$ CC=clang CXX=clang++ ./configure
checking for a BSD-compatible install... /usr/local/bin/ginstall -c
checking whether build environment is sane... yes
checking for a thread-safe mkdir -p... /usr/local/bin/gmkdir -p
checking for gawk... no
checking for mawk... no
checking for nawk... no
checking for awk... awk
checking whether make sets $(MAKE)... yes
checking whether make supports nested variables... yes
checking whether make supports nested variables... (cached) yes
checking build system type... x86_64-apple-darwin16.4.0
checking host system type... x86_64-apple-darwin16.4.0
checking how to print strings... printf
checking for style of include used by make... GNU
checking for gcc... clang
checking whether the C compiler works... yes
checking for C compiler default output file name... a.out
checking for suffix of executables...
checking whether we are cross compiling... no
checking for suffix of object files... o
checking whether we are using the GNU C compiler... yes
checking whether clang accepts -g... yes
checking for clang option to accept ISO C89... none needed
checking whether clang understands -c and -o together... yes
checking dependency style of clang... gcc3
checking for a sed that does not truncate output... /usr/bin/sed
checking for grep that handles long lines and -e... /usr/bin/grep
checking for egrep... /usr/bin/grep -E
checking for fgrep... /usr/bin/grep -F
checking for ld used by clang... /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ld
checking if the linker (/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ld) is GNU ld... no
checking for BSD- or MS-compatible name lister (nm)... /usr/bin/nm -B
checking the name lister (/usr/bin/nm -B) interface... BSD nm
checking whether ln -s works... yes
checking the maximum length of command line arguments... 196608
checking how to convert x86_64-apple-darwin16.4.0 file names to x86_64-apple-darwin16.4.0 format... func_convert_file_noop
checking how to convert x86_64-apple-darwin16.4.0 file names to toolchain format... func_convert_file_noop
checking for /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ld option to reload object files... -r
checking for objdump... objdump
checking how to recognize dependent libraries... pass_all
checking for dlltool... no
checking how to associate runtime and link libraries... printf %s\n
checking for ar... ar
checking for archiver @FILE support... no
checking for strip... strip
checking for ranlib... ranlib
checking command to parse /usr/bin/nm -B output from clang object... ok
checking for sysroot... no
checking for a working dd... /bin/dd
checking how to truncate binary pipes... /bin/dd bs=4096 count=1
checking for mt... no
checking if : is a manifest tool... no
checking for dsymutil... dsymutil
checking for nmedit... nmedit
checking for lipo... lipo
checking for otool... otool
checking for otool64... no
checking for -single_module linker flag... yes
checking for -exported_symbols_list linker flag... yes
checking for -force_load linker flag... yes
checking how to run the C preprocessor... clang -E
checking for ANSI C header files... yes
checking for sys/types.h... yes
checking for sys/stat.h... yes
checking for stdlib.h... yes
checking for string.h... yes
checking for memory.h... yes
checking for strings.h... yes
checking for inttypes.h... yes
checking for stdint.h... yes
checking for unistd.h... yes
checking for dlfcn.h... yes
checking for objdir... .libs
checking if clang supports -fno-rtti -fno-exceptions... yes
checking for clang option to produce PIC... -fno-common -DPIC
checking if clang PIC flag -fno-common -DPIC works... yes
checking if clang static flag -static works... no
checking if clang supports -c -o file.o... yes
checking if clang supports -c -o file.o... (cached) yes
checking whether the clang linker (/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ld) supports shared libraries... yes
checking dynamic linker characteristics... darwin16.4.0 dyld
checking how to hardcode library paths into programs... immediate
checking whether stripping libraries is possible... yes
checking if libtool supports shared libraries... yes
checking whether to build shared libraries... yes
checking whether to build static libraries... no
checking whether we are using the GNU C++ compiler... yes
checking whether clang++ accepts -g... yes
checking dependency style of clang++... gcc3
checking how to run the C++ preprocessor... clang++ -E
checking for ld used by clang++... /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ld
checking if the linker (/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ld) is GNU ld... no
checking whether the clang++ linker (/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ld) supports shared libraries... yes
checking for clang++ option to produce PIC... -fno-common -DPIC
checking if clang++ PIC flag -fno-common -DPIC works... yes
checking if clang++ static flag -static works... no
checking if clang++ supports -c -o file.o... yes
checking if clang++ supports -c -o file.o... (cached) yes
checking whether the clang++ linker (/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ld) supports shared libraries... yes
checking dynamic linker characteristics... darwin16.4.0 dyld
checking how to hardcode library paths into programs... immediate
checking for pkg-config... /usr/local/bin/pkg-config
checking pkg-config is at least version 0.9.0... yes
checking for VapourSynth... yes
checking that generated files are newer than configure... done
configure: creating ./config.status
config.status: creating Makefile
config.status: executing depfiles commands
config.status: executing libtool commands
$ make V=1
/bin/sh ./libtool  --tag=CXX   --mode=link clang++ -std=c++14 -O3 -ffast-math -mfpmath=sse -msse2 -Wall -Wextra -Wno-unused-parameter -Wshadow  -no-undefined -avoid-version   -o libtcanny.la -rpath /usr/local/lib TCanny/TCanny.lo TCanny/vectorclass/instrset_detect.lo TCanny/TCanny_SSE2.lo libavx.la libavx2.la
libtool: link: clang++ -dynamiclib  -o .libs/libtcanny.dylib  TCanny/.libs/TCanny.o TCanny/vectorclass/.libs/instrset_detect.o TCanny/.libs/TCanny_SSE2.o   -Wl,-force_load,./.libs/libavx.a -Wl,-force_load,./.libs/libavx2.a   -O3 -mfpmath=sse -msse2   -install_name  /usr/local/lib/libtcanny.dylib  -Wl,-single_module
Undefined symbols for architecture x86_64:
  "binarizeCE<float>", referenced from:
      tcannyCreate(VSMap const*, VSMap*, void*, VSCore*, VSAPI const*) in TCanny.o
      tcannyGetFrame(int, int, void**, void**, VSFrameContext*, VSCore*, VSAPI const*) in TCanny.o
  "binarizeCE<unsigned char>", referenced from:
      tcannyCreate(VSMap const*, VSMap*, void*, VSCore*, VSAPI const*) in TCanny.o
      tcannyGetFrame(int, int, void**, void**, VSFrameContext*, VSCore*, VSAPI const*) in TCanny.o
  "binarizeCE<unsigned short>", referenced from:
      tcannyCreate(VSMap const*, VSMap*, void*, VSCore*, VSAPI const*) in TCanny.o
      tcannyGetFrame(int, int, void**, void**, VSFrameContext*, VSCore*, VSAPI const*) in TCanny.o
  "discretizeGM<float>", referenced from:
      tcannyCreate(VSMap const*, VSMap*, void*, VSCore*, VSAPI const*) in TCanny.o
      tcannyGetFrame(int, int, void**, void**, VSFrameContext*, VSCore*, VSAPI const*) in TCanny.o
  "discretizeGM<unsigned char>", referenced from:
      tcannyCreate(VSMap const*, VSMap*, void*, VSCore*, VSAPI const*) in TCanny.o
      tcannyGetFrame(int, int, void**, void**, VSFrameContext*, VSCore*, VSAPI const*) in TCanny.o
  "discretizeGM<unsigned short>", referenced from:
      tcannyCreate(VSMap const*, VSMap*, void*, VSCore*, VSAPI const*) in TCanny.o
      tcannyGetFrame(int, int, void**, void**, VSFrameContext*, VSCore*, VSAPI const*) in TCanny.o
  "gaussianBlurVertical<float>", referenced from:
      tcannyCreate(VSMap const*, VSMap*, void*, VSCore*, VSAPI const*) in TCanny.o
      tcannyGetFrame(int, int, void**, void**, VSFrameContext*, VSCore*, VSAPI const*) in TCanny.o
  "gaussianBlurVertical<unsigned char>", referenced from:
      tcannyCreate(VSMap const*, VSMap*, void*, VSCore*, VSAPI const*) in TCanny.o
      tcannyGetFrame(int, int, void**, void**, VSFrameContext*, VSCore*, VSAPI const*) in TCanny.o
  "gaussianBlurVertical<unsigned short>", referenced from:
      tcannyCreate(VSMap const*, VSMap*, void*, VSCore*, VSAPI const*) in TCanny.o
      tcannyGetFrame(int, int, void**, void**, VSFrameContext*, VSCore*, VSAPI const*) in TCanny.o
  "copyData<float>", referenced from:
      tcannyCreate(VSMap const*, VSMap*, void*, VSCore*, VSAPI const*) in TCanny.o
      tcannyGetFrame(int, int, void**, void**, VSFrameContext*, VSCore*, VSAPI const*) in TCanny.o
  "copyData<unsigned char>", referenced from:
      tcannyCreate(VSMap const*, VSMap*, void*, VSCore*, VSAPI const*) in TCanny.o
      tcannyGetFrame(int, int, void**, void**, VSFrameContext*, VSCore*, VSAPI const*) in TCanny.o
  "copyData<unsigned short>", referenced from:
      tcannyCreate(VSMap const*, VSMap*, void*, VSCore*, VSAPI const*) in TCanny.o
      tcannyGetFrame(int, int, void**, void**, VSFrameContext*, VSCore*, VSAPI const*) in TCanny.o
  "outputGB<float>", referenced from:
      tcannyCreate(VSMap const*, VSMap*, void*, VSCore*, VSAPI const*) in TCanny.o
      tcannyGetFrame(int, int, void**, void**, VSFrameContext*, VSCore*, VSAPI const*) in TCanny.o
  "outputGB<unsigned char>", referenced from:
      tcannyCreate(VSMap const*, VSMap*, void*, VSCore*, VSAPI const*) in TCanny.o
      tcannyGetFrame(int, int, void**, void**, VSFrameContext*, VSCore*, VSAPI const*) in TCanny.o
  "outputGB<unsigned short>", referenced from:
      tcannyCreate(VSMap const*, VSMap*, void*, VSCore*, VSAPI const*) in TCanny.o
      tcannyGetFrame(int, int, void**, void**, VSFrameContext*, VSCore*, VSAPI const*) in TCanny.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [libtcanny.la] Error 1