nixpkgs/pkgs/stdenv/adapters.nix

/* This file contains various functions that take a stdenv and return
   a new stdenv with different behaviour, e.g. using a different C
   compiler. */

{dietlibc, fetchurl, runCommand}:
   
   
rec {


  # Override the compiler in stdenv for specific packages.
  overrideGCC = stdenv: gcc: stdenv //
    { mkDerivation = args: stdenv.mkDerivation (args // { NIX_GCC = gcc; });
    };

    
  # Add some arbitrary packages to buildInputs for specific packages.
  # Used to override packages in stenv like Make.  Should not be used
  # for other dependencies.
  overrideInStdenv = stdenv: pkgs: stdenv //
    { mkDerivation = args: stdenv.mkDerivation (args //
        { buildInputs = (if args ? buildInputs then args.buildInputs else []) ++ pkgs; }
      );
    };


  # Override the setup script of stdenv.  Useful for testing new
  # versions of the setup script without causing a rebuild of
  # everything.
  #
  # Example:
  #   randomPkg = import ../bla { ...
  #     stdenv = overrideSetup stdenv ../stdenv/generic/setup-latest.sh;
  #   };
  overrideSetup = stdenv: setup: stdenv.regenerate setup;


  # Return a modified stdenv that uses dietlibc to create small
  # statically linked binaries.
  useDietLibC = stdenv: stdenv //
    { mkDerivation = args: stdenv.mkDerivation (args // {
        NIX_CFLAGS_LINK = "-static";

        # libcompat.a contains some commonly used functions.
        NIX_LDFLAGS = "-lcompat";

        # These are added *after* the command-line flags, so we'll
        # always optimise for size.
        NIX_CFLAGS_COMPILE =
          (if args ? NIX_CFLAGS_COMPILE then args.NIX_CFLAGS_COMPILE else "")
          + " -Os -s -D_BSD_SOURCE=1";

        configureFlags =
          (if args ? configureFlags then args.configureFlags else "")
          + " --disable-shared"; # brrr...

        NIX_GCC = import ../build-support/gcc-wrapper {
          inherit stdenv;
          libc = dietlibc;
          inherit (stdenv.gcc) gcc binutils name nativeTools nativePrefix;
          nativeLibc = false;
        };
      });
      isDietLibC = true;
    } // {inherit fetchurl;};

    
  # Return a modified stdenv that uses klibc to create small
  # statically linked binaries.
  useKlibc = stdenv: klibc: stdenv //
    { mkDerivation = args: stdenv.mkDerivation (args // {
        NIX_CFLAGS_LINK = "-static";

        # These are added *after* the command-line flags, so we'll
        # always optimise for size.
        NIX_CFLAGS_COMPILE =
          (if args ? NIX_CFLAGS_COMPILE then args.NIX_CFLAGS_COMPILE else "")
          + " -Os -s";

        configureFlags =
          (if args ? configureFlags then args.configureFlags else "")
          + " --disable-shared"; # brrr...

        NIX_GCC = runCommand "klibc-wrapper" {} ''
          ensureDir $out/bin
          ln -s ${klibc}/bin/klcc $out/bin/gcc
          ln -s ${klibc}/bin/klcc $out/bin/cc
          ensureDir $out/nix-support
          echo 'PATH=$PATH:${stdenv.gcc.binutils}/bin' > $out/nix-support/setup-hook
        '';
      });
      isKlibc = true;
      isStatic = true;
    } // {inherit fetchurl;};

    
  # Return a modified stdenv that tries to build statically linked
  # binaries.
  makeStaticBinaries = stdenv: stdenv //
    { mkDerivation = args: stdenv.mkDerivation (args // {
        NIX_CFLAGS_LINK = "-static";

        configureFlags =
          (if args ? configureFlags then args.configureFlags else "")
          + " --disable-shared"; # brrr...
      });
      isStatic = true;
    } // {inherit fetchurl;};

      
}