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# Distributed under the OSI-approved BSD 3-Clause License. See accompanying
# file LICENSE.rst or https://cmake.org/licensing for details.
#[=======================================================================[.rst:
CMakeBackwardCompatibilityCXX
-----------------------------
This module defines several backward compatibility cache variables for the
``CXX`` language to support early C++ (pre-C++98, ANSI C++).
Load this module in a CMake project with:
.. code-block:: cmake
include(CMakeBackwardCompatibilityCXX)
The following modules are included by this module:
* :module:`TestForANSIForScope`
* :module:`TestForANSIStreamHeaders`
* :module:`TestForSSTREAM`
* :module:`TestForSTDNamespace`
Additionally, the following cache variable may be defined:
``CMAKE_ANSI_CXXFLAGS``
A space-separated string of compiler options for enabling ANSI C++ mode, if
available.
.. note::
This module is intended for C++ code written before ``C++ 98``. As of the
``C++ 98`` standard, these issues have been formally addressed, making such
checks obsolete.
Examples
^^^^^^^^
Including this module provides backward compatibility cache variables, which
can be used in C++. For example:
.. code-block:: cmake
:caption: ``CMakeLists.txt``
include(CMakeBackwardCompatibilityCXX)
file(
CONFIGURE
OUTPUT config.h
CONTENT [[
#cmakedefine CMAKE_NO_ANSI_FOR_SCOPE
#cmakedefine CMAKE_NO_ANSI_STRING_STREAM
#cmakedefine CMAKE_NO_ANSI_STREAM_HEADERS
#cmakedefine CMAKE_NO_STD_NAMESPACE
]]
)
#]=======================================================================]
if(NOT CMAKE_SKIP_COMPATIBILITY_TESTS)
# check for some ANSI flags in the CXX compiler if it is not gnu
if(NOT CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
include(TestCXXAcceptsFlag)
set(CMAKE_TRY_ANSI_CXX_FLAGS "")
if(CMAKE_SYSTEM_NAME MATCHES "OSF")
set(CMAKE_TRY_ANSI_CXX_FLAGS "-std strict_ansi -nopure_cname")
endif()
# if CMAKE_TRY_ANSI_CXX_FLAGS has something in it, see
# if the compiler accepts it
if(NOT CMAKE_TRY_ANSI_CXX_FLAGS STREQUAL "")
check_cxx_accepts_flag(${CMAKE_TRY_ANSI_CXX_FLAGS} CMAKE_CXX_ACCEPTS_FLAGS)
# if the compiler liked the flag then set CMAKE_ANSI_CXXFLAGS
# to the flag
if(CMAKE_CXX_ACCEPTS_FLAGS)
set(CMAKE_ANSI_CXXFLAGS ${CMAKE_TRY_ANSI_CXX_FLAGS} CACHE INTERNAL
"What flags are required by the c++ compiler to make it ansi." )
endif()
endif()
endif()
set(CMAKE_CXX_FLAGS_SAVE ${CMAKE_CXX_FLAGS})
string(APPEND CMAKE_CXX_FLAGS " ${CMAKE_ANSI_CXXFLAGS}")
include(TestForANSIStreamHeaders)
include(CheckIncludeFileCXX)
include(TestForSTDNamespace)
include(TestForANSIForScope)
include(TestForSSTREAM)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS_SAVE}")
endif()
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