From c4095d0e4129dd7914a885a0f4088b2ff8f0b2c5 Mon Sep 17 00:00:00 2001
From: Stig Palmquist <stig@stig.io>
Date: Fri, 13 Aug 2021 15:10:35 +0200
Subject: [PATCH] perlPackages.mod_perl2: fix build on perl-5.34.0

---
 .../perl-modules/mod_perl2-PL_hash_seed.patch       | 13 +++++++++++++
 .../http/apache-modules/mod_perl/default.nix        |  5 +++++
 pkgs/top-level/perl-packages.nix                    |  6 ++++++
 3 files changed, 24 insertions(+)
 create mode 100644 pkgs/development/perl-modules/mod_perl2-PL_hash_seed.patch

diff --git a/pkgs/development/perl-modules/mod_perl2-PL_hash_seed.patch b/pkgs/development/perl-modules/mod_perl2-PL_hash_seed.patch
new file mode 100644
index 00000000000..a8aac88de31
--- /dev/null
+++ b/pkgs/development/perl-modules/mod_perl2-PL_hash_seed.patch
@@ -0,0 +1,13 @@
+From https://github.com/Perl/perl5/issues/18617#issuecomment-822056978 by Leont
+
+--- a/src/modules/perl/modperl_perl.c
++++ a/src/modules/perl/modperl_perl.c
+@@ -268,7 +268,7 @@
+ #ifdef MP_NEED_HASH_SEED_FIXUP
+     if (MP_init_hash_seed_set) {
+ #if MP_PERL_VERSION_AT_LEAST(5, 17, 6)
+-        memcpy(&PL_hash_seed, &MP_init_hash_seed,
++        memcpy(PL_hash_seed, &MP_init_hash_seed,
+                 sizeof(PL_hash_seed) > sizeof(MP_init_hash_seed) ?
+                     sizeof(MP_init_hash_seed) : sizeof(PL_hash_seed));
+         PL_hash_seed_set   = MP_init_hash_seed_set;
diff --git a/pkgs/servers/http/apache-modules/mod_perl/default.nix b/pkgs/servers/http/apache-modules/mod_perl/default.nix
index 2762f636f59..febbaf768b7 100644
--- a/pkgs/servers/http/apache-modules/mod_perl/default.nix
+++ b/pkgs/servers/http/apache-modules/mod_perl/default.nix
@@ -9,6 +9,11 @@ stdenv.mkDerivation rec {
     sha256 = "0x3gq4nz96y202cymgrf56n8spm7bffkd1p74dh9q3zrrlc9wana";
   };
 
+  patches = [
+    # Fix build on perl-5.34.0, https://github.com/Perl/perl5/issues/18617
+    ../../../../development/perl-modules/mod_perl2-PL_hash_seed.patch
+  ];
+
   buildInputs = [ apacheHttpd perl ];
   buildPhase = ''
     perl Makefile.PL \
diff --git a/pkgs/top-level/perl-packages.nix b/pkgs/top-level/perl-packages.nix
index 93e7acff553..90938b265bb 100644
--- a/pkgs/top-level/perl-packages.nix
+++ b/pkgs/top-level/perl-packages.nix
@@ -13678,6 +13678,12 @@ let
       url = "mirror://cpan/authors/id/S/SH/SHAY/mod_perl-2.0.11.tar.gz";
       sha256 = "0x3gq4nz96y202cymgrf56n8spm7bffkd1p74dh9q3zrrlc9wana";
     };
+
+    patches = [
+      # Fix build on perl-5.34.0, https://github.com/Perl/perl5/issues/18617
+      ../development/perl-modules/mod_perl2-PL_hash_seed.patch
+    ];
+
     makeMakerFlags = "MP_AP_DESTDIR=$out";
     buildInputs = [ pkgs.apacheHttpd ];
     doCheck = false; # would try to start Apache HTTP server