build(cmake)!: Add support for installation and usage as a library in other CMake projects; Add example project to test this use case.

.gersemirc

@@ -2,7 +2,7 @@
 # yaml-language-server: $schema=https://raw.githubusercontent.com/BlankSpruce/gersemi/master/gersemi/configuration.schema.json
 
 definitions:
-  - "CMake/ystdlib-cpp-helpers.cmake"
+  - "cmake/ystdlib-helpers.cmake"
   - "build/deps/Catch2/Catch2-src/extras/Catch.cmake"
 line_length: 100
 list_expansion: "favour-expansion"

CMakeLists.txt

@@ -1,73 +1,76 @@
-cmake_minimum_required(VERSION 3.22.1)
+cmake_minimum_required(VERSION 3.23)
 
-list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/CMake")
-include(ystdlib-cpp-helpers)
+project(ystdlib VERSION "0.1.0" LANGUAGES CXX)
 
-project(YSTDLIB_CPP LANGUAGES CXX)
-
-set(YSTDLIB_CPP_VERSION "0.0.1" CACHE STRING "Project version.")
+list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/cmake")
+include(CMakePackageConfigHelpers)
+include(GNUInstallDirs)
+include(ystdlib-helpers)
 
 option(BUILD_SHARED_LIBS "Build using shared libraries." OFF)
-option(YSTDLIB_CPP_BUILD_TESTING "Build the testing tree for ystdlib-cpp." ON)
+option(ystdlib_BUILD_TESTING "Build the testing tree for ystdlib." ON)
 
-# Require compiler versions that support the C++20 features necessary for compiling ystdlib-cpp
+# Require compiler versions that support the C++20 features necessary for compiling ystdlib
 if("AppleClang" STREQUAL "${CMAKE_CXX_COMPILER_ID}")
-    set(YSTDLIB_CPP_CMAKE_CXX_COMPILER_MIN_VERSION "16")
+    set(ystdlib_CMAKE_CXX_COMPILER_MIN_VERSION "16")
 elseif("Clang" STREQUAL "${CMAKE_CXX_COMPILER_ID}")
-    set(YSTDLIB_CPP_CMAKE_CXX_COMPILER_MIN_VERSION "16")
+    set(ystdlib_CMAKE_CXX_COMPILER_MIN_VERSION "16")
 elseif("GNU" STREQUAL "${CMAKE_CXX_COMPILER_ID}")
-    set(YSTDLIB_CPP_CMAKE_CXX_COMPILER_MIN_VERSION "11")
+    set(ystdlib_CMAKE_CXX_COMPILER_MIN_VERSION "11")
 else()
     message(
         FATAL_ERROR
         "Unsupported compiler: ${CMAKE_CXX_COMPILER_ID}. Please use AppleClang, Clang, or GNU."
     )
 endif()
-if("${CMAKE_CXX_COMPILER_VERSION}" VERSION_LESS "${YSTDLIB_CPP_CMAKE_CXX_COMPILER_MIN_VERSION}")
+if("${CMAKE_CXX_COMPILER_VERSION}" VERSION_LESS "${ystdlib_CMAKE_CXX_COMPILER_MIN_VERSION}")
     message(
         FATAL_ERROR
         "${CMAKE_CXX_COMPILER_ID} version ${CMAKE_CXX_COMPILER_VERSION} is too low. Must be at \
-        least ${YSTDLIB_CPP_CMAKE_CXX_COMPILER_MIN_VERSION}."
+        least ${ystdlib_CMAKE_CXX_COMPILER_MIN_VERSION}."
     )
 endif()
 
-# Enable exporting compile commands
 set(CMAKE_EXPORT_COMPILE_COMMANDS
     ON
     CACHE BOOL
     "Enable/Disable output of compile commands during generation."
     FORCE
 )
 
-if(YSTDLIB_CPP_IS_TOP_LEVEL)
+set(ystdlib_LIBRARIES
+    "containers"
+    "error_handling"
+    "io_interface"
+    "wrapped_facade_headers"
+    CACHE STRING
+    "Semicolon-separated list of libraries to be built."
+)
+
+message(STATUS "Building the following libraries:")
+foreach(LIB IN LISTS ystdlib_LIBRARIES)
+    message(STATUS " - ${LIB}")
+endforeach()
+
+if(ystdlib_IS_TOP_LEVEL)
     # Include dependency settings if the project isn't being included as a subproject.
     # NOTE: We mark the file optional because if the user happens to have the dependencies
     # installed, this file is not necessary.
-    include("build/deps/cmake-settings/settings.cmake" OPTIONAL)
+    include("build/deps/cmake-settings/all.cmake" OPTIONAL)
 
     # If previously undefined, `BUILD_TESTING` will be set to ON.
     include(CTest)
 endif()
 
-if(BUILD_TESTING AND YSTDLIB_CPP_BUILD_TESTING)
-    set(YSTDLIB_CPP_ENABLE_TESTS ON)
+if(BUILD_TESTING AND ystdlib_BUILD_TESTING)
+    set(ystdlib_ENABLE_TESTS ON)
 endif()
 
-find_package(Boost REQUIRED)
-if(Boost_FOUND)
-    message(STATUS "Found Boost ${Boost_VERSION}.")
-endif()
-
-if(YSTDLIB_CPP_ENABLE_TESTS)
+if(ystdlib_ENABLE_TESTS)
     find_package(Catch2 3.8.0 REQUIRED)
-    if(Catch2_FOUND)
-        message(STATUS "Found Catch2 ${Catch2_VERSION}.")
-    else()
-        message(FATAL_ERROR "Could not find libraries for Catch2.")
-    endif()
+    message(STATUS "Found Catch2 ${Catch2_VERSION}.")
     include(Catch)
 
-    # Set up the unified unit test target
     set(UNIFIED_UNIT_TEST_TARGET "unit-test-all")
     add_executable(${UNIFIED_UNIT_TEST_TARGET})
     target_link_libraries(${UNIFIED_UNIT_TEST_TARGET} PRIVATE Catch2::Catch2WithMain)
@@ -82,4 +85,32 @@ if(YSTDLIB_CPP_ENABLE_TESTS)
     catch_discover_tests(${UNIFIED_UNIT_TEST_TARGET} WORKING_DIRECTORY ${CMAKE_BINARY_DIR}/testbin)
 endif()
 
+# We require all libraries use the same minimum version of dependencies to avoid issues.
+set(BOOST_MIN_VERSION "1.81.0")
+
+set(CONFIG_PATH_SUFFIX "cmake/ystdlib")
+set(CONFIG_LIBS_PATH_SUFFIX "${CONFIG_PATH_SUFFIX}/libs")
+
+# Used by libraries and must come before add_subdirectory.
+set(CONFIG_LIBS_DEST_DIR "${CMAKE_INSTALL_LIBDIR}/${CONFIG_LIBS_PATH_SUFFIX}")
+set(CONFIG_LIBS_INPUT_DIR "${PROJECT_SOURCE_DIR}/${CONFIG_LIBS_PATH_SUFFIX}")
+
 add_subdirectory(src/ystdlib)
+
+set(CONFIG_FILE_PREFIX "ystdlib-config")
+set(CONFIG_INSTALL_DIR ${CMAKE_INSTALL_LIBDIR}/${CONFIG_PATH_SUFFIX})
+set(CONFIG_OUTPUT_PATH "${CMAKE_CURRENT_BINARY_DIR}/${CONFIG_FILE_PREFIX}.cmake")
+set(CONFIG_VERSION_OUTPUT_PATH "${CMAKE_CURRENT_BINARY_DIR}/${CONFIG_FILE_PREFIX}-version.cmake")
+
+configure_package_config_file(
+    "${CMAKE_CURRENT_LIST_DIR}/${CONFIG_PATH_SUFFIX}/${CONFIG_FILE_PREFIX}.cmake.in"
+    "${CONFIG_OUTPUT_PATH}"
+    INSTALL_DESTINATION "${CONFIG_INSTALL_DIR}"
+)
+write_basic_package_version_file("${CONFIG_VERSION_OUTPUT_PATH}" COMPATIBILITY SameMajorVersion)
+install(
+    FILES
+        "${CONFIG_OUTPUT_PATH}"
+        "${CONFIG_VERSION_OUTPUT_PATH}"
+    DESTINATION "${CONFIG_INSTALL_DIR}"
+)