ada: Pass Error_Node to calls to Error_Msg in lib-load.adb
When not passing Error_Node, Error_Msg will treat Current_Node as the
node attached to the message. When this happens in lib-load.adb due to a
file that cannot be loaded, Current_Node might reference a node that
doesn't actually exist. This is a problem when using -gnatdJ and
-fdiagnostics-format, as in this case GNAT will attempt to retrieve
information from the node attached to the message and thus crash when
said node is invalid.
gcc/ada/
* lib-load.adb (Load_Unit): Pass Error_Node to calls to Error_Msg.