[PROJ] Why is std=gnu89 tested/enabled ?

Wed Aug 21 05:10:10 PDT 2019

No, I don’t think so. Internally PROJ defines some math functions that is first introduced with C99. If the build system detects that they are available with your compiler the system functions are used instead. As far as I remember that is the only difference between using C89 and C99 to build PROJ 5.2.0. Try running the test suite, it should give you a good indication if it works or not.

/Kristian

On 21 Aug 2019, at 13:55, Dechaux Eric CEN (BCQ STIG) <eric.dechaux at gendarmerie.interieur.gouv.fr<mailto:eric.dechaux at gendarmerie.interieur.gouv.fr>> wrote:

Thanks Kristian,

On Solaris, NAN is not available with C89. Is there an issue to build proj 5 forcing C99 by replacing -std=c89 to -std=c99 in the Makefile, after configure ?

Regards.

Le 21/08/2019 à 12:43, Kristian Evers a écrit :
Eric,

A C++11 compatible compiler is only required for PROJ 6 and onwards. This was introduced with RFC3 [0]. Previous versions was strictly C89, hence the enforcement of that standard in PROJ 5.2.0.

/Kristian

[0] https://proj.org/community/rfc/rfc-3.html

On 16 Aug 2019, at 14:57, Dechaux Eric CEN (BCQ STIG) <eric.dechaux at gendarmerie.interieur.gouv.fr<mailto:eric.dechaux at gendarmerie.interieur.gouv.fr>> wrote:

Greetings,

I have been investigating proj 5.2.0 build failure on Solaris 11.3 for amd64. At some point the build stops on error because of the NAN being not declared :

gcc -DHAVE_CONFIG_H -I. -DPROJ_LIB=\"/appli/stig/11.3-20190816-104632/share/proj\" -DMUTEX_pthread  -D_FORTIFY_SOURCE=2 -I/usr/include/pcre -I/appli/stig/11.3-20190816-104632/include -Wall -Wdeclaration-after-statement -Wextra -Winit-self -Wunused-parameter -Wmissing-prototypes -Wmissing-declarations -Wformat -Werror=format-security -Wno-format-nonliteral -Wlogical-op -Wshadow -Werror=vla -Wdeclaration-after-statement -Wdate-time -Wfloat-conversion -std=gnu89 -m64 -O2 -fstack-protector-strong -fpic -fPIC --param=ssp-buffer-size=4 -I/appli/stig/11.3-20190816-104632/include -DHAVE_C99_MATH=1 -MT proj_strtod.o -MD -MP -MF .deps/proj_strtod.Tpo -c -o proj_strtod.o proj_strtod.c
gie.c: In function ‘cart_selftest’:
gie.c:2008:20: error: ‘NAN’ undeclared (first use in this function)
     a = proj_coord(NAN, NAN, NAN, NAN);
                    ^
gie.c:2008:20: note: each undeclared identifier is reported only once for each function it appears in
make[2]: *** [gie.o] Erreur 1

As the documentation specify a C and C++11 compiler is required I changed the CFLAGS to include -std=gnu11. The build and checks run without errror. Solaris 11.3 is bundled with GCC 5.3 with uses gnu11 by default for C and there should be no reason to force for it on the CFLAGS.

I noticed the configure script detects and automatically adds -std=gnu89 to the CFLAGS :

    checking whether C compiler accepts -Wdocumentation -Wno-documentation-deprecated-sync... no
    checking if -std=gnu89 can be enabled... yes
    checking whether C++ compiler accepts -Wunused-private-field... no

On Solaris this disables the NAN macro as it is C99:

$ cat test.c
#include <stdlib.h>
#include <math.h>

int main (void) {

        float f ;
        f = NAN ;

        exit (EXIT_SUCCESS) ;
}

$ gcc -std=gnu89 test.c
test.c: In function ‘main’:
test.c:7:6: error: ‘NAN’ undeclared (first use in this function)
  f = NAN ;
      ^
test.c:7:6: note: each undeclared identifier is reported only once for each function it appears in

$ gcc -std=gnu99 test.c

$ gcc -std=gnu11 test.c

What is the purpose of forcing C standard to gnu89  ?

Thanks.

-- Eric

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