Find all source files in a directory.

aux_source_directory(<dir> <variable>)

Collects the names of all the source files in the specified directory and stores the list in the <variable> provided. This command is intended to be used by projects that use explicit template instantiation. Template instantiation files can be stored in a “Templates” subdirectory and collected automatically using this command to avoid manually listing all instantiations.

It is tempting to use this command to avoid writing the list of source files for a library or executable target. While this seems to work, there is no way for CMake to generate a build system that knows when a new source file has been added. Normally the generated build system knows when it needs to rerun CMake because the CMakeLists.txt file is modified to add a new source. When the source is just added to the directory without modifying this file, one would have to manually rerun CMake to generate a build system incorporating the new file.