Function templates can be explicitly instantiated (including those with inferred template parameters), but cxxheaderparser will not have it. Per https://github.com/robotpy/cxxheaderparser/blob/544c253a77d0f706418ee61b986c2b246d4eaf1f/cxxheaderparser/parser.py#L738 all instantiations must be class or struct, and the TemplateInst type seems to assume this also. https://en.cppreference.com/w/cpp/language/function_template explicit instantiation https://coliru.stacked-crooked.com/a/15000b7567cd61ca <- compiles fine