DebugMode
From The Battle for Wesnoth Wiki
Building the game with extra debugging
The game can be built to support debugging by supplying --enable-debug as an argument to configure during the build process. Currently this enables a few code snippets for the benefit of an external debugging tool like gdb, and calls the compiler with -g and -O0 flags. You probably don't want to strip a debugging build, since the symbols are needed for the debugging tool.
An unstripped debug build on linux is over 80MB, compared to 2-3MB stripped. It is a good idea to run a debug build of the game if you do development, since it can be necessary to diagnose serious problems.