Experimental Physics and
Industrial Control System

All;

My setup: Linux Debian 12 (bookworm) with gcc/g++ 12, EPICS 7.0.7.

We recently starting using EPICS 7 for our IOCs, and it's been going (mostly) smoothly so far.  But yesterday I ran into an issue where an IOC shell command in one of my c++ modules no longer properly pipes to an output file.  It creates a 0-byte file but the output just displays in the shell, it's not written to the file.

I went looking for why that was.  I lazily use "printf"s in my code, include <epicsStdioRedirect.h> at the top, and the magic has always just happened.  But in EPICS 7 it turns out that the macro redefinition of "printf" is getting stepped on by other include files.  In my case, by including <epicsTime.h> after the include of <epicsStdioRedirect.h>.

epicsTime.h includes <stdexcept>, which touches off a string of other includes until it finally includes <cstdio>, which does an #undef printf thus removing the printf redefinition made by epicsStdioRedirect.h (well, epicsStdio.h).  I found there are other header files in EPICS base 7 that include <stdexcept>, epicsTime.h was just the one that got me.

This isn't particular to gcc 12, btw, I went looking on an older IOC with gcc 10 and it has the same string of includes from stdexcept.  But it's using EPICS 3.15.9 and it's epicsTime.h doesn't include <stdexcept>, so the magic happened okay.

I have a test.cpp and a Makefile that recreate the problem, if anyone wants to play around with it.  For now I'm just including <epicsTime.h> BEFORE <epicsStdioRedirect.h> and the magic works again.  I also tried patching epicsTime.h with a kludge to re-include <epicsStdio.h> after <stdexcept> and that worked:

// KLUDGE

#ifdef epicsStdioh

  #ifndef printf

    #undef epicsStdioh

    #include <epicsStdio.h>

  #endif

#endif

But as advertised, that's a kludge.  What I should *probably* do is replace all my printf()s with epicsStdoutPrintf()s, but that's a lot of code revision, so for now I'm going with my work-around on changing order of includes.

Thanks,

JP