[C++] Merge explicit rules
diff --git a/rule.h b/rule.h
index 6434281..8728f0e 100644
--- a/rule.h
+++ b/rule.h
@@ -17,6 +17,8 @@
  public:
   Rule();
 
+  Loc cmd_loc() const { return Loc(loc.filename, cmd_lineno); }
+
   string DebugString() const;
 
   vector<StringPiece> outputs;