adds MacroPlugin.pluginsIsBlackbox

This is an important omission in the current macro plugin API, which was
designed before the blackbox vs whitebox separation was implemented.

Even if one overrides pluginsTypedMacroBody and pluginsMacroExpand,
that would still be not enough to write a custom macro expander, because
typedImplicit1 uses isBlackbox, which is tightly coupled with the standard
way of reading/writing macro signatures.

1 files changed, 18 insertions, 0 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/AnalyzerPlugins.scala b/src/compiler/scala/tools/nsc/typechecker/AnalyzerPlugins.scala
index fa6e5399eb..5a70d4c524 100644
--- a/src/compiler/scala/tools/nsc/typechecker/AnalyzerPlugins.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/AnalyzerPlugins.scala
@@ -190,6 +190,16 @@ trait AnalyzerPlugins { self: Analyzer =>
     def pluginsTypedMacroBody(typer: Typer, ddef: DefDef): Option[Tree] = None
 
     /**
+     * Figures out whether the given macro definition is blackbox or whitebox.
+     *
+     * Default implementation provided in `self.standardIsBlackbox` loads the macro impl binding
+     * and fetches boxity from the "isBlackbox" field of the macro signature.
+     *
+     * $nonCumulativeReturnValueDoc.
+     */
+    def pluginsIsBlackbox(macroDef: Symbol): Option[Boolean] = None
+
+    /**
      * Expands an application of a def macro (i.e. of a symbol that has the MACRO flag set),
      * possibly using the current typer mode and the provided prototype.
      *
@@ -375,6 +385,14 @@ trait AnalyzerPlugins { self: Analyzer =>
     def custom(plugin: MacroPlugin) = plugin.pluginsTypedMacroBody(typer, ddef)
   })
 
+  /** @see MacroPlugin.pluginsIsBlackbox */
+  def pluginsIsBlackbox(macroDef: Symbol): Boolean = invoke(new NonCumulativeOp[Boolean] {
+    def position = macroDef.pos
+    def description = "compute boxity for this macro definition"
+    def default = standardIsBlackbox(macroDef)
+    def custom(plugin: MacroPlugin) = plugin.pluginsIsBlackbox(macroDef)
+  })
+
   /** @see MacroPlugin.pluginsMacroExpand */
   def pluginsMacroExpand(typer: Typer, expandee: Tree, mode: Mode, pt: Type): Tree = invoke(new NonCumulativeOp[Tree] {
     def position = expandee.pos