modernize build with proper install/export and metadata

CMakeLists.txt

@@ -1,30 +1,77 @@
 cmake_minimum_required(VERSION 3.23)
 
-project(zeus_expected)
+project(
+    zeus_expected
+    VERSION 1.3.3
+    DESCRIPTION "Backporting std::expected to C++17."
+    HOMEPAGE_URL "https://github.com/zeus-cpp/expected"
+    LANGUAGES CXX
+)
 
 add_library(${PROJECT_NAME} INTERFACE)
 add_library(zeus::expected ALIAS ${PROJECT_NAME})
 
-target_include_directories(${PROJECT_NAME} INTERFACE
-    $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
-    $<INSTALL_INTERFACE:include>
+target_sources(${PROJECT_NAME} INTERFACE
+    FILE_SET exports
+    TYPE HEADERS
+    BASE_DIRS include
+    FILES
+        include/zeus/expected.hpp
 )
-target_sources(${PROJECT_NAME} PUBLIC FILE_SET exports TYPE HEADERS BASE_DIRS include FILES
-    include/zeus/expected.hpp
+
+set_target_properties(zeus_expected PROPERTIES
+    EXPORT_NAME expected
 )
 
-include(GNUInstallDirs)
+target_compile_features(${PROJECT_NAME} INTERFACE cxx_std_17)
 
-install(TARGETS ${PROJECT_NAME}
-    EXPORT ${PROJECT_NAME}-targets
-    FILE_SET exports
-)
-install(EXPORT ${PROJECT_NAME}-targets DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}"
-    FILE ${PROJECT_NAME}.cmake
-    COMPONENT Development EXCLUDE_FROM_ALL
-)
+option(ZEUS_EXPECTED_INSTALL "Generate install targets" ${PROJECT_IS_TOP_LEVEL})
+option(ZEUS_EXPECTED_BUILD_TESTS "Build tests" ${PROJECT_IS_TOP_LEVEL})
+
+if(ZEUS_EXPECTED_INSTALL)
+    include(GNUInstallDirs)
+
+    install(TARGETS ${PROJECT_NAME}
+        EXPORT ${PROJECT_NAME}-targets
+        FILE_SET exports
+        DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+        COMPONENT Development
+    )
+
+    install(EXPORT ${PROJECT_NAME}-targets
+        NAMESPACE zeus::
+        DESTINATION "${CMAKE_INSTALL_DATADIR}/cmake/${PROJECT_NAME}"
+        FILE ${PROJECT_NAME}Targets.cmake
+        COMPONENT Development
+    )
+
+    include(CMakePackageConfigHelpers)
+
+    write_basic_package_version_file(
+        "${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}ConfigVersion.cmake"
+        VERSION ${PROJECT_VERSION}
+        COMPATIBILITY SameMajorVersion
+        ARCH_INDEPENDENT
+    )
+
+    configure_package_config_file(
+        "${CMAKE_CURRENT_SOURCE_DIR}/cmake/${PROJECT_NAME}Config.cmake.in"
+        "${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}Config.cmake"
+        INSTALL_DESTINATION "${CMAKE_INSTALL_DATADIR}/cmake/${PROJECT_NAME}"
+    )
+
+    install(
+        FILES
+            "${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}Config.cmake"
+            "${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}ConfigVersion.cmake"
+        DESTINATION "${CMAKE_INSTALL_DATADIR}/cmake/${PROJECT_NAME}"
+        COMPONENT Development
+    )
+endif()
 
-include(CTest)
-if (BUILD_TESTING)
-    add_subdirectory(tests)
+if(ZEUS_EXPECTED_BUILD_TESTS)
+    include(CTest)
+    if (BUILD_TESTING)
+        add_subdirectory(tests)
+    endif ()
 endif ()

cmake/zeus_expectedConfig.cmake.in

@@ -0,0 +1,6 @@
+@PACKAGE_INIT@
+
+include("${CMAKE_CURRENT_LIST_DIR}/zeus_expectedTargets.cmake")
+
+include(FindPackageHandleStandardArgs)
+check_required_components(zeus_expected)

tests/test_expected/CMakeLists.txt

@@ -1,35 +1,40 @@
-project(test_expected)
+project(test_expected LANGUAGES CXX)
 
 set(SOURCES
     base_tests.cpp
     monadic_tests.cpp
     noexcept_tests.cpp
     equality_tests.cpp
     lwg_3886_tests.cpp
-    test_expected_main.cpp
 )
 
+find_package(Catch2 3 REQUIRED)
+
+include(Catch)
+
 function(add_test_expected CPP_STANDARD)
     set(TARGET_NAME ${PROJECT_NAME}_cpp${CPP_STANDARD})
 
     add_executable(${TARGET_NAME})
-    set_target_properties(${TARGET_NAME} PROPERTIES CXX_STANDARD ${CPP_STANDARD})
-
-    target_link_libraries(${TARGET_NAME} zeus::expected)
-
-    find_package(Catch2 REQUIRED)
-    target_link_libraries(${TARGET_NAME} Catch2::Catch2)
-
+    set_target_properties(${TARGET_NAME}
+        PROPERTIES CXX_STANDARD ${CPP_STANDARD})
+    # The two targets belong to different scopes,
+    # so linking them separately is better for clarity.
+    target_link_libraries(${TARGET_NAME}
+        PRIVATE Catch2::Catch2WithMain)
+    target_link_libraries(${TARGET_NAME}
+        PRIVATE zeus::expected)
     target_sources(${TARGET_NAME} PRIVATE ${SOURCES})
 
-    include(Catch)
     catch_discover_tests(${TARGET_NAME})
 endfunction()
 
 add_test_expected(17)
+
 if (cxx_std_20 IN_LIST CMAKE_CXX_COMPILE_FEATURES)
     add_test_expected(20)
 endif ()
+
 if (cxx_std_23 IN_LIST CMAKE_CXX_COMPILE_FEATURES)
     add_test_expected(23)
 endif ()

tests/test_no_exceptions/CMakeLists.txt

@@ -1,7 +1,7 @@
-project(test_no_exceptions)
+project(test_no_exceptions LANGUAGES CXX)
 
 add_executable(${PROJECT_NAME} test_no_exceptions.cpp)
-target_link_libraries(${PROJECT_NAME} zeus::expected)
+target_link_libraries(${PROJECT_NAME} PRIVATE zeus::expected)
 
 if (MSVC)
     target_compile_options(${PROJECT_NAME} PRIVATE /EHs-c-)

tests/third_party/msvc/msvc_stl_p0323r12_test/CMakeLists.txt

@@ -1,8 +1,8 @@
-project(msvc_stl_p0323r12_test)
+project(msvc_stl_p0323r12_test LANGUAGES CXX)
 add_executable(${PROJECT_NAME})
 set_target_properties(${PROJECT_NAME} PROPERTIES CXX_STANDARD 20)
 
-target_link_libraries(${PROJECT_NAME} zeus::expected)
+target_link_libraries(${PROJECT_NAME} PRIVATE zeus::expected)
 
 target_sources(${PROJECT_NAME}
     PRIVATE

tests/third_party/msvc/msvc_stl_p2505r5_test/CMakeLists.txt

@@ -1,8 +1,8 @@
-project(msvc_stl_p2505r5_test)
+project(msvc_stl_p2505r5_test LANGUAGES CXX)
 add_executable(${PROJECT_NAME})
 set_target_properties(${PROJECT_NAME} PROPERTIES CXX_STANDARD 20)
 
-target_link_libraries(${PROJECT_NAME} zeus::expected)
+target_link_libraries(${PROJECT_NAME} PRIVATE zeus::expected)
 
 target_sources(${PROJECT_NAME}
     PRIVATE