nixpkgs/pkgs/development/compilers/gcc/common/configure-flags.nix

{
  lib,
  stdenv,
  targetPackages,

  withoutTargetLibc,
  libcCross,
  threadsCross,
  version,

  apple-sdk,
  binutils,
  gmp,
  mpfr,
  libmpc,
  isl,

  enableLTO,
  enableMultilib,
  enablePlugin,
  disableGdbPlugin ? !enablePlugin,
  enableShared,

  langC,
  langCC,
  langD ? false,
  langFortran,
  langAda ? false,
  langGo,
  langObjC,
  langObjCpp,
  langJit,
  langRust ? false,
  disableBootstrap ? (!lib.systems.equals stdenv.targetPlatform stdenv.hostPlatform),
}:

assert !enablePlugin -> disableGdbPlugin;

# Note [Windows Exception Handling]
# sjlj (short jump long jump) exception handling makes no sense on x86_64,
# it's forcably slowing programs down as it produces a constant overhead.
# On x86_64 we have SEH (Structured Exception Handling) and we should use
# that. On i686, we do not have SEH, and have to use sjlj with dwarf2.
# Hence it's now conditional on x86_32 (i686 is 32bit).
#
# ref: https://stackoverflow.com/questions/15670169/what-is-difference-between-sjlj-vs-dwarf-vs-seh

let
  inherit (stdenv)
    buildPlatform
    hostPlatform
    targetPlatform
    ;

  # See https://github.com/NixOS/nixpkgs/pull/209870#issuecomment-1500550903
  disableBootstrap' = disableBootstrap && !langFortran && !langGo;

  crossMingw = (!lib.systems.equals targetPlatform hostPlatform) && targetPlatform.isMinGW;
  crossDarwin =
    (!lib.systems.equals targetPlatform hostPlatform) && targetPlatform.libc == "libSystem";

  targetPrefix = lib.optionalString (
    !lib.systems.equals stdenv.targetPlatform stdenv.hostPlatform
  ) "${stdenv.targetPlatform.config}-";

  crossConfigureFlags =
    # Ensure that -print-prog-name is able to find the correct programs.
    [
      "--with-as=${
        if targetPackages.stdenv.cc.bintools.isLLVM then binutils else targetPackages.stdenv.cc.bintools
      }/bin/${targetPlatform.config}-as"
      "--with-ld=${targetPackages.stdenv.cc.bintools}/bin/${targetPlatform.config}-ld"
    ]
    ++ (
      if withoutTargetLibc then
        [
          "--disable-libssp"
          "--disable-nls"
          "--without-headers"
          "--disable-threads"
          "--disable-libgomp"
          "--disable-libquadmath"
          (lib.enableFeature enableShared "shared")
          "--disable-libatomic" # requires libc
          "--disable-decimal-float" # requires libc
          "--disable-libmpx" # requires libc
        ]
        ++ lib.optionals crossMingw [
          "--with-headers=${lib.getDev libcCross}/include"
          "--with-gcc"
          "--with-gnu-as"
          "--with-gnu-ld"
          "--disable-debug"
          "--disable-win32-registry"
          "--enable-hash-synchronization"
          "--enable-libssp"
          "--disable-nls"
          # To keep ABI compatibility with upstream mingw-w64
          "--enable-fully-dynamic-string"
        ]
        ++ lib.optionals (crossMingw && targetPlatform.isx86_32) [
          # See Note [Windows Exception Handling]
          "--enable-sjlj-exceptions"
          "--with-dwarf2"
        ]
      else
        [
          (
            if crossDarwin then
              "--with-sysroot=${lib.getLib libcCross}/share/sysroot"
            else
              "--with-headers=${lib.getDev libcCross}${libcCross.incdir or "/include"}"
          )
          "--enable-__cxa_atexit"
          "--enable-long-long"
          "--enable-threads=${
            if targetPlatform.isUnix then
              "posix"
            else if targetPlatform.isWindows then
              (threadsCross.model or "win32")
            else
              "single"
          }"
          "--enable-nls"
        ]
        ++ lib.optionals (targetPlatform.libc == "uclibc" || targetPlatform.libc == "musl") [
          # libsanitizer requires netrom/netrom.h which is not
          # available in uclibc.
          "--disable-libsanitizer"
        ]
        ++ lib.optional (
          targetPlatform.libc == "newlib" || targetPlatform.libc == "newlib-nano"
        ) "--with-newlib"
        ++ lib.optional (targetPlatform.libc == "avrlibc") "--with-avrlibc"
    );

  configureFlags =
    # Basic dependencies
    [
      "--with-gmp-include=${gmp.dev}/include"
      "--with-gmp-lib=${gmp.out}/lib"
      "--with-mpfr-include=${mpfr.dev}/include"
      "--with-mpfr-lib=${mpfr.out}/lib"
      "--with-mpc=${libmpc}"
    ]
    ++ lib.optionals (!withoutTargetLibc) [
      (
        if libcCross == null then
          (
            # GCC will search for the headers relative to SDKROOT on Darwin, so it will find them in the store.
            if targetPlatform.isDarwin then
              "--with-native-system-header-dir=/usr/include"
            else
              "--with-native-system-header-dir=${lib.getDev stdenv.cc.libc}/include"
          )
        else
          "--with-native-system-header-dir=${lib.getDev libcCross}${libcCross.incdir or "/include"}"
      )
      # gcc builds for cross-compilers (build != host) or cross-built
      # gcc (host != target) always apply the offset prefix to disentangle
      # target headers from build or host headers:
      #     ${with_build_sysroot}${native_system_header_dir}
      #  or ${test_exec_prefix}/${target_noncanonical}/sys-include
      #  or ${with_sysroot}${native_system_header_dir}
      # While native build (build == host == target) uses passed headers
      # path as is:
      #    ${with_build_sysroot}${native_system_header_dir}
      #
      # Nixpkgs uses flat directory structure for both native and cross
      # cases. As a result libc headers don't get found for cross case
      # and many modern features get disabled (libssp is used instead of
      # target-specific implementations and similar). More details at:
      #   https://github.com/NixOS/nixpkgs/pull/181802#issuecomment-1186822355
      #
      # We pick "/" path to effectively avoid sysroot offset and make it work
      # as a native case.
      # Darwin requires using the SDK as the sysroot for `SDKROOT` to work correctly.
      "--with-build-sysroot=${if targetPlatform.isDarwin then apple-sdk.sdkroot else "/"}"
      # Same with the stdlibc++ headers embedded in the gcc output
      "--with-gxx-include-dir=${placeholder "out"}/include/c++/${version}/"
    ]

    # Basic configuration
    ++ [
      # Force target prefix. The behavior if `--target` and `--host`
      # are specified is inconsistent: Sometimes specifying `--target`
      # always causes a prefix to be generated, sometimes it's only
      # added if the `--host` and `--target` differ. This means that
      # sometimes there may be a prefix even though nixpkgs doesn't
      # expect one and sometimes there may be none even though nixpkgs
      # expects one (since not all information is serialized into the
      # config attribute). The easiest way out of these problems is to
      # always set the program prefix, so gcc will conform to our
      # expectations.
      "--program-prefix=${targetPrefix}"

      (lib.enableFeature enableLTO "lto")
      "--disable-libstdcxx-pch"
      "--without-included-gettext"
      "--with-system-zlib"
      "--enable-static"
      "--enable-languages=${
        lib.concatStringsSep "," (
          lib.optional langC "c"
          ++ lib.optional langCC "c++"
          ++ lib.optional langD "d"
          ++ lib.optional langFortran "fortran"
          ++ lib.optional langAda "ada"
          ++ lib.optional langGo "go"
          ++ lib.optional langObjC "objc"
          ++ lib.optional langObjCpp "obj-c++"
          ++ lib.optionals crossDarwin [
            "objc"
            "obj-c++"
          ]
          ++ lib.optional langJit "jit"
          ++ lib.optional langRust "rust"
        )
      }"
    ]

    ++ (
      if (enableMultilib || targetPlatform.isAvr) then
        [
          "--enable-multilib"
          "--disable-libquadmath"
        ]
      else
        [ "--disable-multilib" ]
    )
    ++ lib.optional (!enableShared) "--disable-shared"
    ++ lib.singleton (lib.enableFeature enablePlugin "plugin")
    # Libcc1 is the GCC cc1 plugin for the GDB debugger which is only used by gdb
    ++ lib.optional disableGdbPlugin "--disable-libcc1"

    # Support -m32 on powerpc64le/be
    ++ lib.optional (targetPlatform.system == "powerpc64le-linux") "--enable-targets=powerpcle-linux"
    ++ lib.optional (targetPlatform.system == "powerpc64-linux") "--enable-targets=powerpc-linux"

    # Fix "unknown long double size, cannot define BFP_FMT"
    ++ lib.optional (targetPlatform.isPower && targetPlatform.isMusl) "--disable-decimal-float"

    # Optional features
    ++ lib.optional (isl != null) "--with-isl=${isl}"

    # Ada options, gcc can't build the runtime library for a cross compiler
    ++ lib.optional langAda (
      if lib.systems.equals hostPlatform targetPlatform then "--enable-libada" else "--disable-libada"
    )

    ++ import ../common/platform-flags.nix {
      inherit (stdenv) targetPlatform;
      inherit lib;
    }
    ++ lib.optionals (!lib.systems.equals targetPlatform hostPlatform) crossConfigureFlags
    ++ lib.optional disableBootstrap' "--disable-bootstrap"

    # Platform-specific flags
    ++ lib.optional (
      lib.systems.equals targetPlatform hostPlatform && targetPlatform.isx86_32
    ) "--with-arch=${stdenv.hostPlatform.parsed.cpu.name}"
    ++ lib.optional targetPlatform.isNetBSD "--disable-libssp" # Provided by libc.
    ++ lib.optionals hostPlatform.isSunOS [
      "--enable-long-long"
      "--enable-libssp"
      "--enable-threads=posix"
      "--disable-nls"
      "--enable-__cxa_atexit"
      # On Illumos/Solaris GNU as is preferred
      "--with-gnu-as"
      "--without-gnu-ld"
    ]
    ++
      lib.optional (targetPlatform.libc == "musl")
        # musl at least, disable: https://git.buildroot.net/buildroot/commit/?id=873d4019f7fb00f6a80592224236b3ba7d657865
        "--disable-libmpx"
    ++ lib.optionals (lib.systems.equals targetPlatform hostPlatform && targetPlatform.libc == "musl") [
      "--disable-libsanitizer"
      "--disable-symvers"
      "libat_cv_have_ifunc=no"
      "--disable-gnu-indirect-function"
    ]
    ++ lib.optionals langJit [
      "--enable-host-shared"
    ]
    ++ lib.optionals (langD) [
      "--with-target-system-zlib=yes"
    ]
    # On mips64-unknown-linux-gnu libsanitizer defines collide with
    # glibc's definitions and fail the build. It was fixed in gcc-13+.
    ++
      lib.optionals
        (
          targetPlatform.isMips
          && targetPlatform.parsed.abi.name == "gnu"
          && lib.versions.major version == "12"
        )
        [
          "--disable-libsanitizer"
        ]
    ++ lib.optionals targetPlatform.isAlpha [
      # Workaround build failures like:
      #   cc1: error: fp software completion requires '-mtrap-precision=i' [-Werror]
      "--disable-werror"
    ];

in
configureFlags