Warning: L6320W: Ignoring --keep command. Cannot find argument '--summary_stderr'.

I recently switched to uVision 5 (from 4) and added a generic I/O pin class to a project I inherited, and then proceeded to use the class like I've done in many other projects. Unfortunately, when I build it I get this error.

project.axf: Warning: L6320W: Ignoring --keep command. Cannot find argument '--summary_stderr'.
project.axf: Error: L6218E: Undefined symbol --summary_stderr (referred from anon$$obj.o).

The online help for L6320W is not much help, since I don't know what command is referencing --summary_stderr.

L6320W: Ignoring <cmd> command. Cannot find argument '<argname>'.

Eventually I used a guard to find a way to get the project to build (by not defining DOES_NOT_WORK), but using this approach will require lots of changes to existing code, so I don't want to take that route.

From just above int main(void)...

#define DOES_NOT_WORK

#ifdef DOES_NOT_WORK
iopin LED_HB(0, 17); // but works in many other projects
#else
iopin * LED_HB;
#endif

and just below that in main()...

#ifdef DOES_NOT_WORK
#else
        LED_HB = new iopin(0,17);
#endif

Can anyone point me to a solution so that my build will succeed even when DOES_NOT_WORK is defined?

Thanks.

P.S. I am including the KEIL provided system and startup files.