optimization

Summary: - if a type alias doesn't have parameters, there is no need to copy-paste its body (`Subst.subst` with an empty substitution will traverse and copy the structure)

Reviewed By: robertoaloi

Differential Revision: D60760134

fbshipit-source-id: 6ee5cf7a304445ace324c35cfb0dc50386552e00

eqwalizer/src/main/scala/com/whatsapp/eqwalizer/tc/Util.scala

@@ -92,10 +92,13 @@ class Util(pipelineContext: PipelineContext) {
       case _ =>
     }
     val id = Id(remoteId.name, remoteId.arity)
-    def applyType(decl: TypeDecl): Type = {
-      val subst = decl.params.zip(args).map { case (VarType(n), ty) => n -> ty }.toMap
-      Subst.subst(subst, decl.body)
-    }
+    def applyType(decl: TypeDecl): Type =
+      if (id.arity == 0)
+        decl.body
+      else {
+        val subst = decl.params.zip(args).map { case (VarType(n), ty) => n -> ty }.toMap
+        Subst.subst(subst, decl.body)
+      }
 
     DbApi
       .getType(remoteId.module, id)