qt5base-lts/cmake/QtBuildInternals/QtBuildInternalsConfig.cmake
Joerg Bornemann 2746051522 CMake: Disconnect docs installation targets from generation targets
"ninja install_docs" should not run the "docs" target, because with
the usual workflow
    ninja docs
    ninja install_docs
the documentation would be built twice.

That of course means that "ninja install_docs" will fail if "ninja
docs" wasn't run before.

Analogous for html_docs, qch_docs, the repository-level and
module-level documentation targets.

Change-Id: I8ad83602dd393b5afc79a19ab3d395987c889d0d
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
2020-11-06 22:03:51 +01:00

528 lines
22 KiB
CMake

if (CMAKE_VERSION VERSION_LESS 3.1.0)
message(FATAL_ERROR "Qt requires at least CMake version 3.1.0")
endif()
######################################
#
# Macros for building Qt modules
#
######################################
set(QT_BACKUP_CMAKE_INSTALL_PREFIX_BEFORE_EXTRA_INCLUDE "${CMAKE_INSTALL_PREFIX}")
if(EXISTS "${CMAKE_CURRENT_LIST_DIR}/QtBuildInternalsExtra.cmake")
include(${CMAKE_CURRENT_LIST_DIR}/QtBuildInternalsExtra.cmake)
endif()
macro(qt_set_up_build_internals_paths)
# Set up the paths for the cmake modules located in the prefix dir. Prepend, so the paths are
# least important compared to the source dir ones, but more important than command line
# provided ones.
set(QT_CMAKE_MODULE_PATH "${QT_BUILD_INTERNALS_PATH}/../${QT_CMAKE_EXPORT_NAMESPACE}")
list(PREPEND CMAKE_MODULE_PATH "${QT_CMAKE_MODULE_PATH}")
# Prepend the qtbase source cmake directory to CMAKE_MODULE_PATH,
# so that if a change is done in cmake/QtBuild.cmake, it gets automatically picked up when
# building qtdeclarative, rather than having to build qtbase first (which will copy
# QtBuild.cmake to the build dir). This is similar to qmake non-prefix builds, where the
# source qtbase/mkspecs directory is used.
if(EXISTS "${QT_SOURCE_TREE}/cmake")
list(PREPEND CMAKE_MODULE_PATH "${QT_SOURCE_TREE}/cmake")
endif()
# If the repo has its own cmake modules, include those in the module path.
if(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
list(PREPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
endif()
# Find the cmake files when doing a standalone tests build.
if(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/../cmake")
list(PREPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/../cmake")
endif()
endmacro()
# Set up the build internal paths unless explicitly requested not to.
if(NOT QT_BUILD_INTERNALS_SKIP_CMAKE_MODULE_PATH_ADDITION)
qt_set_up_build_internals_paths()
endif()
# Define some constants to check for certain platforms, etc.
# Needs to be loaded before qt_repo_build() to handle require() clauses before even starting a repo
# build.
include(QtPlatformSupport)
function(qt_build_internals_disable_pkg_config_if_needed)
# pkg-config should not be used by default on Darwin and Windows platforms (and QNX), as defined
# in the qtbase/configure.json. Unfortunately by the time the feature is evaluated there are
# already a few find_package() calls that try to use the FindPkgConfig module.
# Thus, we have to duplicate the condition logic here and disable pkg-config for those platforms
# by default.
# We also need to check if the pkg-config executable exists, to mirror the condition test in
# configure.json. We do that by trying to find the executable ourselves, and not delegating to
# the FindPkgConfig module because that has more unwanted side-effects.
#
# Note that on macOS, if the pkg-config feature is enabled by the user explicitly, we will also
# tell CMake to consider paths like /usr/local (Homebrew) as system paths when looking for
# packages.
# We have to do that because disabling these paths but keeping pkg-config
# enabled won't enable finding all system libraries via pkg-config alone, many libraries can
# only be found via FooConfig.cmake files which means /usr/local should be in the system prefix
# path.
set(pkg_config_enabled ON)
qt_build_internals_find_pkg_config_executable()
if(APPLE OR WIN32 OR QNX OR ANDROID OR (NOT PKG_CONFIG_EXECUTABLE))
set(pkg_config_enabled OFF)
endif()
# If user explicitly specified a value for the feature, honor it, even if it might break
# the build.
if(DEFINED FEATURE_pkg_config)
if(FEATURE_pkg_config)
set(pkg_config_enabled ON)
else()
set(pkg_config_enabled OFF)
endif()
endif()
set(FEATURE_pkg_config "${pkg_config_enabled}" CACHE STRING "Using pkg-config")
if(NOT pkg_config_enabled)
qt_build_internals_disable_pkg_config()
else()
unset(PKG_CONFIG_EXECUTABLE CACHE)
endif()
endfunction()
# This is a copy of the first few lines in FindPkgConfig.cmake.
function(qt_build_internals_find_pkg_config_executable)
# find pkg-config, use PKG_CONFIG if set
if((NOT PKG_CONFIG_EXECUTABLE) AND (NOT "$ENV{PKG_CONFIG}" STREQUAL ""))
set(PKG_CONFIG_EXECUTABLE "$ENV{PKG_CONFIG}" CACHE FILEPATH "pkg-config executable")
endif()
find_program(PKG_CONFIG_EXECUTABLE NAMES pkg-config DOC "pkg-config executable")
mark_as_advanced(PKG_CONFIG_EXECUTABLE)
endfunction()
function(qt_build_internals_disable_pkg_config)
# Disable pkg-config by setting an empty executable path. There's no documented way to
# mark the package as not found, but we can force all pkg_check_modules calls to do nothing
# by setting the variable to an empty value.
set(PKG_CONFIG_EXECUTABLE "" CACHE STRING "Disabled pkg-config usage." FORCE)
endfunction()
if(NOT QT_BUILD_INTERNALS_SKIP_PKG_CONFIG_ADJUSTMENT)
qt_build_internals_disable_pkg_config_if_needed()
endif()
macro(qt_build_internals_find_pkg_config)
# Find package config once before any system prefix modifications.
find_package(PkgConfig QUIET)
endmacro()
if(NOT QT_BUILD_INTERNALS_SKIP_FIND_PKG_CONFIG)
qt_build_internals_find_pkg_config()
endif()
function(qt_build_internals_set_up_system_prefixes)
if(APPLE AND NOT FEATURE_pkg_config)
# Remove /usr/local and other paths like that which CMake considers as system prefixes on
# darwin platforms. CMake considers them as system prefixes, but in qmake / Qt land we only
# consider the SDK path as a system prefix.
# 3rd party libraries in these locations should not be picked up when building Qt,
# unless opted-in via the pkg-config feature, which in turn will disable this behavior.
#
# Note that we can't remove /usr as a system prefix path, because many programs won't be
# found then (e.g. perl).
set(QT_CMAKE_SYSTEM_PREFIX_PATH_BACKUP "${CMAKE_SYSTEM_PREFIX_PATH}" PARENT_SCOPE)
set(QT_CMAKE_SYSTEM_FRAMEWORK_PATH_BACKUP "${CMAKE_SYSTEM_FRAMEWORK_PATH}" PARENT_SCOPE)
list(REMOVE_ITEM CMAKE_SYSTEM_PREFIX_PATH
"/usr/local" # Homebrew
"/usr/X11R6"
"/usr/pkg"
"/opt"
"/sw" # Fink
"/opt/local" # MacPorts
)
if(_CMAKE_INSTALL_DIR)
list(REMOVE_ITEM CMAKE_SYSTEM_PREFIX_PATH "${_CMAKE_INSTALL_DIR}")
endif()
list(REMOVE_ITEM CMAKE_SYSTEM_FRAMEWORK_PATH "~/Library/Frameworks")
set(CMAKE_SYSTEM_PREFIX_PATH "${CMAKE_SYSTEM_PREFIX_PATH}" PARENT_SCOPE)
set(CMAKE_SYSTEM_FRAMEWORK_PATH "${CMAKE_SYSTEM_FRAMEWORK_PATH}" PARENT_SCOPE)
# Also tell qt_find_package() not to use PATH when looking for packages.
# We can't simply set CMAKE_FIND_USE_SYSTEM_ENVIRONMENT_PATH to OFF because that will break
# find_program(), and for instance ccache won't be found.
# That's why we set a different variable which is used by qt_find_package.
set(QT_NO_USE_FIND_PACKAGE_SYSTEM_ENVIRONMENT_PATH "ON" PARENT_SCOPE)
endif()
endfunction()
if(NOT QT_BUILD_INTERNALS_SKIP_SYSTEM_PREFIX_ADJUSTMENT)
qt_build_internals_set_up_system_prefixes()
endif()
macro(qt_build_internals_set_up_private_api)
# Check for the minimum CMake version.
include(QtCMakeVersionHelpers)
qt_internal_require_suitable_cmake_version()
# Qt specific setup common for all modules:
include(QtSetup)
include(FeatureSummary)
# Optionally include a repo specific Setup module.
include(${PROJECT_NAME}Setup OPTIONAL)
include(QtRepoSetup OPTIONAL)
# Find Apple frameworks if needed.
qt_find_apple_system_frameworks()
# Decide whether tools will be built.
qt_check_if_tools_will_be_built()
endmacro()
macro(qt_enable_cmake_languages)
include(CheckLanguage)
set(__qt_required_language_list C CXX)
set(__qt_optional_language_list )
# https://gitlab.kitware.com/cmake/cmake/-/issues/20545
if(APPLE)
list(APPEND __qt_optional_language_list OBJC OBJCXX)
endif()
foreach(__qt_lang ${__qt_required_language_list})
enable_language(${__qt_lang})
endforeach()
foreach(__qt_lang ${__qt_optional_language_list})
check_language(${__qt_lang})
if(CMAKE_${__qt_lang}_COMPILER)
enable_language(${__qt_lang})
endif()
endforeach()
# The qtbase call is handled in qtbase/CMakeLists.txt.
# This call is used for projects other than qtbase, including for other project's standalone
# tests.
# Because the function uses QT_FEATURE_foo values, it's important that find_package(Qt6Core) is
# called before this function. but that's usually the case for Qt repos.
if(NOT PROJECT_NAME STREQUAL "QtBase")
qt_internal_set_up_config_optimizations_like_in_qmake()
endif()
endmacro()
# Minimum setup required to have any CMakeList.txt build as as a standalone
# project after importing BuildInternals
macro(qt_prepare_standalone_project)
qt_set_up_build_internals_paths()
qt_build_internals_set_up_private_api()
qt_enable_cmake_languages()
endmacro()
macro(qt_build_repo_begin)
qt_build_internals_set_up_private_api()
qt_enable_cmake_languages()
# Add global docs targets that will work both for per-repo builds, and super builds.
if(NOT TARGET docs)
add_custom_target(docs)
add_custom_target(prepare_docs)
add_custom_target(generate_docs)
add_custom_target(html_docs)
add_custom_target(qch_docs)
add_custom_target(install_html_docs)
add_custom_target(install_qch_docs)
add_custom_target(install_docs)
add_dependencies(html_docs generate_docs)
add_dependencies(docs html_docs qch_docs)
add_dependencies(install_docs install_html_docs install_qch_docs)
endif()
# Add global qt_plugins, qpa_plugins and qpa_default_plugins convenience custom targets.
# Internal executables will add a dependency on the qpa_default_plugins target,
# so that building and running a test ensures it won't fail at runtime due to a missing qpa
# plugin.
if(NOT TARGET qt_plugins)
add_custom_target(qt_plugins)
add_custom_target(qpa_plugins)
add_custom_target(qpa_default_plugins)
endif()
string(TOLOWER ${PROJECT_NAME} project_name_lower)
set(qt_docs_target_name docs_${project_name_lower})
set(qt_docs_prepare_target_name prepare_docs_${project_name_lower})
set(qt_docs_generate_target_name generate_docs_${project_name_lower})
set(qt_docs_html_target_name html_docs_${project_name_lower})
set(qt_docs_qch_target_name qch_docs_${project_name_lower})
set(qt_docs_install_html_target_name install_html_docs_${project_name_lower})
set(qt_docs_install_qch_target_name install_qch_docs_${project_name_lower})
set(qt_docs_install_target_name install_docs_${project_name_lower})
add_custom_target(${qt_docs_target_name})
add_custom_target(${qt_docs_prepare_target_name})
add_custom_target(${qt_docs_generate_target_name})
add_custom_target(${qt_docs_qch_target_name})
add_custom_target(${qt_docs_html_target_name})
add_custom_target(${qt_docs_install_html_target_name})
add_custom_target(${qt_docs_install_qch_target_name})
add_custom_target(${qt_docs_install_target_name})
add_dependencies(${qt_docs_generate_target_name} ${qt_docs_prepare_target_name})
add_dependencies(${qt_docs_html_target_name} ${qt_docs_generate_target_name})
add_dependencies(${qt_docs_target_name} ${qt_docs_html_target_name} ${qt_docs_qch_target_name})
add_dependencies(${qt_docs_install_target_name} ${qt_docs_install_html_target_name} ${qt_docs_install_qch_target_name})
# Make top-level prepare_docs target depend on the repository-level prepare_docs_<repo> target.
add_dependencies(prepare_docs ${qt_docs_prepare_target_name})
# Make top-level install_*_docs targets depend on the repository-level install_*_docs targets.
add_dependencies(install_html_docs ${qt_docs_install_html_target_name})
add_dependencies(install_qch_docs ${qt_docs_install_qch_target_name})
# Add host_tools meta target, so that developrs can easily build only tools and their
# dependencies when working in qtbase.
if(NOT TARGET host_tools)
add_custom_target(host_tools)
add_custom_target(bootstrap_tools)
endif()
endmacro()
macro(qt_build_repo_end)
if(NOT QT_BUILD_STANDALONE_TESTS)
# Delayed actions on some of the Qt targets:
include(QtPostProcess)
# Install the repo-specific cmake find modules.
qt_path_join(__qt_repo_install_dir ${QT_CONFIG_INSTALL_DIR} ${INSTALL_CMAKE_NAMESPACE})
if(NOT PROJECT_NAME STREQUAL "QtBase")
if (EXISTS cmake)
qt_copy_or_install(DIRECTORY cmake/
DESTINATION "${__qt_repo_install_dir}"
FILES_MATCHING PATTERN "Find*.cmake"
)
endif()
endif()
if(NOT QT_SUPERBUILD)
qt_print_feature_summary()
endif()
endif()
if(NOT QT_SUPERBUILD)
qt_print_build_instructions()
endif()
endmacro()
macro(qt_build_repo)
qt_build_repo_begin(${ARGN})
# If testing is enabled, try to find the qtbase Test package.
# Do this before adding src, because there might be test related conditions
# in source.
if (BUILD_TESTING AND NOT QT_BUILD_STANDALONE_TESTS)
find_package(Qt6 ${PROJECT_VERSION} CONFIG REQUIRED COMPONENTS Test)
endif()
if(NOT QT_BUILD_STANDALONE_TESTS)
if (EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/src/CMakeLists.txt")
add_subdirectory(src)
endif()
if (EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/tools/CMakeLists.txt")
add_subdirectory(tools)
endif()
endif()
if (BUILD_TESTING AND EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/tests/CMakeLists.txt")
add_subdirectory(tests)
if(QT_NO_MAKE_TESTS)
set_property(DIRECTORY tests PROPERTY EXCLUDE_FROM_ALL TRUE)
endif()
endif()
qt_build_repo_end()
if (BUILD_EXAMPLES AND BUILD_SHARED_LIBS
AND EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/examples/CMakeLists.txt"
AND NOT QT_BUILD_STANDALONE_TESTS)
add_subdirectory(examples)
if(QT_NO_MAKE_EXAMPLES)
set_property(DIRECTORY examples PROPERTY EXCLUDE_FROM_ALL TRUE)
endif()
endif()
endmacro()
macro(qt_set_up_standalone_tests_build)
# Remove this macro once all usages of it have been removed.
# Standalone tests are not handled via the main repo project and qt_build_tests.
endmacro()
function(qt_get_standalone_tests_confg_files_path out_var)
set(path "${QT_CONFIG_INSTALL_DIR}/${INSTALL_CMAKE_NAMESPACE}BuildInternals/StandaloneTests")
# QT_CONFIG_INSTALL_DIR is relative in prefix builds.
if(QT_WILL_INSTALL)
qt_path_join(path "${CMAKE_INSTALL_PREFIX}" "${path}")
endif()
set("${out_var}" "${path}" PARENT_SCOPE)
endfunction()
macro(qt_build_tests)
if(QT_BUILD_STANDALONE_TESTS)
# Find location of TestsConfig.cmake. These contain the modules that need to be
# find_package'd when testing.
qt_get_standalone_tests_confg_files_path(_qt_build_tests_install_prefix)
include("${_qt_build_tests_install_prefix}/${PROJECT_NAME}TestsConfig.cmake" OPTIONAL)
# Of course we always need the test module as well.
find_package(Qt6 ${PROJECT_VERSION} CONFIG REQUIRED COMPONENTS Test)
# Set language standards after finding Core, because that's when the relevant
# feature variables are available, and the call in QtSetup is too early when building
# standalone tests, because Core was not find_package()'d yet.
qt_set_language_standards()
if(NOT QT_SUPERBUILD)
# Set up fake standalone tests install prefix, so we don't pollute the Qt install
# prefix. For super builds it needs to be done in qt5/CMakeLists.txt.
qt_set_up_fake_standalone_tests_install_prefix()
endif()
endif()
if(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/auto/CMakeLists.txt")
add_subdirectory(auto)
endif()
if(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/benchmarks/CMakeLists.txt" AND QT_BUILD_BENCHMARKS)
add_subdirectory(benchmarks)
endif()
if(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/manual/CMakeLists.txt")
# add_subdirectory(manual) don't build manual tests for now, because qmake doesn't.
endif()
endmacro()
function(qt_compute_relative_path_from_cmake_config_dir_to_prefix)
# Compute the reverse relative path from the CMake config dir to the install prefix.
# This is used in QtBuildInternalsExtras to create a relocatable relative install prefix path.
# This path is used for finding syncqt and other things, regardless of initial install prefix
# (e.g installed Qt was archived and unpacked to a different path on a different machine).
#
# This is meant to be called only once when configuring qtbase.
#
# Similar code exists in Qt6CoreConfigExtras.cmake.in and src/corelib/CMakeLists.txt which
# might not be needed anymore.
if(QT_WILL_INSTALL)
get_filename_component(clean_config_prefix
"${CMAKE_INSTALL_PREFIX}/${QT_CONFIG_INSTALL_DIR}" ABSOLUTE)
else()
get_filename_component(clean_config_prefix "${QT_CONFIG_BUILD_DIR}" ABSOLUTE)
endif()
file(RELATIVE_PATH
qt_path_from_cmake_config_dir_to_prefix
"${clean_config_prefix}" "${CMAKE_INSTALL_PREFIX}")
set(qt_path_from_cmake_config_dir_to_prefix "${qt_path_from_cmake_config_dir_to_prefix}"
PARENT_SCOPE)
endfunction()
function(qt_get_relocatable_install_prefix out_var)
# We need to compute it only once while building qtbase. Afterwards it's loaded from
# QtBuildInternalsExtras.cmake.
if(QT_BUILD_INTERNALS_RELOCATABLE_INSTALL_PREFIX)
return()
endif()
# The QtBuildInternalsExtras value is dynamically computed, whereas the initial qtbase
# configuration uses an absolute path.
set(${out_var} "${CMAKE_INSTALL_PREFIX}" PARENT_SCOPE)
endfunction()
function(qt_set_up_fake_standalone_tests_install_prefix)
# Set a fake local (non-cache) CMAKE_INSTALL_PREFIX.
# Needed for standalone tests, we don't want to accidentally install a test into the Qt prefix.
# Allow opt-out, if a user knows what they're doing.
if(QT_NO_FAKE_STANDALONE_TESTS_INSTALL_PREFIX)
return()
endif()
set(new_install_prefix "${CMAKE_BINARY_DIR}/fake_prefix")
# It's IMPORTANT that this is not a cache variable. Otherwise
# qt_get_standalone_tests_confg_files_path() will not work on re-configuration.
message(STATUS
"Setting local standalone test install prefix (non-cached) to '${new_install_prefix}'.")
set(CMAKE_INSTALL_PREFIX "${new_install_prefix}" PARENT_SCOPE)
# We also need to clear the staging prefix if it's set, otherwise CMake will modify any computed
# rpaths containing the staging prefix to point to the new fake prefix, which is not what we
# want. This replacement is done in cmComputeLinkInformation::GetRPath().
#
# By clearing the staging prefix for the standalone tests, any detected link time
# rpaths will be embedded as-is, which will point to the place where Qt was installed (aka
# the staging prefix).
if(DEFINED CMAKE_STAGING_PREFIX)
message(STATUS "Clearing local standalone test staging prefix (non-cached).")
set(CMAKE_STAGING_PREFIX "" PARENT_SCOPE)
endif()
endfunction()
# Mean to be called when configuring examples as part of the main build tree, as well as for CMake
# tests (tests that call CMake to try and build CMake applications).
macro(qt_internal_set_up_build_dir_package_paths)
list(APPEND CMAKE_PREFIX_PATH "${QT_BUILD_DIR}")
# Make sure the CMake config files do not recreate the already-existing targets
set(QT_NO_CREATE_TARGETS TRUE)
set(BACKUP_CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ${CMAKE_FIND_ROOT_PATH_MODE_PACKAGE})
set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE "BOTH")
endmacro()
macro(qt_examples_build_begin)
# Examples that are built as part of the Qt build need to use the CMake config files from the
# build dir, because they are not installed yet in a prefix build.
# Appending to CMAKE_PREFIX_PATH helps find the initial Qt6Config.cmake.
# Appending to QT_EXAMPLES_CMAKE_PREFIX_PATH helps find components of Qt6, because those
# find_package calls use NO_DEFAULT_PATH, and thus CMAKE_PREFIX_PATH is ignored.
qt_internal_set_up_build_dir_package_paths()
list(APPEND QT_EXAMPLES_CMAKE_PREFIX_PATH "${QT_BUILD_DIR}")
# Because CMAKE_INSTALL_RPATH is empty by default in the repo project, examples need to have
# it set here, so they can run when installed.
# This means that installed examples are not relocatable at the moment. We would need to
# annotate where each example is installed to, to be able to derive a relative rpath, and it
# seems there's no way to query such information from CMake itself.
set(CMAKE_INSTALL_RPATH "${_default_install_rpath}")
set(QT_DISABLE_QT_ADD_PLUGIN_COMPATIBILITY TRUE)
endmacro()
macro(qt_examples_build_end)
# We use AUTOMOC/UIC/RCC in the examples. Make sure to not fail on a fresh Qt build, that e.g. the moc binary does not exist yet.
# This function gets all targets below this directory
function(get_all_targets _result _dir)
get_property(_subdirs DIRECTORY "${_dir}" PROPERTY SUBDIRECTORIES)
foreach(_subdir IN LISTS _subdirs)
get_all_targets(${_result} "${_subdir}")
endforeach()
get_property(_sub_targets DIRECTORY "${_dir}" PROPERTY BUILDSYSTEM_TARGETS)
set(${_result} ${${_result}} ${_sub_targets} PARENT_SCOPE)
endfunction()
get_all_targets(targets "${CMAKE_CURRENT_SOURCE_DIR}")
foreach(target ${targets})
qt_autogen_tools(${target} ENABLE_AUTOGEN_TOOLS "moc" "rcc")
if(TARGET Qt::Widgets)
qt_autogen_tools(${target} ENABLE_AUTOGEN_TOOLS "uic")
endif()
endforeach()
set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ${BACKUP_CMAKE_FIND_ROOT_PATH_MODE_PACKAGE})
endmacro()
if (ANDROID)
include(${CMAKE_CURRENT_LIST_DIR}/QtBuildInternalsAndroid.cmake)
endif()