From 8d35362651e9c08f57cac421e31756dc2c9c79f3 Mon Sep 17 00:00:00 2001
From: zowoq <59103226+zowoq@users.noreply.github.com>
Date: Mon, 4 May 2026 15:10:07 +1000
Subject: [PATCH] nix: fix withMimalloc

fixes https://github.com/NixOS/nixpkgs/commit/d22a182395ccfc06d84b1b13a6ea660b0aeddb47
---
 .../nix/modular/src/nix/package.nix                 | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/pkgs/tools/package-management/nix/modular/src/nix/package.nix b/pkgs/tools/package-management/nix/modular/src/nix/package.nix
index deb49c9e7b4d..737b57f9433e 100644
--- a/pkgs/tools/package-management/nix/modular/src/nix/package.nix
+++ b/pkgs/tools/package-management/nix/modular/src/nix/package.nix
@@ -1,6 +1,7 @@
 {
   lib,
   mkMesonExecutable,
+  stdenv,
 
   nix-store,
   nix-expr,
@@ -12,6 +13,11 @@
   # Configuration Options
 
   version,
+
+  # Whether to link against mimalloc for malloc override.
+  # Significantly improves evaluation performance on allocation-heavy
+  # workloads (~10-15% on large evaluations).
+  withMimalloc ? !stdenv.hostPlatform.isWindows,
 }:
 
 mkMesonExecutable (finalAttrs: {
@@ -25,10 +31,11 @@ mkMesonExecutable (finalAttrs: {
     nix-expr
     nix-main
     nix-cmd
-    mimalloc
-  ];
+  ]
+  ++ lib.optional ((lib.versionAtLeast version "2.35pre") && withMimalloc) mimalloc;
 
-  mesonFlags = [
+  mesonFlags = lib.optionals (lib.versionAtLeast version "2.35pre") [
+    (lib.mesonEnable "mimalloc" withMimalloc)
   ];
 
   meta = {