From 4e06af5256928863447691afd9678bfb24d6edc3 Mon Sep 17 00:00:00 2001
From: Gabriel Ferreira <gabrielcarvfer@gmail.com>
Date: Wed, 18 Oct 2023 12:39:34 -0300
Subject: [PATCH] build: disable `restrict` warning when using GCC 12.1-12.3

Prevents warning raised by a compiler bug when using GCC 12.1-12.3 with C++20

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105545
---
 CHANGES.md                                 | 1 +
 build-support/macros-and-definitions.cmake | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/CHANGES.md b/CHANGES.md
index 4f897f354..f49cff082 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -30,6 +30,7 @@ Changes from ns-3.40 to ns-3-dev
 
 * In preparation to enable C++20, the following actions have been taken due to compiler issues:
   * Precompiled headers have been disabled in GCC versions >= 12.2.
+  * The `restrict` warning has been disabled in GCC versions 12.1-12.3.1.
 
 ### Changed behavior
 
diff --git a/build-support/macros-and-definitions.cmake b/build-support/macros-and-definitions.cmake
index ca4974c4b..e09d634ec 100644
--- a/build-support/macros-and-definitions.cmake
+++ b/build-support/macros-and-definitions.cmake
@@ -251,6 +251,13 @@ if("${CMAKE_CXX_COMPILER_ID}" MATCHES "GNU")
         CACHE BOOL "Precompile module headers to speed up compilation" FORCE
     )
   endif()
+  if((CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL "12.1.0")
+          AND (CMAKE_CXX_COMPILER_VERSION VERSION_LESS "12.3.2")
+  )
+    # Disable warnings-as-errors for certain versions of GCC when C++20 is
+    # enabled https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105545
+    add_compile_options(-Wno-restrict)
+  endif()
   set(GCC TRUE)
   add_definitions(-fno-semantic-interposition)
   if(${NS3_COLORED_OUTPUT} OR "$ENV{CLICOLOR}")