Errors related to C++11

[Jimmy Johnson]

Late 2013 iMac

macOS Catalina Version 10.15.7

Xcode Version 11.7

I'm trying to include a C++ library, but the compiler gives external warnings and errors when compiling a header file, complaining that so-and-so is a C++11 extension or only supported in C++11.

When setting up a project in Xcode, I can select under "Project Document, Project Format" the value "Xcode 11.4-compatible".  Does that mean that Xcode is compiling as 11.4 or just the text is formatted such.

Anyway, is there a way to fix these errors in the external compilation of an Eiffel project?

thanks,

jjj