On Tue, Sep 27, 2016 at 12:51:59AM +0530, Arun Isaac wrote:
> 
> > make[2]: Leaving directory '/tmp/nix-build-optipng-0.7.6.drv-0/optipng-0.7.6/src/pngxtern'
> > gcc -c  -O2 -Wall -Wextra -I../cexcept -I../zlib -I../libpng -I../opngreduc -I../pngxtern -o optipng.o optipng.c
> > gcc -c  -O2 -Wall -Wextra -I../cexcept -I../zlib -I../libpng -I../opngreduc -I../pngxtern -o optim.o optim.c
> > gcc -s -o optipng optipng.o optim.o bitset.o ratio.o osys.o wildargs.o ../opngreduc/libopngreduc.a ../pngxtern/libpngxtern.a ../libpng/libpng.a ../zlib/libz.a ../gifread/libgifread.a ../pnmio/libpnmio.a ../minitiff/libminitiff.a   -lm 
> > ../libpng/libpng.a(pngrutil.o): In function `png_read_filter_row':
> > pngrutil.c:(.text+0x13bc): undefined reference to `png_init_filter_functions_neon'
> > collect2: error: ld returned 1 exit status
> > make[1]: *** [Makefile:99: optipng] Error 1
> > make[1]: Leaving directory '/tmp/nix-build-optipng-0.7.6.drv-0/optipng-0.7.6/src/optipng'
> > make: *** [Makefile:2: all] Error 2
> 
> This seems related: https://sourceforge.net/p/libpng/bugs/230/
> The bug was apparently fixed in libpng-1.6.15, and guix is still on
> 1.5.26. Could this be the issue?

We have libpng 1.6.25 on core-updates. So this question will be answered
eventually.