latest version of jasper causes build to break

[edwardhartnett]

With jasper-3.0.3:

[ 47%] Building C object CMakeFiles/g2c.dir/src/dec_jpeg2000.c.o
In file included from /usr/local/jasper-3.0.3/include/jasper/jasper.h:73,
                 from /home/ed/NCEPLIBS-g2c/src/dec_jpeg2000.c:10:
/usr/local/jasper-3.0.3/include/jasper/jas_config.h:115:2: warning: #warning "Your code is being built against an older version of the C standard than JasPer was.  Although this is supported, this may require some extra preprocessor defines when building." [-Wcpp]
  115 | #warning "Your code is being built against an older version of the C standard than JasPer was.  Although this is supported, this may require some extra preprocessor defines when building."
      |  ^~~~~~~
[ 48%] Building C object CMakeFiles/g2c.dir/src/enc_jpeg2000.c.o
In file included from /usr/local/jasper-3.0.3/include/jasper/jasper.h:73,
                 from /home/ed/NCEPLIBS-g2c/src/enc_jpeg2000.c:9:
/usr/local/jasper-3.0.3/include/jasper/jas_config.h:115:2: warning: #warning "Your code is being built against an older version of the C standard than JasPer was.  Although this is supported, this may require some extra preprocessor defines when building." [-Wcpp]
  115 | #warning "Your code is being built against an older version of the C standard than JasPer was.  Although this is supported, this may require some extra preprocessor defines when building."
      |  ^~~~~~~
[ 50%] Building C object CMakeFiles/g2c.dir/src/jpcpack.c.o
[ 51%] Building C object CMakeFiles/g2c.dir/src/jpcunpack.c.o
[ 52%] Linking C static library libg2c.a
[ 52%] Built target g2c
[ 53%] Building C object tests/CMakeFiles/tst_addfield3.dir/tst_addfield3.c.o
[ 54%] Linking C executable tst_addfield3
/usr/bin/ld: ../libg2c.a(dec_jpeg2000.c.o): in function `dec_jpeg2000':
/home/ed/NCEPLIBS-g2c/src/dec_jpeg2000.c:46: undefined reference to `jpc_decode'
/usr/bin/ld: ../libg2c.a(enc_jpeg2000.c.o): in function `enc_jpeg2000':
/home/ed/NCEPLIBS-g2c/src/enc_jpeg2000.c:104: undefined reference to `jpc_encode'
collect2: error: ld returned 1 exit status
make[2]: *** [tests/CMakeFiles/tst_addfield3.dir/build.make:89: tests/tst_addfield3] Error 1
make[1]: *** [CMakeFiles/Makefile2:968: tests/CMakeFiles/tst_addfield3.dir/all] Error 2
make: *** [Makefile:141: all] Error 2
ed@mikado:~/NCEPLIBS-g2c/b$ 

[edwardhartnett]

The warning is coming from here: /usr/local/jasper-3.0.3/include/jasper/jas_config.h

Which has:

#if (__STDC_VERSION__ - 0 < JAS_STDC_VERSION)
#warning "Your code is being built against an older version of the C standard than JasPer was.  Although this is supported, this may require some extra preprocessor defines when building."
#endif

Also:

/*
The version of the C standard against which JasPer was built.
*/
#define JAS_STDC_VERSION 201112L

When I check __STDC_VERSION__ I see that it is later than the Jasper one.

gcc -dM -E - < /dev/null | grep "__STDC_"

#define __STDC_HOSTED__ 1
#define __STDC_UTF_16__ 1
#define __STDC_IEC_559__ 1
#define __STDC_ISO_10646__ 201706L
#define __STDC_IEC_559_COMPLEX__ 1
#define __STDC_VERSION__ 201710L
#define __STDC_UTF_32__ 1
#define __STDC__ 1

This seems like japser dumbness in some way. Firstly I built jasper yesterday with the exact same compiler, so why is JAS_STDC_VERSION different from __STDC_VERSION__?

Secondly, why is the warning happening when __STDC_VERSION__ is actually greater than JAS_STDC_VERSION?

[edwardhartnett]

Here's some preprocessor code I used to debug the problem of warnings:

#define XSTR(x) STR(x)
#define STR(x) #x
#pragma message "The value of __STDC_VERSION__ is: " XSTR(__STDC_VERSION__)
#pragma message "The value of JAS_STDC_VERSION is: " XSTR(JAS_STDC_VERSION)

Turns out the problem is in the g2c CMakefile.txt:

set_property(TARGET ${lib_name} PROPERTY C_STANDARD 99)
Should be:

set_property(TARGET ${lib_name} PROPERTY C_STANDARD 11)

[edwardhartnett]

Seems like the functions we are using, jpc_encode() and jpc_decode() are internal functions of Jasper that we should not be using. Seems like the author wants us to use jas_image_encode()/jas_image_decode() instead.

The jpc functions are not documented in the jasper documentation.

[edwardhartnett]

OK, the problem is that jpc_encode/jpc_decode are no longer exported functions of the library.

ed@mikado:~/Downloads$ find /usr/local/jasper-3.0.3/include/jasper/ -name '*.h'|xargs grep jpc_encode
/usr/local/jasper-3.0.3/include/jasper/jas_image.h:int jpc_encode(jas_image_t *image, jas_stream_t *out, const char *optstr);
ed@mikado:~/Downloads$ find /usr/local/jasper-2.0.33/include/jasper/ -name '*.h'|xargs grep jpc_encode
/usr/local/jasper-2.0.33/include/jasper/jas_image.h:JAS_DLLEXPORT int jpc_encode(jas_image_t *image, jas_stream_t *out, const char *optstr);

I think the answer here is to use the jas_image_encode/jas_image_decode instead. These are the public functions we are supposed to be using, according to the jasper documentation.

I also see in the release notes for jasper-3.0.0:

More effort has been made to hide functions/macros that are internal to the JasPer library in an effort to prevent applications using such functions/macros (which can lead to many types of problems).