What should we do about compiler-rt-libc-20.1.8-x86_64-darwin who has been failing since the staging-next merge in late December?

Should we mark it as broken?

can one use gcc instead of clang on aarch64-darwin?
tried nix-build -E "with import ./. {}; pkgs.hello.override { stdenv = pkgs.gccStdenv; }" which fails with

configure:5654: checking whether the C compiler works
configure:5676: gcc    conftest.c  >&5
ld: library not found for -liconv
collect2: error: ld returned 1 exit status
...
configure:5728: error: C compiler cannot create executables
See 'config.log' for more details

$ nix-shell -E "with import ./. {}; pkgs.hello.override { stdenv = pkgs.gccStdenv; }"
Using versionCheckHook

# echo $NIX_LDFLAGS
-liconv

# which ld
/nix/store/cjkf5fm587xv34pz9zfs3q2qpvij61fz-gcc-wrapper-15.2.0/bin/ld

$ nix-shell -E "with import ./. {}; pkgs.hello.override { stdenv = pkgs.gccStdenv; }"
Using versionCheckHook

# echo $NIX_LDFLAGS
-liconv

# which ld
/nix/store/cjkf5fm587xv34pz9zfs3q2qpvij61fz-gcc-wrapper-15.2.0/bin/ld

# ld
ld: library not found for -liconv

$ nix-shell -E "with import ./. {}; pkgs.hello.override { stdenv = pkgs.gccStdenv; }"
Using versionCheckHook

# env | grep iconv
NIX_LDFLAGS=-liconv

# which ld
/nix/store/cjkf5fm587xv34pz9zfs3q2qpvij61fz-gcc-wrapper-15.2.0/bin/ld

# ld
ld: library not found for -liconv

gccStdenv =
  if stdenv.cc.isGNU then
    stdenv
  else
    stdenv.override {
      cc = buildPackages.gcc;
      allowedRequisites = null;
      # Remove libcxx/libcxxabi, and add clang for AS if on darwin (it uses
      # clang's internal assembler).
      extraBuildInputs = lib.optional stdenv.hostPlatform.isDarwin clang.cc;
    };