Optional build dependencies incomplete

[termi-official]

Turns out the build scripts make use if xxd if we want to have the logo in the built program. See https://github.com/GLVis/glvis/blob/master/makefile#L278-L280 . Technically xxd is a tool from vim, which just happens to be shipped with Fedora and Ubuntu by default. Not sure if this belongs here or on the web repo. Might be an issue for novice users, as this can be easily be missed, yielding a linker error:

mpicxx -Xclang -load -Xclang LLVMPolly.so -mllvm -polly -I../mfem -I../mfem/../hypre/src/hypre/include -I../mfem/../metis-5.0/include -I../mfem/../gslib/build/include -I../mfem/../caliper/include -g -fopenmp -DGLVIS_MULTISAMPLE=4 -DGLVIS_MS_LINEWIDTH=1.4 -DGLVIS_OGL3 -DGLVIS_USE_LOGO -I/usr/include/freetype2 -I/usr/include -I/usr/include -I/usr/include -I/usr/include -DGLVIS_USE_LIBPNG -o glvis glvis.cpp -Llib -lglvis -L../mfem -lmfem -L../mfem/../hypre/src/hypre/lib -lHYPRE -L../mfem/../metis-5.0/lib -lmetis -L../mfem/../gslib/build/lib -lgs -Wl,-rpath,../mfem/../caliper/lib64 -L../mfem/../caliper/lib64 -lcaliper -lunwind -ldl -lrt -lz -L/usr/lib -L/usr/lib -Wl,-rpath,/usr/lib -L/usr/lib -Wl,-rpath,/usr/lib -lfreetype -lfontconfig -lSDL2 -lGLEW -lGL -lpng -lpthread
/usr/bin/ld: lib/libglvis.a(sdl_main.o): in function `SdlMainThread::setWindowIcon(SDL_Window*)':
/home/dogiermann/Repos/glvis/lib/sdl_main.cpp:445: undefined reference to `logo_rgba_len'
/usr/bin/ld: /home/dogiermann/Repos/glvis/lib/sdl_main.cpp:446: undefined reference to `logo_rgba_len'
/usr/bin/ld: /home/dogiermann/Repos/glvis/lib/sdl_main.cpp:453: undefined reference to `logo_rgba'
clang-13: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [makefile:276: glvis] Error 1

Maybe we should just check if the tool is there in the make and cmake files - however I am not sure which command line tools are allowed, so I opened an issue instead of a PR.

[v-dobrev]

I think I've seen this issue before: https://github.com/GLVis/glvis/issues/210.

We can add a check in the makefile with something like this:

XXD_BIN = $(or $(shell command -v xxd),$(error Required tool not found: xxd. Stop.))

I'm not sure what happens with CMake -- maybe it stops with an error if does not find xxd?

[termi-official]

Indeed, this is the same issue.

I would also have opted for checking if xxd is installed by using command, but with ?= instead of direct assignment.

"Fixing" the cmake build should be as easy as

find_program(XXD_BIN xxd)
if(NOT XXD_BIN)
    error(FATAL_ERROR "xxd not found!")
endif()

[termi-official]

Should I make a PR?

[v-dobrev]

Should I make a PR?

A PR will be welcome! Thanks!

[tzanio]

Discussion continued in @222