Fix: Scalafix rename that leads to a name collision breaks compilation …

…scalacenter#1305

scalafix-core/src/main/scala/scalafix/internal/patch/ReplaceSymbolOps.scala

@@ -10,6 +10,8 @@ import scalafix.patch.Patch
 import scalafix.patch.Patch.internal.ReplaceSymbol
 import scalafix.syntax._
 import scalafix.v0._
+import scala.annotation.tailrec
+
 
 object ReplaceSymbolOps {
   private object Select {
@@ -19,6 +21,20 @@ object ReplaceSymbolOps {
       case _ => None
     }
   }
+  private def extractImports(stats: Seq[Stat]): Seq[Import] = {
+    stats
+      .takeWhile(_.is[Import])
+      .collect { case i: Import => i }
+  }
+
+  @tailrec private final def getGlobalImports(ast: Tree): Seq[Import] =
+    ast match {
+      case Pkg(_, Seq(pkg: Pkg)) => getGlobalImports(pkg)
+      case Source(Seq(pkg: Pkg)) => getGlobalImports(pkg)
+      case Pkg(_, stats) => extractImports(stats)
+      case Source(stats) => extractImports(stats)
+      case _ => Nil
+    }
 
   def naiveMoveSymbolPatch(
       moveSymbols: Seq[ReplaceSymbol]
@@ -92,6 +108,7 @@ object ReplaceSymbolOps {
         case _ => None
       }
     }
+
     val patches = ctx.tree.collect { case n @ Move(to) =>
       // was this written as `to = "blah"` instead of `to = _root_.blah`
       val isSelected = to match {
@@ -126,10 +143,20 @@ object ReplaceSymbolOps {
             if sig.name != parent.value =>
           Patch.empty // do nothing because it was a renamed symbol
         case Some(parent) =>
+          val causesCollision = getGlobalImports(ctx.tree).exists { importStmt =>
+            importStmt.importers.flatMap(_.importees).exists {
+              case Importee.Name(name) => name.value == to.signature.name
+              case Importee.Rename(_, rename) => rename.value == to.signature.name
+              case _ => false
+            }
+          }
           val addImport =
-            if (n.isDefinition) Patch.empty
+            if (n.isDefinition || causesCollision) Patch.empty
             else ctx.addGlobalImport(to)
-          addImport + ctx.replaceTree(n, to.signature.name)
+          if(causesCollision)
+            addImport + ctx.replaceTree(n, to.owner.syntax + to.signature.name)
+          else
+            addImport + ctx.replaceTree(n, to.signature.name)
         case _ =>
           Patch.empty
       }

scalafix-tests/input/src/main/scala-2/test/ReplaceSymbol.scala

@@ -12,6 +12,8 @@ patches.replaceSymbols = [
     to = "com.geirsson.mutable.CoolBuffer" }
   { from = "scala.collection.mutable.HashMap"
     to = "com.geirsson.mutable.unsafe.CoolMap" }
+  { from = "scala.collection.immutable.TreeMap"
+    to = "com.geirsson.immutable.SortedMap" }
   { from = "scala.math.sqrt"
     to = "com.geirsson.fastmath.sqrt" }
   // normalized symbol renames all overloaded methods
@@ -29,6 +31,8 @@ patches.replaceSymbols = [
  */
 package fix
 
+import scala.collection.immutable.SortedMap
+import scala.collection.immutable.TreeMap
 import scala.collection.mutable.HashMap
 import scala.collection.mutable.ListBuffer
 import scala.collection.mutable
@@ -42,8 +46,9 @@ object ReplaceSymbol {
   "blah".substring(1)
   "blah".substring(1, 2)
   val u: mutable.HashMap[Int, Int] = HashMap.empty[Int, Int]
+  val v: SortedMap[Int, Int] = TreeMap.empty[Int, Int]
   val x: ListBuffer[Int] = ListBuffer.empty[Int]
   val y: mutable.ListBuffer[Int] = mutable.ListBuffer.empty[Int]
   val z: scala.collection.mutable.ListBuffer[Int] =
     scala.collection.mutable.ListBuffer.empty[Int]
-}
+}

scalafix-tests/output/src/main/scala-2/com/geirsson/mutable/immutable.scala

@@ -0,0 +1,11 @@
+package com.geirsson
+
+import scala.collection.immutable.TreeMap
+
+package object immutable {
+  type SortedMap[A, B] = TreeMap[A, B]
+
+  object SortedMap {
+    def empty[A : Ordering, B]: SortedMap[A, B] = TreeMap.empty[A, B]
+  }
+}

scalafix-tests/output/src/main/scala-2/test/ReplaceSymbol.scala

@@ -1,5 +1,6 @@
 package fix
 
+import scala.collection.immutable.SortedMap
 import com.geirsson.Future
 import com.geirsson.{ fastmath, mutable }
 import com.geirsson.mutable.{ CoolBuffer, unsafe }
@@ -13,8 +14,9 @@ object ReplaceSymbol {
   "blah".substringFrom(1)
   "blah".substringBetween(1, 2)
   val u: unsafe.CoolMap[Int, Int] = CoolMap.empty[Int, Int]
+  val v: SortedMap[Int, Int] = com.geirsson.immutable.SortedMap.empty[Int, Int]
   val x: CoolBuffer[Int] = CoolBuffer.empty[Int]
   val y: mutable.CoolBuffer[Int] = mutable.CoolBuffer.empty[Int]
   val z: com.geirsson.mutable.CoolBuffer[Int] =
     com.geirsson.mutable.CoolBuffer.empty[Int]
-}
+}