Generate only TASTy in stdlib-bootstrapped

.github/workflows/ci.yaml

@@ -134,7 +134,7 @@ jobs:
 
       - name: Cmd Tests
         run: |
-          ./project/scripts/sbt ";dist/pack; scala3-bootstrapped/compile; scala3-bootstrapped/test ;sbt-test/scripted scala2-compat/* ;stdlib-bootstrapped/test:run ;stdlib-bootstrapped-tasty-tests/test; scala3-compiler-bootstrapped/scala3CompilerCoursierTest:test"
+          ./project/scripts/sbt ";dist/pack; scala3-bootstrapped/compile; scala3-bootstrapped/test ;sbt-test/scripted scala2-compat/* ;stdlib-bootstrapped-tasty-tests/run ;stdlib-bootstrapped-tasty-tests/test; scala3-compiler-bootstrapped/scala3CompilerCoursierTest:test"
           ./project/scripts/cmdTests
           ./project/scripts/bootstrappedOnlyCmdTests
 
@@ -488,7 +488,7 @@ jobs:
 
       - name: Test
         run: |
-          ./project/scripts/sbt ";dist/pack ;scala3-bootstrapped/compile ;scala3-bootstrapped/test ;sbt-test/scripted scala2-compat/* ;stdlib-bootstrapped/test:run ;stdlib-bootstrapped-tasty-tests/test"
+          ./project/scripts/sbt ";dist/pack ;scala3-bootstrapped/compile ;scala3-bootstrapped/test ;sbt-test/scripted scala2-compat/* ;stdlib-bootstrapped-tasty-tests/run ;stdlib-bootstrapped-tasty-tests/test"
           ./project/scripts/cmdTests
           ./project/scripts/bootstrappedOnlyCmdTests
 

build.sbt

@@ -15,6 +15,7 @@ val `scala3-bench` = Build.`scala3-bench`
 val `scala3-bench-bootstrapped` = Build.`scala3-bench-bootstrapped`
 val `scala3-bench-micro` = Build.`scala3-bench-micro`
 val `stdlib-bootstrapped` = Build.`stdlib-bootstrapped`
+val `stdlib-bootstrapped-tasty` = Build.`stdlib-bootstrapped-tasty`
 val `stdlib-bootstrapped-tasty-tests` = Build.`stdlib-bootstrapped-tasty-tests`
 val `tasty-core` = Build.`tasty-core`
 val `tasty-core-bootstrapped` = Build.`tasty-core-bootstrapped`

project/Build.scala

@@ -936,7 +936,7 @@ object Build {
     dependsOn(dottyCompiler(Bootstrapped) % "provided; compile->runtime; test->test").
     settings(commonBootstrappedSettings).
     settings(
-      moduleName := "scala-library",
+      moduleName := "scala2-library",
       javaOptions := (`scala3-compiler-bootstrapped` / javaOptions).value,
       Compile / scalacOptions ++= {
         Seq("-sourcepath", ((Compile/sourceManaged).value / "scala-library-src").toString)
@@ -1025,10 +1025,10 @@ object Build {
              |""".stripMargin)
 
       }).value,
-      // TODO package only TASTy files.
-      // We first need to check that a project can depend on a JAR that only contains TASTy files.
-      // Compile / exportJars := true,
-      // Compile / packageBin / mappings ~= { _.filter(_._2.endsWith(".tasty")) },
+      Compile / exportJars := true,
+      artifactName := { (sv: ScalaVersion, module: ModuleID, artifact: Artifact) =>
+        "scala2-library-" + dottyVersion + "." + artifact.extension
+      },
       run := {
         val log = streams.value.log
         val args: Seq[String] = spaceDelimited("<arg>").parsed
@@ -1077,7 +1077,21 @@ object Build {
       }
     )
 
+  /** Packages the TASTy files of `stdlib-bootstrapped` in a jar */
+  lazy val `stdlib-bootstrapped-tasty` = project.in(file("stdlib-bootstrapped-tasty")).
+    withCommonSettings(Bootstrapped).
+    settings(
+      exportJars := true,
+      Compile / packageBin / mappings := {
+        (`stdlib-bootstrapped` / Compile / packageBin / mappings).value
+          .filter(_._2.endsWith(".tasty"))
+      },
+    )
+
   /** Test the tasty generated by `stdlib-bootstrapped`
+   *
+   *  The sources in src are compiled using TASTy from stdlib-bootstrapped-tasty but then run
+   *  with the scala-library compiled be Scala 2.
    *
    *  The tests are run with the bootstrapped compiler and the tasty inpector on the classpath.
    *  The classpath has the default `scala-library` and not `stdlib-bootstrapped`.
@@ -1088,11 +1102,23 @@ object Build {
    */
   lazy val `stdlib-bootstrapped-tasty-tests` = project.in(file("stdlib-bootstrapped-tasty-tests")).
     withCommonSettings(Bootstrapped).
+    dependsOn(dottyCompiler(Bootstrapped) % "compile->compile").
     dependsOn(`scala3-tasty-inspector` % "test->test").
+    dependsOn(`stdlib-bootstrapped-tasty`).
     settings(commonBootstrappedSettings).
     settings(
       javaOptions := (`scala3-compiler-bootstrapped` / javaOptions).value,
-      javaOptions += "-Ddotty.scala.library=" + (`stdlib-bootstrapped` / Compile / packageBin).value.getAbsolutePath
+      Test / javaOptions += "-Ddotty.scala.library=" + (`stdlib-bootstrapped` / Compile / packageBin).value.getAbsolutePath,
+      Compile / compile / fullClasspath ~= {
+        _.filterNot(file => file.data.getName == s"scala-library-${stdlibVersion(Bootstrapped)}.jar")
+      },
+      Compile / compile / dependencyClasspath := {
+        // make sure that the scala2-library (tasty of `stdlib-bootstrapped-tasty`) is listed before the scala-library (classfiles)
+        val (bootstrappedLib, otherLibs) =
+          (Compile / compile / dependencyClasspath).value
+            .partition(_.data.getName == s"scala2-library-${dottyVersion}.jar")
+        bootstrappedLib ++ otherLibs
+      },
     )
 
   lazy val `scala3-sbt-bridge` = project.in(file("sbt-bridge/src")).