4.7.4 fails to build on big endian architectures (error: static declaration of ‘byteswap8’ follows non-static declaration)

[sebastic]

The Debian package build of NetCDF 4.7.4 failed on the 390x architecture:

[ 10%] Building C object libdispatch/CMakeFiles/dispatch.dir/dfilter.c.o
cd /<<PKGBUILDDIR>>/obj-s390x-linux-gnu/libdispatch && /usr/bin/cc -DCURL_STATICLIB=1 -DENABLE_SET_LOG_LEVEL -DH5_BUILT_AS_DYNAMIC_LIB -DHAVE_CONFIG_H -DRELAX_COORD_BOUND -I/<<PKGBUILDDIR>>/include -I/<<PKGBUILDDIR>>/oc2 -I/<<PKGBUILDDIR>>/libsrc -I/usr/include/hdf5/serial -I/<<PKGBUILDDIR>>/obj-s390x-linux-gnu  -g -O2 -fdebug-prefix-map=/<<PKGBUILDDIR>>=. -fstack-protector-strong -Wformat -Werror=format-security -DNDEBUG -Wdate-time -D_FORTIFY_SOURCE=2 -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -fPIC   -o CMakeFiles/dispatch.dir/dfilter.c.o   -c /<<PKGBUILDDIR>>/libdispatch/dfilter.c
/<<PKGBUILDDIR>>/libdispatch/dfilter.c: In function ‘NC4_filterfix8’:
/<<PKGBUILDDIR>>/libdispatch/dfilter.c:366:2: warning: implicit declaration of function ‘byteswap4’ [-Wimplicit-function-declaration]
  366 |  byteswap4(mem); /* step 1: byte-swap each piece */
      |  ^~~~~~~~~
/<<PKGBUILDDIR>>/libdispatch/dfilter.c:368:2: warning: implicit declaration of function ‘byteswap8’ [-Wimplicit-function-declaration]
  368 |  byteswap8(mem); /* step 2: convert to little endian format */
      |  ^~~~~~~~~
/<<PKGBUILDDIR>>/libdispatch/dfilter.c: At top level:
/<<PKGBUILDDIR>>/libdispatch/dfilter.c:681:1: warning: conflicting types for ‘byteswap8’
  681 | byteswap8(unsigned char* mem)
      | ^~~~~~~~~
/<<PKGBUILDDIR>>/libdispatch/dfilter.c:681:1: error: static declaration of ‘byteswap8’ follows non-static declaration
/<<PKGBUILDDIR>>/libdispatch/dfilter.c:368:2: note: previous implicit declaration of ‘byteswap8’ was here
  368 |  byteswap8(mem); /* step 2: convert to little endian format */
      |  ^~~~~~~~~
/<<PKGBUILDDIR>>/libdispatch/dfilter.c:700:1: warning: conflicting types for ‘byteswap4’
  700 | byteswap4(unsigned char* mem)
      | ^~~~~~~~~
/<<PKGBUILDDIR>>/libdispatch/dfilter.c:700:1: error: static declaration of ‘byteswap4’ follows non-static declaration
/<<PKGBUILDDIR>>/libdispatch/dfilter.c:366:2: note: previous implicit declaration of ‘byteswap4’ was here
  366 |  byteswap4(mem); /* step 1: byte-swap each piece */
      |  ^~~~~~~~~
make[3]: *** [libdispatch/CMakeFiles/dispatch.dir/build.make:625: libdispatch/CMakeFiles/dispatch.dir/dfilter.c.o] Error 1
make[3]: Leaving directory '/<<PKGBUILDDIR>>/obj-s390x-linux-gnu'
make[2]: *** [CMakeFiles/Makefile2:2123: libdispatch/CMakeFiles/dispatch.dir/all] Error 2
make[2]: *** Waiting for unfinished jobs....

Full buildlog

[DennisHeimbigner]

It looks like I forgot to put forward declarations for byteswap8
and byteswap4 in the file.
Try this and let me know if it works.
Insert the following two lines just after the #include lines
of the libdispatch/dfilter.c file.

static void byteswap8(unsigned char*);
static void byteswap4(unsigned char*);

[sebastic]

Thanks, with the patch in netcdf (1:4.7.4-1~exp2) it now built successfully on s390x, powerpc & ppc64.

[DennisHeimbigner]

Ok, I will submit an official patch

[thesamesam]

Thanks for this! Patch works here on Gentoo too.

[edwardhartnett]

I believe this issue can be closed.