| Define a grouping for source files in IDE project generation. |
| source_group(<name> [FILES <src>...] [REGULAR_EXPRESSION <regex>]) |
| Defines a group into which sources will be placed in project files. |
| This is intended to set up file tabs in Visual Studio. |
| Any source file specified explicitly will be placed in group |
| ``<name>``. Relative paths are interpreted with respect to the |
| current source directory. |
| Any source file whose name matches the regular expression will |
| be placed in group ``<name>``. |
| If a source file matches multiple groups, the *last* group that |
| explicitly lists the file with ``FILES`` will be favored, if any. |
| If no group explicitly lists the file, the *last* group whose |
| regular expression matches the file will be favored. |
| The ``<name>`` of the group may contain backslashes to specify subgroups: |
| source_group(outer\\inner ...) |
| For backwards compatibility, the short-hand signature |
| source_group(<name> <regex>) |
| source_group(<name> REGULAR_EXPRESSION <regex>) |