SI-8126 Add a '-Xsource' flag allowing compilation in e.g. 2.10 mode

This is aimed at letting the 2.11+ compiler operate, at least until
phase:typer, on a 2.10 codebase.

1 files changed, 43 insertions, 36 deletions

diff --git a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
index 6ec364bcb6..307f42c0bc 100644
--- a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
+++ b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
@@ -73,48 +73,55 @@ trait ScalaSettings extends AbsScalaSettings
   val nospecialization = BooleanSetting    ("-no-specialization", "Ignore @specialize annotations.")
   val language      = MultiStringSetting("-language", "feature", "Enable one or more language features.")
 
+  /*
+   * The previous "-source" option is intended to be used mainly
+   * though this helper.
+   */
+  lazy val isScala211: Boolean = (source.value >= ScalaVersion("2.11.0"))
+
   /**
    * -X "Advanced" settings
    */
-  val Xhelp         = BooleanSetting    ("-X", "Print a synopsis of advanced options.")
-  val checkInit     = BooleanSetting    ("-Xcheckinit", "Wrap field accessors to throw an exception on uninitialized access.")
-  val developer     = BooleanSetting    ("-Xdev", "Indicates user is a developer - issue warnings about anything which seems amiss")
-  val noassertions  = BooleanSetting    ("-Xdisable-assertions", "Generate no assertions or assumptions.")
-  val elidebelow    = IntSetting        ("-Xelide-below", "Calls to @elidable methods are omitted if method priority is lower than argument",
+  val Xhelp              = BooleanSetting      ("-X", "Print a synopsis of advanced options.")
+  val checkInit          = BooleanSetting      ("-Xcheckinit", "Wrap field accessors to throw an exception on uninitialized access.")
+  val developer          = BooleanSetting      ("-Xdev", "Indicates user is a developer - issue warnings about anything which seems amiss")
+  val noassertions       = BooleanSetting      ("-Xdisable-assertions", "Generate no assertions or assumptions.")
+  val elidebelow         = IntSetting          ("-Xelide-below", "Calls to @elidable methods are omitted if method priority is lower than argument",
                                                 elidable.MINIMUM, None, elidable.byName get _)
-  val noForwarders  = BooleanSetting    ("-Xno-forwarders", "Do not generate static forwarders in mirror classes.")
-  val genPhaseGraph = StringSetting     ("-Xgenerate-phase-graph", "file", "Generate the phase graphs (outputs .dot files) to fileX.dot.", "")
-  val XlogImplicits = BooleanSetting    ("-Xlog-implicits", "Show more detail on why some implicits are not applicable.")
-  val logImplicitConv = BooleanSetting  ("-Xlog-implicit-conversions", "Print a message whenever an implicit conversion is inserted.")
-  val logReflectiveCalls = BooleanSetting("-Xlog-reflective-calls", "Print a message when a reflective method call is generated")
-  val logFreeTerms  = BooleanSetting    ("-Xlog-free-terms", "Print a message when reification creates a free term.")
-  val logFreeTypes  = BooleanSetting    ("-Xlog-free-types", "Print a message when reification resorts to generating a free type.")
-  val maxClassfileName = IntSetting     ("-Xmax-classfile-name", "Maximum filename length for generated classes", 255, Some((72, 255)), _ => None)
-  val Xmigration    = ScalaVersionSetting("-Xmigration", "version", "Warn about constructs whose behavior may have changed since version.", AnyScalaVersion)
-  val nouescape     = BooleanSetting    ("-Xno-uescape", "Disable handling of \\u unicode escapes.")
-  val Xnojline      = BooleanSetting    ("-Xnojline", "Do not use JLine for editing.")
-  val Xverify       = BooleanSetting    ("-Xverify", "Verify generic signatures in generated bytecode (asm backend only.)")
-  val plugin        = MultiStringSetting("-Xplugin", "paths", "Load a plugin from each classpath.")
-  val disable       = MultiStringSetting("-Xplugin-disable", "plugin", "Disable plugins by name.")
-  val showPlugins   = BooleanSetting    ("-Xplugin-list", "Print a synopsis of loaded plugins.")
-  val require       = MultiStringSetting("-Xplugin-require", "plugin", "Abort if a named plugin is not loaded.")
-  val pluginsDir    = StringSetting     ("-Xpluginsdir", "path", "Path to search for plugin archives.", Defaults.scalaPluginPath)
-  val Xprint        = PhasesSetting     ("-Xprint", "Print out program after")
-  val writeICode    = PhasesSetting     ("-Xprint-icode", "Log internal icode to *.icode files after", "icode")
-  val Xprintpos     = BooleanSetting    ("-Xprint-pos", "Print tree positions, as offsets.")
-  val printtypes    = BooleanSetting    ("-Xprint-types", "Print tree types (debugging option).")
-  val prompt        = BooleanSetting    ("-Xprompt", "Display a prompt after each error (debugging option).")
-  val resident      = BooleanSetting    ("-Xresident", "Compiler stays resident: read source filenames from standard input.")
-  val script        = StringSetting     ("-Xscript", "object", "Treat the source file as a script and wrap it in a main method.", "")
-  val mainClass     = StringSetting     ("-Xmain-class", "path", "Class for manifest's Main-Class entry (only useful with -d <jar>)", "")
-  val Xshowcls      = StringSetting     ("-Xshow-class", "class", "Show internal representation of class.", "")
-  val Xshowobj      = StringSetting     ("-Xshow-object", "object", "Show internal representation of object.", "")
-  val showPhases    = BooleanSetting    ("-Xshow-phases", "Print a synopsis of compiler phases.")
-  val sourceReader  = StringSetting     ("-Xsource-reader", "classname", "Specify a custom method for reading source files.", "")
-  val strictInference = BooleanSetting  ("-Xstrict-inference", "Don't infer known-unsound types")
+  val noForwarders       = BooleanSetting      ("-Xno-forwarders", "Do not generate static forwarders in mirror classes.")
+  val genPhaseGraph      = StringSetting       ("-Xgenerate-phase-graph", "file", "Generate the phase graphs (outputs .dot files) to fileX.dot.", "")
+  val XlogImplicits      = BooleanSetting      ("-Xlog-implicits", "Show more detail on why some implicits are not applicable.")
+  val logImplicitConv    = BooleanSetting      ("-Xlog-implicit-conversions", "Print a message whenever an implicit conversion is inserted.")
+  val logReflectiveCalls = BooleanSetting      ("-Xlog-reflective-calls", "Print a message when a reflective method call is generated")
+  val logFreeTerms       = BooleanSetting      ("-Xlog-free-terms", "Print a message when reification creates a free term.")
+  val logFreeTypes       = BooleanSetting      ("-Xlog-free-types", "Print a message when reification resorts to generating a free type.")
+  val maxClassfileName   = IntSetting          ("-Xmax-classfile-name", "Maximum filename length for generated classes", 255, Some((72, 255)), _ => None)
+  val Xmigration         = ScalaVersionSetting ("-Xmigration", "version", "Warn about constructs whose behavior may have changed since version.", AnyScalaVersion)
+  val nouescape          = BooleanSetting      ("-Xno-uescape", "Disable handling of \\u unicode escapes.")
+  val Xnojline           = BooleanSetting      ("-Xnojline", "Do not use JLine for editing.")
+  val Xverify            = BooleanSetting      ("-Xverify", "Verify generic signatures in generated bytecode (asm backend only.)")
+  val plugin             = MultiStringSetting  ("-Xplugin", "paths", "Load a plugin from each classpath.")
+  val disable            = MultiStringSetting  ("-Xplugin-disable", "plugin", "Disable plugins by name.")
+  val showPlugins        = BooleanSetting      ("-Xplugin-list", "Print a synopsis of loaded plugins.")
+  val require            = MultiStringSetting  ("-Xplugin-require", "plugin", "Abort if a named plugin is not loaded.")
+  val pluginsDir         = StringSetting       ("-Xpluginsdir", "path", "Path to search for plugin archives.", Defaults.scalaPluginPath)
+  val Xprint             = PhasesSetting       ("-Xprint", "Print out program after")
+  val writeICode         = PhasesSetting       ("-Xprint-icode", "Log internal icode to *.icode files after", "icode")
+  val Xprintpos          = BooleanSetting      ("-Xprint-pos", "Print tree positions, as offsets.")
+  val printtypes         = BooleanSetting      ("-Xprint-types", "Print tree types (debugging option).")
+  val prompt             = BooleanSetting      ("-Xprompt", "Display a prompt after each error (debugging option).")
+  val resident           = BooleanSetting      ("-Xresident", "Compiler stays resident: read source filenames from standard input.")
+  val script             = StringSetting       ("-Xscript", "object", "Treat the source file as a script and wrap it in a main method.", "")
+  val mainClass          = StringSetting       ("-Xmain-class", "path", "Class for manifest's Main-Class entry (only useful with -d <jar>)", "")
+  val Xshowcls           = StringSetting       ("-Xshow-class", "class", "Show internal representation of class.", "")
+  val Xshowobj           = StringSetting       ("-Xshow-object", "object", "Show internal representation of object.", "")
+  val showPhases         = BooleanSetting      ("-Xshow-phases", "Print a synopsis of compiler phases.")
+  val sourceReader       = StringSetting       ("-Xsource-reader", "classname", "Specify a custom method for reading source files.", "")
+  val strictInference    = BooleanSetting      ("-Xstrict-inference", "Don't infer known-unsound types")
+  val source             = ScalaVersionSetting ("-Xsource", "version", "Treat compiler input as Scala source for the specified version, see SI-8126.", ScalaVersion("2.11")) withPostSetHook ( _ => isScala211)
 
   val XnoPatmatAnalysis = BooleanSetting ("-Xno-patmat-analysis", "Don't perform exhaustivity/unreachability analysis. Also, ignore @switch annotation.")
-  val XfullLubs     = BooleanSetting    ("-Xfull-lubs", "Retains pre 2.10 behavior of less aggressive truncation of least upper bounds.")
+  val XfullLubs         = BooleanSetting ("-Xfull-lubs", "Retains pre 2.10 behavior of less aggressive truncation of least upper bounds.")
 
   /** Compatibility stubs for options whose value name did
    *  not previously match the option name.