circumvent bug in cmake <3.30.3 (#605)

Co-authored-by: Avus <48911667+Avus@users.noreply.github.com>

.github/workflows/test.yaml

@@ -19,7 +19,7 @@ jobs:
         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', '3.27.5']
+        cmake_version: ['3.16.3', '3.27.5', '3.30.0']
         exclude:
           # there seems to be an issue with CMake 3.16 not finding a C++ compiler on windows-2022 
           - os: windows-2022

README.md

@@ -214,6 +214,13 @@ In the case that `find_package` requires additional arguments, the parameter `FI
 
 Note that this does not apply to dependencies that have been defined with a truthy `FORCE` parameter. These will be added as defined.
 
+### CPM_DONT_UPDATE_MODULE_PATH
+
+By default, CPM will override any `find_package` commands to use the CPM downloaded version.
+This is equivalent to the `OVERRIDE_FIND_PACKAGE` FetchContent option, which has no effect in CPM.
+To disable this behaviour set the `CPM_DONT_UPDATE_MODULE_PATH` option.
+This will not work for `find_package(CONFIG)` in CMake versions before 3.24.
+
 ### 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.

cmake/CPM.cmake

@@ -162,7 +162,7 @@ set(CPM_SOURCE_CACHE
     CACHE PATH "Directory to download CPM dependencies"
 )
 
-if(NOT CPM_DONT_UPDATE_MODULE_PATH)
+if(NOT CPM_DONT_UPDATE_MODULE_PATH AND NOT DEFINED CMAKE_FIND_PACKAGE_REDIRECTS_DIR)
   set(CPM_MODULE_PATH
       "${CMAKE_BINARY_DIR}/CPM_modules"
       CACHE INTERNAL ""
@@ -269,10 +269,25 @@ endfunction()
 # finding the system library
 function(cpm_create_module_file Name)
   if(NOT CPM_DONT_UPDATE_MODULE_PATH)
-    # erase any previous modules
+    if(DEFINED CMAKE_FIND_PACKAGE_REDIRECTS_DIR)
-    file(WRITE ${CPM_MODULE_PATH}/Find${Name}.cmake
+      # Redirect find_package calls to the CPM package. This is what FetchContent does when you set
-         "include(\"${CPM_FILE}\")\n${ARGN}\nset(${Name}_FOUND TRUE)"
+      # OVERRIDE_FIND_PACKAGE. The CMAKE_FIND_PACKAGE_REDIRECTS_DIR works for find_package in CONFIG
-    )
+      # mode, unlike the Find${Name}.cmake fallback. CMAKE_FIND_PACKAGE_REDIRECTS_DIR is not defined
+      # in script mode, or in CMake < 3.24.
+      # https://cmake.org/cmake/help/latest/module/FetchContent.html#fetchcontent-find-package-integration-examples
+      string(TOLOWER ${Name} NameLower)
+      file(WRITE ${CMAKE_FIND_PACKAGE_REDIRECTS_DIR}/${NameLower}-config.cmake
+           "include(\"${CMAKE_CURRENT_LIST_DIR}/${NameLower}-extra.cmake\" OPTIONAL)\n"
+           "include(\"${CMAKE_CURRENT_LIST_DIR}/${Name}Extra.cmake\" OPTIONAL)\n"
+      )
+      file(WRITE ${CMAKE_FIND_PACKAGE_REDIRECTS_DIR}/${NameLower}-version.cmake
+           "set(PACKAGE_VERSION_COMPATIBLE TRUE)\n" "set(PACKAGE_VERSION_EXACT TRUE)\n"
+      )
+    else()
+      file(WRITE ${CPM_MODULE_PATH}/Find${Name}.cmake
+           "include(\"${CPM_FILE}\")\n${ARGN}\nset(${Name}_FOUND TRUE)"
+      )
+    endif()
   endif()
 endfunction()
 
@@ -477,13 +492,16 @@ function(cpm_add_patches)
   find_program(PATCH_EXECUTABLE patch)
   if(WIN32 AND NOT PATCH_EXECUTABLE)
     # The Windows git executable is distributed with patch.exe. Find the path to the executable, if
-    # it exists, then search `../../usr/bin` for patch.exe.
+    # it exists, then search `../usr/bin` and `../../usr/bin` for patch.exe.
     find_package(Git QUIET)
     if(GIT_EXECUTABLE)
       get_filename_component(extra_search_path ${GIT_EXECUTABLE} DIRECTORY)
-      get_filename_component(extra_search_path ${extra_search_path} DIRECTORY)
+      get_filename_component(extra_search_path_1up ${extra_search_path} DIRECTORY)
-      get_filename_component(extra_search_path ${extra_search_path} DIRECTORY)
+      get_filename_component(extra_search_path_2up ${extra_search_path_1up} DIRECTORY)
-      find_program(PATCH_EXECUTABLE patch HINTS "${extra_search_path}/usr/bin")
+      find_program(
+        PATCH_EXECUTABLE patch HINTS "${extra_search_path_1up}/usr/bin"
+                                     "${extra_search_path_2up}/usr/bin"
+      )
     endif()
   endif()
   if(NOT PATCH_EXECUTABLE)
@@ -862,14 +880,39 @@ function(CPMAddPackage)
   )
 
   if(NOT CPM_SKIP_FETCH)
+    # CMake 3.28 added EXCLUDE, SYSTEM (3.25), and SOURCE_SUBDIR (3.18) to FetchContent_Declare.
+    # Calling FetchContent_MakeAvailable will then internally forward these options to
+    # add_subdirectory. Up until these changes, we had to call FetchContent_Populate and
+    # add_subdirectory separately, which is no longer necessary and has been deprecated as of 3.30.
+    # A Bug in CMake prevents us to use the non-deprecated functions until 3.30.3.
+    set(fetchContentDeclareExtraArgs "")
+    if(${CMAKE_VERSION} VERSION_GREATER_EQUAL "3.30.3")
+      if(${CPM_ARGS_EXCLUDE_FROM_ALL})
+        list(APPEND fetchContentDeclareExtraArgs EXCLUDE_FROM_ALL)
+      endif()
+      if(${CPM_ARGS_SYSTEM})
+        list(APPEND fetchContentDeclareExtraArgs SYSTEM)
+      endif()
+      if(DEFINED CPM_ARGS_SOURCE_SUBDIR)
+        list(APPEND fetchContentDeclareExtraArgs SOURCE_SUBDIR ${CPM_ARGS_SOURCE_SUBDIR})
+      endif()
+      # For CMake version <3.28 OPTIONS are parsed in cpm_add_subdirectory
+      if(CPM_ARGS_OPTIONS AND NOT DOWNLOAD_ONLY)
+        foreach(OPTION ${CPM_ARGS_OPTIONS})
+          cpm_parse_option("${OPTION}")
+          set(${OPTION_KEY} "${OPTION_VALUE}")
+        endforeach()
+      endif()
+    endif()
     cpm_declare_fetch(
-      "${CPM_ARGS_NAME}" "${CPM_ARGS_VERSION}" "${PACKAGE_INFO}" "${CPM_ARGS_UNPARSED_ARGUMENTS}"
+      "${CPM_ARGS_NAME}" ${fetchContentDeclareExtraArgs} "${CPM_ARGS_UNPARSED_ARGUMENTS}"
     )
-    cpm_fetch_package("${CPM_ARGS_NAME}" populated)
+
+    cpm_fetch_package("${CPM_ARGS_NAME}" ${DOWNLOAD_ONLY} populated ${CPM_ARGS_UNPARSED_ARGUMENTS})
     if(CPM_SOURCE_CACHE AND download_directory)
       file(LOCK ${download_directory}/../cmake.lock RELEASE)
     endif()
-    if(${populated})
+    if(${populated} AND ${CMAKE_VERSION} VERSION_LESS "3.30.3")
       cpm_add_subdirectory(
         "${CPM_ARGS_NAME}"
         "${DOWNLOAD_ONLY}"
@@ -980,7 +1023,7 @@ function(CPMGetPackageVersion PACKAGE OUTPUT)
 endfunction()
 
 # declares a package in FetchContent_Declare
-function(cpm_declare_fetch PACKAGE VERSION INFO)
+function(cpm_declare_fetch PACKAGE)
   if(${CPM_DRY_RUN})
     cpm_message(STATUS "${CPM_INDENT} Package not declared (dry run)")
     return()
@@ -1056,7 +1099,7 @@ endfunction()
 
 # downloads a previously declared package via FetchContent and exports the variables
 # `${PACKAGE}_SOURCE_DIR` and `${PACKAGE}_BINARY_DIR` to the parent scope
-function(cpm_fetch_package PACKAGE populated)
+function(cpm_fetch_package PACKAGE DOWNLOAD_ONLY populated)
   set(${populated}
       FALSE
       PARENT_SCOPE
@@ -1071,7 +1114,24 @@ function(cpm_fetch_package PACKAGE populated)
   string(TOLOWER "${PACKAGE}" lower_case_name)
 
   if(NOT ${lower_case_name}_POPULATED)
-    FetchContent_Populate(${PACKAGE})
+    if(${CMAKE_VERSION} VERSION_GREATER_EQUAL "3.30.3")
+      if(DOWNLOAD_ONLY)
+        # MakeAvailable will call add_subdirectory internally which is not what we want when
+        # DOWNLOAD_ONLY is set. Populate will only download the dependency without adding it to the
+        # build
+        FetchContent_Populate(
+          ${PACKAGE}
+          SOURCE_DIR "${CPM_FETCHCONTENT_BASE_DIR}/${lower_case_name}-src"
+          BINARY_DIR "${CPM_FETCHCONTENT_BASE_DIR}/${lower_case_name}-build"
+          SUBBUILD_DIR "${CPM_FETCHCONTENT_BASE_DIR}/${lower_case_name}-subbuild"
+          ${ARGN}
+        )
+      else()
+        FetchContent_MakeAvailable(${PACKAGE})
+      endif()
+    else()
+      FetchContent_Populate(${PACKAGE})
+    endif()
     set(${populated}
         TRUE
         PARENT_SCOPE

test/integration/test_basics.rb

@@ -31,7 +31,9 @@ class Basics < IntegrationTest
     assert_same_path File.join(prj.bin_dir, 'cpm-package-lock.cmake'), check_and_get('CPM_PACKAGE_LOCK_FILE')
 
     assert_equal 'OFF', check_and_get('CPM_DONT_UPDATE_MODULE_PATH', 'BOOL')
-    assert_same_path File.join(prj.bin_dir, 'CPM_modules'), check_and_get('CPM_MODULE_PATH')
+    if @cache.entries['CMAKE_FIND_PACKAGE_REDIRECTS_DIR'].nil?
+      assert_same_path File.join(prj.bin_dir, 'CPM_modules'), check_and_get('CPM_MODULE_PATH')
+    end
   end
 
   # Test when env CPM_SOURCE_CACHE is set

test/unit/local_dependency/ModuleCMakeLists.txt.in

@@ -8,6 +8,10 @@ option(ENABLE_TEST_COVERAGE "Enable test coverage" OFF)
 
 # ---- Dependencies ----
 
+if (@TEST_FORCE_MODULE_MODE@)
+  unset(CMAKE_FIND_PACKAGE_REDIRECTS_DIR CACHE)
+endif()
+
 include(@CPM_PATH@/CPM.cmake)
 
 CPMAddPackage(
@@ -15,21 +19,23 @@ CPMAddPackage(
   SOURCE_DIR ${CMAKE_CURRENT_LIST_DIR}/dependency
 )
 
-# ---- check if generated modules override find_package ----
-
-if (@test_check_find_package@)
-  find_package(@TEST_DEPENDENCY_NAME@ REQUIRED)
-endif()
-
 # ---- Call dependency method to validate correct addition of directory ----
 
 dependency_function()
 
-# ---- Check parameters ----
+# ---- Check newly added ----
-
 include(@CPM_PATH@/testing.cmake)
-
 ASSERT_TRUTHY(@TEST_DEPENDENCY_NAME@_ADDED)
+
+# ---- Check if generated modules override find_package ----
+
+if (@TEST_FIND_PACKAGE@)
+  find_package(@TEST_DEPENDENCY_NAME@ @TEST_FIND_PACKAGE_CONFIG@ REQUIRED)
+  find_package(@TEST_CANT_FIND_PACKAGE_NAME@ @TEST_FIND_PACKAGE_CONFIG@ QUIET)
+  ASSERT_FALSY(@TEST_CANT_FIND_PACKAGE_NAME@_FOUND)
+endif()
+
+# ---- Check parameters ----
 ASSERT_DEFINED(@TEST_DEPENDENCY_NAME@_SOURCE_DIR)
 ASSERT_DEFINED(@TEST_DEPENDENCY_NAME@_BINARY_DIR)
 ASSERT_EQUAL("${CPM_LAST_PACKAGE_NAME}" "@TEST_DEPENDENCY_NAME@")

test/unit/modules.cmake

@@ -3,7 +3,8 @@ include(${CPM_PATH}/testing.cmake)
 
 set(TEST_BUILD_DIR ${CMAKE_CURRENT_BINARY_DIR}/modules)
 
-function(init_project_with_dependency TEST_DEPENDENCY_NAME)
+function(init_project_with_dependency TEST_DEPENDENCY_NAME TEST_CANT_FIND_PACKAGE_NAME)
+  set(TEST_FIND_PACKAGE ON)
   configure_package_config_file(
     "${CMAKE_CURRENT_LIST_DIR}/local_dependency/ModuleCMakeLists.txt.in"
     "${CMAKE_CURRENT_LIST_DIR}/local_dependency/CMakeLists.txt"
@@ -18,11 +19,17 @@ function(init_project_with_dependency TEST_DEPENDENCY_NAME)
   assert_equal(${ret} "0")
 endfunction()
 
-init_project_with_dependency(A)
+init_project_with_dependency(A B)
-assert_exists(${TEST_BUILD_DIR}/CPM_modules)
+init_project_with_dependency(B A)
-assert_exists(${TEST_BUILD_DIR}/CPM_modules/FindA.cmake)
-assert_not_exists(${TEST_BUILD_DIR}/CPM_modules/FindB.cmake)
 
-init_project_with_dependency(B)
+if(${CMAKE_VERSION} VERSION_GREATER_EQUAL "3.24.0")
-assert_not_exists(${TEST_BUILD_DIR}/CPM_modules/FindA.cmake)
+  set(TEST_FIND_PACKAGE_CONFIG CONFIG)
-assert_exists(${TEST_BUILD_DIR}/CPM_modules/FindB.cmake)
+  init_project_with_dependency(A B)
+  init_project_with_dependency(B A)
+
+  # Test the fallback path for CMake <3.24 works
+  set(TEST_FIND_PACKAGE_CONFIG)
+  set(TEST_FORCE_MODULE_MODE ON)
+  init_project_with_dependency(A B)
+  init_project_with_dependency(B A)
+endif()