Sometimes the compiler generates confusing warnings or error messages because it is looking for a file that you don’t intend to compile. Usually, the problem is that a file, for example foo.h, contains template declarations and another file, such as foo.cc, gets implicitly included.
If a header file, foo.h, has template declarations, the compiler searches for a file called foo with a C++ file extension (.C, .c, .cc, .cpp, .cxx, or .c++) by default. If the compiler finds such a file, it includes the file automatically. See Template Definition Searching for more information on such searches.
If you have a file foo.cc that you don’t intend to be treated this way, you have two options:
Change the name of the .h or the .cc file to eliminate the name match.
Disable the automatic search for template definition files by specifying the -template=no%extdef option. You must then include all template definitions explicitly in your code and will not be able to use the “definitions separate” model.