CMakePushCheckState¶
This module provides macros for managing the state of variables that influence
how various CMake check commands (e.g., check_symbol_exists()
, etc.) are
performed. These macros save, reset, and restore the following variables:
CMAKE_REQUIRED_FLAGS
CMAKE_REQUIRED_DEFINITIONS
CMAKE_REQUIRED_INCLUDES
CMAKE_REQUIRED_LINK_OPTIONS
CMAKE_REQUIRED_LIBRARIES
CMAKE_REQUIRED_LINK_DIRECTORIES
CMAKE_REQUIRED_QUIET
CMAKE_EXTRA_INCLUDE_FILES
Macros¶
- cmake_push_check_state¶
Saves (pushes) the current states of the above variables onto a stack. This is typically used to preserve the current configuration before making temporary modifications for specific checks.
cmake_push_check_state([RESET])
RESET
When this option is specified, the macro not only saves the current states of the listed variables but also resets them to empty, allowing them to be reconfigured from a clean state.
- cmake_reset_check_state¶
Resets (clears) the contents of the variables listed above to empty states.
cmake_reset_check_state()
This macro can be used, for example, when performing multiple sequential checks that require entirely new configurations, ensuring no previous configuration unintentionally carries over.
- cmake_pop_check_state¶
Restores the states of the variables listed above to their values at the time of the most recent
cmake_push_check_state()
call.cmake_pop_check_state()
This macro is used to revert temporary changes made during a check. To prevent unexpected behavior, pair each
cmake_push_check_state()
with a correspondingcmake_pop_check_state()
.
These macros are useful for scoped configuration, for example, in Find modules or when performing checks in a controlled environment, ensuring that temporary modifications are isolated to the scope of the check and do not propagate into other parts of the build system.
Note
Other CMake variables, such as CMAKE_<LANG>_FLAGS
, propagate to all checks
regardless of these macros, as those fundamental variables are designed to
influence the global state of the build system.
Examples¶
include(CMakePushCheckState)
# Save and reset the current state
cmake_push_check_state(RESET)
# Perform check with specific compile definitions
set(CMAKE_REQUIRED_DEFINITIONS -D_GNU_SOURCE)
include(CheckSymbolExists)
check_symbol_exists(memfd_create "sys/mman.h" HAVE_MEMFD_CREATE)
# Restore the original state
cmake_pop_check_state()
Variable states can be pushed onto the stack multiple times, allowing for nested
or sequential configurations. Each cmake_pop_check_state()
restores the
most recent pushed states.
include(CMakePushCheckState)
# Save and reset the current state
cmake_push_check_state(RESET)
# Perform the first check with additional libraries
set(CMAKE_REQUIRED_LIBRARIES ${CMAKE_DL_LIBS})
include(CheckSymbolExists)
check_symbol_exists(dlopen "dlfcn.h" HAVE_DLOPEN)
# Save current state
cmake_push_check_state()
# Perform the second check with libraries and additional compile definitions
set(CMAKE_REQUIRED_DEFINITIONS -D_GNU_SOURCE)
check_symbol_exists(dladdr "dlfcn.h" HAVE_DLADDR)
message(STATUS "${CMAKE_REQUIRED_DEFINITIONS}")
# Output: -D_GNU_SOURCE
# Restore the previous state
cmake_pop_check_state()
message(STATUS "${CMAKE_REQUIRED_DEFINITIONS}")
# Output here is empty
# Reset variables to prepare for the next check
cmake_reset_check_state()
# Perform the next check only with additional compile definitions
set(CMAKE_REQUIRED_DEFINITIONS -D_GNU_SOURCE)
check_symbol_exists(dl_iterate_phdr "link.h" HAVE_DL_ITERATE_PHDR)
# Restore the original state
cmake_pop_check_state()