Merge pull request scala#4588 from retronym/topic/icodish

GenBCode: fix incrementatal compilation by mimicing GenASM

src/compiler/scala/tools/nsc/backend/jvm/GenBCode.scala

@@ -167,6 +167,11 @@ abstract class GenBCode extends BCodeSyncAndTry {
             )
         }
 
+        // shim for SBT, see https://github.com/sbt/sbt/issues/2076
+        // TODO put this closer to classfile writing once we have closure elimination
+        // TODO create a nicer public API to find out the correspondence between sourcefile and ultimate classfiles
+        currentUnit.icode += new icodes.IClass(cd.symbol)
+
         // -------------- mirror class, if needed --------------
         val mirrorC =
           if (isTopLevelModuleClass(claszSymbol)) {

test/files/run/sbt-icode-interface.scala

@@ -0,0 +1,42 @@
+import scala.tools.partest._
+import scala.tools.nsc._
+
+object Test extends DirectTest {
+
+  def code = """
+    class C { class D }
+    object O
+  """.trim
+
+  def show() {
+    for (b <- List("GenASM", "GenBCode")) {
+      val global = newCompiler("-usejavacp", s"-Ybackend:$b")
+      import global._
+      val r = new Run
+      r.compileSources(newSourceFile(code) :: Nil)
+
+      val results = collection.mutable.Buffer[(Boolean, String)]()
+
+      // Nailing down defacto compiler API from SBT's usage
+      // https://github.com/sbt/sbt/blob/adb41611cf73260938274915d8462d924df200c8/compile/interface/src/main/scala/xsbt/Analyzer.scala#L29-L41
+      def isTopLevelModule(sym: Symbol) = sym.isTopLevel && sym.isModule
+      for (unit <- currentRun.units if !unit.isJava) {
+        val sourceFile = unit.source.file.file
+        for (iclass <- unit.icode) {
+          val sym = iclass.symbol
+          def addGenerated(separatorRequired: Boolean) {
+            results += (separatorRequired -> sym.fullName)
+          }
+          if (sym.isModuleClass && !sym.isImplClass) {
+            if (isTopLevelModule(sym) && sym.companionClass == NoSymbol)
+              addGenerated(false)
+            addGenerated(true)
+          } else
+            addGenerated(false)
+        }
+      }
+      val expected = List((false, "C"), (true, "O"), (false, "C$D"))
+      assert(results.toList == expected, b + ": " + results.toList)
+    }
+  }
+}