[CMake] Get native build command with CMake 3+

Fri Dec 5 16:43:32 EST 2014

Isn't it as smiple as

add_subdirectory( examples_dir ) which has it's own CMakeLists?
Does it really have to build as an extra step or would

OPTION( BUILD_EXAMPLES "Build Examples?" ON )
....
if( BUILD_EXAMPLES)
add_subdirectory( examples_dir)
endif( BUILD_EXAMPLES)

On Fri, Dec 5, 2014 at 7:41 AM, Petr Kmoch <petr.kmoch at gmail.com> wrote:

> OK, sorry for misunderstanding. But then I don't have a target like this.
> Basically, I am trying to create a custom target that would do this:
>
> # When using Makefile generator
> add_custom_target(
>   examples
>   COMMAND make -C example_dir all
>   VERBATIM
> )
>
> # When using vs2008 generator
> add_custom_target(
>   examples
>   COMMAND devenv Examples.sln /Build /Project:ALL_BUILD
> /ProjectConfig:$<CONFIG>
>   WORKING_DIRECTORY example_dir
>   VERBATIM
> )
>
> # When using vs2010 generator, use msbuild
> # etc...
>
> without having to hardcode the logic (CMake must have this info inside
> somewhere). So I am effectively trying to *create* the target 'examples'.
>
> My current solution is to make the custom target empty and have it depend
> on all the targets in example_dir. But this has two consequences I don't
> like:
> 1. I have to collect the target names in example_dir/CMakeLists.txt, as it
> has to communicate them to its parent
> 2. Being dependecies, the targets from example_dir show up in the toplevel
> solution file/Makefile. I was trying to prevent that.
>
> I looked at the commit message which changed build_command() from
> returning the native command line to returning cmake --build, at it
> mentions the fact that sometimes, the native tool has to be selected based
> on the contents of the solution (devenv instead of msbuild when ifort is
> involved). So I guess the only way to get what I want would be with a
> generator expression (one which does not currently exist).
>
> I guess I'll stick to my workaround with dependencies. But thanks for your
> help.
>
> Petr
>
> On Fri, Dec 5, 2014 at 4:19 PM, David Cole <DLRdave at aol.com> wrote:
>
>> No, I meant exactly what I said.
>>
>> --target takes a CMake target name.
>>
>>
>> HTH,
>> D
>>
>>
>>
>> On Fri, Dec 5, 2014 at 9:23 AM, Petr Kmoch <petr.kmoch at gmail.com> wrote:
>> > I assume you actually meant 'cmake --build . --target example_dir', the
>> name
>> > of the directory. 'examples' is the name of the custom target; if that
>> > target's command was to build itself, I believe it would become a fork
>> bomb.
>> >
>> > Anyway, I tried it with the directory name, it doesn't work. I'm
>> generating
>> > with VS2008, and devenv was complaining about "Invalid project." Which
>> kind
>> > of makes sense, there is no 'example_dir' project in the solution.
>> >
>> > On Fri, Dec 5, 2014 at 2:59 PM, David Cole <DLRdave at aol.com> wrote:
>> >>
>> >> Try:
>> >>
>> >> cmake --build . --target examples
>> >>
>> >> (where "." represents the current working directory, and assumes
>> >> you're in the top level build tree...)
>> >>
>> >>
>> >> On Fri, Dec 5, 2014 at 5:46 AM, Petr Kmoch <petr.kmoch at gmail.com>
>> wrote:
>> >> > Hi all.
>> >> >
>> >> > I'm converting a small Makefile-based project to CMake. The project
>> is
>> >> > not
>> >> > mine, so I am trying to match its existing buildsystem as closely as
>> >> > possible.
>> >> >
>> >> > One of the rules in the original Makefile is (simplified) as follows:
>> >> >
>> >> > examples: all
>> >> >   make -C example_dir all
>> >> >
>> >> > This gives a target 'examples' in the top-level Makefile, which is
>> not
>> >> > included in 'all', but can be used to build all examples. I would
>> like
>> >> > to
>> >> > achieve something similar with CMake.
>> >> >
>> >> > I added example_dir/CMakeLists.txt, which includes a project()
>> command
>> >> > and
>> >> > defines all the targets for example executables. In the toplevel
>> >> > CMakeList,
>> >> > I did this:
>> >> >
>> >> > # Add the subdirectory but don't include its targets by default
>> >> > add_subdirectory(example_dir EXCLUDE_FROM_ALL)
>> >> >
>> >> > # Add a custom target to build all examples
>> >> > add_custom_target(examples ???)
>> >> >
>> >> > I'm stuck at the custom target. What I need for its command is a
>> >> > generator-agnostic equivalent for 'make -C example_dir all' (or
>> 'make -f
>> >> > example_dir/Makefile all').
>> >> >
>> >> > I tried 'cmake --build ${CMAKE_CURRENT_BINARY_DIR}/example_dir ...',
>> but
>> >> > this complains that example_dir does not contain a CMakeCache.txt
>> (which
>> >> > is
>> >> > correct of course, it's not the toplevel directory). Then I
>> remembered
>> >> > that
>> >> > build_command() can be used to get a command line to build a project;
>> >> > unfortunately, in 3.0 and later, this just returns 'cmake --build
>> ...'
>> >> > and
>> >> > so is unusable in my situation.
>> >> >
>> >> > Is there a way to query CMake for the native command line (or
>> something
>> >> > else) I could use to build the CMake-generated buildsystem in the
>> >> > subdirectory? I thought a bit about CMAKE_MAKE_PROGRAM, but that
>> doesn't
>> >> > tell me anything about what arguments I should pass, and it's not
>> even
>> >> > set
>> >> > on Visual Studio generators.
>> >> >
>> >> > As a workaround, I thought of not doing add_subdirectory() at all and
>> >> > instead adding a custom target with 'ctest --build-and-test ...',
>> but I
>> >> > would prefer to configure & generate the two directories together. I
>> >> > plan to
>> >> > eventually add install() rules for the examples as well, and the
>> >> > examples
>> >> > also use one of the targets from the toplevel cmakelist in
>> >> > add_custom_command(OUTPUT ...), so I would really like to keep them
>> as
>> >> > one
>> >> > CMake system. Is there a way to do so?
>> >> >
>> >> > Petr
>> >> >
>> >> > --
>> >> >
>> >> > Powered by www.kitware.com
>> >> >
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>>
>
>
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