mkDerivation: use __structuredAttrs to pass makeFlags/cmakeFlags/... as array of strings

[milahu]

NixOS#114044

https://discourse.nixos.org/t/cmakeflags-and-spaces-in-option-values/20170

cmakeFlags are currently passed to CMake as follows:

pkgs/development/tools/build-managers/cmake/setup-hook.sh

cmake ${cmakeDir:-.} $cmakeFlags "${cmakeFlagsArray[@]}"

so Bash will tokenize them on spaces and there is no way to prevent it.

The only alternative is adding the flag to cmakeFlagsArray in a Bash code. For example:

preConfigure = ''
  cmakeFlagsArray+=(
    "-DSOMELIB_CXX_FLAGS=\"-O3 -march=native\""
  )
'';

In the future, this might be possible from Nix through __structuredAttrs.

NixOS#175649

workaround

{
  makeFlags = [
    # FIXME stdenv.mkDerivation fails to preserve the space after "-fcommon"
    #''EXTRA_CFLAGS="-fcommon -DTARGET_FORMAT=${targetFormat}"''
    # no. in bash, the backslash is a separate char of the string
    #"EXTRA_CFLAGS=-fcommon\\ -DTARGET_FORMAT=${targetFormat}"
  ]; 

  preConfigure = ''
    # no. gcc: error: unrecognized command-line option '-fcommon -DTARGET_FORMAT=AVM_LE'
    #makeFlagsArray+=('EXTRA_CFLAGS="-fcommon -DTARGET_FORMAT=${targetFormat}"')
    makeFlagsArray+=('EXTRA_CFLAGS=-fcommon -DTARGET_FORMAT=${targetFormat}')
  '';