Update nixpkgs

This requires two main changes:
- An update to the nixpkgs patch. It is now based on this draft PR:
  NixOS/nixpkgs#352629
- An update to the Lean runtime, as Lean is updated to v4.10.0. The
  changes come from Lean commit
  0a1a855ba80e51515570439f3d73d3d9414ac053.

flake.nix

@@ -1,5 +1,5 @@
 {
-  inputs.nixpkgs.url = "github:NixOS/nixpkgs";
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs?rev=fafe46fca0a8431dcdd3926a01fb06f51c33cab5";
   outputs = { self, nixpkgs }:
     let
       eachDefaultSystem = f: builtins.zipAttrsWith
@@ -18,7 +18,19 @@
         nixpkgs-patched = pkgsNative.applyPatches {
           name = "nixpkgs-patched";
           src = nixpkgs;
-          patches = [ ./patches/nixpkgs.patch ];
+          patches = [
+            (pkgsNative.fetchpatch {
+              # llvmPackages.libcxx: use hasSharedLibraries instead of isStatic
+              url = "https://github.com/NixOS/nixpkgs/commit/5a52d927a64347319bc08584f96e6ad0f2ec6f4f.patch";
+              hash = "sha256-pviFTa5C3Lk6YyyjQ9hEMUQpk4kfAQ4wPVEhwhK0lIc=";
+            })
+            (pkgsNative.fetchpatch {
+              # lib.systems: add various has* flags useful for embedded systems
+              url = "https://github.com/NixOS/nixpkgs/commit/e76ac5d0835e9e939c518ecb161491e595094907.patch";
+              hash = "sha256-3eJXYyMwkl6749ydcQ/pSNxKqjTOzpiRUUSvcOQMFWU=";
+            })
+            ./patches/nixpkgs-ffunction-sections.patch
+          ];
         };
 
         # Nixpkgs only has newlib, not picolibc, so we have to package it.
@@ -185,7 +197,7 @@
               '';
               hash = "sha256-yJ54S+HB3CH5/wb+GFwNkz3/990J8Z6GbuttDhWqN5Q=";
             };
-            patches = finalAttrs.patches ++ [ ./patches/qemu.patch ];
+            patches = [ ./patches/qemu.patch ];
             buildInputs = finalAttrs.buildInputs ++ [ pkgsNative.libgcrypt ];
             configureFlags = finalAttrs.configureFlags ++ [ "--enable-gcrypt" ];
           });

patches/nixpkgs-ffunction-sections.patch

@@ -0,0 +1,25 @@
+From 39d3adfb1a91cff9a49172c3e17e6632a00f4b35 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Gy=C3=B6rgy=20Kurucz?= <[email protected]>
+Date: Thu, 31 Oct 2024 15:24:34 +0100
+Subject: [PATCH] [HACK DO NOT MERGE] -ffunction-sections
+
+---
+ pkgs/development/compilers/llvm/common/libcxx/default.nix | 2 ++
+ 1 file changed, 2 insertions(+)
+
+diff --git a/pkgs/development/compilers/llvm/common/libcxx/default.nix b/pkgs/development/compilers/llvm/common/libcxx/default.nix
+index 57fd748d0f39..8be9c118d7f5 100644
+--- a/pkgs/development/compilers/llvm/common/libcxx/default.nix
++++ b/pkgs/development/compilers/llvm/common/libcxx/default.nix
+@@ -129,6 +129,8 @@ in
+ stdenv.mkDerivation (rec {
+   inherit pname version cmakeFlags patches;
+
++  NIX_CFLAGS_COMPILE = [ "-ffunction-sections" ];
++
+   src = src';
+
+   outputs = [ "out" "dev" ];
+-- 
+2.47.0
+

platform/lean/lean.h

@@ -1119,7 +1119,12 @@ static inline size_t lean_string_byte_size(lean_object *o) {
 }
 /* instance : inhabited char := ⟨'A'⟩ */
 static inline uint32_t lean_char_default_value() { return 'A'; }
+LEAN_EXPORT lean_obj_res lean_mk_string_unchecked(char const *s, size_t sz,
+                                                  size_t len);
 LEAN_EXPORT lean_obj_res lean_mk_string_from_bytes(char const *s, size_t sz);
+LEAN_EXPORT lean_obj_res lean_mk_string_from_bytes_unchecked(char const *s,
+                                                             size_t sz);
+LEAN_EXPORT lean_obj_res lean_mk_ascii_string_unchecked(char const *s);
 LEAN_EXPORT lean_obj_res lean_mk_string(char const *s);
 static inline char const *lean_string_cstr(b_lean_obj_arg o) {
   assert(lean_is_string(o));