Support 2.11.12 by using old cats (#211)

* Support 2.11.12 by using old cats

* don't do js for scala 2.11

* try to fix a compile warning

* disable patmat analysis, mima

* disable mima for 2.11

* remove commented code.

.github/workflows/ci.yml

@@ -26,7 +26,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        scala: [3.0.0-RC2, 3.0.0-RC3, 2.12.13, 2.13.5]
+        scala: [3.0.0-RC2, 3.0.0-RC3, 2.11.12, 2.12.13, 2.13.5]
         java: [adopt@1.8]
     runs-on: ${{ matrix.os }}
     steps:
@@ -122,6 +122,16 @@ jobs:
           tar xf targets.tar
           rm targets.tar
 
+      - name: Download target directories (2.11.12)
+        uses: actions/download-artifact@v2
+        with:
+          name: target-${{ matrix.os }}-2.11.12-${{ matrix.java }}
+
+      - name: Inflate target directories (2.11.12)
+        run: |
+          tar xf targets.tar
+          rm targets.tar
+
       - name: Download target directories (2.12.13)
         uses: actions/download-artifact@v2
         with:

build.sbt

@@ -14,12 +14,7 @@ ThisBuild / organizationName := "Typelevel"
 ThisBuild / publishGithubUser := "johnynek"
 ThisBuild / publishFullName := "P. Oscar Boykin"
 
-ThisBuild / crossScalaVersions := List("3.0.0-RC2", "3.0.0-RC3", "2.12.13", "2.13.5")
-
-ThisBuild / versionIntroduced := Map(
-  "3.0.0-M2" -> "0.1.99",
-  "3.0.0-M3" -> "0.1.99"
-)
+ThisBuild / crossScalaVersions := List("3.0.0-RC2", "3.0.0-RC3", "2.11.12", "2.12.13", "2.13.5")
 
 ThisBuild / spiewakCiReleaseSnapshots := true
 
@@ -122,15 +117,27 @@ lazy val core = crossProject(JSPlatform, JVMPlatform)
   .crossType(CrossType.Full)
   .settings(
     name := "cats-parse",
-    libraryDependencies ++=
+    libraryDependencies ++= {
+      val isScala211 = CrossVersion.partialVersion(scalaVersion.value).contains((2, 11))
       Seq(
-        cats.value,
+        if (isScala211) cats211.value else cats.value,
         munit.value % Test,
         munitScalacheck.value % Test
       )
+    },
+    scalacOptions ++= {
+      val isScala211 = CrossVersion.partialVersion(scalaVersion.value).contains((2, 11))
+      // this code seems to trigger a bug in 2.11 pattern analysis
+      if (isScala211) List("-Xno-patmat-analysis") else Nil
+    },
+    mimaPreviousArtifacts := {
+      val isScala211 = CrossVersion.partialVersion(scalaVersion.value).contains((2, 11))
+      if (isScala211) Set.empty else mimaPreviousArtifacts.value
+    }
   )
   .settings(dottyJsSettings(ThisBuild / crossScalaVersions))
   .jsSettings(
+    crossScalaVersions := (ThisBuild / crossScalaVersions).value.filterNot(_.startsWith("2.11")),
     Global / scalaJSStage := FastOptStage,
     parallelExecution := false,
     jsEnv := new org.scalajs.jsenv.nodejs.NodeJSEnv(),
@@ -150,7 +157,9 @@ lazy val bench = project
   .settings(
     name := "bench",
     coverageEnabled := false,
-    crossScalaVersions := (ThisBuild / crossScalaVersions).value.filter(_.startsWith("2.")),
+    crossScalaVersions := (ThisBuild / crossScalaVersions).value.filter { v =>
+      v.startsWith("2.12") || v.startsWith("2.13")
+    },
     libraryDependencies ++=
       Seq(
         fastParse,

core/shared/src/main/scala/cats/parse/Parser.scala

@@ -1803,9 +1803,6 @@ object Parser {
       override def defer[A](pa: => Parser[A]): Parser[A] =
         Parser.this.defer(pa)
 
-      override def fix[A](fn: Parser[A] => Parser[A]): Parser[A] =
-        Parser.recursive(fn)
-
       override def functor = this
 
       override def map[A, B](fa: Parser[A])(fn: A => B): Parser[B] =
@@ -1817,9 +1814,6 @@ object Parser {
       override def filter[A](fa: Parser[A])(fn: A => Boolean): Parser[A] =
         fa.filter(fn)
 
-      override def filterNot[A](fa: Parser[A])(fn: A => Boolean): Parser[A] =
-        fa.filter { a => !fn(a) }
-
       override def flatMap[A, B](fa: Parser[A])(fn: A => Parser[B]): Parser[B] =
         Parser.this.flatMap10(fa)(fn)
 
@@ -2894,9 +2888,6 @@ object Parser0 {
       override def filter[A](fa: Parser0[A])(fn: A => Boolean): Parser0[A] =
         fa.filter(fn)
 
-      override def filterNot[A](fa: Parser0[A])(fn: A => Boolean): Parser0[A] =
-        fa.filter { a => !fn(a) }
-
       override def product[A, B](fa: Parser0[A], fb: Parser0[B]): Parser0[(A, B)] =
         Parser.product0(fa, fb)
 

core/shared/src/test/scala/cats/parse/ParserTest.scala

@@ -1117,11 +1117,15 @@ class ParserTest extends munit.ScalaCheckSuite {
   property("rep0 can be reimplemented with oneOf0 and defer") {
     forAll(ParserGen.gen, Arbitrary.arbitrary[String]) { (genP, str) =>
       def rep0[A](pa: Parser[A]): Parser0[List[A]] =
-        Defer[Parser0].fix[List[A]] { tail =>
-          (pa ~ tail)
-            .map { case (h, t) => h :: t }
-            .orElse(Parser.pure(Nil))
-        }
+        Parser
+          .recursive[List[A]] { tail =>
+            (pa ~ tail.?)
+              .map {
+                case (h, Some(t)) => h :: t
+                case (h, None) => h :: Nil
+              }
+          }
+          .orElse(Parser.pure(Nil))
 
       val lst1 = rep0(genP.fa)
       val lst2 = genP.fa.rep0

project/Dependencies.scala

@@ -3,6 +3,7 @@ import org.portablescala.sbtplatformdeps.PlatformDepsPlugin.autoImport._
 
 object Dependencies {
   lazy val cats = Def.setting("org.typelevel" %%% "cats-core" % "2.6.0")
+  lazy val cats211 = Def.setting("org.typelevel" %%% "cats-core" % "2.0.0")
   lazy val munit = Def.setting("org.scalameta" %%% "munit" % "0.7.25")
   lazy val munitScalacheck = Def.setting("org.scalameta" %%% "munit-scalacheck" % "0.7.25")
   lazy val fastParse = "com.lihaoyi" %% "fastparse" % "2.3.2"