| # Distributed under the OSI-approved BSD 3-Clause License. See accompanying |
| # file LICENSE.rst or https://cmake.org/licensing for details. |
| |
| #[=======================================================================[.rst: |
| TestForANSIForScope |
| ------------------- |
| |
| This module checks whether the ``CXX`` compiler restricts the scope of variables |
| declared in a for-init-statement to the loop body. |
| |
| Load this module in a CMake project with: |
| |
| .. code-block:: cmake |
| |
| include(TestForANSIForScope) |
| |
| In early C++ (pre-C++98), variables declared in ``for(<init-statement> ...)`` |
| could remain accessible outside the loop after its body (``for() { <body> }``). |
| |
| This module defines the following cache variable: |
| |
| ``CMAKE_NO_ANSI_FOR_SCOPE`` |
| A cache variable containing the result of the check. It will be set to value |
| ``0`` if the for-init-statement has restricted scope (``C++ 98`` and newer), |
| and to value ``1`` if not (``ANSI C++``). |
| |
| .. note:: |
| |
| As of the ``C++ 98`` standard, variables declared in a for-init-statement are |
| restricted to the loop body, making this behavior obsolete. |
| |
| Examples |
| ^^^^^^^^ |
| |
| Including this module will check the ``for()`` loop scope behavior and define |
| the ``CMAKE_NO_ANSI_FOR_SCOPE`` cache variable: |
| |
| .. code-block:: cmake |
| :caption: ``CMakeLists.txt`` |
| |
| include(TestForANSIForScope) |
| file( |
| CONFIGURE |
| OUTPUT config.h |
| CONTENT "#cmakedefine CMAKE_NO_ANSI_FOR_SCOPE" |
| ) |
| |
| which can be then used in a C++ program: |
| |
| .. code-block:: c++ |
| :caption: ``example.cxx`` |
| |
| #include "config.h" |
| |
| #ifdef CMAKE_NO_ANSI_FOR_SCOPE |
| # define for if(false) {} else for |
| #endif |
| |
| See Also |
| ^^^^^^^^ |
| |
| * The :module:`CMakeBackwardCompatibilityCXX` module. |
| #]=======================================================================] |
| |
| if(NOT DEFINED CMAKE_ANSI_FOR_SCOPE) |
| message(CHECK_START "Check for ANSI scope") |
| try_compile(CMAKE_ANSI_FOR_SCOPE |
| SOURCES ${CMAKE_ROOT}/Modules/TestForAnsiForScope.cxx |
| ) |
| if (CMAKE_ANSI_FOR_SCOPE) |
| message(CHECK_PASS "found") |
| set (CMAKE_NO_ANSI_FOR_SCOPE 0 CACHE INTERNAL |
| "Does the compiler support ansi for scope.") |
| else () |
| message(CHECK_FAIL "not found") |
| set (CMAKE_NO_ANSI_FOR_SCOPE 1 CACHE INTERNAL |
| "Does the compiler support ansi for scope.") |
| endif () |
| endif() |
