fix: modernize CMake usage

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

.github/CONTRIBUTING.md

@@ -225,6 +225,23 @@ cmake -S . -B build-iwyu -DCMAKE_CXX_INCLUDE_WHAT_YOU_USE=$(which include-what-y
 cmake --build build
 ```
 
+## Timing steps
+
+Make time/memory taken can be set
+`CMAKE_CXX_COMPILER_LAUNCHER`/`CMAKE_CXX_LINKER_LANCHER`. Some examples:
+
+```
+# Linux:
+#   "time"
+#   "time;-v"
+#   "time;-f;'%U user %S system %E elapsed %P CPU %M KB'"
+# macOS:
+#   "time"
+# macOS with brew install gnu-time:
+#   "gtime;-f;'%U user %S system %E elapsed %P CPU %M KB'"
+#
+```
+
 ## Common tasks
 
 <details><summary>Updating dependencies (click to expand)</summary>

CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.15...3.26)
+cmake_minimum_required(VERSION 3.15...3.27)
 
 project(BOOST_HISTOGRAM LANGUAGES CXX)
 # Version is added later
@@ -13,31 +13,6 @@ set(CMAKE_CXX_EXTENSIONS OFF)
 # Adding folders to keep the structure a bit nicer in IDE's
 set_property(GLOBAL PROPERTY USE_FOLDERS ON)
 
-# Make time/memory taken to compile/link available as a setting
-#
-# Useful settings:
-# Linux:
-#   "time"
-#   "time -v"
-#   "time -f '%U user %S system %E elapsed %P CPU %M KB'"
-# macOS:
-#   "time -l"
-# macOS with brew install gnu-time:
-#   "gtime -f '%U user %S system %E elapsed %P CPU %M KB'"
-#
-set(BH_RULE_LAUNCH_COMPILE
-    ""
-    CACHE STRING [=[Use a command, like "time" to wrap the compile]=])
-if(NOT BH_RULE_LAUNCH_COMPILE STREQUAL "")
-  set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE "${BH_RULE_LAUNCH_COMPILE}")
-endif()
-set(BH_RULE_LAUNCH_LINK
-    ""
-    CACHE STRING [=[Use a command, like "time" to wrap the link]=])
-if(NOT BH_RULE_LAUNCH_LINK STREQUAL "")
-  set_property(GLOBAL PROPERTY RULE_LAUNCH_LINK "${BH_RULE_LAUNCH_LINK}")
-endif()
-
 # This will force color output at build time if this env variable is set _at
 # configure time_. This is useful for CI.
 if($ENV{FORCE_COLOR})
@@ -49,11 +24,11 @@ if($ENV{FORCE_COLOR})
 endif()
 
 # This is a standard recipe for setting a default build type
-set(default_build_type "Debug")
+set(_default_build_type "Debug")
 if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
-  message(STATUS "Setting build type to '${default_build_type}' as none was specified.")
+  message(STATUS "Setting build type to '${_default_build_type}' as none was specified.")
   set(CMAKE_BUILD_TYPE
-      "${default_build_type}"
+      "${_default_build_type}"
       CACHE STRING "Choose the type of build." FORCE)
   # Set the possible values of build type for cmake-gui
   set_property(CACHE CMAKE_BUILD_TYPE PROPERTY STRINGS "Debug" "Release" "MinSizeRel"
@@ -65,9 +40,11 @@ message(STATUS "CMake ${CMAKE_VERSION}")
 
 # Adding pybind11 and setting up Python
 # Will display pybind11 version
+set(PYBIND11_FINDPYTHON TRUE)
+set(Python_ARTIFACTS_INTERACTIVE TRUE)
 add_subdirectory(extern/pybind11)
 
-message(STATUS "Python ${PYTHON_VERSION_MAJOR}.${PYTHON_VERSION_MINOR}")
+message(STATUS "Python ${Python_VERSION_MAJOR}.${Python_VERSION_MINOR}")
 
 # This is completely optional and just adds hints to IDEs - no affect on build at all.
 file(GLOB_RECURSE BOOST_HIST_FILES "extern/histogram/include/*.hpp")
@@ -151,8 +128,7 @@ endif()
 # which confuses Python.
 set_property(TARGET _core PROPERTY LIBRARY_OUTPUT_DIRECTORY "$<1:boost_histogram>")
 
-# Collect all the python files and symlink them (3.14+) or copy them (3.12-3.13)
-# into the build directory
+# Collect all the python files and symlink them into the build directory
 # Protects from in-source builds (don't do this, please)
 if(NOT "${CMAKE_CURRENT_SOURCE_DIR}" STREQUAL "${CMAKE_CURRENT_BINARY_DIR}" AND NOT DEFINED
                                                                                 SKBUILD)
@@ -162,15 +138,9 @@ if(NOT "${CMAKE_CURRENT_SOURCE_DIR}" STREQUAL "${CMAKE_CURRENT_BINARY_DIR}" AND
     RELATIVE "${CMAKE_CURRENT_SOURCE_DIR}/src"
     CONFIGURE_DEPENDS "src/boost_histogram/*.py")
   foreach(F IN LISTS BOOST_HIST_PY_FILES)
-    if(CMAKE_VERSION VERSION_LESS 3.14)
-      get_filename_component(FDIR "${F}" DIRECTORY)
-      file(COPY "${CMAKE_CURRENT_SOURCE_DIR}/src/${F}"
-           DESTINATION "${CMAKE_CURRENT_BINARY_DIR}/${FDIR}")
-    else()
-      file(REMOVE "${CMAKE_CURRENT_BINARY_DIR}/${F}")
-      file(CREATE_LINK "${CMAKE_CURRENT_SOURCE_DIR}/src/${F}" "${CMAKE_CURRENT_BINARY_DIR}/${F}"
-           COPY_ON_ERROR SYMBOLIC)
-    endif()
+    file(REMOVE "${CMAKE_CURRENT_BINARY_DIR}/${F}")
+    file(CREATE_LINK "${CMAKE_CURRENT_SOURCE_DIR}/src/${F}" "${CMAKE_CURRENT_BINARY_DIR}/${F}"
+         COPY_ON_ERROR SYMBOLIC)
   endforeach()
 endif()
 

tests/CMakeLists.txt

@@ -1,9 +1,6 @@
 pybind11_find_import(numpy)
 pybind11_find_import(pytest)
 pybind11_find_import(pytest-benchmark)
-if(PYTHON_VERSION VERSION_LESS 3.5)
-  pybind11_find_import(typing)
-endif()
 
 # Support for running from build directory
 file(WRITE "${PROJECT_BINARY_DIR}/pytest.ini" "[pytest]\n" "addopts = --benchmark-disable\n"