1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
|
# Distributed under the OSI-approved BSD 3-Clause License. See accompanying
# file LICENSE.rst or https://cmake.org/licensing for details.
include_guard(GLOBAL)
#[=======================================================================[.rst:
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
^^^^^^
.. command:: 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.
.. code-block:: cmake
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.
.. command:: cmake_reset_check_state
Resets (clears) the contents of the variables listed above to empty states.
.. code-block:: cmake
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.
.. command:: 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.
.. code-block:: cmake
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
corresponding ``cmake_pop_check_state()``.
These macros are useful for scoped configuration, for example, in
:ref:`Find modules <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
^^^^^^^^
.. code-block:: cmake
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.
.. code-block:: cmake
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 "${CMAKE_REQUIRED_DEFINITIONS}")
# Output here is empty
# Reset variables to prepare for the next check
cmake_reset_check_state()
# Perform the next check only with additional compile definitions
set(CMAKE_REQUIRED_DEFINITIONS -D_GNU_SOURCE)
check_symbol_exists(dl_iterate_phdr "link.h" HAVE_DL_ITERATE_PHDR)
# Restore the original state
cmake_pop_check_state()
#]=======================================================================]
macro(CMAKE_RESET_CHECK_STATE)
set(CMAKE_EXTRA_INCLUDE_FILES)
set(CMAKE_REQUIRED_INCLUDES)
set(CMAKE_REQUIRED_DEFINITIONS)
set(CMAKE_REQUIRED_LINK_OPTIONS)
set(CMAKE_REQUIRED_LIBRARIES)
set(CMAKE_REQUIRED_LINK_DIRECTORIES)
set(CMAKE_REQUIRED_FLAGS)
set(CMAKE_REQUIRED_QUIET)
endmacro()
macro(CMAKE_PUSH_CHECK_STATE)
if(NOT DEFINED _CMAKE_PUSH_CHECK_STATE_COUNTER)
set(_CMAKE_PUSH_CHECK_STATE_COUNTER 0)
endif()
math(EXPR _CMAKE_PUSH_CHECK_STATE_COUNTER "${_CMAKE_PUSH_CHECK_STATE_COUNTER}+1")
set(_CMAKE_EXTRA_INCLUDE_FILES_SAVE_${_CMAKE_PUSH_CHECK_STATE_COUNTER} ${CMAKE_EXTRA_INCLUDE_FILES})
set(_CMAKE_REQUIRED_INCLUDES_SAVE_${_CMAKE_PUSH_CHECK_STATE_COUNTER} ${CMAKE_REQUIRED_INCLUDES})
set(_CMAKE_REQUIRED_DEFINITIONS_SAVE_${_CMAKE_PUSH_CHECK_STATE_COUNTER} ${CMAKE_REQUIRED_DEFINITIONS})
set(_CMAKE_REQUIRED_LINK_OPTIONS_SAVE_${_CMAKE_PUSH_CHECK_STATE_COUNTER} ${CMAKE_REQUIRED_LINK_OPTIONS})
set(_CMAKE_REQUIRED_LIBRARIES_SAVE_${_CMAKE_PUSH_CHECK_STATE_COUNTER} ${CMAKE_REQUIRED_LIBRARIES})
set(_CMAKE_REQUIRED_LINK_DIRECTORIES_SAVE_${_CMAKE_PUSH_CHECK_STATE_COUNTER} ${CMAKE_REQUIRED_LINK_DIRECTORIES})
set(_CMAKE_REQUIRED_FLAGS_SAVE_${_CMAKE_PUSH_CHECK_STATE_COUNTER} ${CMAKE_REQUIRED_FLAGS})
set(_CMAKE_REQUIRED_QUIET_SAVE_${_CMAKE_PUSH_CHECK_STATE_COUNTER} ${CMAKE_REQUIRED_QUIET})
if (${ARGC} GREATER 0 AND "${ARGV0}" STREQUAL "RESET")
cmake_reset_check_state()
endif()
endmacro()
macro(CMAKE_POP_CHECK_STATE)
# don't pop more than we pushed
if("${_CMAKE_PUSH_CHECK_STATE_COUNTER}" GREATER "0")
set(CMAKE_EXTRA_INCLUDE_FILES ${_CMAKE_EXTRA_INCLUDE_FILES_SAVE_${_CMAKE_PUSH_CHECK_STATE_COUNTER}})
set(CMAKE_REQUIRED_INCLUDES ${_CMAKE_REQUIRED_INCLUDES_SAVE_${_CMAKE_PUSH_CHECK_STATE_COUNTER}})
set(CMAKE_REQUIRED_DEFINITIONS ${_CMAKE_REQUIRED_DEFINITIONS_SAVE_${_CMAKE_PUSH_CHECK_STATE_COUNTER}})
set(CMAKE_REQUIRED_LINK_OPTIONS ${_CMAKE_REQUIRED_LINK_OPTIONS_SAVE_${_CMAKE_PUSH_CHECK_STATE_COUNTER}})
set(CMAKE_REQUIRED_LIBRARIES ${_CMAKE_REQUIRED_LIBRARIES_SAVE_${_CMAKE_PUSH_CHECK_STATE_COUNTER}})
set(CMAKE_REQUIRED_LINK_DIRECTORIES ${_CMAKE_REQUIRED_LINK_DIRECTORIES_SAVE_${_CMAKE_PUSH_CHECK_STATE_COUNTER}})
set(CMAKE_REQUIRED_FLAGS ${_CMAKE_REQUIRED_FLAGS_SAVE_${_CMAKE_PUSH_CHECK_STATE_COUNTER}})
set(CMAKE_REQUIRED_QUIET ${_CMAKE_REQUIRED_QUIET_SAVE_${_CMAKE_PUSH_CHECK_STATE_COUNTER}})
math(EXPR _CMAKE_PUSH_CHECK_STATE_COUNTER "${_CMAKE_PUSH_CHECK_STATE_COUNTER}-1")
endif()
endmacro()
|
