try_run¶
Contents
Try compiling and then running some code.
Try Compiling and Running Source Files¶
try_run(RUN_RESULT_VAR COMPILE_RESULT_VAR
bindir srcfile [CMAKE_FLAGS <flags>...]
[COMPILE_DEFINITIONS <defs>...]
[LINK_LIBRARIES <libs>...]
[COMPILE_OUTPUT_VARIABLE <var>]
[RUN_OUTPUT_VARIABLE <var>]
[OUTPUT_VARIABLE <var>]
[ARGS <args>...])
Try compiling a <srcfile>
. Returns TRUE
or FALSE
for success
or failure in COMPILE_RESULT_VAR
. If the compile succeeded, runs the
executable and returns its exit code in RUN_RESULT_VAR
. If the
executable was built, but failed to run, then RUN_RESULT_VAR
will be
set to FAILED_TO_RUN
. See the try_compile()
command for
information on how the test project is constructed to build the source file.
The options are:
CMAKE_FLAGS <flags>...
Specify flags of the form
-DVAR:TYPE=VALUE
to be passed to thecmake
command-line used to drive the test build. The example intry_compile()
shows how values for variablesINCLUDE_DIRECTORIES
,LINK_DIRECTORIES
, andLINK_LIBRARIES
are used.COMPILE_DEFINITIONS <defs>...
Specify
-Ddefinition
arguments to pass toadd_definitions
in the generated test project.COMPILE_OUTPUT_VARIABLE <var>
Report the compile step build output in a given variable.
LINK_LIBRARIES <libs>...
Specify libraries to be linked in the generated project. The list of libraries may refer to system libraries and to Imported Targets from the calling project.
If this option is specified, any
-DLINK_LIBRARIES=...
value given to theCMAKE_FLAGS
option will be ignored.OUTPUT_VARIABLE <var>
Report the compile build output and the output from running the executable in the given variable. This option exists for legacy reasons. Prefer
COMPILE_OUTPUT_VARIABLE
andRUN_OUTPUT_VARIABLE
instead.RUN_OUTPUT_VARIABLE <var>
Report the output from running the executable in a given variable.
Other Behavior Settings¶
Set the CMAKE_TRY_COMPILE_CONFIGURATION
variable to choose
a build configuration.
Behavior when Cross Compiling¶
When cross compiling, the executable compiled in the first step
usually cannot be run on the build host. The try_run
command checks
the CMAKE_CROSSCOMPILING
variable to detect whether CMake is in
cross-compiling mode. If that is the case, it will still try to compile
the executable, but it will not try to run the executable unless the
CMAKE_CROSSCOMPILING_EMULATOR
variable is set. Instead it
will create cache variables which must be filled by the user or by
presetting them in some CMake script file to the values the executable
would have produced if it had been run on its actual target platform.
These cache entries are:
<RUN_RESULT_VAR>
Exit code if the executable were to be run on the target platform.
<RUN_RESULT_VAR>__TRYRUN_OUTPUT
Output from stdout and stderr if the executable were to be run on the target platform. This is created only if the
RUN_OUTPUT_VARIABLE
orOUTPUT_VARIABLE
option was used.
In order to make cross compiling your project easier, use try_run
only if really required. If you use try_run
, use the
RUN_OUTPUT_VARIABLE
or OUTPUT_VARIABLE
options only if really
required. Using them will require that when cross-compiling, the cache
variables will have to be set manually to the output of the executable.
You can also “guard” the calls to try_run
with an if()
block checking the CMAKE_CROSSCOMPILING
variable and
provide an easy-to-preset alternative for this case.