-- Lower CMake requirement to 3.31.10
-- Disable -march=native
-- Use system libraries for nlohmann_json, random123, tinyopt, and googletest
-- Use bundled unordered_dense

--- CMakeLists.txt.orig	2026-05-18 07:07:58 UTC
+++ CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 4.0.0)
+cmake_minimum_required(VERSION 3.31.10)
 include(CMakeDependentOption)
 include(CheckIPOSupported)
 
@@ -61,7 +61,7 @@ if (NOT DEFINED ARB_DEFAULT_ARCH)
 # Specify target architecture.
 if (NOT DEFINED ARB_DEFAULT_ARCH)
   check_cxx_compiler_flag("-march=native" CXX_HAS_NATIVE)
-  if(CXX_HAS_NATIVE)
+  if(FALSE AND CXX_HAS_NATIVE)
     set(ARB_DEFAULT_ARCH "native")
   else()
     set(ARB_DEFAULT_ARCH "none")
@@ -306,22 +306,16 @@ install(TARGETS ext-hwloc EXPORT arbor-targets)
 endif()
 install(TARGETS ext-hwloc EXPORT arbor-targets)
 
-CPMFindPackage(NAME nlohmann_json
-               GITHUB_REPOSITORY nlohmann/json
-               VERSION 3.12.0)
+find_package(nlohmann_json REQUIRED)
 add_library(ext-json INTERFACE)
 target_link_libraries(ext-json INTERFACE nlohmann_json::nlohmann_json)
 install(TARGETS ext-json EXPORT arbor-targets)
-if(nlohmann_json_ADDED)
-    install(TARGETS nlohmann_json EXPORT arbor-targets)
-endif()
 
 
 add_library(ext-random123 INTERFACE)
-CPMFindPackage(NAME random123
-               DOWNLOAD_ONLY YES
-               GITHUB_REPOSITORY DEShawResearch/random123
-               VERSION 1.14.0)
+set(random123_SOURCE_DIR /usr/local)
+set(random123_ADDED TRUE)
+
 if(random123_ADDED)
     target_include_directories(ext-random123 INTERFACE $<BUILD_INTERFACE:${random123_SOURCE_DIR}/include>)
 else()
@@ -364,10 +358,8 @@ if (BUILD_TESTING)
                   GITHUB_REPOSITORY google/benchmark
                   VERSION 1.8.3
                   OPTIONS "BENCHMARK_ENABLE_TESTING OFF" "CMAKE_BUILD_TYPE release" "BUILD_SHARED_LIBS OFF")
-    CPMFindPackage(NAME googletest
-                  GITHUB_REPOSITORY google/googletest
-                  VERSION 1.17.0
-                  OPTIONS "INSTALL_GTEST OFF" "BUILD_GMOCK OFF")
+    find_package(GTest REQUIRED)
+set(googletest_ADDED FALSE)
     if(benchmark_ADDED)
         target_link_libraries(ext-bench INTERFACE benchmark)
     else()
@@ -399,16 +391,13 @@ list(APPEND arbor_export_dependencies units)
 endif()
 list(APPEND arbor_export_dependencies units)
 
-CPMFindPackage(NAME unordered_dense
-               GITHUB_REPOSITORY martinus/unordered_dense
-               VERSION 4.5.0
-               SYSTEM YES
-               EXCLUDE_FROM_ALL YES)
+set(unordered_dense_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/external/unordered_dense)
+set(unordered_dense_ADDED TRUE)
 
-CPMFindPackage(NAME tinyopt
-               GITHUB_REPOSITORY halfflat/tinyopt
-               GIT_TAG 7e6d707d49c6cb4be27ebd253856be65293288df
-               DOWNLOAD_ONLY YES)
+
+set(tinyopt_SOURCE_DIR /usr/local)
+set(tinyopt_ADDED TRUE)
+
 
 add_library(ext-tinyopt INTERFACE)
 if(tinyopt_ADDED)