Fix:gui:qt5_qml: Fix -Wwrite-strings warning

We assign string constants to a char* which will lead to an error if
anyone tries to write that pointer, as constant data is mapped
read-only. This patch makes these const char* pointers.
Fixes the warning:

backend.cpp:588:27: warning: ISO C++ forbids converting a string constant to ‘char*’ [-Wwrite-strings]
  588 |         _current_street = "Enter Street";
      |                           ^~~~~~~~~~~~~~

2 files changed, 7 insertions, 7 deletions

diff --git a/navit/gui/qt5_qml/backend.cpp b/navit/gui/qt5_qml/backend.cpp
index c9733b173..11057c76c 100644
--- a/navit/gui/qt5_qml/backend.cpp
+++ b/navit/gui/qt5_qml/backend.cpp
@@ -78,9 +78,9 @@ void Backend::get_maps() {
             label = g_strdup(description.u.str);
         } else {
             if (!map_get_attr(attr.u.map, attr_type, &type, NULL))
-                type.u.str = "";
+                type.u.str = (char*)"";
             if (!map_get_attr(attr.u.map, attr_data, &data, NULL))
-                data.u.str = "";
+                data.u.str = (char*)"";
             label = g_strdup_printf("%s:%s", type.u.str, data.u.str);
         }
         is_active = false;
@@ -501,7 +501,7 @@ void Backend::updateSearch(QString text) {
         search->partial = 1;
         dbg(lvl_debug,"attempting to use country '%s'", _country_iso2);
         search_attr.type=attr_country_iso2;
-        search_attr.u.str=_country_iso2;
+        search_attr.u.str=(char*)_country_iso2;
         search_list_search(search->sl, &search_attr, 0);
 
         while((res=search_list_get_result(search->sl)));
diff --git a/navit/gui/qt5_qml/backend.h b/navit/gui/qt5_qml/backend.h
index 259be516c..9a27590d5 100644
--- a/navit/gui/qt5_qml/backend.h
+++ b/navit/gui/qt5_qml/backend.h
@@ -104,10 +104,10 @@ private:
     VehicleObject * m_currentVehicle;
     QList<QObject *> _search_results;
     void set_default_country();
-    char * _country_iso2;
-    char * _current_country;
-    char * _current_town;
-    char * _current_street;
+    const char * _country_iso2;
+    const char * _current_country;
+    const char * _current_town;
+    const char * _current_street;
     struct search_param *search;
     enum attr_type _search_context;
 };