GambitBSM · anderkve · May 8, 2026 · Apr 30, 2026 · Apr 30, 2026 · May 3, 2026
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -43,7 +43,7 @@ if(${CMAKE_VERSION} VERSION_GREATER_EQUAL 4)
 endif()
 
 # Define minimum cmake version
-cmake_minimum_required(VERSION 2.8.12 FATAL_ERROR)
+cmake_minimum_required(VERSION 3.12 FATAL_ERROR)
 
 
 # Define minimum compiler versions
@@ -124,59 +124,40 @@ SET(CMAKE_INSTALL_RPATH_USE_LINK_PATH TRUE)
 # Check if pybind11 is to be ditched
 string(REGEX MATCH ";pybind;|;pybind11;|;Pybind;|;Pybind11;" DITCH_PYBIND ";${itch};")
 
-# Check for Python interpreter.
-# We also need to search for PythonLibs before letting pybind11 look for them,
-# otherwise it seems to get it wrong.  Also, we need to add versions of python
-# greater than 3.3 manually, for compatibility with CMake 2.8.12.
-# If pybind11 is ditched, do not worry about PythonLibs
-set(Python_ADDITIONAL_VERSIONS 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13)
-find_package(PythonInterp 3)  # We require Python 3.
-if(PYTHONINTERP_FOUND)
-  if(NOT DITCH_PYBIND)
-    find_package(PythonLibs 3) # We require Python 3.
-  endif()
+# Check for Python 3 interpreter and (optionally) development libraries.
+# If pybind11 is ditched, do not worry about Python Development libraries.
+if(DITCH_PYBIND)
+  find_package(Python3 REQUIRED COMPONENTS Interpreter)
 else()
+  find_package(Python3 COMPONENTS Interpreter Development)
+endif()
+if(NOT Python3_Interpreter_FOUND)
   message(FATAL_ERROR "\nPython 3 was not found, but it is required by GAMBIT.  \nIf you need to set the path to the Python interpreter manually, "
-                      "please use -D PYTHON_EXECUTABLE=path/to/preferred/python.")
-endif()
-message("${BoldYellow}   Using Python interpreter version ${PYTHON_VERSION_STRING} for build.${ColourReset}")
-
-if(PYTHONLIBS_FOUND)
-  message("${BoldYellow}   Using Python libraries version ${PYTHONLIBS_VERSION_STRING} for Python backend support.${ColourReset}")
-  # Remove trailing non-numeric characters from version
-  string(REGEX REPLACE "[a-zA-Z]" "" PYTHONLIBS_VERSION_STRING_CLEAN ${PYTHONLIBS_VERSION_STRING})
-  if (NOT "${PYTHON_VERSION_STRING}" STREQUAL "${PYTHONLIBS_VERSION_STRING_CLEAN}")
-    message("${BoldRed}   NOTE: You are using different Python versions for the interpreter and the libraries!${ColourReset}\n"
-            "   In principle this should be fine, as the interpreter is only used for building GAMBIT, and the\n"
-            "   libraries are only used for providing support for Python backends at runtime.  However, if you\n"
-            "   have matching versions installed, you can make this message go away by manually setting the \n"
-            "   following variables when you invoke cmake:\n"
-            "     PYTHON_LIBRARY\n"
-            "     PYTHON_INCLUDE_DIR\n"
-            "     PYTHON_EXECUTABLE\n"
-            "   Make sure to clean out your build dir before reconfiguring with these variables set.")
-  endif()
+                      "please use -DPython3_EXECUTABLE=path/to/preferred/python.")
+endif()
+message("${BoldYellow}   Using Python interpreter version ${Python3_VERSION} for build.${ColourReset}")
+
+if(Python3_Development_FOUND)
+  message("${BoldYellow}   Using Python libraries version ${Python3_VERSION} for Python backend support.${ColourReset}")
 endif()
 
-# Check for pybind11 if PythonLibs were found and not ditched
-if(NOT PYTHONLIBS_FOUND AND NOT NO_PYTHON_LIBS)
+# Check for pybind11 if Python Development libraries were found and not ditched
+if(NOT Python3_Development_FOUND AND NOT NO_PYTHON_LIBS)
   if(DITCH_PYBIND)
     message("${BoldCyan} X Excluding pybind11 from GAMBIT configuration. Ditching support for Python backends.${ColourReset}")
   else()
-    message("${BoldRed}   PythonLibs NOT found, so pybind11 cannot be used. Ditching support for Python backends.${ColourReset}\n"
-            "   If you *do* have the Python libraries installed, you can manually set the following\n"
-            "   variables when invoking cmake (also making sure to clean out your build dir):\n"
-            "     PYTHON_LIBRARY\n"
-            "     PYTHON_INCLUDE_DIR\n"
-            "     PYTHON_EXECUTABLE")
+    message("${BoldRed}   Python3 Development libraries NOT found, so pybind11 cannot be used. Ditching support for Python backends.${ColourReset}\n"
+            "   If you *do* have the Python libraries installed, you can manually set\n"
+            "   -DPython3_ROOT_DIR=path/to/python or -DPython3_EXECUTABLE=path/to/python\n"
+            "   when invoking cmake (also making sure to clean out your build dir).")
   set(itch "${itch};pybind11")
   endif()
 
 else()
   set(MIN_pybind11_VERSION "2.13.6")
   set(PREFERRED_pybind11_VERSION "2.13.6")
   set(pybind11_CONTRIB_DIR "${PROJECT_SOURCE_DIR}/contrib/pybind11")
-  include_directories("${PYTHON_INCLUDE_DIRS}")
+  include_directories("${Python3_INCLUDE_DIRS}")
   unset(PYBIND11_CPP_STANDARD CACHE)
   find_package(pybind11 QUIET)
   if(pybind11_FOUND)
@@ -599,7 +580,7 @@ endif()
 if(EXISTS "${PROJECT_SOURCE_DIR}/ScannerBit/")
   message("${Yellow}-- Updating GAMBIT scanner cmake and related files${ColourReset}")
   set(scanner_harvester ${PROJECT_SOURCE_DIR}/ScannerBit/scripts/scanner+_harvester.py ${PROJECT_BINARY_DIR} -x __not_a_real_name__,${itch_with_commas})
-  execute_process(RESULT_VARIABLE result COMMAND ${PYTHON_EXECUTABLE} ${scanner_harvester} WORKING_DIRECTORY ${PROJECT_SOURCE_DIR})
+  execute_process(RESULT_VARIABLE result COMMAND ${Python3_EXECUTABLE} ${scanner_harvester} WORKING_DIRECTORY ${PROJECT_SOURCE_DIR})
   check_result(${result} ${scanner_harvester})
   message("${Yellow}-- Updating GAMBIT scanner cmake and related files - done.${ColourReset}")
 endif()
@@ -610,7 +591,7 @@ include(cmake/preprocessor.cmake)
 # Generate particle_database.cpp from particle_database.yaml.
 if(EXISTS "${PROJECT_SOURCE_DIR}/Models/")
   set(particle_harvester ${PROJECT_SOURCE_DIR}/Models/scripts/particle_harvester.py ${PROJECT_BINARY_DIR} -x __not_a_real_name__,${itch_with_commas})
-  execute_process(COMMAND ${PYTHON_EXECUTABLE} ${particle_harvester} WORKING_DIRECTORY ${PROJECT_SOURCE_DIR})
+  execute_process(COMMAND ${Python3_EXECUTABLE} ${particle_harvester} WORKING_DIRECTORY ${PROJECT_SOURCE_DIR})
   message("${Yellow}-- Generated particle_database.cpp from particle_database.yaml.${ColourReset}")
 endif()
 
@@ -672,7 +653,7 @@ endif()
 # Generate the CMakeLists.txt files for GAMBIT modules, Backends, Models and Printers)
 message("${Yellow}-- Updating GAMBIT module, model, backend, and printer CMake files.${ColourReset}")
 set(update_cmakelists ${PROJECT_SOURCE_DIR}/cmake/scripts/update_cmakelists.py -x __not_a_real_name__,${itch_with_commas})
-execute_process(RESULT_VARIABLE result COMMAND ${PYTHON_EXECUTABLE} ${update_cmakelists} WORKING_DIRECTORY ${PROJECT_SOURCE_DIR})
+execute_process(RESULT_VARIABLE result COMMAND ${Python3_EXECUTABLE} ${update_cmakelists} WORKING_DIRECTORY ${PROJECT_SOURCE_DIR})
 check_result(${result} ${update_cmakelists})
 message("${Yellow}-- Updating GAMBIT module, backend, and printer CMake files - done.${ColourReset}")
 

diff --git a/ScannerBit/python/CMakeLists.txt b/ScannerBit/python/CMakeLists.txt
@@ -4,13 +4,13 @@ include(cmake/scannerbit_python_interface_utils.cmake)
 include(cmake/boost_python.cmake)
 #include(cmake/yaml.cmake)
 
-if(PYTHONINTERP_FOUND)
+if(Python3_Interpreter_FOUND)
 
     if(VERBOSE_SCANNERBIT_PYTHON_INTERFACE)
         message("${BoldYellow}Python extensive module Python deps:${ColourReset}")
-        message("-- Python version string: ${PYTHON_VERSION_STRING}")
-        message("-- Python include dirs: ${PYTHON_INCLUDE_DIRS}")
-        message("-- Python executable: ${PYTHON_EXECUTABLE}")
+        message("-- Python version string: ${Python3_VERSION}")
+        message("-- Python include dirs: ${Python3_INCLUDE_DIRS}")
+        message("-- Python executable: ${Python3_EXECUTABLE}")
     endif(VERBOSE_SCANNERBIT_PYTHON_INTERFACE)
 
     if(HDF5_FOUND)
@@ -36,7 +36,7 @@ if(PYTHONINTERP_FOUND)
         ${HDF5_INCLUDE_DIRS}
         ${PROJECT_SOURCE_DIR}/contrib/pybind11/include
         ${yaml_INCLUDE_DIR}
-        ${PYTHON_INCLUDE_DIRS}
+        ${Python3_INCLUDE_DIRS}
         ${PROJECT_SOURCE_DIR}/ScannerBit/include
         ${CMAKE_CURRENT_SOURCE_DIR}/include
     )
@@ -95,6 +95,6 @@ if(PYTHONINTERP_FOUND)
 else()
 
     message("${BoldRed}-- The ScannerBit python interface requires Python. ${ColourReset}")
-    message("${Red}-- PYTHONINTERP_FOUND=${PYTHONINTERP_FOUND} ${ColourReset}")
+    message("${Red}-- Python3_Interpreter_FOUND=${Python3_Interpreter_FOUND} ${ColourReset}")
 
 endif()
diff --git a/ScannerBit/python/cmake/boost_python.cmake b/ScannerBit/python/cmake/boost_python.cmake
@@ -6,7 +6,7 @@ ExternalProject_Add(boost_python
     BINARY_DIR "${CMAKE_CURRENT_SOURCE_DIR}/contrib/boost_python/build"
     SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/contrib/boost_python"
     PATCH_COMMAND cp ../../cmake/boost_python_install.cmake CMakeLists.txt
-    CONFIGURE_COMMAND ${CMAKE_COMMAND} -DPYTHON_EXECUTABLE=${PYTHON_EXECUTABLE} -DBoost_INCLUDE_DIRS=${Boost_INCLUDE_DIRS} -DPYTHON_INCLUDE_DIRS=${PYTHON_INCLUDE_DIRS} -DPYTHON_LIBRARIES=${PYTHON_LIBRARIES} -DPYTHON_VERSION_STRING=${PYTHON_VERSION_STRING} -DNUMPY_INCLUDE_DIRS=${NUMPY_INCLUDE_DIRS} -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER} -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER} .. 
+    CONFIGURE_COMMAND ${CMAKE_COMMAND} -DPython3_EXECUTABLE=${Python3_EXECUTABLE} -DBoost_INCLUDE_DIRS=${Boost_INCLUDE_DIRS} -DPython3_INCLUDE_DIRS=${Python3_INCLUDE_DIRS} -DPython3_LIBRARIES=${Python3_LIBRARIES} -DPython3_VERSION=${Python3_VERSION} -DNUMPY_INCLUDE_DIRS=${NUMPY_INCLUDE_DIRS} -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER} -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER} .. 
     BUILD_COMMAND make boost_python
     INSTALL_COMMAND ""
   )

diff --git a/ScannerBit/python/cmake/boost_python_install.cmake b/ScannerBit/python/cmake/boost_python_install.cmake
@@ -1,7 +1,6 @@
-CMAKE_MINIMUM_REQUIRED(VERSION 2.8.10 FATAL_ERROR)
-
-FIND_PACKAGE(PythonInterp REQUIRED)
-FIND_PACKAGE(PythonLibs)
+CMAKE_MINIMUM_REQUIRED(VERSION 3.12 FATAL_ERROR)
+
+find_package(Python3 REQUIRED COMPONENTS Interpreter Development)
 FIND_PACKAGE(NumPy) 
 FIND_PACKAGE(Boost 1.41)
 
@@ -52,39 +51,39 @@ SET(BOOST_PYTHON_FLAGS
 SET(BOOST_PYTHON_INCLUDE_DIRS
                 ${CMAKE_CURRENT_SOURCE_DIR}/include
                 ${Boost_INCLUDE_DIRS}
-                ${PYTHON_INCLUDE_DIRS}
+                ${Python3_INCLUDE_DIRS}
 )
 
 SET(BOOST_NUMPY_INCLUDE_DIRS
                 ${CMAKE_CURRENT_SOURCE_DIR}/include
                 ${Boost_INCLUDE_DIRS}
-                ${PYTHON_INCLUDE_DIRS}
+                ${Python3_INCLUDE_DIRS}
                 ${NUMPY_INCLUDE_DIRS}
 )
 
 ADD_LIBRARY(boost_python SHARED ${BOOST_PYTHON_SRCS})
 
-TARGET_LINK_LIBRARIES(boost_python pthread ${PYTHON_LIBRARIES})
+TARGET_LINK_LIBRARIES(boost_python pthread ${Python3_LIBRARIES})
 
 SET_TARGET_PROPERTIES( boost_python
                        PROPERTIES
                        COMPILE_FLAGS "${BOOST_PYTHON_FLAGS}"
                        INCLUDE_DIRECTORIES "${BOOST_PYTHON_INCLUDE_DIRS}"
                        ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/lib"
                        LIBRARY_OUTPUT_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/lib"
-                       LIBRARY_OUTPUT_NAME "boost_python${PYTHON_VERSION_STRING}"
+                       LIBRARY_OUTPUT_NAME "boost_python${Python3_VERSION}"
                        SUFFIX .so)
 
 ADD_LIBRARY(boost_numpy SHARED ${BOOST_NUMPY_SRCS})
 
-TARGET_LINK_LIBRARIES(boost_numpy pthread ${PYTHON_LIBRARIES})
+TARGET_LINK_LIBRARIES(boost_numpy pthread ${Python3_LIBRARIES})
 
 SET_TARGET_PROPERTIES( boost_numpy
                        PROPERTIES
                        COMPILE_FLAGS "${BOOST_PYTHON_FLAGS}"
                        INCLUDE_DIRECTORIES "${BOOST_NUMPY_INCLUDE_DIRS}"
                        ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/lib"
                        LIBRARY_OUTPUT_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/lib"
-                       LIBRARY_OUTPUT_NAME "boost_numpy${PYTHON_VERSION_STRING}"
+                       LIBRARY_OUTPUT_NAME "boost_numpy${Python3_VERSION}"
                        SUFFIX .so)
 
diff --git a/cmake/FindCython.cmake b/cmake/FindCython.cmake
@@ -36,9 +36,9 @@
 
 # Use the Cython executable that lives next to the Python executable
 # if it is a local installation.
-find_package(PythonInterp)
-if(PYTHONINTERP_FOUND)
-  get_filename_component(_python_path ${PYTHON_EXECUTABLE} PATH)
+find_package(Python3 QUIET COMPONENTS Interpreter)
+if(Python3_Interpreter_FOUND)
+  get_filename_component(_python_path ${Python3_EXECUTABLE} PATH)
   find_program(CYTHON_EXECUTABLE
                NAMES cython cython.bat cython3
                HINTS ${_python_path}
@@ -58,16 +58,16 @@ if(CYTHON_EXECUTABLE)
 #                   RESULT_VARIABLE CYTHON_version_result
 #                   OUTPUT_STRIP_TRAILING_WHITESPACE)
 
-#  message("${PYTHON_EXECUTABLE} -m cython --version")
-  execute_process(COMMAND ${PYTHON_EXECUTABLE} -m cython --version
+#  message("${Python3_EXECUTABLE} -m cython --version")
+  execute_process(COMMAND ${Python3_EXECUTABLE} -m cython --version
                   RESULT_VARIABLE cython_result
                   ERROR_VARIABLE cython_output)
 
   if(cython_result EQUAL 0)
     string(REGEX REPLACE "^Cython version ([0-9]+\\.[0-9]+).*" "\\1" CYTHON_VERSION "${cython_output}")
   else()
     string(REGEX REPLACE "\n" "" cython_output "${cython_output}")
-    message("   Did not find cython${PYTHON_VERSION}: ${cython_output}")
+    message("   Did not find cython${Python3_VERSION}: ${cython_output}")
   endif()
 
 #   if(NOT ${CYTHON_version_result} EQUAL 0)
@@ -84,6 +84,6 @@ endif()
 
 include(FindPackageHandleStandardArgs)
 # FIND_PACKAGE_HANDLE_STANDARD_ARGS(Cython REQUIRED_VARS CYTHON_EXECUTABLE)
-find_package_handle_standard_args(Cython${PYTHON_VERSION} DEFAULT_MSG CYTHON_VERSION)
+find_package_handle_standard_args(Cython${Python3_VERSION} DEFAULT_MSG CYTHON_VERSION)
 
 mark_as_advanced(CYTHON_EXECUTABLE)
diff --git a/cmake/utilities.cmake b/cmake/utilities.cmake
@@ -159,7 +159,7 @@ macro(add_external_clean package dir dl target)
   set(reset_file "${CMAKE_BINARY_DIR}/BOSS_reset_info/reset_info.${safe_package}.boss")
   add_custom_target(clean-${package} COMMAND ${CMAKE_COMMAND} -E remove -f ${rmstring1}-BOSS ${rmstring1}-configure ${rmstring1}-build ${rmstring1}-install ${rmstring1}-done
                                      COMMAND [ -e ${dir} ] && cd ${dir} && ([ -e makefile ] || [ -e Makefile ] && (${target})) || true
-                                     COMMAND [ -e ${reset_file} ] && ${PYTHON_EXECUTABLE} ${BOSS_dir}/boss.py -r ${reset_file} || true)
+                                     COMMAND [ -e ${reset_file} ] && ${Python3_EXECUTABLE} ${BOSS_dir}/boss.py -r ${reset_file} || true)
   add_custom_target(nuke-${package} DEPENDS clean-${package}
                                     COMMAND ${CMAKE_COMMAND} -E remove -f ${rmstring1}-download ${rmstring1}-download-failed ${rmstring1}-mkdir ${rmstring1}-patch ${rmstring1}-update ${rmstring1}-gitclone-lastrun.txt ${dl} || true
                                     COMMAND ${CMAKE_COMMAND} -E remove_directory ${dir} || true
@@ -272,7 +272,7 @@ macro(add_gambit_custom target filename HARVESTER DEPS)
     set(ditch_string "-x __not_a_real_name__,${ARGN}")
   endif()
   add_custom_command(OUTPUT ${CMAKE_BINARY_DIR}/${filename}
-                     COMMAND ${PYTHON_EXECUTABLE} ${${HARVESTER}} ${ditch_string}
+                     COMMAND ${Python3_EXECUTABLE} ${${HARVESTER}} ${ditch_string}
                      COMMAND touch ${CMAKE_BINARY_DIR}/${filename}
                      WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
                      DEPENDS ${${HARVESTER}}
@@ -371,7 +371,7 @@ function(add_gambit_executable executablename LIBRARIES)
     set(LIBRARIES ${LIBRARIES} ${Mathematica_WSTP_LIBRARIES})
   endif()
   if(pybind11_FOUND)
-    set(LIBRARIES ${LIBRARIES} ${PYTHON_LIBRARIES})
+    set(LIBRARIES ${LIBRARIES} ${Python3_LIBRARIES})
   endif()
   if(SQLite3_FOUND)
       set(LIBRARIES ${LIBRARIES} ${SQLite3_LIBRARIES})
@@ -451,7 +451,7 @@ function(add_standalone executablename)
 
     # Set up the target to call the facilitator script to make the functors source file for this standalone.
     add_custom_command(OUTPUT ${STANDALONE_FUNCTORS}
-                       COMMAND ${PYTHON_EXECUTABLE} ${STANDALONE_FACILITATOR} ${executablename} -m __not_a_real_name__,${COMMA_SEPARATED_MODULES}
+                       COMMAND ${Python3_EXECUTABLE} ${STANDALONE_FACILITATOR} ${executablename} -m __not_a_real_name__,${COMMA_SEPARATED_MODULES}
                        COMMAND touch ${STANDALONE_FUNCTORS}
                        WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
                        DEPENDS modules_harvested
@@ -727,7 +727,7 @@ macro(BOSS_backend_full name backend_version ${ARGN})
     add_dependencies(${name}_${ver} castxml)
     ExternalProject_Add_Step(${name}_${ver} BOSS
       # Run BOSS
-      COMMAND ${PYTHON_EXECUTABLE} ${BOSS_dir}/boss.py --no-instructions ${BOSS_castxml_cc} ${BOSS_command_line_options} ${BOSS_includes_Boost} ${BOSS_includes_Eigen3} ${BOSS_includes_GSL} ${name}_${backend_version_safe}
+      COMMAND ${Python3_EXECUTABLE} ${BOSS_dir}/boss.py --no-instructions ${BOSS_castxml_cc} ${BOSS_command_line_options} ${BOSS_includes_Boost} ${BOSS_includes_Eigen3} ${BOSS_includes_GSL} ${name}_${backend_version_safe}
       # Copy BOSS-generated files to correct folders within Backends/include
       COMMAND ${CMAKE_COMMAND} -E remove_directory ${PROJECT_SOURCE_DIR}/Backends/include/gambit/Backends/backend_types/${name_in_frontend}_${backend_version_safe} || true
       COMMAND cp -r BOSS_output/${name_in_frontend}_${backend_version_safe}/for_gambit/backend_types/${name_in_frontend}_${backend_version_safe} ${PROJECT_SOURCE_DIR}/Backends/include/gambit/Backends/backend_types/