Raise CMake min to 3.14 (#1083)

- Explicitly test package manager support with CMake 3.14 and Ninja
- Remove gsl_install.cmake
- Simplify installation code

.github/workflows/cmake_find_package.yml

@@ -0,0 +1,25 @@
+name: cmake_find_package
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  cmake-find-package:
+    name: Build ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ ubuntu-latest, macos-latest ]
+    steps:
+      - uses: actions/checkout@v3
+      - uses: lukka/get-cmake@latest
+        with:
+          cmakeVersion: 3.14.0
+      - name: Configure GSL
+        run: cmake -S . -B build -G "Ninja" -D GSL_TEST=OFF -D CMAKE_INSTALL_PREFIX=${GITHUB_WORKSPACE}/build/install
+      - name: Install GSL
+        run: cmake --build build --target install
+      - name: Test GSL find_package support
+        run: cmake -S tests/ -B build/tests_find_package -G "Ninja" -D CMAKE_PREFIX_PATH=${GITHUB_WORKSPACE}/build/install -D CMAKE_BUILD_TYPE=Release

CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.8...3.16)
+cmake_minimum_required(VERSION 3.14...3.16)
 list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake/")
 include(gsl_functions)
 
@@ -22,11 +22,28 @@ add_subdirectory(include)
 # Add natvis file
 gsl_add_native_visualizer_support()
 
-if (GSL_INSTALL)
-    include(gsl_install)
-endif()
-
 if (GSL_TEST)
     enable_testing()
     add_subdirectory(tests)
 endif()
+
+if (GSL_INSTALL)
+    include(GNUInstallDirs)
+    include(CMakePackageConfigHelpers)
+
+    install(DIRECTORY "${PROJECT_SOURCE_DIR}/include/gsl" DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
+
+    set(export_name "Microsoft.GSLConfig")
+    set(namespace "Microsoft.GSL::")
+    set(cmake_files_install_dir ${CMAKE_INSTALL_DATADIR}/cmake/Microsoft.GSL)
+
+    install(TARGETS GSL EXPORT ${export_name} INCLUDES DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
+    install(EXPORT ${export_name} NAMESPACE ${namespace} DESTINATION ${cmake_files_install_dir})
+    export(TARGETS GSL NAMESPACE ${namespace} FILE ${export_name}.cmake)
+
+    set(gls_config_version "${CMAKE_CURRENT_BINARY_DIR}/Microsoft.GSLConfigVersion.cmake")
+
+    write_basic_package_version_file(${gls_config_version} COMPATIBILITY SameMajorVersion ARCH_INDEPENDENT)
+
+    install(FILES ${gls_config_version} DESTINATION ${cmake_files_install_dir})
+endif()

cmake/gsl_install.cmake

@@ -1,26 +0,0 @@
-include(GNUInstallDirs)
-include(CMakePackageConfigHelpers)
-
-# Install header files
-install(DIRECTORY "${PROJECT_SOURCE_DIR}/include/gsl" DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
-
-set(export_name "Microsoft.GSLConfig")
-set(namespace "Microsoft.GSL::")
-set(cmake_files_install_dir ${CMAKE_INSTALL_DATADIR}/cmake/Microsoft.GSL)
-
-# Add find_package() support
-target_include_directories(GSL INTERFACE $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>)
-install(TARGETS GSL EXPORT ${export_name})
-install(EXPORT ${export_name} NAMESPACE ${namespace} DESTINATION ${cmake_files_install_dir})
-export(TARGETS GSL NAMESPACE ${namespace} FILE ${export_name}.cmake)
-
-set(gls_config_version "${CMAKE_CURRENT_BINARY_DIR}/Microsoft.GSLConfigVersion.cmake")
-
-# Add find_package() versioning support
-if(${CMAKE_VERSION} VERSION_LESS "3.14.0")
-    write_basic_package_version_file(${gls_config_version} COMPATIBILITY SameMajorVersion)
-else()
-    write_basic_package_version_file(${gls_config_version} COMPATIBILITY SameMajorVersion ARCH_INDEPENDENT)
-endif()
-
-install(FILES ${gls_config_version} DESTINATION ${cmake_files_install_dir})

tests/CMakeLists.txt

@@ -1,13 +1,12 @@
-cmake_minimum_required(VERSION 3.8)
+cmake_minimum_required(VERSION 3.14...3.16)
 
 project(GSLTests LANGUAGES CXX)
-enable_testing()  # again, for support standalone testing
 
 set(GSL_CXX_STANDARD "14" CACHE STRING "Use c++ standard")
 
 set(CMAKE_CXX_STANDARD ${GSL_CXX_STANDARD})
 set(CMAKE_CXX_EXTENSIONS OFF)
-set(CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
 include(FindPkgConfig)
 include(ExternalProject)
@@ -58,10 +57,14 @@ if (NOT GTestMain_FOUND)
 endif()
 
 if (CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR)
-    # CMake has been started independently in this directory with tests. Do
-    # import the globally installed Guidelines Support Library and test it
-    # instead of the current version from the include/ folder.
-    find_package(Microsoft.GSL REQUIRED)
+    find_package(Microsoft.GSL CONFIG REQUIRED)
+    enable_testing()
+
+    if (NOT DEFINED Microsoft.GSL_VERSION)
+        message(FATAL_ERROR "Microsoft.GSL_VERSION not defined!")
+    endif()
+
+    message(STATUS "Microsoft.GSL_VERSION = ${Microsoft.GSL_VERSION}")
 endif()
 
 if (MSVC AND (GSL_CXX_STANDARD GREATER_EQUAL 17))