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
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
|
try_compile
-----------
.. only:: html
.. contents::
Try building some code.
.. _`Try Compiling Whole Projects`:
Try Compiling Whole Projects
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.. code-block:: cmake
try_compile(<resultVar> <bindir> <srcdir>
<projectName> [<targetName>] [CMAKE_FLAGS <flags>...]
[OUTPUT_VARIABLE <var>])
Try building a project. The success or failure of the ``try_compile``,
i.e. ``TRUE`` or ``FALSE`` respectively, is returned in ``<resultVar>``.
In this form, ``<srcdir>`` should contain a complete CMake project with a
``CMakeLists.txt`` file and all sources. The ``<bindir>`` and ``<srcdir>``
will not be deleted after this command is run. Specify ``<targetName>`` to
build a specific target instead of the ``all`` or ``ALL_BUILD`` target. See
below for the meaning of other options.
.. versionchanged:: 3.24
CMake variables describing platform settings, and those listed by the
:variable:`CMAKE_TRY_COMPILE_PLATFORM_VARIABLES` variable, are propagated
into the project's build configuration. See policy :policy:`CMP0137`.
Previously this was only done by the
:ref:`source file <Try Compiling Source Files>` signature.
.. _`Try Compiling Source Files`:
Try Compiling Source Files
^^^^^^^^^^^^^^^^^^^^^^^^^^
.. code-block:: cmake
try_compile(<resultVar> SOURCES <srcfile...>
[CMAKE_FLAGS <flags>...]
[COMPILE_DEFINITIONS <defs>...]
[LINK_OPTIONS <options>...]
[LINK_LIBRARIES <libs>...]
[OUTPUT_VARIABLE <var>]
[COPY_FILE <fileName> [COPY_FILE_ERROR <var>]]
[<LANG>_STANDARD <std>]
[<LANG>_STANDARD_REQUIRED <bool>]
[<LANG>_EXTENSIONS <bool>]
)
.. versionadded:: 3.25
Try building an executable or static library from one or more source files
(which one is determined by the :variable:`CMAKE_TRY_COMPILE_TARGET_TYPE`
variable). The success or failure of the ``try_compile``, i.e. ``TRUE`` or
``FALSE`` respectively, is returned in ``<resultVar>``.
In this form, one or more source files must be provided. If
:variable:`CMAKE_TRY_COMPILE_TARGET_TYPE` is unset or is set to ``EXECUTABLE``,
the sources must include a definition for ``main`` and CMake will create a
``CMakeLists.txt`` file to build the source(s) as an executable.
If :variable:`CMAKE_TRY_COMPILE_TARGET_TYPE` is set to ``STATIC_LIBRARY``,
a static library will be built instead and no definition for ``main`` is
required. For an executable, the generated ``CMakeLists.txt`` file would
contain something like the following:
.. code-block:: cmake
add_definitions(<expanded COMPILE_DEFINITIONS from caller>)
include_directories(${INCLUDE_DIRECTORIES})
link_directories(${LINK_DIRECTORIES})
add_executable(cmTryCompileExec <srcfile>...)
target_link_options(cmTryCompileExec PRIVATE <LINK_OPTIONS from caller>)
target_link_libraries(cmTryCompileExec ${LINK_LIBRARIES})
CMake will automatically generate a unique directory for each ``try_compile``
operation in an unspecified location within the project's binary directory.
These directories will be cleaned automatically unless
:option:`--debug-trycompile <cmake --debug-trycompile>` is passed to ``cmake``.
Such directories from previous runs are also unconditionally cleaned at the
beginning of any ``cmake`` execution.
This command also supports an alternate signature
which was present in older versions of CMake:
.. code-block:: cmake
try_compile(<resultVar> <bindir> <srcfile|SOURCES srcfile...>
[CMAKE_FLAGS <flags>...]
[COMPILE_DEFINITIONS <defs>...]
[LINK_OPTIONS <options>...]
[LINK_LIBRARIES <libs>...]
[OUTPUT_VARIABLE <var>]
[COPY_FILE <fileName> [COPY_FILE_ERROR <var>]]
[<LANG>_STANDARD <std>]
[<LANG>_STANDARD_REQUIRED <bool>]
[<LANG>_EXTENSIONS <bool>]
)
In this version, ``try_compile`` will use ``<bindir>/CMakeFiles/CMakeTmp`` for
its operation, and all such files will be cleaned automatically.
For debugging, :option:`--debug-trycompile <cmake --debug-trycompile>` can be
passed to ``cmake`` to avoid this clean. However, multiple sequential
``try_compile`` operations, if given the same ``<bindir>``, will reuse this
single output directory, such that you can only debug one such ``try_compile``
call at a time. Use of the newer signature is recommended to simplify
debugging of multiple ``try_compile`` operations.
The options are:
``CMAKE_FLAGS <flags>...``
Specify flags of the form :option:`-DVAR:TYPE=VALUE <cmake -D>` to be passed
to the :manual:`cmake(1)` command-line used to drive the test build.
The above example shows how values for variables
``INCLUDE_DIRECTORIES``, ``LINK_DIRECTORIES``, and ``LINK_LIBRARIES``
are used.
``COMPILE_DEFINITIONS <defs>...``
Specify ``-Ddefinition`` arguments to pass to :command:`add_definitions`
in the generated test project.
``COPY_FILE <fileName>``
Copy the built executable or static library to the given ``<fileName>``.
``COPY_FILE_ERROR <var>``
Use after ``COPY_FILE`` to capture into variable ``<var>`` any error
message encountered while trying to copy the file.
``LINK_LIBRARIES <libs>...``
Specify libraries to be linked in the generated project.
The list of libraries may refer to system libraries and to
:ref:`Imported Targets <Imported Targets>` from the calling project.
If this option is specified, any ``-DLINK_LIBRARIES=...`` value
given to the ``CMAKE_FLAGS`` option will be ignored.
``LINK_OPTIONS <options>...``
.. versionadded:: 3.14
Specify link step options to pass to :command:`target_link_options` or to
set the :prop_tgt:`STATIC_LIBRARY_OPTIONS` target property in the generated
project, depending on the :variable:`CMAKE_TRY_COMPILE_TARGET_TYPE` variable.
``OUTPUT_VARIABLE <var>``
Store the output from the build process in the given variable.
``<LANG>_STANDARD <std>``
.. versionadded:: 3.8
Specify the :prop_tgt:`C_STANDARD`, :prop_tgt:`CXX_STANDARD`,
:prop_tgt:`OBJC_STANDARD`, :prop_tgt:`OBJCXX_STANDARD`,
or :prop_tgt:`CUDA_STANDARD` target property of the generated project.
``<LANG>_STANDARD_REQUIRED <bool>``
.. versionadded:: 3.8
Specify the :prop_tgt:`C_STANDARD_REQUIRED`,
:prop_tgt:`CXX_STANDARD_REQUIRED`, :prop_tgt:`OBJC_STANDARD_REQUIRED`,
:prop_tgt:`OBJCXX_STANDARD_REQUIRED`,or :prop_tgt:`CUDA_STANDARD_REQUIRED`
target property of the generated project.
``<LANG>_EXTENSIONS <bool>``
.. versionadded:: 3.8
Specify the :prop_tgt:`C_EXTENSIONS`, :prop_tgt:`CXX_EXTENSIONS`,
:prop_tgt:`OBJC_EXTENSIONS`, :prop_tgt:`OBJCXX_EXTENSIONS`,
or :prop_tgt:`CUDA_EXTENSIONS` target property of the generated project.
Other Behavior Settings
^^^^^^^^^^^^^^^^^^^^^^^
.. versionadded:: 3.4
If set, the following variables are passed in to the generated
try_compile CMakeLists.txt to initialize compile target properties with
default values:
* :variable:`CMAKE_CUDA_RUNTIME_LIBRARY`
* :variable:`CMAKE_ENABLE_EXPORTS`
* :variable:`CMAKE_LINK_SEARCH_START_STATIC`
* :variable:`CMAKE_LINK_SEARCH_END_STATIC`
* :variable:`CMAKE_MSVC_RUNTIME_LIBRARY`
* :variable:`CMAKE_POSITION_INDEPENDENT_CODE`
* :variable:`CMAKE_WATCOM_RUNTIME_LIBRARY`
If :policy:`CMP0056` is set to ``NEW``, then
:variable:`CMAKE_EXE_LINKER_FLAGS` is passed in as well.
.. versionchanged:: 3.14
If :policy:`CMP0083` is set to ``NEW``, then in order to obtain correct
behavior at link time, the ``check_pie_supported()`` command from the
:module:`CheckPIESupported` module must be called before using the
:command:`try_compile` command.
The current settings of :policy:`CMP0065` and :policy:`CMP0083` are propagated
through to the generated test project.
Set the :variable:`CMAKE_TRY_COMPILE_CONFIGURATION` variable to choose
a build configuration.
.. versionadded:: 3.6
Set the :variable:`CMAKE_TRY_COMPILE_TARGET_TYPE` variable to specify
the type of target used for the source file signature.
.. versionadded:: 3.6
Set the :variable:`CMAKE_TRY_COMPILE_PLATFORM_VARIABLES` variable to specify
variables that must be propagated into the test project. This variable is
meant for use only in toolchain files and is only honored by the
``try_compile()`` command for the source files form, not when given a whole
project.
.. versionchanged:: 3.8
If :policy:`CMP0067` is set to ``NEW``, or any of the ``<LANG>_STANDARD``,
``<LANG>_STANDARD_REQUIRED``, or ``<LANG>_EXTENSIONS`` options are used,
then the language standard variables are honored:
* :variable:`CMAKE_C_STANDARD`
* :variable:`CMAKE_C_STANDARD_REQUIRED`
* :variable:`CMAKE_C_EXTENSIONS`
* :variable:`CMAKE_CXX_STANDARD`
* :variable:`CMAKE_CXX_STANDARD_REQUIRED`
* :variable:`CMAKE_CXX_EXTENSIONS`
* :variable:`CMAKE_OBJC_STANDARD`
* :variable:`CMAKE_OBJC_STANDARD_REQUIRED`
* :variable:`CMAKE_OBJC_EXTENSIONS`
* :variable:`CMAKE_OBJCXX_STANDARD`
* :variable:`CMAKE_OBJCXX_STANDARD_REQUIRED`
* :variable:`CMAKE_OBJCXX_EXTENSIONS`
* :variable:`CMAKE_CUDA_STANDARD`
* :variable:`CMAKE_CUDA_STANDARD_REQUIRED`
* :variable:`CMAKE_CUDA_EXTENSIONS`
Their values are used to set the corresponding target properties in
the generated project (unless overridden by an explicit option).
.. versionchanged:: 3.14
For the :generator:`Green Hills MULTI` generator the GHS toolset and target
system customization cache variables are also propagated into the test project.
.. versionadded:: 3.24
The :variable:`CMAKE_TRY_COMPILE_NO_PLATFORM_VARIABLES` variable may be
set to disable passing platform variables into the test project.
|
