Use macro expandee, rather than expansion, in pres. compiler

The presentation compiler is primarily interested in trees that
represent the code that one sees in the IDE, not the expansion of
macros.

This commit continues to expand macros, but adds a hook in which
the presentation compiler discards the expansion, retaining instead
the expandee. The expandee is attributed with the type of the
expansion, which allows white box macros to work. In addition,
any domain specific errors and warnings issued by the macro will
still be reported, as a side-effect of the expansion.

The failing test from the last commit now correctly resolves
hyperlinks in macro arguments.

Related IDE ticket:

  https://www.assembla.com/spaces/scala-ide/tickets/1001449#

This facility is configured as follows:

    // expand macros as per normal
    -Ymacro-expand:normal

    // don't expand the macro, takes the place of -Ymacro-no-expand
    -Ymacro-expand:none

    // expand macros to compute type and emit warnings,
    // but retain expandee. Set automatically be the presentation
    // compiler
    -Ymacro-expand:discard

This leaves to door ajar for a new option:

    // Don't expand blackbox macros; expand whitebox
    // but retain expandee
    -Ymacro-expand:discard-whitebox-only

The existing test for SI-6812 has been duplicated. One copy exercises
the now-deprecated -Ymacro-no-expand, and the other uses the new
option.

1 files changed, 7 insertions, 1 deletions

diff --git a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
index 7568c789fb..1f9987c83b 100644
--- a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
+++ b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
@@ -172,7 +172,8 @@ trait ScalaSettings extends AbsScalaSettings
   val Yrangepos       = BooleanSetting    ("-Yrangepos", "Use range positions for syntax trees.")
   val Ymemberpos      = StringSetting     ("-Yshow-member-pos", "output style", "Show start and end positions of members", "") withPostSetHook (_ => Yrangepos.value = true)
   val Yreifycopypaste = BooleanSetting    ("-Yreify-copypaste", "Dump the reified trees in copypasteable representation.")
-  val Ymacronoexpand  = BooleanSetting    ("-Ymacro-no-expand", "Don't expand macros. Might be useful for scaladoc and presentation compiler, but will crash anything which uses macros and gets past typer.")
+  val Ymacroexpand    = ChoiceSetting     ("-Ymacro-expand", "policy", "Control expansion of macros, useful for scaladoc and presentation compiler", List(MacroExpand.Normal, MacroExpand.None, MacroExpand.Discard), MacroExpand.Normal)
+  val Ymacronoexpand  = BooleanSetting    ("-Ymacro-no-expand", "Don't expand macros. Might be useful for scaladoc and presentation compiler, but will crash anything which uses macros and gets past typer.") withDeprecationMessage(s"Use ${Ymacroexpand.name}:${MacroExpand.None}") withPostSetHook(_ => Ymacroexpand.value = MacroExpand.None)
   val Yreplsync       = BooleanSetting    ("-Yrepl-sync", "Do not use asynchronous code for repl startup")
   val Yreplclassbased = BooleanSetting    ("-Yrepl-class-based", "Use classes to wrap REPL snippets instead of objects")
   val Yreploutdir     = StringSetting     ("-Yrepl-outdir", "path", "Write repl-generated classfiles to given output directory (use \"\" to generate a temporary dir)" , "")
@@ -249,4 +250,9 @@ trait ScalaSettings extends AbsScalaSettings
   def isBCodeAskedFor = (Ybackend.value != "GenASM")
   def isICodeAskedFor = ((Ybackend.value == "GenASM") || optimiseSettings.exists(_.value) || writeICode.isSetByUser)
 
+  object MacroExpand {
+    val None = "none"
+    val Normal = "normal"
+    val Discard = "discard"
+  }
 }