From d6563d693c817ec762ccd0bb6c44c56b4f3dc4a3 Mon Sep 17 00:00:00 2001
From: Richard Barnes <rbarnes@meta.com>
Date: Sat, 9 May 2026 01:04:43 -0400
Subject: [PATCH] Require C++20 for compatibility with PyTorch (#40380)

Signed-off-by: Richard Barnes <rbarnes@meta.com>
Co-authored-by: Claude <noreply@anthropic.com>
---
 CMakeLists.txt                         | 6 +++++-
 cmake/cpu_extension.cmake              | 2 +-
 cmake/external_projects/deepgemm.cmake | 1 -
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 13788fa8743..38af64851ed 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -13,8 +13,12 @@ cmake_minimum_required(VERSION 3.26)
 # cmake --install . --component _C
 project(vllm_extensions LANGUAGES CXX)
 
-set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CUDA_STANDARD 20)
+set(CMAKE_CUDA_STANDARD_REQUIRED ON)
+set(CMAKE_HIP_STANDARD 20)
+set(CMAKE_HIP_STANDARD_REQUIRED ON)
 
 
 # CUDA by default, can be overridden by using -DVLLM_TARGET_DEVICE=... (used by setup.py)
diff --git a/cmake/cpu_extension.cmake b/cmake/cpu_extension.cmake
index d27a5ea93de..361f08b5105 100644
--- a/cmake/cpu_extension.cmake
+++ b/cmake/cpu_extension.cmake
@@ -1,7 +1,7 @@
 include(FetchContent)
 
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
-set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_EXTENSIONS ON)
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
diff --git a/cmake/external_projects/deepgemm.cmake b/cmake/external_projects/deepgemm.cmake
index 0d7ea43fb7d..07328c27138 100644
--- a/cmake/external_projects/deepgemm.cmake
+++ b/cmake/external_projects/deepgemm.cmake
@@ -76,7 +76,6 @@ if(DEEPGEMM_ARCHS)
     "${deepgemm_SOURCE_DIR}/third-party/fmt/include")
 
   target_compile_options(_deep_gemm_C PRIVATE
-    $<$<COMPILE_LANGUAGE:CXX>:-std=c++17>
     $<$<COMPILE_LANGUAGE:CXX>:-O3>
     $<$<COMPILE_LANGUAGE:CXX>:-Wno-psabi>
     $<$<COMPILE_LANGUAGE:CXX>:-Wno-deprecated-declarations>)