Can't use external includes on NixOS?

I’m trying to build a library (thin GLFW wrapper, as a test), which requires access to external header files like X11, xcbcommon, etc.

In NixOS I’ve added those packages to my dev shell, and I see them listed in the NIX_CFLAGS_COMPILE environment variable. However, building my library continues to complain that the files can’t be found.

Searching online, it looks like the Zig compiler looks for the NIX_CFLAGS_COMPILE variable, but I’m curious if that is still true when using the build system rather than just compiling on the command-line? Should I instead by manually importing the contents of that environment variable into my build.zig somewhere?

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In zig 0.12.0 there is a NativePaths.detect that uses NIX_ environment variables.
EDIT: the compiler calls it!

  • NIX_CFLAGS_COMPILE is a space separated -framework or -system arguments
  • NIX_LDFLAGS is a space separated -l -L -rpath arguments.

Using addLibraryPath and addIncludePath you can use a library. See also: Linking `ncurses` on NixOS - #5 by RijanHasTwoEars7

Any idea when? I tried running zig build --verbose-cc and never saw mention of it, or of the X11 headers it contains. Here’s the output from just one of the C files it compiled:

/nix/store/vf2rryw77159s12x867whp05ayb7icpj-zig-0.12.0/bin/zig clang /home/nairou/.persist/dev/projects/peepwars/lib/glfw/glfw/src/init.c --no-default-config -fno-caret-diagnostics -D__GLIBC_MINOR__=39 -target x86_64-unknown-linux-gnu -nostdinc -fno-spell-checking -isystem /nix/store/vf2rryw77159s12x867whp05ayb7icpj-zig-0.12.0/lib/include -isystem /nix/store/ij144ma6vs8acil8r9hgr8xkb1dp9azg-glibc-2.39-5-dev/include -Xclang -target-cpu -Xclang skylake -Xclang -target-feature -Xclang -16bit-mode -Xclang -target-feature -Xclang -32bit-mode -Xclang -target-feature -Xclang -3dnow -Xclang -target-feature -Xclang -3dnowa -Xclang -target-feature -Xclang +64bit -Xclang -target-feature -Xclang +adx -Xclang -target-feature -Xclang +aes -Xclang -target-feature -Xclang +allow-light-256-bit -Xclang -target-feature -Xclang -amx-bf16 -Xclang -target-feature -Xclang -amx-complex -Xclang -target-feature -Xclang -amx-fp16 -Xclang -target-feature -Xclang -amx-int8 -Xclang -target-feature -Xclang -amx-tile -Xclang -target-feature -Xclang +avx -Xclang -target-feature -Xclang +avx2 -Xclang -target-feature -Xclang -avx512bf16 -Xclang -target-feature -Xclang -avx512bitalg -Xclang -target-feature -Xclang -avx512bw -Xclang -target-feature -Xclang -avx512cd -Xclang -target-feature -Xclang -avx512dq -Xclang -target-feature -Xclang -avx512er -Xclang -target-feature -Xclang -avx512f -Xclang -target-feature -Xclang -avx512fp16 -Xclang -target-feature -Xclang -avx512ifma -Xclang -target-feature -Xclang -avx512pf -Xclang -target-feature -Xclang -avx512vbmi -Xclang -target-feature -Xclang -avx512vbmi2 -Xclang -target-feature -Xclang -avx512vl -Xclang -target-feature -Xclang -avx512vnni -Xclang -target-feature -Xclang -avx512vp2intersect -Xclang -target-feature -Xclang -avx512vpopcntdq -Xclang -target-feature -Xclang -avxifma -Xclang -target-feature -Xclang -avxneconvert -Xclang -target-feature -Xclang -avxvnni -Xclang -target-feature -Xclang -avxvnniint16 -Xclang -target-feature -Xclang -avxvnniint8 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-fast-11bytenop -Xclang -target-feature -Xclang +fast-15bytenop -Xclang -target-feature -Xclang -fast-7bytenop -Xclang -target-feature -Xclang -fast-bextr -Xclang -target-feature -Xclang +fast-gather -Xclang -target-feature -Xclang -fast-hops -Xclang -target-feature -Xclang -fast-lzcnt -Xclang -target-feature -Xclang -fast-movbe -Xclang -target-feature -Xclang +fast-scalar-fsqrt -Xclang -target-feature -Xclang -fast-scalar-shift-masks -Xclang -target-feature -Xclang +fast-shld-rotate -Xclang -target-feature -Xclang +fast-variable-crosslane-shuffle -Xclang -target-feature -Xclang +fast-variable-perlane-shuffle -Xclang -target-feature -Xclang +fast-vector-fsqrt -Xclang -target-feature -Xclang -fast-vector-shift-masks -Xclang -target-feature -Xclang -faster-shift-than-shuffle -Xclang -target-feature -Xclang +fma -Xclang -target-feature -Xclang -fma4 -Xclang -target-feature -Xclang +fsgsbase -Xclang -target-feature -Xclang -fsrm -Xclang -target-feature -Xclang +fxsr -Xclang -target-feature 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-Xclang -retpoline-indirect-branches -Xclang -target-feature -Xclang -retpoline-indirect-calls -Xclang -target-feature -Xclang -rtm -Xclang -target-feature -Xclang +sahf -Xclang -target-feature -Xclang -sbb-dep-breaking -Xclang -target-feature -Xclang -serialize -Xclang -target-feature -Xclang -seses -Xclang -target-feature -Xclang +sgx -Xclang -target-feature -Xclang -sha -Xclang -target-feature -Xclang -sha512 -Xclang -target-feature -Xclang -shstk -Xclang -target-feature -Xclang +slow-3ops-lea -Xclang -target-feature -Xclang -slow-incdec -Xclang -target-feature -Xclang -slow-lea -Xclang -target-feature -Xclang -slow-pmaddwd -Xclang -target-feature -Xclang -slow-pmulld -Xclang -target-feature -Xclang -slow-shld -Xclang -target-feature -Xclang -slow-two-mem-ops -Xclang -target-feature -Xclang -slow-unaligned-mem-16 -Xclang -target-feature -Xclang -slow-unaligned-mem-32 -Xclang -target-feature -Xclang -sm3 -Xclang -target-feature -Xclang -sm4 -Xclang -target-feature -Xclang -soft-float -Xclang -target-feature -Xclang +sse -Xclang -target-feature -Xclang +sse2 -Xclang -target-feature -Xclang +sse3 -Xclang -target-feature -Xclang +sse4.1 -Xclang -target-feature -Xclang +sse4.2 -Xclang -target-feature -Xclang -sse4a -Xclang -target-feature -Xclang -sse-unaligned-mem -Xclang -target-feature -Xclang +ssse3 -Xclang -target-feature -Xclang -tagged-globals -Xclang -target-feature -Xclang -tbm -Xclang -target-feature -Xclang -tsxldtrk -Xclang -target-feature -Xclang -tuning-fast-imm-vector-shift -Xclang -target-feature -Xclang -uintr -Xclang -target-feature -Xclang -use-glm-div-sqrt-costs -Xclang -target-feature -Xclang -use-slm-arith-costs -Xclang -target-feature -Xclang -vaes -Xclang -target-feature -Xclang -vpclmulqdq -Xclang -target-feature -Xclang +vzeroupper -Xclang -target-feature -Xclang -waitpkg -Xclang -target-feature -Xclang -wbnoinvd -Xclang -target-feature -Xclang -widekl -Xclang -target-feature -Xclang +x87 -Xclang -target-feature -Xclang -xop -Xclang -target-feature -Xclang +xsave -Xclang -target-feature -Xclang +xsavec -Xclang -target-feature -Xclang +xsaveopt -Xclang -target-feature -Xclang +xsaves -fsanitize=undefined -fsanitize-trap=undefined -fno-sanitize=function -mred-zone -fno-omit-frame-pointer -fstack-protector-strong --param ssp-buffer-size=4 -D_DEBUG -O0 -fPIC -funwind-tables -gdwarf-4 -gdwarf32 -MD -MV -MF /home/nairou/.persist/dev/projects/peepwars/lib/glfw/zig-cache/tmp/6a87bbe3e8d407a3-init.o.d -I /home/nairou/.persist/dev/projects/peepwars/lib/glfw/glfw/include -I /home/nairou/.persist/dev/projects/peepwars/lib/glfw/headers/wayland -DWL_MARSHAL_FLAG_DESTROY=1 -Iglfw/src -D_GLFW_X11 -D_GLFW_WAYLAND -c -o /home/nairou/.persist/dev/projects/peepwars/lib/glfw/zig-cache/tmp/6a87bbe3e8d407a3-init.o --serialize-diagnostics /home/nairou/.persist/dev/projects/peepwars/lib/glfw/zig-cache/tmp/6a87bbe3e8d407a3-init.o.diag

Interesting solution, I guess better than nothing. :slight_smile: