https://github.com/NGSolve/netgen/pull/123/commits/5ee4e43393936ab4c00feb58c48bc3a10e6bcbdb

From 76276c5a3b0e70b27d44f7ce0a3ea064b23909da Mon Sep 17 00:00:00 2001
From: Christopher Montgomery <monty@xiph.org>
From: Bernd Waibel <waebbl-gentoo@posteo.net>
Date: Sun, 19 Feb 2023 12:18:12 +0100
Subject: [PATCH] fix nullptr deref in archive

Hardened toolchains (eg, mainline Fedora) no longer tolerate null
derefs that were silently trapped/ignored in earlier versions.  This
eliminates a nullptr deref in archive.hpp that was failing several
unit tests (and causing crashes) when trying to manipulate
default-constructed archive objects.

Adapted original patch according the comment in the PR.

Signed-off-by: Bernd Waibel <waebbl-gentoo@posteo.net>
--- a/libsrc/core/archive.hpp
+++ b/libsrc/core/archive.hpp
@@ -225,7 +225,7 @@ namespace ngcore
       (*this) & size;
       if(Input())
         v.resize(size);
-      Do(&v[0], size);
+      Do(v.data(), size);
       return (*this);
     }
  
-- 
2.39.2