Use __COUNTER__ instead of name for internal dummy name.

The name can be the same for different maps, for instance one mapping
from object id to location and one mapping to an offset. The counter
should always be unique.

Author: joto

include/osmium/index/map.hpp

@@ -285,10 +285,11 @@ namespace osmium {
 
 #define REGISTER_MAP(id, value, klass, name) \
 namespace osmium { namespace index { namespace detail { \
-    const bool OSMIUM_CONCATENATE_(registered_, name) = osmium::index::register_map<id, value, klass>(#name); \
-    inline bool OSMIUM_CONCATENATE_(get_registered_, name)() noexcept { \
-        return OSMIUM_CONCATENATE_(registered_, name); \
-    } \
+    namespace OSMIUM_CONCATENATE_(register_map_, __COUNTER__) { \
+    const bool registered = osmium::index::register_map<id, value, klass>(#name); \
+    inline bool get_registered() noexcept { \
+        return registered; \
+    } } \
 } } }
 
     } // namespace index