core: Move to C++26 and use native_handle to CLOEXEC the debug fd (#7219)

Requires GCC >= 14 / Clang >= 18

---------

Co-authored-by: Mihai Fufezan <mihai@fufexan.net>

nix/default.nix

@@ -71,6 +71,11 @@ assert lib.assertMsg (!hidpiXWayland) "The option `hidpiXWayland` has been remov
       src = lib.cleanSource ../.;
     };
 
+    patches = [
+      # forces GCC to use -std=c++26
+      ./stdcxx.patch
+    ];
+
     postPatch = ''
       # Fix hardcoded paths to /usr installation
       sed -i "s#/usr#$out#" src/render/OpenGL.cpp

nix/overlays.nix

@@ -31,7 +31,7 @@ in {
       date = mkDate (self.lastModifiedDate or "19700101");
     in {
       hyprland = final.callPackage ./default.nix {
-        stdenv = final.gcc13Stdenv;
+        stdenv = final.gcc14Stdenv;
         version = "${version}+date=${date}_${self.shortRev or "dirty"}";
         commit = self.rev or "";
         inherit date;

nix/stdcxx.patch

@@ -0,0 +1,12 @@
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index cfbd431f..73e8e0c2 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -64,6 +64,7 @@ endif()
+ include_directories(. "src/" "subprojects/udis86/" "protocols/")
+ set(CMAKE_CXX_STANDARD 26)
+ add_compile_options(
++  -std=c++26
+   -Wall
+   -Wextra
+   -Wno-unused-parameter