swift-5.10.1 no longer compiling for me on unstable. related issue - https://github.com/NixOS/nixpkgs/issues/483584

pinning nixpkgs to 70801e06d9730c4f1704fbd3bbf5b8e11c03a2a7 seems to do the trick [1]

[1] https://github.com/NixOS/nixpkgs/issues/483584#issuecomment-3796732786

In file included from /nix/store/8pk2m0fn7z5dlb86z5qlv1pxa8w68idx-apple-sdk-14.4/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/secure/_stdio.h:31,
                 from /nix/store/nvx5zr97w93krpl08x796sqai7z43smi-gcc-15.2.0/lib/gcc/arm64-apple-darwin/15.2.0/include-fixed/stdio.h:423,
                 from lib/stdio.h:55,
                 from lib/error.h:47,
                 from src/hello.c:21:
lib/string.h:754:20: error: expected declaration specifiers or '...' before '__builtin_object_size'
  754 | _GL_EXTERN_C void *memcpy (void *__dest, const void *__src, size_t __n)
      |

what fresh hell is this

/* Declarations for ISO C N3322.  */
#if defined __GNUC__ && __GNUC__ >= 15 && !defined __clang__
_GL_EXTERN_C void *memcpy (void *__dest, const void *__src, size_t __n)
  _GL_ATTRIBUTE_NONNULL_IF_NONZERO (1, 3)
  _GL_ATTRIBUTE_NONNULL_IF_NONZERO (2, 3);
_GL_EXTERN_C void *memccpy (void *__dest, const void *__src, int __c, size_t __n)
  _GL_ATTRIBUTE_NONNULL_IF_NONZERO (1, 4)
  _GL_ATTRIBUTE_NONNULL_IF_NONZERO (2, 4);