From 1043895c39088d7175f6f11cff95a9a0c8c0b1de Mon Sep 17 00:00:00 2001
From: Wolfgang Walther <walther@technowledgy.de>
Date: Sun, 21 Sep 2025 16:30:53 +0200
Subject: [PATCH] postgresql: pin LLVM 20

PostgreSQL is still broken with LLVM 21.
---
 pkgs/servers/sql/postgresql/generic.nix | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/pkgs/servers/sql/postgresql/generic.nix b/pkgs/servers/sql/postgresql/generic.nix
index c22a07129971..d07f97e9840c 100644
--- a/pkgs/servers/sql/postgresql/generic.nix
+++ b/pkgs/servers/sql/postgresql/generic.nix
@@ -86,7 +86,7 @@ let
         # Building with JIT in pkgsStatic fails like this:
         #   fatal error: 'stdio.h' file not found
         && !stdenv.hostPlatform.isStatic,
-      llvmPackages,
+      llvmPackages_20,
       nukeReferences,
       overrideCC,
 
@@ -162,6 +162,13 @@ let
 
       dlSuffix = if olderThan "16" then ".so" else stdenv.hostPlatform.extensions.sharedLibrary;
 
+      # Pin LLVM 20 until upstream has resolved:
+      # https://www.postgresql.org/message-id/flat/d25e6e4a-d1b4-84d3-2f8a-6c45b975f53d%40applied-asynchrony.com
+      # TODO: Remove with next minor releases
+      llvmPackages = lib.warnIf (
+        version == "17.7"
+      ) "PostgreSQL: Is the pin for LLVM 20 still needed?" llvmPackages_20;
+
       stdenv' =
         if !stdenv.cc.isClang then
           overrideCC llvmPackages.stdenv (