RE: Compiling EPICS 3.14.12.5 with GCC 6

["Hill, Jeff" <johill@lanl.gov>]

Hi Bob,

Does it compile with gcc 6.1's default c++14 mode if constexpr is substituted for const on that line? Or is the problem related to stricter array length checking at compile time with c++14 which is causing this particular c++ compiler exception support sanity check to fail.

Jeff

> -----Original Message-----
> From: tech-talk-bounces@aps.anl.gov [mailto:tech-talk-bounces@aps.anl.gov]
> On Behalf Of Bob Soliday
> Sent: Tuesday, June 28, 2016 8:12 AM
> To: tech-talk@aps.anl.gov
> Subject: Re: Compiling EPICS 3.14.12.5 with GCC 6
> 
> You can get it to compile with gcc 6.1 if you edit
> epicsExceptionTest.cpp and remove the "const" from the line:
> 
> static const size_t unsuccessfulNewSize = numeric_limits < size_t > :: max ();
> 
> There is a change committed to the for the next release, but it checks
> the version of gcc. It probably should check which -std option was given
> instead.
> 
> --Bob Soliday
> 
> On 06/28/2016 04:00 AM, Luca Cavalli wrote:
> > Dear all,
> >
> > on my office laptop I'm running Fedora 24, which comes with GCC 6 by
> > default.
> >
> > It seems that compiling EPICS 3.14.12.5 with GCC 6 fails here:
> >
> > /usr/bin/g++ -c  -D_GNU_SOURCE -D_DEFAULT_SOURCE            -
> > D_X86_64_  -DUNIX  -Dlinux     -O3 -g   -Wall       -m64      -MMD -I.
> > -I../O.Common -I. -I.. -I../../../../include/os/Linux
> > -I../../../../include         ../epicsExceptionTest.cpp
> > ../epicsExceptionTest.cpp: In function ‘void
> > epicsExceptionTestPrivate()’:
> > ../epicsExceptionTest.cpp:68:49: error: size of array is too large
> >           char * p = new char [unsuccessfulNewSize];
> >                                                   ^
> > ../epicsExceptionTest.cpp:79:38: error: size of array is too large
> >               char [unsuccessfulNewSize];
> >                                        ^
> > ../../../../configure/RULES_BUILD:218: recipe for target
> > 'epicsExceptionTest.o' failed
> >
> > GCC 6 defaults to -std=gnu++14 instead of -std=gnu++98 [1]. Adding this
> > option to compiler command seems to fix the problem, but which is the
> > best place to set the desired standard?
> >
> > I tried in config/CONFIG_COMMON modifying:
> >
> > POSIX_CPPFLAGS += $(POSIX_CPPFLAGS_$(POSIX)) -std=gnu++98
> >
> > or:
> >
> > USR_CXXFLAGS = -std=gnu++98
> >
> > but the option seems to be ignored.
> >
> >
> > Thanks for your help.
> >
> > Cheers,
> >
> > Luca
> >
> >
> > [1] - https://gcc.gnu.org/gcc-6/porting_to.html#gxx14
> >
> >
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