[ 50%] Building CXX object fluid/CMakeFiles/fluid.dir/Fl_Window_Type.cxx.o

In file included from /Users/ian/src/Git/fltk-1.4/fluid/Fl_Window_Type.cxx:24:

/Users/ian/src/Git/fltk-1.4/fluid/fluid.h:113:23: warning: in-class initialization of non-static data member is a C++11

      extension [-Wc++11-extensions]

  int header_file_set = 0;

                      ^

/Users/ian/src/Git/fltk-1.4/fluid/fluid.h:114:21: warning: in-class initialization of non-static data member is a C++11

      extension [-Wc++11-extensions]

  int code_file_set = 0;

                    ^

2 warnings generated.

which I do not remember seeing before - seems like a new warning?

Also this:

[ 91%] Building CXX object examples/CMakeFiles/OpenGL3test.dir/OpenGL3test.cxx.o

In file included from /Users/ian/src/Git/fltk-1.4/examples/OpenGL3test.cxx:33:

In file included from /Users/ian/src/Git/fltk-1.4/FL/gl.h:58:

/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk/System/Library/Frameworks/OpenGL.framework/Headers/gl.h:5:2: warning: 

      gl.h and gl3.h are both included. Compiler will not invoke errors if using removed OpenGL functionality. [-W#warnings]

#warning gl.h and gl3.h are both included.  Compiler will not invoke errors if using removed OpenGL functionality.

 ^

1 warning generated.

which again looks new to me (though TBH I do not check these logs often enough, so...)