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

[Kristian Evers]

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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