1 files changed, 16 insertions, 0 deletions
diff --git a/libbuild2/config/utility.hxx b/libbuild2/config/utility.hxx
index cb82ea6..5a00d00 100644
--- a/libbuild2/config/utility.hxx
+++ b/libbuild2/config/utility.hxx
@@ -501,6 +501,22 @@ namespace build2
     //
     LIBBUILD2_SYMEXPORT bool
     unconfigured (scope& rs, const string& var, bool value);
+
+    // Return the origin of the value of the specified configuration variable
+    // plus the value itself. See $config.origin() for details.
+    //
+    // Throws invalid_argument if the passed variable is not config.*.
+    //
+    enum class variable_origin
+    {
+      undefined,  // Undefined.
+      default_,   // Default value from the config directive.
+      buildfile,  // Value from a buildfile, normally config.build.
+      override_   // Value from a command line override.
+    };
+
+    LIBBUILD2_SYMEXPORT pair<variable_origin, lookup>
+    origin (const scope& rs, const string& name);
   }
 }