Require and target Java 8

 - Require Java 8 in ant build
 - use -source 1.8 and -target 1.8 for javac
 - Default scalac's -target to `jvm-1.8`, ignore and deprecate attempts
   to use `jvm-1.{6.7}`
 - Remove fragile javap-app test. The feature itself is slated for removal.
 - Remove obsolete Java6 checkfile
 - Adapt DCE tests
   - Remove deprecated/redundant -target:jvm-1.6 from flags where the
     intent was to trigger generation of stack map frames.
   - Remove tests with -target:jvm-1.5 that tested without stack
     map frames
 - Ignore OpenJDK JVM warnings (via test/[files|scaladoc]/filters).

Author: retronym

build-ant-macros.xml

@@ -105,7 +105,7 @@
         <then>
           <stopwatch name="@{project}.timer"/>
           <mkdir dir="${@{project}-classes}"/>
-          <javac debug="true" srcdir="${src.dir}/@{project}" destdir="${@{project}-classes}" classpath="${@{project}-classes}" includes="**/*.java" target="1.6" source="1.5" compiler="javac1.6">
+          <javac debug="true" srcdir="${src.dir}/@{project}" destdir="${@{project}-classes}" classpath="${@{project}-classes}" includes="**/*.java" target="1.8" source="1.8" compiler="javac1.8">
             <compilerarg line="${javac.args} @{args}"/>
           </javac>
           <if>
@@ -132,7 +132,7 @@
     <attribute name="args" default=""/>
     <attribute name="excludes" default=""/>
     <sequential>
-      <javac debug="true" srcdir="${src.dir}/@{project}" destdir="${build-@{stage}.dir}/classes/@{destproject}" includes="**/*.java" excludes="@{excludes}" target="1.6" source="1.5">
+      <javac debug="true" srcdir="${src.dir}/@{project}" destdir="${build-@{stage}.dir}/classes/@{destproject}" includes="**/*.java" excludes="@{excludes}" target="1.8" source="1.8">
         <compilerarg line="${javac.args} @{args}"/>
         <classpath refid="@{stage}.@{destproject}.build.path"/>
       </javac>

build.sbt

@@ -83,7 +83,7 @@ lazy val commonSettings = clearSourceAndResourceDirectories ++ Seq[Setting[_]](
   // we always assume that Java classes are standalone and do not have any dependency
   // on Scala classes
   compileOrder := CompileOrder.JavaThenScala,
-  javacOptions in Compile ++= Seq("-g", "-source", "1.5", "-target", "1.6"),
+  javacOptions in Compile ++= Seq("-g", "-source", "1.8", "-target", "1.8"),
   // we don't want any unmanaged jars; as a reminder: unmanaged jar is a jar stored
   // directly on the file system and it's not resolved through Ivy
   // Ant's build stored unmanaged jars in `lib/` directory

build.xml

@@ -193,7 +193,7 @@ TODO:
 
   <!-- if ANT_OPTS is already set by the environment, it will be unaltered,
        but if it is unset it will take this default value. -->
-  <property name="env.ANT_OPTS"            value="-Xms1536M -Xmx1536M -Xss1M -XX:MaxPermSize=192M -XX:+UseParallelGC" />
+  <property name="env.ANT_OPTS"            value="-Xms1536M -Xmx1536M -Xss1M -XX:+UseParallelGC" />
 
   <property name="scalacfork.jvmargs"      value="${env.ANT_OPTS} ${jvm.opts}"/>
 
@@ -477,20 +477,12 @@ TODO:
     <!-- some default in case something went wrong getting the revision -->
     <property name="version.number"       value="-unknown-"/>
 
-    <condition property="has.java6">
-        <equals arg1="${ant.java.version}" arg2="1.6"/>
-    </condition>
-    <condition property="has.java7">
-        <equals arg1="${ant.java.version}" arg2="1.7"/>
-    </condition>
     <condition property="has.java8">
         <equals arg1="${ant.java.version}" arg2="1.8"/>
     </condition>
     <condition property="has.unsupported.jdk">
        <not><or>
          <isset property="has.java8" />
-         <isset property="has.java7" />
-         <isset property="has.java6" />
        </or></not>
     </condition>
 

src/compiler/scala/tools/nsc/Global.scala

@@ -1379,8 +1379,11 @@ class Global(var currentSettings: Settings, var reporter: Reporter)
       settings.userSetSettings filter (_.isDeprecated) foreach { s =>
         currentRun.reporting.deprecationWarning(NoPosition, s.name + " is deprecated: " + s.deprecationMessage.get)
       }
-      if (settings.target.value.contains("jvm-1.5"))
-        currentRun.reporting.deprecationWarning(NoPosition, settings.target.name + ":" + settings.target.value + " is deprecated: use target for Java 1.6 or above.")
+      val supportedTarget = "jvm-1.8"
+      if (settings.target.value != supportedTarget) {
+        currentRun.reporting.deprecationWarning(NoPosition, settings.target.name + ":" + settings.target.value + " is deprecated and has no effect, setting to " + supportedTarget)
+        settings.target.value = supportedTarget
+      }
     }
 
     /* An iterator returning all the units being compiled in this run */

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

@@ -843,7 +843,7 @@ abstract class BCodeBodyBuilder extends BCodeSkelBuilder {
          *     loading another throwable first).
          *
          * New (http://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.10.1)
-         *   - Requires consistent stack map frames. GenBCode generates stack frames if -target:jvm-1.6
+         *   - Requires consistent stack map frames. GenBCode always generates stack frames.
          *     or higher.
          *   - In practice: the ASM library computes stack map frames for us (ClassWriter). Emitting
          *     correct frames after an ATHROW is probably complex, so ASM uses the following strategy:

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

@@ -28,9 +28,6 @@ abstract class BCodeIdiomatic extends SubComponent {
   import coreBTypes._
 
   val classfileVersion: Int = settings.target.value match {
-    case "jvm-1.5"     => asm.Opcodes.V1_5
-    case "jvm-1.6"     => asm.Opcodes.V1_6
-    case "jvm-1.7"     => asm.Opcodes.V1_7
     case "jvm-1.8"     => asm.Opcodes.V1_8
   }
 

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

@@ -441,9 +441,6 @@ abstract class GenASM extends SubComponent with BytecodeWriters { self =>
   // -----------------------------------------------------------------------------------------
 
   private val classfileVersion: Int = settings.target.value match {
-    case "jvm-1.5"     => asm.Opcodes.V1_5
-    case "jvm-1.6"     => asm.Opcodes.V1_6
-    case "jvm-1.7"     => asm.Opcodes.V1_7
     case "jvm-1.8"     => asm.Opcodes.V1_8
   }
 

src/compiler/scala/tools/nsc/settings/AbsScalaSettings.scala

@@ -31,6 +31,7 @@ trait AbsScalaSettings {
 
   def BooleanSetting(name: String, descr: String): BooleanSetting
   def ChoiceSetting(name: String, helpArg: String, descr: String, choices: List[String], default: String): ChoiceSetting
+  def ChoiceSettingForcedDefault(name: String, helpArg: String, descr: String, choices: List[String], default: String): ChoiceSetting
   def IntSetting(name: String, descr: String, default: Int, range: Option[(Int, Int)], parser: String => Option[Int]): IntSetting
   def MultiStringSetting(name: String, helpArg: String, descr: String): MultiStringSetting
   def MultiChoiceSetting[E <: MultiChoiceEnumeration](name: String, helpArg: String, descr: String, domain: E, default: Option[List[String]]): MultiChoiceSetting[E]

src/compiler/scala/tools/nsc/settings/MutableSettings.scala

@@ -221,6 +221,13 @@ class MutableSettings(val errorFn: String => Unit)
   def BooleanSetting(name: String, descr: String) = add(new BooleanSetting(name, descr))
   def ChoiceSetting(name: String, helpArg: String, descr: String, choices: List[String], default: String) =
     add(new ChoiceSetting(name, helpArg, descr, choices, default))
+  def ChoiceSettingForcedDefault(name: String, helpArg: String, descr: String, choices: List[String], default: String) =
+    ChoiceSetting(name, helpArg, descr, choices, default).withPostSetHook(sett =>
+      if (sett.value != default) {
+        sett.withDeprecationMessage(s"${name}:${sett.value} is deprecated, forcing use of $default")
+        sett.value = default
+      }
+    )
   def IntSetting(name: String, descr: String, default: Int, range: Option[(Int, Int)], parser: String => Option[Int]) =
     add(new IntSetting(name, descr, default, range, parser))
   def MultiStringSetting(name: String, arg: String, descr: String) = add(new MultiStringSetting(name, arg, descr))

src/compiler/scala/tools/nsc/settings/StandardScalaSettings.scala

@@ -38,8 +38,8 @@ trait StandardScalaSettings {
   val nowarn =         BooleanSetting ("-nowarn", "Generate no warnings.")
   val optimise:        BooleanSetting // depends on post hook which mutates other settings
   val print =          BooleanSetting ("-print", "Print program with Scala-specific features removed.")
-  val target =          ChoiceSetting ("-target", "target", "Target platform for object files. All JVM 1.5 targets are deprecated.",
-                          List("jvm-1.5", "jvm-1.6", "jvm-1.7", "jvm-1.8"), "jvm-1.6")
+  val target =         ChoiceSettingForcedDefault ("-target", "target", "Target platform for object files. All JVM 1.5 - 1.7 targets are deprecated.",
+                          List("jvm-1.5", "jvm-1.6", "jvm-1.7", "jvm-1.8"), "jvm-1.8")
   val unchecked =      BooleanSetting ("-unchecked", "Enable additional warnings where generated code depends on assumptions.")
   val uniqid =         BooleanSetting ("-uniqid", "Uniquely tag all identifiers in debugging output.")
   val usejavacp =      BooleanSetting ("-usejavacp", "Utilize the java.class.path in classpath resolution.")

src/compiler/scala/tools/nsc/transform/Delambdafy.scala

@@ -18,7 +18,7 @@ import scala.collection.mutable.LinkedHashMap
  *
  * From a lambda, Delambdafy will create:
  *
- * Under -target:jvm-1.7 and below:
+ * Under GenASM
  *
  * 1) a new top level class that
       a) has fields and a constructor taking the captured environment (including possibly the "this"
@@ -27,7 +27,7 @@ import scala.collection.mutable.LinkedHashMap
  *    c) if needed a bridge method for the apply method
  * 2) an instantiation of the newly created class which replaces the lambda
  *
- * Under -target:jvm-1.8 with GenBCode:
+ * Under GenBCode:
  *
  * 1) An application of the captured arguments to a fictional symbol representing the lambda factory.
  *    This will be translated by the backed into an invokedynamic using a bootstrap method in JDK8's `LambdaMetaFactory`.
@@ -477,8 +477,7 @@ abstract class Delambdafy extends Transform with TypingTransformers with ast.Tre
         val methodType: Type = target.info
         methodType.exists(_.isInstanceOf[ErasedValueType])
       }
-      val isTarget18 = settings.target.value.contains("jvm-1.8")
-      settings.isBCodeActive && isTarget18 && !hasValueClass
+      settings.isBCodeActive && !hasValueClass
     }
 
     def functionalInterface: Symbol = {

src/compiler/scala/tools/nsc/transform/UnCurry.scala

@@ -237,7 +237,7 @@ abstract class UnCurry extends InfoTransform
 
           def canUseDelamdafyMethod = (
                (inConstructorFlag == 0) // Avoiding synthesizing code prone to SI-6666, SI-8363 by using old-style lambda translation
-            && (!isSpecialized || (settings.target.value == "jvm-1.8")) // DelambdafyTransformer currently only emits generic FunctionN-s, use the old style in the meantime
+            && (!isSpecialized || settings.isBCodeActive) // DelambdafyTransformer currently only emits generic FunctionN-s, use the old style in the meantime
           )
           if (inlineFunctionExpansion || !canUseDelamdafyMethod) {
             val parents = addSerializable(abstractFunctionForFunctionType(fun.tpe))

src/manual/scala/man1/scalac.scala

@@ -152,11 +152,9 @@ object scalac extends Command {
           CmdOption("sourcepath", Argument("path")),
           "Specify location(s) of source files."),
         Definition(
-          CmdOptionBound("target:", "{jvm-1.5,jvm-1.6,jvm-1.7}"),
+          CmdOptionBound("target:", "{jvm-1.8}"),
 	  SeqPara(
-            Mono("\"jvm-1.5\"") & " target JVM 1.5 (deprecated),",
-            Mono("\"jvm-1.6\"") & " target JVM 1.6 (default),",
-            Mono("\"jvm-1.7\"") & " target JVM 1.7,")),
+            Mono("\"jvm-1.8\"") & " target JVM 1.8 (default)")),
         Definition(
           CmdOption("toolcp", Argument("path")),
           "Add to the runner classpath."),

test/files/filters

@@ -1,6 +1,7 @@
 #
 #Java HotSpot(TM) 64-Bit Server VM warning: Failed to reserve shared memory (errno = 28).
 Java HotSpot\(TM\) .* warning:
+OpenJDK .* warning:
 # Hotspot receiving VM options through the $_JAVA_OPTIONS
 # env variable outputs them on stderr
 Picked up _JAVA_OPTIONS:

test/files/neg/deprecated-target.check

@@ -0,0 +1,4 @@
+warning: -target is deprecated: -target:jvm-1.7 is deprecated, forcing use of jvm-1.8
+error: No warnings can be incurred under -Xfatal-warnings.
+one warning found
+one error found

test/files/neg/deprecated-target.flags

@@ -0,0 +1 @@
+-target:jvm-1.7 -deprecation -Xfatal-warnings

test/files/neg/deprecated-target.scala

@@ -0,0 +1 @@
+class C

test/files/neg/t6289.check

@@ -1,9 +1,3 @@
-#partest java6
-t6289/J.java:2: method does not override or implement a method from a supertype
-  @Override public void foo() { }
-  ^
-1 error
-#partest !java6
 t6289/J.java:2: error: method does not override or implement a method from a supertype
   @Override public void foo() { }
   ^

test/files/run/nothingTypeDce.flags

@@ -1 +1 @@
--target:jvm-1.6 -Ybackend:GenBCode -Yopt:unreachable-code
+-Ybackend:GenBCode -Yopt:unreachable-code

test/files/run/nothingTypeDce.scala

@@ -1,7 +1,6 @@
 // See comment in BCodeBodyBuilder
 
-// -target:jvm-1.6 -Ybackend:GenBCode -Yopt:unreachable-code
-// target enables stack map frames generation
+// -Ybackend:GenBCode -Yopt:unreachable-code
 
 class C {
   // can't just emit a call to ???, that returns value of type Nothing$ (not Int).

test/files/run/nothingTypeNoFramesNoDce.check

@@ -1 +1 @@
--target:jvm-1.6 -Ybackend:GenBCode -Yopt:l:none
+-Ybackend:GenBCode -Yopt:l:none

test/files/run/nothingTypeNoFramesNoDce.flags

@@ -17,8 +17,8 @@ class CompactLocalVariablesTest {
 
   // recurse-unreachable-jumps is required for eliminating catch blocks, in the first dce round they
   // are still live.only after eliminating the empty handler the catch blocks become unreachable.
-  val methodOptCompiler     = newCompiler(extraArgs = "-target:jvm-1.6 -Ybackend:GenBCode -Yopt:unreachable-code,compact-locals")
-  val noCompactVarsCompiler = newCompiler(extraArgs = "-target:jvm-1.6 -Ybackend:GenBCode -Yopt:unreachable-code")
+  val methodOptCompiler     = newCompiler(extraArgs = "-Ybackend:GenBCode -Yopt:unreachable-code,compact-locals")
+  val noCompactVarsCompiler = newCompiler(extraArgs = "-Ybackend:GenBCode -Yopt:unreachable-code")
 
   @Test
   def compactUnused(): Unit = {

test/files/run/nothingTypeNoFramesNoDce.scala

@@ -16,7 +16,7 @@ import ASMConverters._
 import scala.tools.testing.ClearAfterClass
 
 object MethodLevelOpts extends ClearAfterClass.Clearable {
-  var methodOptCompiler = newCompiler(extraArgs = "-target:jvm-1.6 -Ybackend:GenBCode -Yopt:l:method")
+  var methodOptCompiler = newCompiler(extraArgs = "-Ybackend:GenBCode -Yopt:l:method")
   def clear(): Unit = { methodOptCompiler = null }
 }