Fix copying tasty files on incremental compilation

backend/src/main/scala/bloop/BloopClassFileManager.scala

@@ -180,14 +180,21 @@ final class BloopClassFileManager(
       // invalidations can happen in both paths, no-op if missing
       allInvalidatedClassFilesForProject.-=(generatedClassFile)
       allInvalidatedClassFilesForProject.-=(rebasedClassFile)
-      supportedCompileProducts.foreach { supportedProductSuffix =>
-        val productName = rebasedClassFile
+
+      def productFile(classFile: File, supportedProductSuffix: String) = {
+        val productName = classFile
           .getName()
           .stripSuffix(".class") + supportedProductSuffix
-        val productAssociatedToClassFile =
-          new File(rebasedClassFile.getParentFile, productName)
-        if (productAssociatedToClassFile.exists())
-          allInvalidatedExtraCompileProducts.-=(productAssociatedToClassFile)
+        new File(classFile.getParentFile, productName)
+      }
+      supportedCompileProducts.foreach { supportedProductSuffix =>
+        val generatedProductName = productFile(generatedClassFile, supportedProductSuffix)
+        val rebasedProductName = productFile(rebasedClassFile, supportedProductSuffix)
+
+        if (generatedProductName.exists() || rebasedProductName.exists()) {
+          allInvalidatedExtraCompileProducts.-=(generatedProductName)
+          allInvalidatedExtraCompileProducts.-=(rebasedProductName)
+        }
       }
     }
 

frontend/src/test/scala/bloop/BaseCompileSpec.scala

@@ -140,6 +140,38 @@ abstract class BaseCompileSpec extends bloop.testing.BaseSuite {
     }
   }
 
+  test(s"compile scala 3 build incrementally") {
+    TestUtil.withinWorkspace { workspace =>
+      object Sources {
+        val `A.scala` =
+          """/A.scala
+            |class A { def a = 1 }
+          """.stripMargin
+
+        val `A2.scala` =
+          """/A.scala
+            |class A { def a = 2 }
+          """.stripMargin
+      }
+
+      val logger = new RecordingLogger(ansiCodesSupported = false)
+      val `A` = TestProject(workspace, "a", List(Sources.`A.scala`), scalaVersion = Some("3.1.1"))
+      val projects = List(`A`)
+      val state = loadState(workspace, projects, logger)
+      val compiledState = state.compile(`A`)
+      assertExitStatus(compiledState, ExitStatus.Ok)
+      assertValidCompilationState(compiledState, projects)
+
+      assertIsFile(writeFile(`A`.srcFor("A.scala"), Sources.`A2.scala`))
+
+      val secondCompiledState = compiledState.compile(`A`)
+      assertExitStatus(secondCompiledState, ExitStatus.Ok)
+      assertSuccessfulCompilation(secondCompiledState, projects, isNoOp = false)
+      assertValidCompilationState(secondCompiledState, projects)
+      assertSameExternalClassesDirs(compiledState, secondCompiledState, projects)
+    }
+  }
+
   test("compile project / clean / compile it again") {
     TestUtil.withinWorkspace { workspace =>
       val sources = List(

frontend/src/test/scala/bloop/testing/BaseSuite.scala

@@ -425,7 +425,6 @@ abstract class BaseSuite extends TestSuite with BloopHelpers {
         val stamps = analysis.readStamps
         assert(stamps.getAllProductStamps.asScala.nonEmpty)
         assert(stamps.getAllSourceStamps.asScala.nonEmpty)
-        //assert(stamps.getAllBinaryStamps.asScala.nonEmpty)
 
         assert(takeDirectorySnapshot(latestResult.classesDir).nonEmpty)
         val projectClassesDir =

frontend/src/test/scala/bloop/util/TestProject.scala

@@ -124,7 +124,12 @@ abstract class BaseTestProject {
     val version = scalaVersion.getOrElse(Properties.versionNumberString)
 
     val finalScalaOrg = scalaOrg.getOrElse("org.scala-lang")
-    val finalScalaCompiler = scalaCompiler.getOrElse("scala-compiler")
+    val finalScalaCompiler = scalaCompiler.getOrElse {
+      if (version.startsWith("3."))
+        "scala3-compiler_3"
+      else
+        "scala-compiler"
+    }
     val instance =
       mkScalaInstance(finalScalaOrg, finalScalaCompiler, scalaVersion, jars.toList, NoopLogger)