This question is subsequent to my previous one: How to integrate such kind of source generator into CMake build chain?
Currently, the C source file is generated from XS in this way:
set_source_files_properties(${CMAKE_CURRENT_BINARY_DIR}/${file_src_by_xs} PROPERTIES GENERATED 1)
add_custom_target(${file_src_by_xs}
COMMAND ${XSUBPP_EXECUTABLE} ${XSUBPP_EXTRA_OPTIONS} ${lang_args} ${typemap_args} ${file_xs} >${CMAKE_CURRENT_BINARY_DIR}/${file_src_by_xs}
WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
DEPENDS ${file_xs} ${files_xsh} ${_XSUBPP_TYPEMAP_FILES}
COMMENT "generating source from XS file ${file_xs}"
)
The GENERATED property let cmake don't check the existence of this source file at configure time, and add_custom_target let the xsubpp always re-run at each compile. The reason for always rerun is because xsubpp will generate an incomplete source file even if it fails, so there are possibility that the whole compiling continues with an incomplete source file.
I found it is time consuming to always re-run source generator and recompile it. So I want to have it re-run only when dependent XS files are modified. However, if I do so, the incomplete generated source file must be deleted.
So my question is: is there any way to remove the generated file, only when the program exit abnormally at compile time?
Or more generic: is there any way to run a command depending on another command's exit status at compile time?
You can always write a wrapper script in your favorite language, e.g. Perl or Ruby, that runs xsubpp and deletes the output file if the command failed. That way you can be sure that if it exists, it is correct.
In addition, I would suggest that you use the OUTPUT keyword of add_custom_command to tell CMake that the file is a result of executing the command. (And, if you do that, you don't have to set the GENERATED property manually.)
Inspired by #Lindydancer's answer, I achieved the purpose by multiple COMMANDs in one target, and it don't need to write an external wrapper script.
set(source_file_ok ${source_file}.ok)
add_custom_command(
OUTPUT ${source_file} ${source_file_ok}
DEPENDS ${xs_file} ${xsh_files}
COMMAND rm -f ${source_file_ok}
COMMAND xsubpp ...... >${source_file}
COMMAND touch ${source_file_ok}
)
add_library(${xs_lib} ${source_file})
add_dependencies(${xs_lib} ${source_file} ${source_file_ok})
The custom target has 3 commands. The OK file only exists when xsubpp is success, and this file is added as a dependency of the library. When xsubpp is not success, the dependency on the OK file will force the custom command to be run again.
The only flaw is cross-platform: not all OS have touch and rm, so the name of these two commands should be decided according to OS type.
Related
I have python script that is run through add_custom_command in my project, this script analyzes target sources and generate additional one for the target.
get_target_property(TARGET_SOURCES ${target} SOURCES)
add_custom_command(
OUTPUT ${CMAKE_BINARY_DIR}/static_init/generated/${target}/static_init.cpp
COMMAND ${Python3_EXECUTABLE} myscript.py
DEPENDS ${TARGET_SOURCES}
VERBATIM)
target_sources( "${target}" PRIVATE "${CMAKE_BINARY_DIR}/static_init/generated/${target}/static_init.cpp" )
I need my script to rerun when one of sources becomes "dirty" (e.g. one of included headers is changed, probably this file is in another target and it is not guaranteed that another target will be rebuild on header change). As we use Ninja, IMPLICIT_DEPENDS isn't available for us, so it looks DEPFILE property is the way to do it, but I cannot understand, how can I get one for all ${TARGET_SOURCES}?
It doesn't seem to me that ninja will generate something like that automatically, I cannot write it by hands, as it will require to recursively analyze all includes during cmake run. Or maybe there is another way to solve this problem?
To get dependencies of a source you have to compile it. Just depend on the target. I would do:
add_custom_target(target_objects OBJECT all_source_files_for_your_target)
add_custom_command(
OUTPUT ${CMAKE_BINARY_DIR}/static_init/generated/${target}/static_init.cpp
COMMAND ${Python3_EXECUTABLE} myscript.py
DEPENDS $<TARGET_OBJECTS:target_objects>
VERBATIM
)
add_custom_library/executable("${target}" PRIVATE
${CMAKE_BINARY_DIR}/static_init/generated/${target}/static_init.cpp
)
link_target_libraries("${target}" PRIVATE target_objects)
That way the dependencies are linear.
How can I do in meson to run a command after building a target?
Eg. I have an executable:
executable('target.elf', 'source1.c', 'source2.c')
And after target.elf built I want to execute a command (eg. chmod -x target.elf) on it.
I tried custom_target(), but that requires an output. I don't have new output, I just have target.elf. I tried run_command() but I didn't know how to execute it after the building.
executable now has an argument install_mode (added 0.47.0) to specify the file mode in symbolic format and optionally the owner/uid and group/gid for the installed files.
I just noticed that yasushi-shoji has provided this answer already.
The following code should do.
project('tutorial', 'c')
exec = executable('target.elf', 'main.c', build_by_default : false)
custom_target('final binary',
depends : exec,
input : exec,
output : 'fake',
command : ['chmod', '+x', '#INPUT#'],
build_by_default : true)
Note that because I want to always run the fake target, I'm using custom_target(). However, the command chmod + x demo doesn't generate the file fake specified in custom_target(), successive ninja command will always run the target.
If you don't want this behaviour, there are two ways:
You can write a script which chmod the target.elf and then copies it to target, thus effectively creates the target file. Make sure to change the output file in the meson.build if you do so.
If you don't mind typing ninja chmod instead of ninja, you can use run_target().
# optional
run_target('chmod',
command : ['chmod', '+x', exec])
Another alternative is to use install_mode for executable().
Also note that you should always use find_program() instead of plain chmod. This example doesn't use it for simplicity.
I have a program on my computer, let's say C:/Tools/generate_v23_debug.exe
I have a FindGenerate.cmake file which allows CMake to find that exact path to the executable.
So in my CMake code, I do:
find_program(Generate)
if (NOT Generate_FOUND)
message(FATAL_ERROR "Generator not found!")
So CMake has found the executable. Now I want to call this program in a custom command statement. Should I use COMMAND Generator or COMMAND ${GENERATOR_EXECUTABLE}? Will both of these do the same thing? Is one preferred over the other? Is name_EXECUTABLE a variable that CMake will define (it's not in the FindGenerate.cmake file), or is it something specific to someone else's example code I'm looking at? Will COMMAND Generator be expanded to the correct path?
add_custom_command(
OUTPUT blahblah.txt
COMMAND Generator inputfile1.log
DEPENDS Generator
)
find_program stores its result into the variable given as a first argument. You can verify this by inserting some debug output:
find_program(GENERATOR Generate)
message(${GENERATOR})
Note that find_program does not set any additional variables beyond that. In particular, you mentioned Generate_FOUND and GENERATOR_EXECUTABLE in your question and neither of those gets introduced implicitly by the find_program call.
The second mistake in your program is the use of the DEPENDS option on the add_custom_command. DEPENDS is used to model inter-target dependencies at build time and not to manipulate control flow in the CMakeLists. For example, additional custom command can DEPEND on the output of your command (blahblah.txt), but a custom command cannot DEPEND on the result of a previous find operation.
A working example might look something like this:
find_program(GENERATOR Generate)
if(NOT GENERATOR)
message(FATAL_ERROR "Generator not found!")
endif()
add_custom_command(
OUTPUT blahblah.txt
COMMAND ${GENERATOR} inputfile1.log
)
P.S.: You asked why the code examples were not properly formatted in your question. You indented everything correctly, but you need an additional newline between normal text and code paragraphs. I edited your question accordingly.
I have a CMake project with many subprojects.
Each of them can use a function I provide to generate a small text file with some certain information (by calling add_custom_command).
At the final step I'd like to combine all those files into one big text file.
I've created a custom command which searches for created files (all in one place) and merges them.
The problem is that I'd like to make this final step dependend on all of small steps being made in subprojects while I don't actually know how many files will be provided.
My final command looks like:
add_custom_command(OUTPUT combination.txt
COMMAND create combination.txt from all files from /path/)
and my create-small-text-file-for-each-subproject command looks like:
add_custom_command(OUTPUT /path/${sub_project_name}.txt
COMMAND create /path/${sub_project_name}.txt)
And when I create those small files I'd like to do something like to make "combination.txt" depend on /path/${sub_project_name}.txt
So I wish I could:
add_dependency(combination.txt /path/${sub_project_name}.txt)
However this only works for targets.
I've also tried to use set_source_files_properties with OBJECT_DEPENDS, but it seems to doesn't work (maybe its intend to be used with add_target's cpp files ?)
The last way to get it work I see is to use a cache variable which would accumulate all those small files paths and then use it like this:
add_custom_command(OUTPUT combination.txt
COMMAND create combination.txt from all files from /path/
DEPENDS ${all_small_files_list})
but this is the last thing I want to do.
Instead of using add_custom_command you could use add_custom_target with a correct dependency-definition (so that is it not built every time).
add_custom_target(project
COMMAND touch project.txt)
add_custom_target(project2
COMMAND touch project2.txt)
add_custom_target(combination
COMMAND cat project.txt project2.txt > combination.txt)
add_dependencies(combination project2)
add_dependencies(combination project)
add_executable(t t.c)
add_dependencies(t combination.txt)
Again: make sure you're using the DEPENDS argument of add_custom_target to create a real dependency chain so that a project-target and thus the combination-target gets out of date.
UPDATE: I was too premature. In fact cmake (at least up to 2.8.9) works as follows for dependencies: with a call to add_dependencies you cannot add a dependency which is the OUTPUT of a custom command IOW a (generated) file. With add_dependencies you can only add target as created by add_custom_target. However in a add_custom_target you can depend on an output of add_custom_command by using the DEPENDS-directive. That said this makes it work:
add_custom_command(OUTPUT project.txt
COMMAND uptime >> project.txt MAIN_DEPENDENCY t2.c)
add_custom_target(project DEPENDS project.txt)
add_custom_target(combination
COMMAND cat project.txt project2.txt > combination.txt)
add_dependencies(combination project)
This will make the combination target always be regenerated as it has no MAIN_DEPENDENCY or DEPENDS, but the usage of add_dependencies is allowed.
I need to write a custom command that runs whenever file A is newer than file B.
How do I do this in CMake?
Sounds like you want something similar to this:
add_custom_command(OUTPUT B
COMMAND ${CMAKE_COMMAND} -Dinput=A -P script_that_generates_B.cmake
DEPENDS A
)
Where "B" is the full path to the output file, "A" is the full path to some input file, and the command is something that runs at build time to produce B whenever A changes.
In order for the rule producing B to be executed at build time, something else must depend on B also. It should appear either as a DEPENDS of an add_custom_target that is in "all" or as a source file to an add_library or add_executable command to trigger the command to run.
EDIT:
You can also use the
if(file1 IS_NEWER_THAN file2)
construct at CMake configure time, if necessary. The documentation of the IF command is rather lengthy, but searching on this page for IS_NEWER_THAN yields this nugget:
"True if file1 is newer than file2 or if one of the two files doesn't exist. Behavior is well-defined only for full paths."