
@@ -156,6 +162,21 @@ case class Scalacollectioncompat_newcollections(index: SemanticdbIndex)
         ctx.replaceTree(t, "lazyAppendedAll")
     }.asPatch
 
+  def replaceMutSetMapPlus(ctx: RuleCtx): Patch = {
+    def rewriteMutPlus(lhs: Term, op: Term.Name): Patch = {
+      ctx.addRight(lhs, ".clone()") +
+      ctx.addRight(op, "=")
+    }
+
+    ctx.tree.collect {
+      case Term.ApplyInfix(lhs, op @ mutSetPlus(_), _, List(_)) =>
+        rewriteMutPlus(lhs, op)
+
+      case Term.ApplyInfix(lhs, op @ mutMapPlus(_), _, List(_)) =>
+        rewriteMutPlus(lhs, op)
+    }.asPatch
+  }
+
   override def fix(ctx: RuleCtx): Patch = {
     // println(ctx.index.database)
 
@@ -166,6 +187,7 @@ case class Scalacollectioncompat_newcollections(index: SemanticdbIndex)
       replaceStreamAppend(ctx) +
       replaceMutableMap(ctx) + 
       replaceMutableSet(ctx) +
-      replaceSymbolicFold(ctx)
+      replaceSymbolicFold(ctx) +
+      replaceMutSetMapPlus(ctx)
   }
 }