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:

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++).

备注

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:

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:

example.cxx
#include "config.h"

#ifdef CMAKE_NO_ANSI_FOR_SCOPE
#  define for if(false) {} else for
#endif

See Also