Improved FORCE_SYSTEM_<content-name> behavior

Improve the behavior of hfc_make_available_single when FORCE_SYSTEM_<content-name> is set for a given dependency by forcing find_xxx to use the system root for its search. Additionally the system was made more reliable by ensuring that a proxy toolchain is generate to forward necessary project information in addition to enabling the same CMAKE_LANGUAGEs as the invoking project

Co-authored-by: Damien Buhl <damien@tipi.build>

Change-Id: Ia55263361f376fb40a7c4b66dc559c7bbc931feb

cmake/modules/hfc_autotools_restore_or_configure.cmake

@@ -211,7 +211,7 @@ function(hfc_autotools_restore_or_configure content_name)
   cmake_language(CALL ${FN_ARG_CMAKE_ADAPTER_GENERATOR_FN}_get_install_target install_target_name)
 
   # Toolchain to forward arguments
-  set(proxy_toolchain_path "${HERMETIC_FETCHCONTENT_INSTALL_DIR}/${content_name}-toolchain/hfc_hermetic_proxy_toolchain.cmake")
+  hfc_get_content_proxy_toolchain_path(${content_name} proxy_toolchain_path)
   hfc_generate_cmake_proxy_toolchain(${content_name}
     # PROJECT_DEPENDENCIES not passed : Autotools cannot have dependencies, it doesn't "cmake-find_package"
     PROJECT_TOOLCHAIN_EXTENSION "${FN_ARG_PROJECT_TOOLCHAIN_EXTENSION}"

cmake/modules/hfc_cmake_restore_or_configure.cmake

@@ -77,9 +77,8 @@ function(hfc_cmake_restore_or_configure content_name)
     )
   endif()
 
-  set(proxy_toolchain_dir "${HERMETIC_FETCHCONTENT_INSTALL_DIR}/${content_name}-toolchain")
-  set(proxy_toolchain_path "${HERMETIC_FETCHCONTENT_INSTALL_DIR}/${content_name}-toolchain/hfc_hermetic_proxy_toolchain.cmake")
-
+  hfc_get_content_proxy_toolchain_dir(${content_name} proxy_toolchain_dir)
+  hfc_get_content_proxy_toolchain_path(${content_name} proxy_toolchain_path)
   file(LOCK ${proxy_toolchain_dir} DIRECTORY GUARD FUNCTION)
 
   hfc_generate_cmake_proxy_toolchain(${content_name}

cmake/modules/hfc_generate_cmake_proxy_toolchain.cmake

@@ -3,6 +3,16 @@ include_guard()
 include(hfc_log)
 include(hfc_targets_cache_common)
 
+function(hfc_get_content_proxy_toolchain_dir content_name OUT_result)
+  set(${OUT_result} "${FETCHCONTENT_BASE_DIR}/${content_name}-toolchain" PARENT_SCOPE)
+endfunction()
+
+function(hfc_get_content_proxy_toolchain_path content_name OUT_result)
+  hfc_get_content_proxy_toolchain_dir("${content_name}" proxy_toolchain_dir)
+  set(${OUT_result} "${proxy_toolchain_dir}/hfc_hermetic_proxy_toolchain.cmake" PARENT_SCOPE)
+endfunction()
+
+
 #[=======================================================================[.rst:
 hfc_generate_cmake_proxy_toolchain
 ------------------------------------------------------------------------------------------

cmake/modules/hfc_make_available_single.cmake

@@ -4,6 +4,8 @@ include(hfc_cmake_restore_or_configure)
 include(hfc_saved_details)
 include(hfc_determine_cache_id)
 include(hfc_populate_project)
+include(hfc_generate_cmake_proxy_toolchain)
+include(hfc_targets_cache_create)
 
 # This creates prefixes where HermeticFetchContent will reuse buildLocation or installed location
 function(hfc_create_restore_prefixes content_name buildLocation installedLocation)
@@ -148,13 +150,33 @@ function(hfc_make_available_single content_name build_at_configure_time)
 
   if (DEFINED FORCE_SYSTEM_${content_name})
     if (${FORCE_SYSTEM_${content_name}})
+
       hfc_log(WARNING "FORCE_SYSTEM_${content_name} is ON, HermeticFetchContent will only find_package the library on the system.")
 
+      hfc_get_content_proxy_toolchain_path(${content_name} proxy_toolchain_path)
+
+      string(APPEND __PARAMS_HERMETIC_TOOLCHAIN_EXTENSION 
+        [=[
+          set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+          set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY NEVER)
+          set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE NEVER)
+          set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE NEVER)
+        ]=]
+      )
+
+      hfc_generate_cmake_proxy_toolchain(${content_name}
+        HERMETIC_FIND_PACKAGES "${__PARAMS_HERMETIC_FIND_PACKAGES}"
+        PROJECT_TOOLCHAIN_EXTENSION "${__PARAMS_HERMETIC_TOOLCHAIN_EXTENSION}"
+        DESTINATION_TOOLCHAIN_PATH "${proxy_toolchain_path}"
+      ) 
+
       get_hermetic_target_cache_file_path(${content_name} target_cache_file)
       hfc_targets_cache_create_isolated(
+        ${content_name}
         LOAD_TARGETS_CMAKE "[==[find_package(${content_name} REQUIRED ${__PARAMS_FIND_PACKAGE_ARGS} ) \n]==]"
         CACHE_DESTINATION_FILE "${target_cache_file}"
         TEMP_DIR "${HERMETIC_FETCHCONTENT_INSTALL_DIR}/targets_dump_tmp"
+        TOOLCHAIN_FILE ${proxy_toolchain_path}
       )
 
       # Now load the targets in our context

cmake/modules/hfc_targets_cache_create.cmake

@@ -232,7 +232,7 @@ endfunction()
 #   LOAD_TARGETS_CMAKE <cmake code to eval for loading targets>
 #   CACHE_DESTINATION_FILE <path>         # path to the target info cache to write. Parent directory will be created if not already present. Destination file will be overwritten if present
 # )
-function(hfc_targets_cache_create_isolated)  
+function(hfc_targets_cache_create_isolated content_name)  
 
   # arguments parsing
   set(options "")
@@ -252,11 +252,19 @@ function(hfc_targets_cache_create_isolated)
 
   file(MAKE_DIRECTORY "${tmp_proj_dir}")
 
+  # make sure we have the same enabled languages if the FORCE_SYSTEM_<content-name>
+  set(TEMPLATE_ENABLE_LANGUAGES "NONE")
+  if(FORCE_SYSTEM_${content_name})
+    get_property(languages GLOBAL PROPERTY ENABLED_LANGUAGES)
+    set(TEMPLATE_ENABLE_LANGUAGES ${languages})
+  endif()
+
   block(SCOPE_FOR VARIABLES PROPAGATE 
     HERMETIC_FETCHCONTENT_ROOT_DIR 
     FN_ARG_LOAD_TARGETS_CMAKE 
     FN_ARG_CACHE_DESTINATION_FILE 
     FN_ARG_CREATE_TARGET_ALIASES
+    TEMPLATE_ENABLE_LANGUAGES
   )
     set(HERMETIC_FETCHCONTENT_ROOT_DIR "${HERMETIC_FETCHCONTENT_ROOT_DIR}")
     set(LOAD_TARGETS_CMAKE "${FN_ARG_LOAD_TARGETS_CMAKE}")
@@ -317,6 +325,7 @@ function(hfc_targets_cache_create_from_export_declaration content_name)
   hfc_log_debug("Generating targets cache for ${content_name} from export declaration at ${${FN_ARG_OUT_TARGETS_CACHE_FILE}}")
 
   hfc_targets_cache_create_isolated(
+    ${content_name}
     LOAD_TARGETS_CMAKE "[==[${FN_ARG_CMAKE_EXPORT_LIBRARY_DECLARATION}]==]"
     TOOLCHAIN_FILE ${FN_ARG_TOOLCHAIN_FILE}
     CACHE_DESTINATION_FILE "${${FN_ARG_OUT_TARGETS_CACHE_FILE}}"

cmake/templates/create_imported_cmake_targets_cache.CMakeLists.txt.in

@@ -1,5 +1,5 @@
 cmake_minimum_required(VERSION 3.27.0)
-project(create_imported_cmake_targets_cache LANGUAGES NONE)
+project(create_imported_cmake_targets_cache LANGUAGES @TEMPLATE_ENABLE_LANGUAGES@)
 
 list(APPEND CMAKE_MODULE_PATH "@HERMETIC_FETCHCONTENT_ROOT_DIR@")
 list(APPEND CMAKE_MODULE_PATH "@HERMETIC_FETCHCONTENT_ROOT_DIR@/modules")

test/check_openssl_build_system.cpp

@@ -55,6 +55,7 @@ namespace hfc::test {
     BOOST_REQUIRE(!fs::exists(test_project_path / "thirdparty" / "cache" / "openssl-src"));
     BOOST_REQUIRE(!fs::exists(test_project_path / "build" / "_deps" / "OpenSSL-install" / "lib" / "libssl.a"  ));
     BOOST_REQUIRE(!fs::exists(test_project_path / "build" / "_deps" / "OpenSSL-install" / "lib" / "libcrypto.a"  ));
+    BOOST_REQUIRE(fs::exists(test_project_path / "build" / "_deps" / "hermetic_targetcaches" / "OpenSSL.cmake"));
 
     std::string ninja_output = run_command(cmake_build_command, test_project_path);
     BOOST_REQUIRE(boost::contains(ninja_output, "ninja: no work to do"));