SI-6812 scaladoc can opt out of expanding macros

This is a temporary change, possible only because macros currently can't
affect the global symbol table (except for the case when they will steer
inference of a method's return type).

Later on, e.g. with the addition of c.introduceTopLevel in master,
we will have to upgrade Scaladoc to allow for separate generation of
documentation, because then we'll be forced to expand macros in order to
get the whole picture of the code.

1 files changed, 7 insertions, 3 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala b/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala
index dc367b11fd..f76f1a1a65 100644
--- a/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala
@@ -763,10 +763,14 @@ trait ContextErrors {
             else " of " + expanded.getClass
         ))
 
-      def MacroImplementationNotFoundError(expandee: Tree) =
-        macroExpansionError(expandee,
+      def MacroImplementationNotFoundError(expandee: Tree) = {
+        val message =
           "macro implementation not found: " + expandee.symbol.name + " " +
-          "(the most common reason for that is that you cannot use macro implementations in the same compilation run that defines them)")
+          "(the most common reason for that is that you cannot use macro implementations in the same compilation run that defines them)" +
+          (if (forScaladoc) ". When generating scaladocs for multiple projects at once, consider using -Ymacro-no-expand to disable macro expansions altogether."
+           else "")
+        macroExpansionError(expandee, message)
+      }
     }
   }