Re: [CMake] copy_if_different on build
On 2013-04-23 16:00, Skippy VonDrake wrote:
Hmm... that is odd. I think there may be something else going on in your
project that is not obvious from the above information. I wrote a quick
example along the lines of what you show, and it worked fine for me. Actual
CMakeLists.txt I used is attached. (The foo.c can contain any compiling
code, and foo.cfg.in can contain anything or even be empty.)
(Apparently a disadvantage of just using add_custom_target is that it always
runs, regardless of the DEPENDS. Not that this should be a huge problem,
though.)
Have you tried naming the input/output like
${CMAKE_CURRENT_SOURCE_DIR}/name.in and
${CMAKE_CURRENT_BINARY_DIR}/name? (I didn't do that in the attached
example because I was lazy (and the example may only work for in-source
builds as a result), but that is how I would recommend naming the files in a
real project.)
The source of my problem was 'naming'. I did use the CMake 'SOURCE_DIR'
variable but my file extensions were wrong and my path was off by one level!
Everything works fine now.
Ah, good to hear :-). Thanks for letting us know.
I did notice an effect I didn't expect - when
'make clean' is run the 'output' is deleted. Hadn't thought about that...
Well, yes, with the custom commend the output file is effectively a
build artifact, so of course it is deleted by clean :-).
--
Matthew
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Re: [CMake] copy_if_different on build
Please keep this on list so that others may contribute/benefit. Thanks.
On 2013-04-23 10:43, Skippy VonDrake wrote:
Hmm... yes, I'm not sure if add_dependencies can be used to add a file
dependency to a target (the documentation only talks about adding other
targets as dependencies).
Usually things like configured files are used as source files, i.e. as
inputs to add_executable, etc.
If for some reason that doesn't work, I believe you can make your executable
Since this config file is not needed for the code to compile, I want to keep it
separated from the sources list. CMake should be able to accomplish this
task without adding the file to the sources.
dependent on a custom target, which in turn depends on the output file from
your custom command. IOW:
add_custom_command(OUTPUT out DEPENDS in COMMAND stuff)
add_executable(exe sources)
add_custom_target(exe_config DEPENDS out)
add_dependencies(exe exe_config)
So with the example code above this would translate to?:
add_executable (${TARGETNAME}main.cpp)
add_custom_command(OUTPUT ${output} DEPENDS
${input} COMMAND ${CMAKE_COMMAND} -E
copy_if_different ${input} ${output})
add_custom_target(exe_config DEPENDS ${output})
add_dependencies(${TARGETNAME} exe_config)
Which results in make error:
make[2]: *** No rule to make target `../src/bin/config.cfg', needed
by `src/CMakeFiles/exe_config'. Stop.
If you only have one custom command, you can probably use add_custom_target
to run the command instead, i.e.:
add_custom_target(exe_config DEPENDS in COMMAND stuff)
add_executable(exe sources)
add_dependencies(exe exe_config)
With example code this would be?:
add_executable (${TARGETNAME}main.cpp)
add_custom_target(exe_config DEPENDS
${input} COMMAND ${CMAKE_COMMAND} -E
copy_if_different ${input} ${output})
add_dependencies(${TARGETNAME} exe_config)
This created the same make error above. Am I translating your suggestions into
the example code erroneously, Matthew?
Hmm... that is odd. I think there may be something else going on in your
project that is not obvious from the above information. I wrote a quick
example along the lines of what you show, and it worked fine for me.
Actual CMakeLists.txt I used is attached. (The foo.c can contain any
compiling code, and foo.cfg.in can contain anything or even be empty.)
(Apparently a disadvantage of just using add_custom_target is that it
always runs, regardless of the DEPENDS. Not that this should be a huge
problem, though.)
Have you tried naming the input/output like
${CMAKE_CURRENT_SOURCE_DIR}/name.in and
${CMAKE_CURRENT_BINARY_DIR}/name? (I didn't do that in the attached
example because I was lazy (and the example may only work for in-source
builds as a result), but that is how I would recommend naming the files
in a real project.)
(Incidentally, this tickles a ninja generator bug in CMake 2.8.11.)
--
Matthew
project(foo)
cmake_minimum_required(VERSION 2.8)
add_executable(foo foo.c)
if(1) # Just to show doing it both ways
add_custom_command(
OUTPUT foo.cfg
DEPENDS foo.cfg.in
COMMAND ${CMAKE_COMMAND} -E copy foo.cfg.in foo.cfg
)
add_custom_target(foo_config DEPENDS foo.cfg)
else()
add_custom_target(foo_config
DEPENDS foo.cfg.in
COMMAND ${CMAKE_COMMAND} -E copy_if_different foo.cfg.in foo.cfg
)
endif()
add_dependencies(foo foo_config)
--
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Re: [CMake] copy_if_different on build
Hmm... that is odd. I think there may be something else going on in your
project that is not obvious from the above information. I wrote a quick
example along the lines of what you show, and it worked fine for me. Actual
CMakeLists.txt I used is attached. (The foo.c can contain any compiling
code, and foo.cfg.in can contain anything or even be empty.)
(Apparently a disadvantage of just using add_custom_target is that it always
runs, regardless of the DEPENDS. Not that this should be a huge problem,
though.)
Have you tried naming the input/output like
${CMAKE_CURRENT_SOURCE_DIR}/name.in and
${CMAKE_CURRENT_BINARY_DIR}/name? (I didn't do that in the attached
example because I was lazy (and the example may only work for in-source
builds as a result), but that is how I would recommend naming the files in a
real project.)
The source of my problem was 'naming'. I did use the CMake 'SOURCE_DIR'
variable but my file extensions were wrong and my path was off by one level!
Everything works fine now.
(Incidentally, this tickles a ninja generator bug in CMake 2.8.11.)
Don't know about that bug. I did notice an effect I didn't expect - when
'make clean' is run the 'output' is deleted. Hadn't thought about that...
Thanks for your help and patience!
-Skippy
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Re: [CMake] copy_if_different on build
On 2013-04-17 12:41, Skippy VonDrake wrote:
Thought I understood this - but alas my implementation is wrong.
Here's my test case with a top-level cmake file and 3 subdirectories:
'src', 'bin' and 'outdir'.
Top level CMakeLists.txt
cmake_minimum_required (VERSION 2.8)
project (copyFile)
set (TARGETNAME fooCopy)
set (TARGETDEST ${PROJECT_SOURCE_DIR}/bin)
add_subdirectory (src)
src/CMakeLists.txt
add_executable (${TARGETNAME} main.cpp)
set (input ${CMAKE_CURRENT_SOURCE_DIR}/bin/config.cfg)
set (output ${CMAKE_CURRENT_SOURCE_DIR}/outdir/config.cfg)
add_dependencies(${TARGETNAME} ${output})
add_custom_command(
OUTPUT ${output}
DEPENDS ${input}
COMMAND ${CMAKE_COMMAND} -E copy_if_different
${input} ${output}
)
install (TARGETS ${TARGETNAME} DESTINATION ${TARGETDEST})
The config file (config.cfg) is just some text and cpp file is just a
hello world
example.
Since the config file is not source included as a dependency in the
add_executable command, I assume my problem is making the target
properly depend on it? Specifically ${TARGETNAME} should depend
on ${output}?
Hmm... yes, I'm not sure if add_dependencies can be used to add a file
dependency to a target (the documentation only talks about adding other
targets as dependencies).
Usually things like configured files are used as source files, i.e. as
inputs to add_executable, etc.
If for some reason that doesn't work, I believe you can make your
executable dependent on a custom target, which in turn depends on the
output file from your custom command. IOW:
add_custom_command(OUTPUT out DEPENDS in COMMAND stuff)
add_executable(exe sources)
add_custom_target(exe_config DEPENDS out)
add_dependencies(exe exe_config)
If you only have one custom command, you can probably use
add_custom_target to run the command instead, i.e.:
add_custom_target(exe_config DEPENDS in COMMAND stuff)
add_executable(exe sources)
add_dependencies(exe exe_config)
Hope that helps,
--
Matthew
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Re: [CMake] copy_if_different on build
believe what you want is:
add_custom_command(
OUTPUT ${output}
DEPENDS ${input}
COMMAND ${CMAKE_COMMAND} -E copy
${input} ${output}
...which is roughly equivalent to a Makefile rule like:
output: input
cp input output
IOW, the file ${output} depends on the file ${input} (so the target will
only run when ${input} is newer than ${output}), and will be created by
copying ${input} to ${output} (using 'cmake -E' for portability).
Don't forget to have an actual target depend on ${output} :-). (Probably
you are using it as a source file for a library or executable, so there is
no problem.)
You may also want to use 'copy_if_different' instead of just 'copy', which
won't change the time stamp of ${output} if the contents are the same as
${input}. On the plus side, this means that large targets depending on
${output} won't be needlessly rebuilt/relinked. On the down side, the
copy_if_different will remain out of date, and as a result still think it
needs to run after a successful build.
Thought I understood this - but alas my implementation is wrong.
Here's my test case with a top-level cmake file and 3 subdirectories:
'src', 'bin' and 'outdir'.
Top level CMakeLists.txt
cmake_minimum_required (VERSION 2.8)
project (copyFile)
set (TARGETNAME fooCopy)
set (TARGETDEST ${PROJECT_SOURCE_DIR}/bin)
add_subdirectory (src)
src/CMakeLists.txt
add_executable (${TARGETNAME}main.cpp)
set (input ${CMAKE_CURRENT_SOURCE_DIR}/bin/config.cfg)
set (output ${CMAKE_CURRENT_SOURCE_DIR}/outdir/config.cfg)
add_dependencies(${TARGETNAME} ${output})
add_custom_command(
OUTPUT ${output}
DEPENDS ${input}
COMMAND ${CMAKE_COMMAND} -E copy_if_different
${input} ${output}
)
install (TARGETS ${TARGETNAME} DESTINATION ${TARGETDEST})
The config file (config.cfg) is just some text and cpp file is just a
hello world
example.
Since the config file is not source included as a dependency in the
add_executable command, I assume my problem is making the target
properly depend on it? Specifically ${TARGETNAME} should depend
on ${output}?
-Skippy
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Re: [CMake] copy_if_different on build
On 2013-03-29 17:07, Skippy VonDrake wrote:
I'll look closer at add_custom_command. I want the file to copy over if
it has changed - at build time. Not cmake time. And not copy if it hasn't
changed. But that may not be doable.
Seems like every StackOverflow post I see has a different take on how
to do this simple process.
That's a little surprising... as you say, this shouldn't be complicated.
I believe what you want is:
add_custom_command(
OUTPUT ${output}
DEPENDS ${input}
COMMAND ${CMAKE_COMMAND} -E copy
${input} ${output}
...which is roughly equivalent to a Makefile rule like:
output: input
cp input output
IOW, the file ${output} depends on the file ${input} (so the target
will only run when ${input} is newer than ${output}), and will be
created by copying ${input} to ${output} (using 'cmake -E' for
portability).
Don't forget to have an actual target depend on ${output} :-).
(Probably you are using it as a source file for a library or executable,
so there is no problem.)
You may also want to use 'copy_if_different' instead of just 'copy',
which won't change the time stamp of ${output} if the contents are the
same as ${input}. On the plus side, this means that large targets
depending on ${output} won't be needlessly rebuilt/relinked. On the
down side, the copy_if_different will remain out of date, and as a
result still think it needs to run after a successful build.
--
Matthew
--
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[CMake] copy_if_different on build
I'm using:
execute_process(COMMAND ${CMAKE_COMMAND} -E copy_if_different
some-file some-dest-dir)
Should the file be copied when:
the file has changed AND a build is executed?
Or
the file has changed AND CMakeLists.txt has changed AND a build is executed?
Only the 2nd method (when the CMakeLists.txt file is touched) results in the
changed file being copied.
I'd expect the 1st method to also cause a file copy.
If this assumption is wrong please tell me why.
-Skippy
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Re: [CMake] copy_if_different on build
On 2013-03-29 15:15, Skippy VonDrake wrote:
I'm using:
execute_process(COMMAND ${CMAKE_COMMAND} -E copy_if_different
some-file some-dest-dir)
Should the file be copied when:
the file has changed AND a build is executed?
Or
the file has changed AND CMakeLists.txt has changed AND a build is executed?
Only the 2nd method (when the CMakeLists.txt file is touched) results in the
changed file being copied.
I'd expect the 1st method to also cause a file copy.
If this assumption is wrong please tell me why.
execute_process is a configure step. It does not create build rules and
will ONLY execute when CMake is run.
If you want to create a build rule, use add_custom_command or
add_custom_target instead.
Anyway, the above is silly; if you really only wanted the file copied at
cmake time, you should instead use configure_file(... COPY_ONLY) :-)
rather than unnecessarily invoking an extra process.
--
Matthew
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Re: [CMake] copy_if_different on build
I'm using:
execute_process(COMMAND ${CMAKE_COMMAND} -E copy_if_different
some-file some-dest-dir)
Should the file be copied when:
the file has changed AND a build is executed?
Or
the file has changed AND CMakeLists.txt has changed AND a build is
executed?
Only the 2nd method (when the CMakeLists.txt file is touched) results in
the
changed file being copied.
I'd expect the 1st method to also cause a file copy.
If this assumption is wrong please tell me why.
execute_process is a configure step. It does not create build rules and will
ONLY execute when CMake is run.
If you want to create a build rule, use add_custom_command or
add_custom_target instead.
Anyway, the above is silly; if you really only wanted the file copied at
cmake time, you should instead use configure_file(... COPY_ONLY) :-) rather
than unnecessarily invoking an extra process.
I'll look closer at add_custom_command. I want the file to copy over if
it has changed - at build time. Not cmake time. And not copy if it hasn't
changed. But that may not be doable.
Seems like every StackOverflow post I see has a different take on how
to do this simple process.
--
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