Don't complete empty abs_dir_path

The empty value is used as a special indicator

2 files changed, 8 insertions, 4 deletions

diff --git a/build2/types b/build2/types
index df54860..c90b779 100644
--- a/build2/types
+++ b/build2/types
@@ -91,7 +91,8 @@ namespace build2
   // a (variable) value of this type gets initialized from untyped names. See
   // value_type<abs_dir_path> for details.
   //
-  // Note that currently we also normalize and actualize the path.
+  // Note that currently we also normalize and actualize the path. And we
+  // leave empty path as is.
   //
   struct abs_dir_path: dir_path
   {
diff --git a/build2/variable.cxx b/build2/variable.cxx
index 54b61b7..7a13618 100644
--- a/build2/variable.cxx
+++ b/build2/variable.cxx
@@ -598,10 +598,13 @@ namespace build2
   {
     dir_path d (value_traits<dir_path>::convert (move (n), r));
 
-    if (d.relative ())
-      d.complete ();
+    if (!d.empty ())
+    {
+      if (d.relative ())
+        d.complete ();
 
-    d.normalize (true); // Actualize.
+      d.normalize (true); // Actualize.
+    }
 
     return abs_dir_path (move (d));
   }