Keep line numbers when inlining from the same compilation unit

So far, line numbers were kept only when inlining from the same class.
We can also keep them when inlining from a different class defined in
the same compilation unit.

Longer-term we should support JSR-45, see SI-7518 and scala-dev#3.

3 files changed, 58 insertions, 3 deletions

diff --git a/src/compiler/scala/tools/nsc/backend/jvm/opt/Inliner.scala b/src/compiler/scala/tools/nsc/backend/jvm/opt/Inliner.scala
index d18963ec8b..7b4cfe2a18 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/opt/Inliner.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/opt/Inliner.scala
@@ -253,7 +253,7 @@ class Inliner[BT <: BTypes](val btypes: BT) {
   def inlineCallsite(callsite: Callsite): Unit = {
     import callsite.{callsiteClass, callsiteMethod, callsiteInstruction, receiverKnownNotNull, callsiteStackHeight}
     val Right(callsiteCallee) = callsite.callee
-    import callsiteCallee.{callee, calleeDeclarationClass}
+    import callsiteCallee.{callee, calleeDeclarationClass, sourceFilePath}
 
     // Inlining requires the callee not to have unreachable code, the analyzer used below should not
     // return any `null` frames. Note that inlining a method can create unreachable code. Example:
@@ -268,7 +268,14 @@ class Inliner[BT <: BTypes](val btypes: BT) {
 
     // New labels for the cloned instructions
     val labelsMap = cloneLabels(callee)
-    val (clonedInstructions, instructionMap, hasSerializableClosureInstantiation) = cloneInstructions(callee, labelsMap, keepLineNumbers = callsiteClass == calleeDeclarationClass)
+    val sameSourceFile = sourceFilePath match {
+      case Some(calleeSource) => byteCodeRepository.compilingClasses.get(callsiteClass.internalName) match {
+        case Some((_, `calleeSource`)) => true
+        case _ => false
+      }
+      case _ => false
+    }
+    val (clonedInstructions, instructionMap, hasSerializableClosureInstantiation) = cloneInstructions(callee, labelsMap, keepLineNumbers = sameSourceFile)
 
     // local vars in the callee are shifted by the number of locals at the callsite
     val localVarShift = callsiteMethod.maxLocals
diff --git a/test/junit/scala/tools/nsc/backend/jvm/opt/InlinerTest.scala b/test/junit/scala/tools/nsc/backend/jvm/opt/InlinerTest.scala
index 9b538573dc..9173a1d189 100644
--- a/test/junit/scala/tools/nsc/backend/jvm/opt/InlinerTest.scala
+++ b/test/junit/scala/tools/nsc/backend/jvm/opt/InlinerTest.scala
@@ -1526,4 +1526,52 @@ class InlinerTest extends BytecodeTesting {
     val c :: _ = compileClassesSeparately(codes, extraArgs = compilerArgs)
     assertInvoke(getMethod(c, "t"), "p1/Implicits$RichFunction1$", "toRx$extension")
   }
+
+  @Test
+  def keepLineNumbersPerCompilationUnit(): Unit = {
+    val code1 =
+      """class A {
+        |  def fx(): Unit = ()
+        |  @inline final def ma = {
+        |    fx()
+        |    1
+        |  }
+        |}
+      """.stripMargin
+    val code2 =
+      """class B extends A {
+        |  @inline final def mb = {
+        |    fx()
+        |    1
+        |  }
+        |}
+        |class C extends B {
+        |  @inline final def mc = {
+        |    fx()
+        |    1
+        |  }
+        |  def t1 = ma // no lines, not the same source file
+        |  def t2 = mb // lines
+        |  def t3 = mc // lines
+        |}
+      """.stripMargin
+    notPerRun.foreach(_.clear())
+    val run = compiler.newRun
+    run.compileSources(List(makeSourceFile(code1, "A.scala"), makeSourceFile(code2, "B.scala")))
+    val List(_, _, c) = readAsmClasses(getGeneratedClassfiles(global.settings.outputDirs.getSingleOutput.get))
+    def is(name: String) = getMethod(c, name).instructions.filterNot(_.isInstanceOf[FrameEntry])
+
+    assertSameCode(is("t1"), List(
+      Label(0), LineNumber(12, Label(0)),
+      VarOp(ALOAD, 0), Invoke(INVOKEVIRTUAL, "A", "fx", "()V", false),
+      Op(ICONST_1), Op(IRETURN), Label(6)))
+
+    assertSameCode(is("t2"), List(
+      Label(0), LineNumber(3, Label(0)), VarOp(ALOAD, 0), Invoke(INVOKEVIRTUAL, "B", "fx", "()V", false),
+      Label(4), LineNumber(4, Label(4)), Op(ICONST_1), Op(IRETURN), Label(8)))
+
+    assertSameCode(is("t3"), List(
+      Label(0), LineNumber(9, Label(0)), VarOp(ALOAD, 0), Invoke(INVOKEVIRTUAL, "C", "fx", "()V", false),
+      Label(4), LineNumber(10, Label(4)), Op(ICONST_1), Op(IRETURN), Label(8)))
+  }
 }
diff --git a/test/junit/scala/tools/testing/BytecodeTesting.scala b/test/junit/scala/tools/testing/BytecodeTesting.scala
index 1a0c1e210a..4ddb6580df 100644
--- a/test/junit/scala/tools/testing/BytecodeTesting.scala
+++ b/test/junit/scala/tools/testing/BytecodeTesting.scala
@@ -29,7 +29,7 @@ class Compiler(val global: Global) {
     global.settings.outputDirs.setSingleOutput(new VirtualDirectory("(memory)", None))
   }
 
-  private def newRun: global.Run = {
+  def newRun: global.Run = {
     global.reporter.reset()
     resetOutput()
     new global.Run()