{ lib, stdenv, llvm_meta, src, substituteAll, cmake, libxml2, libllvm, version, python3
, buildLlvmTools
, fixDarwinDylibNames
, enableManpages ? false
}:

let
  self = stdenv.mkDerivation ({
    pname = "clang";
    inherit version;

    inherit src;
    sourceRoot = "source/clang";

    nativeBuildInputs = [ cmake python3 ]
      ++ lib.optional enableManpages python3.pkgs.sphinx
      ++ lib.optional stdenv.hostPlatform.isDarwin fixDarwinDylibNames;

    buildInputs = [ libxml2 libllvm ];

    cmakeFlags = [
      "-DCMAKE_CXX_FLAGS=-std=c++14"
      "-DCLANGD_BUILD_XPC=OFF"
      "-DLLVM_ENABLE_RTTI=ON"
    ] ++ lib.optionals enableManpages [
      "-DCLANG_INCLUDE_DOCS=ON"
      "-DLLVM_ENABLE_SPHINX=ON"
      "-DSPHINX_OUTPUT_MAN=ON"
      "-DSPHINX_OUTPUT_HTML=OFF"
      "-DSPHINX_WARNINGS_AS_ERRORS=OFF"
    ] ++ lib.optionals (stdenv.hostPlatform != stdenv.buildPlatform) [
      "-DLLVM_TABLEGEN_EXE=${buildLlvmTools.llvm}/bin/llvm-tblgen"
      "-DCLANG_TABLEGEN=${buildLlvmTools.libclang.dev}/bin/clang-tblgen"
    ];

    patches = [
      ./purity.patch
      # https://reviews.llvm.org/D51899
      ./gnu-install-dirs.patch
      # Revert of https://reviews.llvm.org/D100879
      # The malloc alignment assumption is incorrect for jemalloc and causes
      # mis-compilation in firefox.
      # See: https://bugzilla.mozilla.org/show_bug.cgi?id=1741454
      ./revert-malloc-alignment-assumption.patch
      ./add-nostdlibinc-flag.patch
      (substituteAll {
        src = ../../clang-11-12-LLVMgold-path.patch;
        libllvmLibdir = "${libllvm.lib}/lib";
      })
    ];

    postPatch = ''
      (cd tools && ln -s ../../clang-tools-extra extra)

      # Patch for standalone doc building
      sed -i '1s,^,find_package(Sphinx REQUIRED)\n,' docs/CMakeLists.txt
    '' + lib.optionalString stdenv.hostPlatform.isMusl ''
      sed -i -e 's/lgcc_s/lgcc_eh/' lib/Driver/ToolChains/*.cpp
    '';

    outputs = [ "out" "lib" "dev" "python" ];

    postInstall = ''
      ln -sv $out/bin/clang $out/bin/cpp

      # Move libclang to 'lib' output
      moveToOutput "lib/libclang.*" "$lib"
      moveToOutput "lib/libclang-cpp.*" "$lib"
      substituteInPlace $out/lib/cmake/clang/ClangTargets-release.cmake \
          --replace "\''${_IMPORT_PREFIX}/lib/libclang." "$lib/lib/libclang." \
          --replace "\''${_IMPORT_PREFIX}/lib/libclang-cpp." "$lib/lib/libclang-cpp."

      mkdir -p $python/bin $python/share/clang/
      mv $out/bin/{git-clang-format,scan-view} $python/bin
      if [ -e $out/bin/set-xcode-analyzer ]; then
        mv $out/bin/set-xcode-analyzer $python/bin
      fi
      mv $out/share/clang/*.py $python/share/clang
      rm $out/bin/c-index-test
      patchShebangs $python/bin

      mkdir -p $dev/bin
      cp bin/clang-tblgen $dev/bin
    '';

    passthru = {
      isClang = true;
      inherit libllvm;
    };

    meta = llvm_meta // {
      homepage = "https://clang.llvm.org/";
      description = "A C language family frontend for LLVM";
      longDescription = ''
        The Clang project provides a language front-end and tooling
        infrastructure for languages in the C language family (C, C++, Objective
        C/C++, OpenCL, CUDA, and RenderScript) for the LLVM project.
        It aims to deliver amazingly fast compiles, extremely useful error and
        warning messages and to provide a platform for building great source
        level tools. The Clang Static Analyzer and clang-tidy are tools that
        automatically find bugs in your code, and are great examples of the sort
        of tools that can be built using the Clang frontend as a library to
        parse C/C++ code.
      '';
    };
  } // lib.optionalAttrs enableManpages {
    pname = "clang-manpages";

    buildPhase = ''
      make docs-clang-man
    '';

    installPhase = ''
      mkdir -p $out/share/man/man1
      # Manually install clang manpage
      cp docs/man/*.1 $out/share/man/man1/
    '';

    outputs = [ "out" ];

    doCheck = false;

    meta = llvm_meta // {
      description = "man page for Clang ${version}";
    };
  });
in self