diff options
Diffstat (limited to 'Modules/CheckFunctionExists.cmake')
-rw-r--r-- | Modules/CheckFunctionExists.cmake | 87 |
1 files changed, 57 insertions, 30 deletions
diff --git a/Modules/CheckFunctionExists.cmake b/Modules/CheckFunctionExists.cmake index ead135441..ef080621d 100644 --- a/Modules/CheckFunctionExists.cmake +++ b/Modules/CheckFunctionExists.cmake @@ -1,39 +1,50 @@ -# - Check if a C function can be linked -# CHECK_FUNCTION_EXISTS(<function> <variable>) +# Distributed under the OSI-approved BSD 3-Clause License. See accompanying +# file Copyright.txt or https://cmake.org/licensing for details. + +#.rst: +# CheckFunctionExists +# ------------------- # -# Check that the <function> is provided by libraries on the system and -# store the result in a <variable>. This does not verify that any -# system header file declares the function, only that it can be found -# at link time (consider using CheckSymbolExists). +# Check if a C function can be linked:: # -# The following variables may be set before calling this macro to -# modify the way the check is run: +# check_function_exists(<function> <variable>) # -# CMAKE_REQUIRED_FLAGS = string of compile command line flags -# CMAKE_REQUIRED_DEFINITIONS = list of macros to define (-DFOO=bar) -# CMAKE_REQUIRED_INCLUDES = list of include directories -# CMAKE_REQUIRED_LIBRARIES = list of libraries to link - -#============================================================================= -# Copyright 2002-2011 Kitware, Inc. +# Check that the ``<function>`` is provided by libraries on the system and store +# the result in a ``<variable>``. ``<variable>`` will be created as an internal +# cache variable. # -# Distributed under the OSI-approved BSD License (the "License"); -# see accompanying file Copyright.txt for details. +# The following variables may be set before calling this macro to modify the +# way the check is run: # -# This software is distributed WITHOUT ANY WARRANTY; without even the -# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. -# See the License for more information. -#============================================================================= -# (To distribute this file outside of CMake, substitute the full -# License text for the above reference.) - - +# :: +# +# CMAKE_REQUIRED_FLAGS = string of compile command line flags +# CMAKE_REQUIRED_DEFINITIONS = list of macros to define (-DFOO=bar) +# CMAKE_REQUIRED_INCLUDES = list of include directories +# CMAKE_REQUIRED_LIBRARIES = list of libraries to link +# CMAKE_REQUIRED_QUIET = execute quietly without messages +# +# .. note:: +# +# Prefer using :Module:`CheckSymbolExists` instead of this module, +# for the following reasons: +# +# * ``check_function_exists()`` can't detect functions that are inlined +# in headers or specified as a macro. +# +# * ``check_function_exists()`` can't detect anything in the 32-bit +# versions of the Win32 API, because of a mismatch in calling conventions. +# +# * ``check_function_exists()`` only verifies linking, it does not verify +# that the function is declared in system headers. macro(CHECK_FUNCTION_EXISTS FUNCTION VARIABLE) - if("${VARIABLE}" MATCHES "^${VARIABLE}$") + if(NOT DEFINED "${VARIABLE}" OR "x${${VARIABLE}}" STREQUAL "x${VARIABLE}") set(MACRO_CHECK_FUNCTION_DEFINITIONS "-DCHECK_FUNCTION_EXISTS=${FUNCTION} ${CMAKE_REQUIRED_FLAGS}") - message(STATUS "Looking for ${FUNCTION}") + if(NOT CMAKE_REQUIRED_QUIET) + message(STATUS "Looking for ${FUNCTION}") + endif() if(CMAKE_REQUIRED_LIBRARIES) set(CHECK_FUNCTION_EXISTS_ADD_LIBRARIES LINK_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES}) @@ -46,22 +57,38 @@ macro(CHECK_FUNCTION_EXISTS FUNCTION VARIABLE) else() set(CHECK_FUNCTION_EXISTS_ADD_INCLUDES) endif() + + if(CMAKE_C_COMPILER_LOADED) + set(_cfe_source ${CMAKE_ROOT}/Modules/CheckFunctionExists.c) + elseif(CMAKE_CXX_COMPILER_LOADED) + set(_cfe_source ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CheckFunctionExists/CheckFunctionExists.cxx) + configure_file(${CMAKE_ROOT}/Modules/CheckFunctionExists.c "${_cfe_source}" COPYONLY) + else() + message(FATAL_ERROR "CHECK_FUNCTION_EXISTS needs either C or CXX language enabled") + endif() + try_compile(${VARIABLE} ${CMAKE_BINARY_DIR} - ${CMAKE_ROOT}/Modules/CheckFunctionExists.c + ${_cfe_source} COMPILE_DEFINITIONS ${CMAKE_REQUIRED_DEFINITIONS} ${CHECK_FUNCTION_EXISTS_ADD_LIBRARIES} CMAKE_FLAGS -DCOMPILE_DEFINITIONS:STRING=${MACRO_CHECK_FUNCTION_DEFINITIONS} "${CHECK_FUNCTION_EXISTS_ADD_INCLUDES}" OUTPUT_VARIABLE OUTPUT) + unset(_cfe_source) + if(${VARIABLE}) set(${VARIABLE} 1 CACHE INTERNAL "Have function ${FUNCTION}") - message(STATUS "Looking for ${FUNCTION} - found") + if(NOT CMAKE_REQUIRED_QUIET) + message(STATUS "Looking for ${FUNCTION} - found") + endif() file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log "Determining if the function ${FUNCTION} exists passed with the following output:\n" "${OUTPUT}\n\n") else() - message(STATUS "Looking for ${FUNCTION} - not found") + if(NOT CMAKE_REQUIRED_QUIET) + message(STATUS "Looking for ${FUNCTION} - not found") + endif() set(${VARIABLE} "" CACHE INTERNAL "Have function ${FUNCTION}") file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log "Determining if the function ${FUNCTION} exists failed with the following output:\n" |