Introduce the Scala version into the codegen cache namespace (#1590)

* add a failing sbt scripted test to demonstrate #1589
* add the Scala version to the caches used by codegen
* properly isolate the cache stores

modules/codegen-plugin/src/sbt-test/codegen-plugin/cross-builds/build.sbt

@@ -0,0 +1,8 @@
+lazy val root = (project in file("."))
+  .enablePlugins(Smithy4sCodegenPlugin)
+  .settings(
+    crossScalaVersions := Seq("2.13.15", "3.3.3"),
+    libraryDependencies ++= Seq(
+      "com.disneystreaming.smithy4s" %% "smithy4s-core" % smithy4sVersion.value
+    )
+  )

modules/codegen-plugin/src/sbt-test/codegen-plugin/cross-builds/project/build.properties

@@ -0,0 +1 @@
+sbt.version=1.8.0

modules/codegen-plugin/src/sbt-test/codegen-plugin/cross-builds/project/plugins.sbt

@@ -0,0 +1,9 @@
+sys.props.get("plugin.version") match {
+  case Some(x) =>
+    addSbtPlugin("com.disneystreaming.smithy4s" % "smithy4s-sbt-codegen" % x)
+  case _ =>
+    sys.error(
+      """|The system property 'plugin.version' is not defined.
+         |Specify this property using the scriptedLaunchOpts -D.""".stripMargin
+    )
+}

modules/codegen-plugin/src/sbt-test/codegen-plugin/cross-builds/src/main/smithy/simple.smithy

@@ -0,0 +1,3 @@
+namespace smithy4s.example
+
+structure Simple {}

modules/codegen-plugin/src/sbt-test/codegen-plugin/cross-builds/test

@@ -0,0 +1,19 @@
+# generate for Scala 2.13
+> ++ 2.13
+> compile
+
+$ exists target/scala-2.13/src_managed/main/smithy/generated-metadata.smithy
+$ exists target/scala-2.13/src_managed/main/smithy4s/smithy4s/example/Simple.scala
+
+> ++ 3
+> compile
+
+$ exists target/scala-3.3.3/src_managed/main/smithy/generated-metadata.smithy
+$ exists target/scala-3.3.3/src_managed/main/smithy4s/smithy4s/example/Simple.scala
+
+# switch back to Scala 2.13 and compile again; codegen should not happen a second time
+> ++ 2.13
+> compile
+
+$ newer target/scala-3.3.3/src_managed/main/smithy/generated-metadata.smithy target/scala-2.13/src_managed/main/smithy/generated-metadata.smithy
+$ newer target/scala-3.3.3/src_managed/main/smithy4s/smithy4s/example/Simple.scala target/scala-2.13/src_managed/main/smithy4s/smithy4s/example/Simple.scala

modules/codegen-plugin/src/smithy4s/codegen/Smithy4sCodegenPlugin.scala

@@ -264,7 +264,8 @@ object Smithy4sCodegenPlugin extends AutoPlugin {
       (config / sourceManaged).value / "smithy" / "generated-metadata.smithy"
     },
     config / smithy4sGeneratedSmithyFiles := {
-      val cacheFactory = (config / streams).value.cacheStoreFactory
+      val cacheFactory =
+        (config / streams).value.cacheStoreFactory.sub(scalaVersion.value)
       val cached = Tracked.inputChanged[(String, Boolean), Seq[File]](
         cacheFactory.make("smithy4sGeneratedSmithyFilesInput")
       ) { case (changed, (wildcardArg, shouldGenerateOptics)) =>
@@ -454,14 +455,15 @@ object Smithy4sCodegenPlugin extends AutoPlugin {
       smithyBuild = smithyBuildValue
     )
 
+    val cacheStoreFactory = s.cacheStoreFactory.sub(scalaVersion.value)
     val cached =
       CachedTask.inputChanged[CodegenArgs, Seq[File]](
-        s.cacheStoreFactory.make("input"),
+        cacheStoreFactory.make("input"),
         s.log
       ) {
         Function.untupled {
           Tracked.lastOutput[(Boolean, CodegenArgs), Seq[File]](
-            s.cacheStoreFactory.make("output")
+            cacheStoreFactory.make("output")
           ) { case ((inputChanged, args), outputs) =>
             if (inputChanged || outputs.isEmpty) {
               s.log.debug(s"[smithy4s] Input changed: $inputChanged")