Clang-tooling woes on NixOS

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So… i got at least include-what-you-use to work with the following frankenstein-trick that reuses the clang++ wrapper script to wrap iwyu.

{
  include-what-you-use,
  clangStdenv
}:
clangStdenv.mkDerivation {
  name = "include-what-you-use-fix";
  src = include-what-you-use;

  phases = [ "installPhase" ];

  installPhase = ''
    mkdir $out/
    cp -r $src/bin $out
    chmod +w -R $out/bin

    # copy the c++ wrapper and patch the last exec line to use iwyu
    mv $out/bin/include-what-you-use $out/bin/.include-what-you-use
    cp ${clangStdenv.cc}/bin/c++ $out/bin/include-what-you-use
    sed -i "s;^exec[^\\]*;exec $out/bin/.include-what-you-use ;" $out/bin/include-what-you-use

    # the python tool is hardcoded to the original iwyu, fix that too
    sed -i "s;${include-what-you-use};$out;" $out/bin/iwyu_tool.py
  '';
}

For my use case, this turned out to work pretty well.

Of course that does not work with clang-tidy… although i got that running by creating an “echo wrapper” of the clang++ wrapper, and a tiny python script that simply “fixes” all command lines in the compile_commands.json file. This of course still does not fix the cmake integration of clang-tidy

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