fix ascription when extending from non-polymorphic trait with polymor…

…phic grandparent class (fix #456)
twitter · Jul 29, 2019 · ab32e2c · ab32e2c
1 parent 97637a9
commit ab32e2c
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Showing 3 changed files with 47 additions and 2 deletions.
diff --git a/scalafix/input/src/main/scala/rsc/tests/BetterRscCompat.scala b/scalafix/input/src/main/scala/rsc/tests/BetterRscCompat.scala
@@ -263,4 +263,24 @@ object BetterRscCompat_Test {
   object NestedTuples {
     val foo = (("1", 1), 1.0)
   }
+
+  object PolymorphicGrandparent {
+    class C[A]
+
+    abstract class D[A]
+
+    trait E[A]
+
+    trait T extends C[Int]
+
+    trait U extends D[Int]
+
+    trait V extends E[Int]
+
+    class F extends T
+
+    class G extends U
+
+    class H extends V
+  }
 }
diff --git a/scalafix/output/src/main/scala/rsc/tests/BetterRscCompat.scala b/scalafix/output/src/main/scala/rsc/tests/BetterRscCompat.scala
@@ -263,4 +263,24 @@ object BetterRscCompat_Test {
   object NestedTuples {
     val foo: ((String, Int), Double) = (("1", 1), 1.0)
   }
+
+  object PolymorphicGrandparent {
+    class C[A]
+
+    abstract class D[A]
+
+    trait E[A]
+
+    trait T extends C[Int]
+
+    trait U extends D[Int]
+
+    trait V extends E[Int]
+
+    class F extends T
+
+    class G extends U
+
+    class H extends V
+  }
 }
diff --git a/scalafix/rules/src/main/scala/rsc/rules/RscCompat.scala b/scalafix/rules/src/main/scala/rsc/rules/RscCompat.scala
@@ -15,6 +15,7 @@ import scala.meta.internal.{semanticdb => s}
 import scala.meta.internal.semanticdb.Scala._
 import scala.meta.internal.semanticdb.Scala.{Names => n}
 import scala.meta.internal.semanticdb.Scala.{Descriptor => d}
+import scala.meta.internal.semanticdb.SymbolInformation.Kind
 import scalafix.internal.v0._
 import scalafix.syntax._
 import scalafix.util.TokenOps
@@ -129,8 +130,12 @@ case class RscCompat(legacyIndex: SemanticdbIndex, config: RscCompatConfig)
           val name = templ.name.get
           inits.headOption.foreach { init =>
             val tokens = init.tpe.tokens
-            // If type params of init may be inferred
-            if (!tokens.exists(_.is[Token.LeftBracket])) {
+            lazy val isTrait = (for {
+              symbol <- init.symbol
+              info <- symbols.info(symbol.syntax)
+            } yield info.kind == Kind.TRAIT).get
+            // If type params of init may be inferred and init is not a trait
+            if (!tokens.exists(_.is[Token.LeftBracket]) && !isTrait) {
               buf += RewriteInit(env, name, tokens.last)
             }
           }