From b85bc36b0c1eb40925424d2812e51361d84d0a47 Mon Sep 17 00:00:00 2001
From: Joshua Kammeraad <joshkamm@umich.edu>
Date: Mon, 13 Apr 2026 22:06:26 -0700
Subject: [PATCH] Make USE_ACC configurable via environment variable

Default behavior is unchanged (GPU enabled). Setting USE_ACC=OFF
in the environment before cmake configure disables OpenACC/GPU
compilation, using the existing CPU fallback paths in subdirectory
CMakeLists files.

Also switch from True/False to ON/OFF convention for consistency
with ZEST and standard CMake idioms.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 CMakeLists.txt | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 29ec023..b6fc849 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -17,7 +17,11 @@ project(SlaterGPU VERSION 0.1
                   DESCRIPTION "Integrals over Slater type orbitals with GPU Acceleration"
                   LANGUAGES C CXX)
 
-set(USE_ACC True)
+set(USE_ACC ON)
+if("$ENV{USE_ACC}" STREQUAL "OFF")
+    set(USE_ACC OFF)
+endif()
+message(STATUS "USE_ACC: ${USE_ACC}")
 set(USE_MPI True)
 set(USE_OMP True)
 set(RED_DOUBLE True)