[clang-tidy] cpp: Turn reference operators to const

Found with cppcoreguidelines-c-copy-assignment-signature

Signed-off-by: Rosen Penev <rosenp@gmail.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/include/plist/Date.h b/include/plist/Date.h
index 510a349..3cfb7d1 100644
--- a/include/plist/Date.h
+++ b/include/plist/Date.h
@@ -35,7 +35,7 @@ public :
     Date(Node* parent = NULL);
     Date(plist_t node, Node* parent = NULL);
     Date(const Date& d);
-    Date& operator=(Date& d);
+    Date& operator=(const Date& d);
     Date(timeval t);
     virtual ~Date();