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-rw-r--r--Modules/CheckFunctionExists.cmake87
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"