I see. where has the complaining happened?

I checked the patch - it does some static array of a limited size carrying results over subsequent calls. looks like an actual fix.

# if !NL_LANGINFO_MTSAFE /* macOS, Solaris */

#  ifdef __sun /* Solaris */
#   define ITEMS (MAXSTRMSG + 1)
#  else /* macOS */
#   define ITEMS (CRNCYSTR + 20)
#  endif
#  define MAX_RESULT_LEN 80

static char *
nl_langinfo_unlocked (nl_item item)
{
  static char result[ITEMS][MAX_RESULT_LEN];

  /* The result of nl_langinfo is in storage that can be overwritten by
     other calls to nl_langinfo.  */
  char *tmp = nl_langinfo (item);
  if (item >= 0 && item < ITEMS && tmp != NULL)

No. I ran into it trying to get Lix to use a fixed curl in my configs. I ended up doing this lovely override:

lixPackageSets.stable = nixpkgs-unstable.lixPackageSets.stable.overrideScope (final: prev: {
    lix = prev.lix.override {
      curl = nixpkgs-unstable.curl.override {
        c-aresMinimal = inputs.lix-fixed.legacyPackages.${pkgs.system}.c-aresMinimal.override {
          inherit (nixpkgs-unstable) cmake stdenv updateAutotoolsGnuConfigScriptsHook;
        };
      };
    };
  });

No. I ran into it trying to get Lix to use a fixed curl in my configs. I ended up doing this lovely override:

lixPackageSets.stable = nixpkgs-unstable.lixPackageSets.stable.overrideScope (final: prev: {
  lix = prev.lix.override {
    curl = nixpkgs-unstable.curl.override {
      c-aresMinimal = inputs.lix-fixed.legacyPackages.${pkgs.system}.c-aresMinimal.override {
        inherit (nixpkgs-unstable) cmake stdenv updateAutotoolsGnuConfigScriptsHook;
      };
    };
  };
});