Added download status, added comparison by hash sum (#474)

Add [SPDX][1] licensing/copyright tags to the `get_cpm.cmake` script,
so that anybody that copies the `get_cpm.cmake` script into their repo
(following the instructions in the README.md)
will automatically comply with CPM's MIT license.

[1]: https://spdx.dev/

.cmake-format

@@ -1,73 +1,5 @@
+include: ["cmake/.cmake-format-additional_commands-cpm"]
 format:
   tab_size: 2
   line_width: 100
   dangle_parens: true
-
-parse:
-  additional_commands:
-    cpmaddpackage:
-      pargs:
-        nargs: '*'
-        flags: []
-      spelling: CPMAddPackage
-      kwargs: &cpmaddpackagekwargs
-        NAME: 1
-        FORCE: 1
-        VERSION: 1
-        GIT_TAG: 1
-        DOWNLOAD_ONLY: 1
-        GITHUB_REPOSITORY: 1
-        GITLAB_REPOSITORY: 1
-        GIT_REPOSITORY: 1
-        SVN_REPOSITORY: 1
-        SVN_REVISION: 1
-        SOURCE_DIR: 1
-        DOWNLOAD_COMMAND: 1
-        FIND_PACKAGE_ARGUMENTS: 1
-        NO_CACHE: 1
-        GIT_SHALLOW: 1
-        URL: 1
-        URL_HASH: 1
-        URL_MD5: 1
-        DOWNLOAD_NAME: 1
-        DOWNLOAD_NO_EXTRACT: 1
-        HTTP_USERNAME: 1
-        HTTP_PASSWORD: 1
-        EXCLUDE_FROM_ALL: 1
-        SOURCE_SUBDIR: 1
-        OPTIONS: +
-    cpmfindpackage:
-      pargs:
-        nargs: '*'
-        flags: []
-      spelling: CPMFindPackage
-      kwargs: *cpmaddpackagekwargs
-    cpmdeclarepackage:
-      pargs:
-        nargs: '*'
-        flags: []
-      spelling: CPMDeclarePackage
-      kwargs: *cpmaddpackagekwargs
-    packageproject:
-      pargs:
-        nargs: '*'
-        flags: []
-      spelling: packageProject
-      kwargs:
-        NAME: 1
-        VERSION: 1
-        INCLUDE_DIR: 1
-        INCLUDE_DESTINATION: 1
-        BINARY_DIR: 1
-        COMPATIBILITY: 1
-        VERSION_HEADER: 1
-        DEPENDENCIES: +
-    cpmusepackagelock:
-      pargs: 1
-      spelling: CPMUsePackageLock
-    cpmregisterpackage:
-      pargs: 1
-      spelling: CPMRegisterPackage
-    cpmgetpackageversion:
-      pargs: 2
-      spelling: CPMGetPackageVersion

.github/workflows/examples.yaml

@@ -12,7 +12,7 @@ jobs:
   gcc:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: build all
         env:
           CC: gcc
@@ -22,7 +22,7 @@ jobs:
   clang:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: build all
         env:
           CC: clang

.github/workflows/publish.yaml

@@ -10,13 +10,14 @@ jobs:
     name: Publish CPM.cmake
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v3
 
       - name: Set CPM version by tag
         run: |
           mkdir dist
-          sed "s/1.0.0-development-version/${GITHUB_REF/refs\/tags\/v}/g" cmake/CPM.cmake > dist/CPM.cmake
-          sed "s/1.0.0-development-version/${GITHUB_REF/refs\/tags\/v}/g" cmake/get_cpm.cmake > dist/get_cpm.cmake
+          sed -e "s/1.0.0-development-version/${GITHUB_REF/refs\/tags\//v}/g" cmake/CPM.cmake > dist/CPM.cmake
+          sed -e "s/1.0.0-development-version/${GITHUB_REF/refs\/tags\//v}/g" \
+              -e "s/EMPTY_HASH_SUM/$(sha256sum cmake/CPM.cmake | cut -d' ' -f1)/" cmake/get_cpm.cmake > dist/get_cpm.cmake
 
       - name: Upload CPM.cmake to release
         uses: svenstaro/upload-release-action@v1-release

.github/workflows/style.yaml

@@ -14,7 +14,12 @@ jobs:
     runs-on: ubuntu-latest
     
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v3
+
+    - name: Setup cmake
+      uses: jwlawson/actions-setup-cmake@v1.13
+      with:
+        cmake-version: '3.25.x'
     
     - name: Install format dependencies
       run: pip3 install clang-format==14.0.6 cmake_format==0.6.11 pyyaml

.github/workflows/test.yaml

@@ -17,17 +17,32 @@ jobs:
         # we need at least ruby 2.7 for the tests
         # instead of dealing with installing a modern version of ruby on 2019, we'll just use windows-2022 here
         os: [ubuntu-latest, windows-2022, macos-latest]
+        # we want to ensure compatibility with a recent CMake version as well as the lowest officially supported
+        # legacy version that we define as the default version of the second-latest Ubuntu LTS release currently available
+        cmake_version: ['3.16.3', '3.25.1']
+        exclude:
+          # there seems to be an issue with CMake 3.16 not finding a C++ compiler on windows-2022 
+          - os: windows-2022
+            cmake_version: '3.16.3'
 
     steps:
       - name: clone
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
+
+      - name: Setup cmake
+        uses: jwlawson/actions-setup-cmake@v1.13
+        with:
+          cmake-version: ${{ matrix.cmake_version }}
 
       - name: unit tests
         run: |
           cmake -Stest -Bbuild/test
           cmake --build build/test --target test-verbose
+        env:
+          CMAKE_VERSION: ${{ matrix.cmake_version }}
 
       - name: integration tests
         run: ruby test/integration/runner.rb
         env:
           CPM_INTEGRATION_TEST_DIR: ./build/integration
+          CMAKE_VERSION: ${{ matrix.cmake_version }}

README.md

@@ -12,7 +12,7 @@ It's built as a thin wrapper around CMake's [FetchContent](https://cmake.org/cma
 
 ## Manage everything
 
-Any downloadable project or resource can be added as a version-controlled dependency though CPM, it is not necessary to modify or package anything.
+Any downloadable project or resource can be added as a version-controlled dependency through CPM, it is not necessary to modify or package anything.
 Projects using modern CMake are automatically configured and their targets can be used immediately.
 For everything else, the targets can be created manually after the dependency has been downloaded (see the [snippets](#snippets) below for examples).
 
@@ -45,6 +45,18 @@ target_link_libraries(main fmt::fmt nlohmann_json::nlohmann_json Catch2::Catch2W
 
 See the [examples directory](https://github.com/cpm-cmake/CPM.cmake/tree/master/examples) for complete examples with source code and check [below](#snippets) or in the [wiki](https://github.com/cpm-cmake/CPM.cmake/wiki/More-Snippets) for example snippets.
 
+## Adding CPM
+
+To add CPM to your current project, simply add the [latest release](https://github.com/cpm-cmake/CPM.cmake/releases/latest) of `CPM.cmake` or `get_cpm.cmake` to your project's `cmake` directory.
+The command below will perform this automatically.
+
+```bash
+mkdir -p cmake
+wget -O cmake/CPM.cmake https://github.com/cpm-cmake/CPM.cmake/releases/latest/download/get_cpm.cmake
+```
+
+You can also download CPM.cmake directly from your project's `CMakeLists.txt`. See the [wiki](https://github.com/cpm-cmake/CPM.cmake/wiki/Downloading-CPM.cmake-in-CMake) for more details.
+
 ## Usage
 
 After `CPM.cmake` has been [added](#adding-cpm) to your project, the function `CPMAddPackage` can be used to fetch and configure a dependency.
@@ -68,6 +80,10 @@ On the other hand, if `VERSION` hasn't been explicitly specified, CPM can automa
 
 If an additional optional parameter `EXCLUDE_FROM_ALL` is set to a truthy value, then any targets defined inside the dependency won't be built by default. See the [CMake docs](https://cmake.org/cmake/help/latest/prop_tgt/EXCLUDE_FROM_ALL.html) for details.
 
+If an additional optional parameter `SYSTEM` is set to a truthy value, the SYSTEM directory property of the subdirectory added will be set to true.
+See the [add_subdirectory ](https://cmake.org/cmake/help/latest/command/add_subdirectory.html?highlight=add_subdirectory)
+and [SYSTEM](https://cmake.org/cmake/help/latest/prop_tgt/SYSTEM.html#prop_tgt:SYSTEM) target property for details.
+
 A single-argument compact syntax is also supported:
 
 ```cmake
@@ -79,7 +95,7 @@ CPMAddPackage("uri#tag")
 CPMAddPackage("uri@version#tag")
 ```
 
-In the shorthand syntax if the URI is of the form `gh:user/name`, it is interpreted as GitHub URI and converted to `https://github.com/user/name.git`. If the URI is of the form `gl:user/name`, it is interpreted as a [GitLab](https://gitlab.com/explore/) URI and converted to `https://gitlab.com/user/name.git`. If the URI is of the form `bb:user/name`, it is interpreted as a [Bitbucket](https://bitbucket.org/) URI and converted to `https://bitbucket.org/user/name.git`. Otherwise the URI used verbatim as a git URL. All packages added using the shorthand syntax will be added using the [EXCLUDE_FROM_ALL](https://cmake.org/cmake/help/latest/prop_tgt/EXCLUDE_FROM_ALL.html) flag.
+In the shorthand syntax if the URI is of the form `gh:user/name`, it is interpreted as GitHub URI and converted to `https://github.com/user/name.git`. If the URI is of the form `gl:user/name`, it is interpreted as a [GitLab](https://gitlab.com/explore/) URI and converted to `https://gitlab.com/user/name.git`. If the URI is of the form `bb:user/name`, it is interpreted as a [Bitbucket](https://bitbucket.org/) URI and converted to `https://bitbucket.org/user/name.git`. Otherwise the URI used verbatim as a git URL. All packages added using the shorthand syntax will be added using the [EXCLUDE_FROM_ALL](https://cmake.org/cmake/help/latest/prop_tgt/EXCLUDE_FROM_ALL.html) and [SYSTEM](https://cmake.org/cmake/help/latest/prop_tgt/SYSTEM.html#prop_tgt:SYSTEM) flag.
 
 The single-argument syntax also works for URLs:
 
@@ -103,21 +119,9 @@ For using CPM.cmake projects with external package managers, such as conan or vc
 
 In rare cases, this behaviour may be desirable by default. The function `CPMFindPackage` will try to find a local dependency via CMake's `find_package` and fallback to `CPMAddPackage`, if the dependency is not found.
 
-## Adding CPM
-
-To add CPM to your current project, simply add the [latest release](https://github.com/cpm-cmake/CPM.cmake/releases/latest) of `CPM.cmake` or `get_cpm.cmake` to your project's `cmake` directory.
-The command below will perform this automatically.
-
-```bash
-mkdir -p cmake
-wget -O cmake/CPM.cmake https://github.com/cpm-cmake/CPM.cmake/releases/latest/download/get_cpm.cmake
-```
-
-You can also download CPM.cmake directly from your project's `CMakeLists.txt`. See the [wiki](https://github.com/cpm-cmake/CPM.cmake/wiki/Downloading-CPM.cmake-in-CMake) for more details.
-
 ## Updating CPM
 
-To update CPM to the newest version, update the script in the project's root directory, for example by running the command above.
+To update CPM to the newest version, update the script in the project's root directory, for example by running the same command as for [adding CPM](#adding-cpm).
 Dependencies using CPM will automatically use the updated script of the outermost project.
 
 ## Advantages
@@ -195,11 +199,14 @@ This can be controlled on a per package basis with the `CPM_DOWNLOAD_<dependency
 ### CPM_USE_LOCAL_PACKAGES
 
 CPM can be configured to use `find_package` to search for locally installed dependencies first by setting the CMake option `CPM_USE_LOCAL_PACKAGES`.
+
 If the option `CPM_LOCAL_PACKAGES_ONLY` is set, CPM will emit an error if the dependency is not found locally.
 These options can also be set as environmental variables.
 
 In the case that `find_package` requires additional arguments, the parameter `FIND_PACKAGE_ARGUMENTS` may be specified in the `CPMAddPackage` call. The value of this parameter will be forwarded to `find_package`.
 
+Note that this does not apply to dependencies that have been defined with a truthy `FORCE` parameter. These will be added as defined.
+
 ### CPM_USE_NAMED_CACHE_DIRECTORIES
 
 If set, CPM use additional directory level in cache to improve readability of packages names in IDEs like CLion. It changes cache structure, so all dependencies are downloaded again. There is no problem to mix both structures in one cache directory but then there may be 2 copies of some dependencies.
@@ -317,8 +324,22 @@ If you know others, feel free to add them here through a PR.
         <p align="center"><b>JNGL - easy to use cross-platform 2D game library</b></p>
       </a>
     </td>
-    <td/>
-    <td/>
+    <td>
+      <a href="https://github.com/sillydan1/aaltitoad">
+        <p align="center">
+          <img src="https://github.com/sillydan1/aaltitoad/raw/v1.1.0/.github/resources/logo/toad_only.svg" alt="aaltitoad" width="100pt" />
+        </p>
+        <p align="center"><b>AALTITOAD - verifier and simulator for Tick Tock Automata</b></p>
+      </a>
+    </td>
+    <td>
+      <a href="https://github.com/ZIMO-Elektronik">
+        <p align="center">
+          <img src="https://avatars.githubusercontent.com/u/117935012?s=400&u=9a871a46dd13437f0adcae166e9efbe518ff0b99&v=4" alt="ZIMO-Elektronik" width="100pt" />
+        </p>
+        <p align="center"><b>ZIMO-Elektronik</b></p>
+      </a>
+    </td>
   </tr>
 </table>
 

cmake/.cmake-format-additional_commands-cpm

@@ -0,0 +1,69 @@
+parse:
+  additional_commands:
+    cpmaddpackage:
+      pargs:
+        nargs: '*'
+        flags: []
+      spelling: CPMAddPackage
+      kwargs: &cpmaddpackagekwargs
+        NAME: 1
+        FORCE: 1
+        VERSION: 1
+        GIT_TAG: 1
+        DOWNLOAD_ONLY: 1
+        GITHUB_REPOSITORY: 1
+        GITLAB_REPOSITORY: 1
+        GIT_REPOSITORY: 1
+        SVN_REPOSITORY: 1
+        SVN_REVISION: 1
+        SOURCE_DIR: 1
+        DOWNLOAD_COMMAND: 1
+        FIND_PACKAGE_ARGUMENTS: 1
+        NO_CACHE: 1
+        GIT_SHALLOW: 1
+        URL: 1
+        URL_HASH: 1
+        URL_MD5: 1
+        DOWNLOAD_NAME: 1
+        DOWNLOAD_NO_EXTRACT: 1
+        HTTP_USERNAME: 1
+        HTTP_PASSWORD: 1
+        EXCLUDE_FROM_ALL: 1
+        SYSTEM: 1
+        SOURCE_SUBDIR: 1
+        OPTIONS: +
+    cpmfindpackage:
+      pargs:
+        nargs: '*'
+        flags: []
+      spelling: CPMFindPackage
+      kwargs: *cpmaddpackagekwargs
+    cpmdeclarepackage:
+      pargs:
+        nargs: '*'
+        flags: []
+      spelling: CPMDeclarePackage
+      kwargs: *cpmaddpackagekwargs
+    packageproject:
+      pargs:
+        nargs: '*'
+        flags: []
+      spelling: packageProject
+      kwargs:
+        NAME: 1
+        VERSION: 1
+        INCLUDE_DIR: 1
+        INCLUDE_DESTINATION: 1
+        BINARY_DIR: 1
+        COMPATIBILITY: 1
+        VERSION_HEADER: 1
+        DEPENDENCIES: +
+    cpmusepackagelock:
+      pargs: 1
+      spelling: CPMUsePackageLock
+    cpmregisterpackage:
+      pargs: 1
+      spelling: CPMRegisterPackage
+    cpmgetpackageversion:
+      pargs: 2
+      spelling: CPMGetPackageVersion

cmake/CPM.cmake

@@ -5,7 +5,7 @@
 # MIT License
 # -----------
 #[[
-  Copyright (c) 2019-2022 Lars Melchior and contributors
+  Copyright (c) 2019-2023 Lars Melchior and contributors
 
   Permission is hereby granted, free of charge, to any person obtaining a copy
   of this software and associated documentation files (the "Software"), to deal
@@ -513,8 +513,8 @@ function(CPMAddPackage)
   if(argnLength EQUAL 1)
     cpm_parse_add_package_single_arg("${ARGN}" ARGN)
 
-    # The shorthand syntax implies EXCLUDE_FROM_ALL
-    set(ARGN "${ARGN};EXCLUDE_FROM_ALL;YES")
+    # The shorthand syntax implies EXCLUDE_FROM_ALL and SYSTEM
+    set(ARGN "${ARGN};EXCLUDE_FROM_ALL;YES;SYSTEM;YES;")
   endif()
 
   set(oneValueArgs
@@ -531,6 +531,7 @@ function(CPMAddPackage)
       DOWNLOAD_COMMAND
       FIND_PACKAGE_ARGUMENTS
       NO_CACHE
+      SYSTEM
       GIT_SHALLOW
       EXCLUDE_FROM_ALL
       SOURCE_SUBDIR
@@ -626,6 +627,7 @@ function(CPMAddPackage)
       NAME "${CPM_ARGS_NAME}"
       SOURCE_DIR "${PACKAGE_SOURCE}"
       EXCLUDE_FROM_ALL "${CPM_ARGS_EXCLUDE_FROM_ALL}"
+      SYSTEM "${CPM_ARGS_SYSTEM}"
       OPTIONS "${CPM_ARGS_OPTIONS}"
       SOURCE_SUBDIR "${CPM_ARGS_SOURCE_SUBDIR}"
       DOWNLOAD_ONLY "${DOWNLOAD_ONLY}"
@@ -646,19 +648,21 @@ function(CPMAddPackage)
     return()
   endif()
 
-  if(CPM_USE_LOCAL_PACKAGES OR CPM_LOCAL_PACKAGES_ONLY)
-    cpm_find_package(${CPM_ARGS_NAME} "${CPM_ARGS_VERSION}" ${CPM_ARGS_FIND_PACKAGE_ARGUMENTS})
+  if(NOT CPM_ARGS_FORCE)
+    if(CPM_USE_LOCAL_PACKAGES OR CPM_LOCAL_PACKAGES_ONLY)
+      cpm_find_package(${CPM_ARGS_NAME} "${CPM_ARGS_VERSION}" ${CPM_ARGS_FIND_PACKAGE_ARGUMENTS})
 
-    if(CPM_PACKAGE_FOUND)
-      cpm_export_variables(${CPM_ARGS_NAME})
-      return()
-    endif()
+      if(CPM_PACKAGE_FOUND)
+        cpm_export_variables(${CPM_ARGS_NAME})
+        return()
+      endif()
 
-    if(CPM_LOCAL_PACKAGES_ONLY)
-      message(
-        SEND_ERROR
-          "${CPM_INDENT} ${CPM_ARGS_NAME} not found via find_package(${CPM_ARGS_NAME} ${CPM_ARGS_VERSION})"
-      )
+      if(CPM_LOCAL_PACKAGES_ONLY)
+        message(
+          SEND_ERROR
+            "${CPM_INDENT} ${CPM_ARGS_NAME} not found via find_package(${CPM_ARGS_NAME} ${CPM_ARGS_VERSION})"
+        )
+      endif()
     endif()
   endif()
 
@@ -713,9 +717,15 @@ function(CPMAddPackage)
     get_filename_component(download_directory ${download_directory} ABSOLUTE)
     list(APPEND CPM_ARGS_UNPARSED_ARGUMENTS SOURCE_DIR ${download_directory})
 
-    file(LOCK ${download_directory}/../cmake.lock)
+    if(CPM_SOURCE_CACHE)
+      file(LOCK ${download_directory}/../cmake.lock)
+    endif()
 
     if(EXISTS ${download_directory})
+      if(CPM_SOURCE_CACHE)
+        file(LOCK ${download_directory}/../cmake.lock RELEASE)
+      endif()
+
       cpm_store_fetch_properties(
         ${CPM_ARGS_NAME} "${download_directory}"
         "${CPM_FETCHCONTENT_BASE_DIR}/${lower_case_name}-build"
@@ -733,9 +743,13 @@ function(CPMAddPackage)
       endif()
 
       cpm_add_subdirectory(
-        "${CPM_ARGS_NAME}" "${DOWNLOAD_ONLY}"
-        "${${CPM_ARGS_NAME}_SOURCE_DIR}/${CPM_ARGS_SOURCE_SUBDIR}" "${${CPM_ARGS_NAME}_BINARY_DIR}"
-        "${CPM_ARGS_EXCLUDE_FROM_ALL}" "${CPM_ARGS_OPTIONS}"
+        "${CPM_ARGS_NAME}"
+        "${DOWNLOAD_ONLY}"
+        "${${CPM_ARGS_NAME}_SOURCE_DIR}/${CPM_ARGS_SOURCE_SUBDIR}"
+        "${${CPM_ARGS_NAME}_BINARY_DIR}"
+        "${CPM_ARGS_EXCLUDE_FROM_ALL}"
+        "${CPM_ARGS_SYSTEM}"
+        "${CPM_ARGS_OPTIONS}"
       )
       set(PACKAGE_INFO "${PACKAGE_INFO} at ${download_directory}")
 
@@ -783,20 +797,23 @@ function(CPMAddPackage)
       "${CPM_ARGS_NAME}" "${CPM_ARGS_VERSION}" "${PACKAGE_INFO}" "${CPM_ARGS_UNPARSED_ARGUMENTS}"
     )
     cpm_fetch_package("${CPM_ARGS_NAME}" populated)
+    if(CPM_SOURCE_CACHE AND download_directory)
+      file(LOCK ${download_directory}/../cmake.lock RELEASE)
+    endif()
     if(${populated})
       cpm_add_subdirectory(
-        "${CPM_ARGS_NAME}" "${DOWNLOAD_ONLY}"
-        "${${CPM_ARGS_NAME}_SOURCE_DIR}/${CPM_ARGS_SOURCE_SUBDIR}" "${${CPM_ARGS_NAME}_BINARY_DIR}"
-        "${CPM_ARGS_EXCLUDE_FROM_ALL}" "${CPM_ARGS_OPTIONS}"
+        "${CPM_ARGS_NAME}"
+        "${DOWNLOAD_ONLY}"
+        "${${CPM_ARGS_NAME}_SOURCE_DIR}/${CPM_ARGS_SOURCE_SUBDIR}"
+        "${${CPM_ARGS_NAME}_BINARY_DIR}"
+        "${CPM_ARGS_EXCLUDE_FROM_ALL}"
+        "${CPM_ARGS_SYSTEM}"
+        "${CPM_ARGS_OPTIONS}"
       )
     endif()
     cpm_get_fetch_properties("${CPM_ARGS_NAME}")
   endif()
 
-  if(EXISTS ${download_directory}/../cmake.lock)
-    file(LOCK ${download_directory}/../cmake.lock RELEASE)
-  endif()
-
   set(${CPM_ARGS_NAME}_ADDED YES)
   cpm_export_variables("${CPM_ARGS_NAME}")
 endfunction()
@@ -942,13 +959,18 @@ function(
   SOURCE_DIR
   BINARY_DIR
   EXCLUDE
+  SYSTEM
   OPTIONS
 )
+
   if(NOT DOWNLOAD_ONLY AND EXISTS ${SOURCE_DIR}/CMakeLists.txt)
+    set(addSubdirectoryExtraArgs "")
     if(EXCLUDE)
-      set(addSubdirectoryExtraArgs EXCLUDE_FROM_ALL)
-    else()
-      set(addSubdirectoryExtraArgs "")
+      list(APPEND addSubdirectoryExtraArgs EXCLUDE_FROM_ALL)
+    endif()
+    if("${SYSTEM}" AND "${CMAKE_VERSION}" VERSION_GREATER_EQUAL "3.25")
+      # https://cmake.org/cmake/help/latest/prop_dir/SYSTEM.html#prop_dir:SYSTEM
+      list(APPEND addSubdirectoryExtraArgs SYSTEM)
     endif()
     if(OPTIONS)
       foreach(OPTION ${OPTIONS})
@@ -1079,6 +1101,7 @@ function(cpm_prettify_package_arguments OUT_VAR IS_IN_COMMENT)
       DOWNLOAD_COMMAND
       FIND_PACKAGE_ARGUMENTS
       NO_CACHE
+      SYSTEM
       GIT_SHALLOW
   )
   set(multiValueArgs OPTIONS)

cmake/get_cpm.cmake

@@ -1,4 +1,9 @@
+# SPDX-License-Identifier: MIT
+#
+# SPDX-FileCopyrightText: Copyright (c) 2019-2023 Lars Melchior and contributors
+
 set(CPM_DOWNLOAD_VERSION 1.0.0-development-version)
+set(CPM_HASH_SUM "HASH_SUM_PLACEHOLDER")
 
 if(CPM_SOURCE_CACHE)
   set(CPM_DOWNLOAD_LOCATION "${CPM_SOURCE_CACHE}/cpm/CPM_${CPM_DOWNLOAD_VERSION}.cmake")
@@ -11,22 +16,20 @@ endif()
 # Expand relative path. This is important if the provided path contains a tilde (~)
 get_filename_component(CPM_DOWNLOAD_LOCATION ${CPM_DOWNLOAD_LOCATION} ABSOLUTE)
 
-function(download_cpm)
-  message(STATUS "Downloading CPM.cmake to ${CPM_DOWNLOAD_LOCATION}")
-  file(DOWNLOAD
-       https://github.com/cpm-cmake/CPM.cmake/releases/download/v${CPM_DOWNLOAD_VERSION}/CPM.cmake
-       ${CPM_DOWNLOAD_LOCATION}
-  )
-endfunction()
-
-if(NOT (EXISTS ${CPM_DOWNLOAD_LOCATION}))
-  download_cpm()
+message(STATUS "Downloading CPM.cmake to ${CPM_DOWNLOAD_LOCATION}")
+file(
+  DOWNLOAD
+  https://github.com/cpm-cmake/CPM.cmake/releases/download/v${CPM_DOWNLOAD_VERSION}/CPM.cmake
+  ${CPM_DOWNLOAD_LOCATION}
+  STATUS CPM_DOWNLOAD_STATUS
+  EXPECTED_HASH SHA256=${CPM_HASH_SUM}
+)
+list(GET CPM_DOWNLOAD_STATUS 0 CPM_DOWNLOAD_STATUS_CODE)
+list(GET CPM_DOWNLOAD_STATUS 1 CPM_DOWNLOAD_ERROR_MESSAGE)
+if(${CPM_DOWNLOAD_STATUS_CODE} EQUAL 0)
+  message(STATUS "CPM: Download completed successfully.")
 else()
-  # resume download if it previously failed
-  file(READ ${CPM_DOWNLOAD_LOCATION} check)
-  if("${check}" STREQUAL "")
-    download_cpm()
-  endif()
+  message(FATAL_ERROR "CPM: Error occurred during download: ${CPM_DOWNLOAD_ERROR_MESSAGE}")
 endif()
 
 include(${CPM_DOWNLOAD_LOCATION})

test/integration/lib.rb

@@ -157,6 +157,11 @@ class IntegrationTest < Test::Unit::TestCase
     assert_block(msg) { res.status.success? }
   end
 
+  def assert_failure(res)
+    msg = build_message(nil, "command status was expected to be a failure, but succeeded")
+    assert_block(msg) { !res.status.success? }
+  end
+
   def assert_same_path(a, b)
     msg = build_message(nil, "<?> expected but was\n<?>", a, b)
     assert_block(msg) { File.identical? a, b }

test/integration/test_system_warnings.rb

@@ -0,0 +1,57 @@
+require_relative './lib'
+
+class SystemWarnings < IntegrationTest
+  
+  def setup
+    # system is only supported for CMake >= 3.25 
+    @system_supported = (!ENV['CMAKE_VERSION']) || (Gem::Version.new(ENV['CMAKE_VERSION']) >= Gem::Version.new('3.25'))
+  end
+
+  def test_dependency_added_using_system
+    for use_system in [true, false] do
+      prj = make_project name: use_system ? "system" : "no_system", from_template: 'using-adder'
+      prj.create_lists_from_default_template package: <<~PACK
+        # this commit has a warning in a public header
+        CPMAddPackage(
+          NAME Adder
+          GITHUB_REPOSITORY cpm-cmake/testpack-adder
+          GIT_TAG v1.0.1-warnings
+          SYSTEM #{use_system ? "YES" : "NO"}
+        )
+        # all packages using `adder` will error on warnings
+        target_compile_options(adder INTERFACE
+          $<$<CXX_COMPILER_ID:MSVC>:/Wall /WX>
+          $<$<NOT:$<CXX_COMPILER_ID:MSVC>>:-Wall -Werror>
+        )
+      PACK
+
+      assert_success prj.configure
+      if use_system and @system_supported
+        assert_success prj.build
+      else
+        assert_failure prj.build
+      end
+    end
+  end
+  
+  def test_dependency_added_implicitly_using_system
+    prj = make_project from_template: 'using-adder'
+    prj.create_lists_from_default_template package: <<~PACK
+      # this commit has a warning in a public header
+      CPMAddPackage("gh:cpm-cmake/testpack-adder@1.0.1-warnings")
+      # all packages using `adder` will error on warnings
+      target_compile_options(adder INTERFACE
+        $<$<CXX_COMPILER_ID:MSVC>:/Wall /WX>
+        $<$<NOT:$<CXX_COMPILER_ID:MSVC>>:-Wall -Werror>
+      )
+    PACK
+
+    assert_success prj.configure
+    if @system_supported
+      assert_success prj.build
+    else
+      assert_failure prj.build
+    end
+  end
+
+end