Merge pull request #564 from http4s/scala-2.12.15

Update Scala 2.12 to `2.12.15`

.github/workflows/ci.yml

@@ -27,7 +27,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest]
-        scala: [2.12.14, 2.13.6, 3.0.2]
+        scala: [2.12.15, 2.13.6, 3.0.2]
         java: [[email protected]]
     runs-on: ${{ matrix.os }}
     steps:

build.sbt

@@ -13,7 +13,11 @@ ThisBuild / versionIntroduced := Map(
   "3.0.0-RC3" -> "0.15.0"
 )
 
-ThisBuild / crossScalaVersions := Seq("2.12.14", "2.13.6", "3.0.2")
+val Scala212 = "2.12.15"
+val Scala213 = "2.13.6"
+val Scala3 = "3.0.2"
+
+ThisBuild / crossScalaVersions := Seq(Scala212, Scala213, Scala3)
 ThisBuild / scalaVersion := crossScalaVersions.value.filter(_.startsWith("2.")).last
 
 lazy val commonSettings = Seq(
@@ -56,7 +60,14 @@ lazy val commonSettings = Seq(
       Some("scm:git:[email protected]:http4s/blaze.git")
     )
   ),
-  startYear := Some(2014)
+  startYear := Some(2014),
+  libraryDependencies ++= (
+    if (ScalaArtifacts.isScala3(scalaVersion.value)) Nil
+    else
+      Seq(
+        compilerPlugin(kindProjector.cross(CrossVersion.full))
+      )
+  )
 )
 
 ThisBuild / githubWorkflowJavaVersions := Seq("[email protected]")

project/Dependencies.scala

@@ -7,4 +7,5 @@ object Dependencies {
   lazy val log4s = "org.log4s" %% "log4s" % "1.10.0"
   lazy val munit = "org.scalameta" %% "munit" % "0.7.27"
   lazy val scalacheckMunit = "org.scalameta" %% "munit-scalacheck" % munit.revision
+  lazy val kindProjector = "org.typelevel" % "kind-projector" % "0.13.2"
 }