Add install and FetchContent

Author: flagarde

CMakeLists.txt

@@ -0,0 +1,44 @@
+cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
+
+project(CPM VERSION 0.37.0 LANGUAGES NONE)
+
+option(CPM_INSTALL "Install CPM" OFF)
+
+include(CMakePackageConfigHelpers)
+configure_package_config_file("${CMAKE_CURRENT_SOURCE_DIR}/cmake/CPMConfig.cmake.in"
+                              "${CMAKE_CURRENT_BINARY_DIR}/CPMConfig.cmake"
+                              INSTALL_DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/CPM"
+                              )
+write_basic_package_version_file("${CMAKE_CURRENT_BINARY_DIR}/CPMConfigVersion.cmake" COMPATIBILITY SameMajorVersion ARCH_INDEPENDENT)
+
+# For consumer using FetchContent
+if(NOT ${CMAKE_PROJECT_NAME} STREQUAL ${PROJECT_NAME})
+  # Trick to use the find_package
+  configure_file("${CMAKE_CURRENT_SOURCE_DIR}/cmake/CPM.cmake" "${CMAKE_CURRENT_BINARY_DIR}/CPM.cmake" COPYONLY)
+  set(CPM_DIR "${CMAKE_CURRENT_BINARY_DIR}")
+  find_package(CPM CONFIG REQUIRED NO_POLICY_SCOPE)
+  # Check if the user download the repo with git and not in an official release
+  if(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/.git" AND IS_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/.git")
+    find_package(Git REQUIRED QUIET)
+    # Generate a git-describe version string from Git repository tags.
+    execute_process(
+      COMMAND ${GIT_EXECUTABLE} tag --points-at HEAD
+      WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
+      OUTPUT_VARIABLE CPM_TAG
+      RESULT_VARIABLE GIT_DESCRIBE_ERROR_CODE
+      OUTPUT_STRIP_TRAILING_WHITESPACE
+    )
+    if(NOT GIT_DESCRIBE_ERROR_CODE AND NOT CPM_TAG STREQUAL "")
+      set(CPM_RELEASE TRUE)
+    else()
+      set(CPM_RELEASE FALSE)
+    endif()
+  endif()
+endif()
+
+if(CPM_INSTALL)
+  ## Without it : Unable to determine default CMAKE_INSTALL_LIBDIR directory because no target architecture is known.  Please enable at least one language before including GNUInstallDirs.
+  enable_language(C)
+  include(GNUInstallDirs)
+  install(FILES "${CMAKE_CURRENT_BINARY_DIR}/CPMConfig.cmake" "${CMAKE_CURRENT_BINARY_DIR}/CPMConfigVersion.cmake" "${CMAKE_CURRENT_SOURCE_DIR}/cmake/CPM.cmake" DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/CPM")
+endif()

cmake/CPM.cmake

@@ -42,7 +42,11 @@ if(NOT COMMAND cpm_message)
   endfunction()
 endif()
 
-set(CURRENT_CPM_VERSION 1.0.0-development-version)
+if(${PROJECT_NAME} STREQUAL "CPM" AND CPM_RELEASE)
+  set(CURRENT_CPM_VERSION "${PROJECT_VERSION}")
+else()
+  set(CURRENT_CPM_VERSION 1.0.0-development-version)
+endif()
 
 get_filename_component(CPM_CURRENT_DIRECTORY "${CMAKE_CURRENT_LIST_DIR}" REALPATH)
 if(CPM_DIRECTORY)

cmake/CPMConfig.cmake.in

@@ -0,0 +1,5 @@
+@PACKAGE_INIT@
+
+include("${CMAKE_CURRENT_LIST_DIR}/CPM.cmake" NO_POLICY_SCOPE)
+
+check_required_components(CPM)