Add CheckCXXSymbolExists.cmake, so this can be used also for C++

This commit splits check_symbol_exists() so that the actual
implementation can be also used by check_cxx_symbol_exists()

Alex

Modules/CheckCXXSymbolExists.cmake

@@ -0,0 +1,42 @@
+# - Check if a symbol exists as a function, variable, or macro in C++
+# CHECK_CXX_SYMBOL_EXISTS(<symbol> <files> <variable>)
+#
+# Check that the <symbol> is available after including given header
+# <files> and store the result in a <variable>.  Specify the list
+# of files in one argument as a semicolon-separated list.
+# CHECK_CXX_SYMBOL_EXISTS() can be used to check in C++ files, as opposed
+# to CHECK_SYMBOL_EXISTS(), which works only for C.
+#
+# If the header files define the symbol as a macro it is considered
+# available and assumed to work.  If the header files declare the
+# symbol as a function or variable then the symbol must also be
+# available for linking.  If the symbol is a type or enum value
+# it will not be recognized (consider using CheckTypeSize or
+# CheckCSourceCompiles).
+#
+# The following variables may be set before calling this macro to
+# modify the way the check is run:
+#
+#  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 2003-2011 Kitware, Inc.
+#
+# Distributed under the OSI-approved BSD License (the "License");
+# see accompanying file Copyright.txt for details.
+#
+# 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.)
+
+INCLUDE(CheckSymbolExists)
+
+MACRO(CHECK_CXX_SYMBOL_EXISTS SYMBOL FILES VARIABLE)
+  _CHECK_SYMBOL_EXISTS("${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/CheckSymbolExists.cxx" "${SYMBOL}" "${FILES}" "${VARIABLE}" )
+ENDMACRO(CHECK_CXX_SYMBOL_EXISTS)

Modules/CheckSymbolExists.cmake

@@ -11,6 +11,8 @@
 # available for linking.  If the symbol is a type or enum value
 # it will not be recognized (consider using CheckTypeSize or
 # CheckCSourceCompiles).
+# If the check needs to be done in C++, consider using CHECK_CXX_SYMBOL_EXISTS(),
+# which does the same as CHECK_SYMBOL_EXISTS(), but in C++.
 #
 # The following variables may be set before calling this macro to
 # modify the way the check is run:
@@ -34,6 +36,11 @@
 #  License text for the above reference.)
 
 MACRO(CHECK_SYMBOL_EXISTS SYMBOL FILES VARIABLE)
+  _CHECK_SYMBOL_EXISTS("${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/CheckSymbolExists.c" "${SYMBOL}" "${FILES}" "${VARIABLE}" )
+ENDMACRO(CHECK_SYMBOL_EXISTS)
+
+MACRO(_CHECK_SYMBOL_EXISTS SOURCEFILE SYMBOL FILES VARIABLE)
+message(STATUS "files: -${FILES}-")
   IF("${VARIABLE}" MATCHES "^${VARIABLE}$")
     SET(CMAKE_CONFIGURABLE_FILE_CONTENT "/* */\n")
     SET(MACRO_CHECK_SYMBOL_EXISTS_FLAGS ${CMAKE_REQUIRED_FLAGS})
@@ -57,12 +64,12 @@ MACRO(CHECK_SYMBOL_EXISTS SYMBOL FILES VARIABLE)
       "${CMAKE_CONFIGURABLE_FILE_CONTENT}\nvoid cmakeRequireSymbol(int dummy,...){(void)dummy;}\nint main()\n{\n#ifndef ${SYMBOL}\n  cmakeRequireSymbol(0,&${SYMBOL});\n#endif\n  return 0;\n}\n")
 
     CONFIGURE_FILE("${CMAKE_ROOT}/Modules/CMakeConfigurableFile.in"
-      "${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/CheckSymbolExists.c" @ONLY)
+      "${SOURCEFILE}" @ONLY)
 
     MESSAGE(STATUS "Looking for ${SYMBOL}")
     TRY_COMPILE(${VARIABLE}
       ${CMAKE_BINARY_DIR}
-      ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/CheckSymbolExists.c
+      "${SOURCEFILE}"
       COMPILE_DEFINITIONS ${CMAKE_REQUIRED_DEFINITIONS}
       CMAKE_FLAGS
       -DCOMPILE_DEFINITIONS:STRING=${MACRO_CHECK_SYMBOL_EXISTS_FLAGS}
@@ -75,7 +82,7 @@ MACRO(CHECK_SYMBOL_EXISTS SYMBOL FILES VARIABLE)
       FILE(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
         "Determining if the ${SYMBOL} "
         "exist passed with the following output:\n"
-        "${OUTPUT}\nFile ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/CheckSymbolExists.c:\n"
+        "${OUTPUT}\nFile ${SOURCEFILE}:\n"
         "${CMAKE_CONFIGURABLE_FILE_CONTENT}\n")
     ELSE(${VARIABLE})
       MESSAGE(STATUS "Looking for ${SYMBOL} - not found.")
@@ -83,8 +90,8 @@ MACRO(CHECK_SYMBOL_EXISTS SYMBOL FILES VARIABLE)
       FILE(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
         "Determining if the ${SYMBOL} "
         "exist failed with the following output:\n"
-        "${OUTPUT}\nFile ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/CheckSymbolExists.c:\n"
+        "${OUTPUT}\nFile ${SOURCEFILE}:\n"
         "${CMAKE_CONFIGURABLE_FILE_CONTENT}\n")
     ENDIF(${VARIABLE})
   ENDIF("${VARIABLE}" MATCHES "^${VARIABLE}$")
-ENDMACRO(CHECK_SYMBOL_EXISTS)
+ENDMACRO(_CHECK_SYMBOL_EXISTS)