From 05de0a91873036ac07da4457fc586131c65ff8cb Mon Sep 17 00:00:00 2001
From: Stefan Frijters <sfrijters@gmail.com>
Date: Sun, 15 Feb 2026 18:58:44 +0100
Subject: [PATCH] ns-3: move CXXFLAGS into env for structuredAttrs

---
 pkgs/by-name/ns/ns-3/package.nix | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pkgs/by-name/ns/ns-3/package.nix b/pkgs/by-name/ns/ns-3/package.nix
index ffeac414ee46..64f4beb62aa4 100644
--- a/pkgs/by-name/ns/ns-3/package.nix
+++ b/pkgs/by-name/ns/ns-3/package.nix
@@ -133,7 +133,7 @@ stdenv.mkDerivation (finalAttrs: {
     "build" + lib.optionalString enableDoxygen " doxygen" + lib.optionalString withManual "sphinx";
 
   # to prevent fatal error: 'backward_warning.h' file not found
-  CXXFLAGS = "-D_GLIBCXX_PERMIT_BACKWARD_HASH";
+  env.CXXFLAGS = "-D_GLIBCXX_PERMIT_BACKWARD_HASH";
 
   # Make generated python bindings discoverable in customized python environment
   passthru = {