{ lib, runCommand, rustc-unwrapped, sysroot ? null }:

runCommand "${rustc-unwrapped.pname}-wrapper-${rustc-unwrapped.version}" {
  preferLocalBuild = true;
  strictDeps = true;
  inherit (rustc-unwrapped) outputs;

  env = {
    sysroot = lib.optionalString (sysroot != null) "--sysroot ${sysroot}";

    # Upstream rustc still assumes that musl = static[1].  The fix for
    # this is to disable crt-static by default for non-static musl
    # targets.
    #
    # Even though Cargo will build build.rs files for the build platform,
    # cross-compiling _from_ musl appears to work fine, so we only need
    # to do this when rustc's target platform is dynamically linked musl.
    #
    # [1]: https://github.com/rust-lang/compiler-team/issues/422
    #
    # WARNING: using defaultArgs is dangerous, as it will apply to all
    # targets used by this compiler (host and target).  This means
    # that it can't be used to set arguments that should only be
    # applied to the target.  It's fine to do this for -crt-static,
    # because rustc does not support +crt-static host platforms
    # anyway.
    defaultArgs = lib.optionalString
      (with rustc-unwrapped.stdenv.targetPlatform; isMusl && !isStatic)
      "-C target-feature=-crt-static";
  };

  passthru = {
    inherit (rustc-unwrapped) pname version src llvm llvmPackages;
    unwrapped = rustc-unwrapped;
  };

  meta = rustc-unwrapped.meta // {
    description = "${rustc-unwrapped.meta.description} (wrapper script)";
    priority = 10;
  };
} ''
  mkdir -p $out/bin
  ln -s ${rustc-unwrapped}/bin/* $out/bin
  rm $out/bin/{rustc,rustdoc}
  prog=${rustc-unwrapped}/bin/rustc extraFlagsVar=NIX_RUSTFLAGS \
      substituteAll ${./rustc-wrapper.sh} $out/bin/rustc
  prog=${rustc-unwrapped}/bin/rustdoc extraFlagsVar=NIX_RUSTDOCFLAGS \
      substituteAll ${./rustc-wrapper.sh} $out/bin/rustdoc
  chmod +x $out/bin/{rustc,rustdoc}
  ${lib.concatMapStrings (output: "ln -s ${rustc-unwrapped.${output}} \$${output}\n")
    (lib.remove "out" rustc-unwrapped.outputs)}
''