From b087c806fe9cc350c8932f34b4e2913332f540ae Mon Sep 17 00:00:00 2001
From: "M. Chornyi" <99709299+mc-nv@users.noreply.github.com>
Date: Wed, 9 Sep 2026 20:36:01 +0000
Subject: [PATCH 1/2] build: Update C++ standard from c++17 to c++20

Upstream PyTorch raised ATen's minimum required C++ standard from 17
to 20 (pytorch/pytorch#178150), which broke the pytorch_backend build.
Align this repo's TRITON_MIN_CXX_STANDARD/CMAKE_CXX_STANDARD default
with that floor for consistency across the stack.

TRI-1877
---
 CMakeLists.txt | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0fb8595..3782de3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -28,8 +28,8 @@ cmake_minimum_required (VERSION 3.31.8)
 
 project(tritonpytorchbackend LANGUAGES C CXX)
 
-# Use C++17 standard as Triton's minimum required.
-set(TRITON_MIN_CXX_STANDARD 17 CACHE STRING "The minimum C++ standard which features are requested to build this target.")
+# Use C++20 standard as Triton's minimum required.
+set(TRITON_MIN_CXX_STANDARD 20 CACHE STRING "The minimum C++ standard which features are requested to build this target.")
 
 #
 # Options

From fa172d8a8bbf97ef2858e29090dcf233310e7d22 Mon Sep 17 00:00:00 2001
From: "M. Chornyi" <99709299+mc-nv@users.noreply.github.com>
Date: Thu, 10 Sep 2026 18:06:06 +0000
Subject: [PATCH 2/2] fix: raise stale cached TRITON_MIN_CXX_STANDARD to the
 new C++20 floor

---
 CMakeLists.txt | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3782de3..bc9a651 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -29,7 +29,14 @@ cmake_minimum_required (VERSION 3.31.8)
 project(tritonpytorchbackend LANGUAGES C CXX)
 
 # Use C++20 standard as Triton's minimum required.
-set(TRITON_MIN_CXX_STANDARD 20 CACHE STRING "The minimum C++ standard which features are requested to build this target.")
+# A stale CMake cache from a build tree configured before this bump would
+# otherwise keep TRITON_MIN_CXX_STANDARD at its old cached value, so raise it
+# to the new floor while still allowing a user to cache a higher override.
+if(DEFINED TRITON_MIN_CXX_STANDARD AND TRITON_MIN_CXX_STANDARD LESS 20)
+  set(TRITON_MIN_CXX_STANDARD 20 CACHE STRING "The minimum C++ standard which features are requested to build this target." FORCE)
+else()
+  set(TRITON_MIN_CXX_STANDARD 20 CACHE STRING "The minimum C++ standard which features are requested to build this target.")
+endif()
 
 #
 # Options