pkgsMusl.javaPackages.compiler.openjdk18: fix build

pkgs/development/compilers/openjdk/18.nix

@@ -1,4 +1,4 @@
-{ stdenv, lib, fetchurl, fetchFromGitHub, bash, pkg-config, autoconf, cpio
+{ stdenv, lib, fetchurl, fetchpatch, fetchFromGitHub, bash, pkg-config, autoconf, cpio
 , file, which, unzip, zip, perl, cups, freetype, harfbuzz, alsa-lib, libjpeg, giflib
 , libpng, zlib, lcms2, libX11, libICE, libXrender, libXext, libXt, libXtst
 , libXi, libXinerama, libXcursor, libXrandr, fontconfig, openjdk18-bootstrap
@@ -49,6 +49,13 @@ let
         url = "https://src.fedoraproject.org/rpms/java-openjdk/raw/06c001c7d87f2e9fe4fedeef2d993bcd5d7afa2a/f/rh1673833-remove_removal_of_wformat_during_test_compilation.patch";
         sha256 = "082lmc30x64x583vqq00c8y0wqih3y4r0mp1c4bqq36l22qv6b6r";
       })
+
+      # Patch borrowed from Alpine to fix build errors with musl libc and recent gcc.
+      # This is applied anywhere to prevent patchrot.
+      (fetchpatch {
+        url = "https://git.alpinelinux.org/aports/plain/testing/openjdk18/FixNullPtrCast.patch?id=b93d1fc37fcf106144958d957bb97c7db67bd41f";
+        hash = "sha256-nvO8RcmKwMcPdzq28mZ4If1XJ6FQ76CYWqRIozPCk5U=";
+      })
     ] ++ lib.optionals (!headless && enableGnome2) [
       ./swing-use-gtk-jdk13.patch
     ];