From af33502badc3b1cd0f39b3c10ec5d7f00b7e0547 Mon Sep 17 00:00:00 2001
From: Rhys-T <108157737+Rhys-T@users.noreply.github.com>
Date: Sun, 13 Jul 2025 02:19:57 -0400
Subject: [PATCH] fpc: fix on x86_64-darwin by downgrading Clang

An [upstream issue][] in fpc keeps it from building for x86_64-darwin on
Clang 18 or higher. Override it to use Clang 17 for now.

Fixes #416485.

[upstream issue]: https://gitlab.com/freepascal.org/fpc/source/-/issues/41045
---
 pkgs/top-level/all-packages.nix | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 92d5f2bb6c13..0826594726da 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -4990,7 +4990,13 @@ with pkgs;
   flutter327 = flutterPackages.v3_27;
   flutter324 = flutterPackages.v3_24;
 
-  fpc = callPackage ../development/compilers/fpc { };
+  fpc = callPackage ../development/compilers/fpc {
+    # https://github.com/NixOS/nixpkgs/issues/416485
+    # TODO: remove when upstream issue is fixed:
+    # https://gitlab.com/freepascal.org/fpc/source/-/issues/41045
+    stdenv =
+      if stdenv.cc.isClang && stdenv.hostPlatform.isx86_64 then llvmPackages_17.stdenv else stdenv;
+  };
 
   gambit = callPackage ../development/compilers/gambit { };
   gambit-unstable = callPackage ../development/compilers/gambit/unstable.nix { };