Merge pull request #1645 from scalamacros/ticket/6673

SI-6673 fixes macro problems with eta expansions 

1 files changed, 17 insertions, 0 deletions

diff --git a/src/reflect/scala/reflect/internal/StdAttachments.scala b/src/reflect/scala/reflect/internal/StdAttachments.scala
index 9fe443bf50..1df91a67b0 100644
--- a/src/reflect/scala/reflect/internal/StdAttachments.scala
+++ b/src/reflect/scala/reflect/internal/StdAttachments.scala
@@ -19,9 +19,26 @@ trait StdAttachments {
     def setPos(newpos: Position): this.type = { pos = newpos; this }
   }
 
+  /** When present, indicates that the host `Ident` has been created from a backquoted identifier.
+   */
   case object BackquotedIdentifierAttachment
 
+  /** Stores the trees that give rise to a refined type to be used in reification.
+   *  Unfortunately typed `CompoundTypeTree` is lacking essential info, and the reifier cannot use `CompoundTypeTree.tpe`.
+   *  Therefore we need this hack (see `Reshape.toPreTyperTypeTree` for a detailed explanation).
+   */
   case class CompoundTypeTreeOriginalAttachment(parents: List[Tree], stats: List[Tree])
 
+  /** Is added by the macro engine to the results of macro expansions.
+   *  Stores the original expandee as it entered the `macroExpand` function.
+   */
   case class MacroExpansionAttachment(original: Tree)
+
+  /** When present, suppresses macro expansion for the host.
+   *  This is occasionally necessary, e.g. to prohibit eta-expansion of macros.
+   *
+   *  Does not affect expandability of child nodes, there's context.withMacrosDisabled for that
+   *  (but think thrice before using that API - see the discussion at https://github.com/scala/scala/pull/1639).
+   */
+  case object SuppressMacroExpansionAttachment
 }