Re: [CMake] Get linker flags / include directories for a library target
On Sat, 2018-12-29 at 16:06 -0500, frodak17 wrote:
> On Fri, Dec 28, 2018 at 6:04 PM Unknown wrote:
> > I would like to thank all of you for your suggestions. I have
> > gathered
> >
> > the following (correct me if I am wrong):
> >
> >
> >
> > - The LINK_FLAGS target property is used in cmake 2.x, the
> >
> > INTERFACE_LINK_LIBRARIES in cmake 3.x, the latter contains a ;-
> > list
> >
> > of libraries.
> >
> > - The list may contain generator expressions, it is however
> >
> > possible to to use file(GENERATE ..) to obtain evaluate those.
> >
> > - In any case, the library list contains libraries having
> > different
> >
> > formats (see [1]), full paths, (imported) targets, and plain
> > names.
> >
> > - When Makefiles (or files for other build systems) are generated,
> >
> > the list is turned into -L/-l flags used by ld. This happens
> >
> > on the C++ side of things, the functionality is not exposed
> >
> > to cmake scripts.
> >
> >
> >
> > As for automatic generation of a pkg-config .pc file, there have
> >
> > been some inquiries ([2], [3], and [4]), the last one being rather
> >
> > recent.
> >
> >
> >
> > The answers point out that pkg-config files can be generated using
> >
> > configure_file(...), that cmake has its own (imported target)
> > method
> >
> > for handling dependencies.
> >
> >
> >
> > I don't mean to be disrespectful or unappreciative of the work put
> >
> > into cmake (in fact I think it is a vast improvement over
> > automake),
> >
> > but since there is no way to obtain the required information
> >
> > programatically, all users of my library have to either use
> >
> > cmake themselves, or use non-portable workarounds which are prone
> >
> > to break sooner than later.
> >
> >
> >
> > If I want to use an external tool (think setup.py) to build
> >
> > extensions (in-place or not), the same problem occurs.
> >
> >
> >
> > This is rather disappointing to be honest...
> >
> >
> >
> > ax487
> >
> >
> >
> >
>
> The answer to [2] was that the information required to automatically
> generate
> a .pc file was not available.
> https://linux.die.net/man/1/pkg-config
> https://people.freedesktop.org/~dbn/pkg-config-guide.html#writing
> I don't see how CMake could know which packages your library
> conflicts with or which versions of which libraries are required.For
> example a library target can link against an imported target but it
> won't know that only imported target version 1.0.0 is compatible as
> opposed to versions >= 1.5.
>
>
>
>
> It seems that you are trying to provide more than how to link
> against
> your library but also against everything your library wants to be
> linked
> against.
>
> For example the .pc file you want generated contains "Libs:
> -L${libdirbar}
> -L${libdirfoo}
>
> -lbar -lfoo".But that isn't the proper way of a .pc file should
> reference separate libraries it should use the Requires field.
>
> Also if your library is linking against an imported library
> `libbaz::libbaz` how is this library being provided to the people
> using your library?Are you trying to generate a .pc file for the
> imported library because it didn't provide one and incorporate the
> flags into library you are creating?
> I think that no one has volunteered to write a CMake package to
> create .pc files is because generating a .pc file is pretty simple.
> It's just a template and a configure_file() command.
> https://cmake.org/pipermail/cmake/2018-March/067293.html
>
>
Thank you for your reply,
As for the answer provided in [2]: I don't expect conflict or version
detection to be conducted automatically. Clearly, you have to require
the correct packages in the correct versions,
and you have to pass that information along to a generated pc file,
that much is clear. But I think that the same holds true for imported
targets, unless something really
clever happens in the background which I am not aware of.
You are quite right in assuming that I want to (mis-)use the Libs /
Libs.private field. I would of course prefer the Requires field, but
unfortunately a lot of my dependencies don't
generate pc files either, so I don't really see any other way to get
pkg-config working.
A dependency of the form libbaz::libbaz would be provided as an
imported target. That is, the authors of libbaz are using cmake as
well, and they are installing a target.
I am assuming that the users of my library have the dependency libbaz
installed as well. I simply want to pass that information along in a
format understood by pkg-config.
I would also go through the dependency libraries, but I doubt that any
contributions of pc file generators to those projects would be
accepted.
Regarding the fact that no one has written a generator for .pc files:
It is obviously possible to use configure_file templates. In fact it is
quite easy. But it hinges on the libraries as well.
The post you mention references a project which generates linker
Re: [CMake] Get linker flags / include directories for a library target
On Fri, Dec 28, 2018 at 6:04 PM Unknown wrote:
> I would like to thank all of you for your suggestions. I have gathered
> the following (correct me if I am wrong):
>
> - The LINK_FLAGS target property is used in cmake 2.x, the
> INTERFACE_LINK_LIBRARIES in cmake 3.x, the latter contains a ;-list
> of libraries.
> - The list may contain generator expressions, it is however
> possible to to use file(GENERATE ..) to obtain evaluate those.
> - In any case, the library list contains libraries having different
> formats (see [1]), full paths, (imported) targets, and plain names.
> - When Makefiles (or files for other build systems) are generated,
> the list is turned into -L/-l flags used by ld. This happens
> on the C++ side of things, the functionality is not exposed
> to cmake scripts.
>
> As for automatic generation of a pkg-config .pc file, there have
> been some inquiries ([2], [3], and [4]), the last one being rather
> recent.
>
> The answers point out that pkg-config files can be generated using
> configure_file(...), that cmake has its own (imported target) method
> for handling dependencies.
>
> I don't mean to be disrespectful or unappreciative of the work put
> into cmake (in fact I think it is a vast improvement over automake),
> but since there is no way to obtain the required information
> programatically, all users of my library have to either use
> cmake themselves, or use non-portable workarounds which are prone
> to break sooner than later.
>
> If I want to use an external tool (think setup.py) to build
> extensions (in-place or not), the same problem occurs.
>
> This is rather disappointing to be honest...
>
> ax487
>
>
>
The answer to [2] was that the information required to automatically
generate a .pc file was not available.
https://linux.die.net/man/1/pkg-config
https://people.freedesktop.org/~dbn/pkg-config-guide.html#writing
I don't see how CMake could know which packages your library conflicts with
or which versions of which libraries are required.
For example a library target can link against an imported target but it
won't know that only imported target version 1.0.0 is compatible as opposed
to versions >= 1.5.
It seems that you are trying to provide more than how to link against your
library but also against everything your library wants to be linked
against.
For example the .pc file you want generated contains "Libs: -L${libdirbar}
-L${libdirfoo} -lbar -lfoo".
But that isn't the proper way of a .pc file should reference separate
libraries it should use the Requires field.
Also if your library is linking against an imported library
`libbaz::libbaz` how is this library being provided to the people using
your library?
Are you trying to generate a .pc file for the imported library because it
didn't provide one and incorporate the flags into library you are creating?
I think that no one has volunteered to write a CMake package to create .pc
files is because generating a .pc file is pretty simple. It's just a
template and a configure_file() command.
https://cmake.org/pipermail/cmake/2018-March/067293.html
--
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Re: [CMake] Get linker flags / include directories for a library target
I would like to thank all of you for your suggestions. I have gathered the following (correct me if I am wrong): - The LINK_FLAGS target property is used in cmake 2.x, the INTERFACE_LINK_LIBRARIES in cmake 3.x, the latter contains a ;-list of libraries. - The list may contain generator expressions, it is however possible to to use file(GENERATE ..) to obtain evaluate those. - In any case, the library list contains libraries having different formats (see [1]), full paths, (imported) targets, and plain names. - When Makefiles (or files for other build systems) are generated, the list is turned into -L/-l flags used by ld. This happens on the C++ side of things, the functionality is not exposed to cmake scripts. As for automatic generation of a pkg-config .pc file, there have been some inquiries ([2], [3], and [4]), the last one being rather recent. The answers point out that pkg-config files can be generated using configure_file(...), that cmake has its own (imported target) method for handling dependencies. I don't mean to be disrespectful or unappreciative of the work put into cmake (in fact I think it is a vast improvement over automake), but since there is no way to obtain the required information programatically, all users of my library have to either use cmake themselves, or use non-portable workarounds which are prone to break sooner than later. If I want to use an external tool (think setup.py) to build extensions (in-place or not), the same problem occurs. This is rather disappointing to be honest... ax487 [1] https://cmake.org/cmake/help/latest/command/target_link_libraries.html [2] https://cmake.org/pipermail/cmake/2006-August/010747.html [3] https://cmake.org/pipermail/cmake/2008-January/019533.html [4] https://cmake.org/pipermail/cmake/2018-March/067289.html On Mon, 2018-12-24 at 10:46 -0500, Robert Maynard wrote: > That functionality exists in the C++ side of the code base and is run > during the 'generate' stage ( CMakeLists are parsed during > 'configure', than a 'generate' step is run ). > > To get access to how import targets and generator expressions are > resolved you have two options. > 1. You can try to use file(GENERATE but it doesn't support all the > generator expressions currently > 2. You use cmake-server > (https://cmake.org/cmake/help/latest/manual/cmake-server.7.html) to > query a build directory for all this information. > > On Fri, Dec 21, 2018 at 9:12 AM Unknown wrote: > > Hello Kai, > > > > thanks for your suggestion. I tried the property, > > but I just got "foo_linker_flags-NOTFOUND" as a > > result (I am using cmake 3.13.1 btw). The > > same goes for > > > > LINK_OPTIONS, and > > INTERFACE_LINK_OPTIONS. > > > > I tried using the INTERFACE_LINK_LIBRARIES property > > instead. The resulting list contains things I can use, > > such as /usr/lib/libz.so > > > > However, I am using another cmake imported library. > > Therefore, the list contains some libbaz::libbaz > > dependency as well. > > > > In order to get the actual list of libraries, I would > > have to also resolve these names. > > > > But this has to be done somewhere during the > > generation of the Makefiles, so that functionality > > must exist somewhere in cmake. > > > > > > On Fri, 2018-12-21 at 09:33 +0100, Kai Wolf wrote: > > > You can ask a CMake build target for its properties using > > > get_target_property(). > > > For instance, to retrieve the linker flags for a given target > > > foo, > > > you’d write: > > > > > > get_target_prooperty(foo_linker_flags foo LINK_FLAGS) > > > > > > See [1] for a list of valid parameters. > > > > > > Greetings, > > > > > > Kai > > > > > > [1] > > > https://cmake.org/cmake/help/latest/manual/cmake-properties.7.html#properties-on-targets > > > > > > http://kai-wolf.me > > > http://effective-cmake.com > > > > > > > Am 20.12.2018 um 23:14 schrieb Unknown : > > > > > > > > Dear community, > > > > > > > > I have been wondering on multiple occasions about how to get > > > > the > > > > linker flags (i.e. all -llib -Ldir) and include flags (-Idir) > > > > for a library (i.e. a target added to the project using > > > > add_library) within a cmake. > > > > > > > > There are many cases in which the flags are required, > > > > noticeably > > > > generating a suitable pkg-config file or creating a wrappers > > > > around > > > > C/C++ libraries. > > > > > > > > I think that it should be possible to derive the flags from > > > > some of the target properties of the library, but I don't > > > > know exactly how. > > > > > > > > Could you give me a hand? > > > > > > > > ax487 > > > > > > > > -- > > > > > > > > Powered by www.kitware.com > > > > > > > > Please keep messages on-topic and check the CMake FAQ at: > > > > http://www.cmake.org/Wiki/CMake_FAQ > > > > > > > > Kitware offers various services to support the CMake community. > > > > For > > > > more information on each offering, please visit: > > > > > > > > CMake Support:
Re: [CMake] Get linker flags / include directories for a library target
All the flags/options in the CMake they could be considered as a list. So it's much more easier to handle it as this set(WIN_DEFINITIONS -DNOMINMAX) Remember the list is the object, so we could construct the new list for the specific target. Then to the specific target, just use the 3 commands. target_compile_options() target_include_directories() target_link_libraries() We use this method to organize the cross-platform with library and executable without any problem, and super easy to control and manage. Thanks. On Fri, Dec 21, 2018 at 7:19 AM Unknown wrote: > Dear community, > > I have been wondering on multiple occasions about how to get the > linker flags (i.e. all -llib -Ldir) and include flags (-Idir) > for a library (i.e. a target added to the project using > add_library) within a cmake. > > There are many cases in which the flags are required, noticeably > generating a suitable pkg-config file or creating a wrappers around > C/C++ libraries. > > I think that it should be possible to derive the flags from > some of the target properties of the library, but I don't > know exactly how. > > Could you give me a hand? > > ax487 > > -- > > Powered by www.kitware.com > > Please keep messages on-topic and check the CMake FAQ at: > http://www.cmake.org/Wiki/CMake_FAQ > > Kitware offers various services to support the CMake community. For more > information on each offering, please visit: > > CMake Support: http://cmake.org/cmake/help/support.html > CMake Consulting: http://cmake.org/cmake/help/consulting.html > CMake Training Courses: http://cmake.org/cmake/help/training.html > > Visit other Kitware open-source projects at > http://www.kitware.com/opensource/opensource.html > > Follow this link to subscribe/unsubscribe: > https://cmake.org/mailman/listinfo/cmake > -- Powered by www.kitware.com Please keep messages on-topic and check the CMake FAQ at: http://www.cmake.org/Wiki/CMake_FAQ Kitware offers various services to support the CMake community. For more information on each offering, please visit: CMake Support: http://cmake.org/cmake/help/support.html CMake Consulting: http://cmake.org/cmake/help/consulting.html CMake Training Courses: http://cmake.org/cmake/help/training.html Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Follow this link to subscribe/unsubscribe: https://cmake.org/mailman/listinfo/cmake
Re: [CMake] Get linker flags / include directories for a library target
That functionality exists in the C++ side of the code base and is run during the 'generate' stage ( CMakeLists are parsed during 'configure', than a 'generate' step is run ). To get access to how import targets and generator expressions are resolved you have two options. 1. You can try to use file(GENERATE but it doesn't support all the generator expressions currently 2. You use cmake-server (https://cmake.org/cmake/help/latest/manual/cmake-server.7.html) to query a build directory for all this information. On Fri, Dec 21, 2018 at 9:12 AM Unknown wrote: > > Hello Kai, > > thanks for your suggestion. I tried the property, > but I just got "foo_linker_flags-NOTFOUND" as a > result (I am using cmake 3.13.1 btw). The > same goes for > > LINK_OPTIONS, and > INTERFACE_LINK_OPTIONS. > > I tried using the INTERFACE_LINK_LIBRARIES property > instead. The resulting list contains things I can use, > such as /usr/lib/libz.so > > However, I am using another cmake imported library. > Therefore, the list contains some libbaz::libbaz > dependency as well. > > In order to get the actual list of libraries, I would > have to also resolve these names. > > But this has to be done somewhere during the > generation of the Makefiles, so that functionality > must exist somewhere in cmake. > > > On Fri, 2018-12-21 at 09:33 +0100, Kai Wolf wrote: > > You can ask a CMake build target for its properties using > > get_target_property(). > > For instance, to retrieve the linker flags for a given target foo, > > you’d write: > > > > get_target_prooperty(foo_linker_flags foo LINK_FLAGS) > > > > See [1] for a list of valid parameters. > > > > Greetings, > > > > Kai > > > > [1] > > https://cmake.org/cmake/help/latest/manual/cmake-properties.7.html#properties-on-targets > > > > http://kai-wolf.me > > http://effective-cmake.com > > > > > Am 20.12.2018 um 23:14 schrieb Unknown : > > > > > > Dear community, > > > > > > I have been wondering on multiple occasions about how to get the > > > linker flags (i.e. all -llib -Ldir) and include flags (-Idir) > > > for a library (i.e. a target added to the project using > > > add_library) within a cmake. > > > > > > There are many cases in which the flags are required, noticeably > > > generating a suitable pkg-config file or creating a wrappers around > > > C/C++ libraries. > > > > > > I think that it should be possible to derive the flags from > > > some of the target properties of the library, but I don't > > > know exactly how. > > > > > > Could you give me a hand? > > > > > > ax487 > > > > > > -- > > > > > > Powered by www.kitware.com > > > > > > Please keep messages on-topic and check the CMake FAQ at: > > > http://www.cmake.org/Wiki/CMake_FAQ > > > > > > Kitware offers various services to support the CMake community. For > > > more information on each offering, please visit: > > > > > > CMake Support: http://cmake.org/cmake/help/support.html > > > CMake Consulting: http://cmake.org/cmake/help/consulting.html > > > CMake Training Courses: http://cmake.org/cmake/help/training.html > > > > > > Visit other Kitware open-source projects at > > > http://www.kitware.com/opensource/opensource.html > > > > > > Follow this link to subscribe/unsubscribe: > > > https://cmake.org/mailman/listinfo/cmake > > -- > > Powered by www.kitware.com > > Please keep messages on-topic and check the CMake FAQ at: > http://www.cmake.org/Wiki/CMake_FAQ > > Kitware offers various services to support the CMake community. For more > information on each offering, please visit: > > CMake Support: http://cmake.org/cmake/help/support.html > CMake Consulting: http://cmake.org/cmake/help/consulting.html > CMake Training Courses: http://cmake.org/cmake/help/training.html > > Visit other Kitware open-source projects at > http://www.kitware.com/opensource/opensource.html > > Follow this link to subscribe/unsubscribe: > https://cmake.org/mailman/listinfo/cmake -- Powered by www.kitware.com Please keep messages on-topic and check the CMake FAQ at: http://www.cmake.org/Wiki/CMake_FAQ Kitware offers various services to support the CMake community. For more information on each offering, please visit: CMake Support: http://cmake.org/cmake/help/support.html CMake Consulting: http://cmake.org/cmake/help/consulting.html CMake Training Courses: http://cmake.org/cmake/help/training.html Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Follow this link to subscribe/unsubscribe: https://cmake.org/mailman/listinfo/cmake
Re: [CMake] Get linker flags / include directories for a library target
Hello Kai, thanks for your suggestion. I tried the property, but I just got "foo_linker_flags-NOTFOUND" as a result (I am using cmake 3.13.1 btw). The same goes for LINK_OPTIONS, and INTERFACE_LINK_OPTIONS. I tried using the INTERFACE_LINK_LIBRARIES property instead. The resulting list contains things I can use, such as /usr/lib/libz.so However, I am using another cmake imported library. Therefore, the list contains some libbaz::libbaz dependency as well. In order to get the actual list of libraries, I would have to also resolve these names. But this has to be done somewhere during the generation of the Makefiles, so that functionality must exist somewhere in cmake. On Fri, 2018-12-21 at 09:33 +0100, Kai Wolf wrote: > You can ask a CMake build target for its properties using > get_target_property(). > For instance, to retrieve the linker flags for a given target foo, > you’d write: > > get_target_prooperty(foo_linker_flags foo LINK_FLAGS) > > See [1] for a list of valid parameters. > > Greetings, > > Kai > > [1] > https://cmake.org/cmake/help/latest/manual/cmake-properties.7.html#properties-on-targets > > http://kai-wolf.me > http://effective-cmake.com > > > Am 20.12.2018 um 23:14 schrieb Unknown : > > > > Dear community, > > > > I have been wondering on multiple occasions about how to get the > > linker flags (i.e. all -llib -Ldir) and include flags (-Idir) > > for a library (i.e. a target added to the project using > > add_library) within a cmake. > > > > There are many cases in which the flags are required, noticeably > > generating a suitable pkg-config file or creating a wrappers around > > C/C++ libraries. > > > > I think that it should be possible to derive the flags from > > some of the target properties of the library, but I don't > > know exactly how. > > > > Could you give me a hand? > > > > ax487 > > > > -- > > > > Powered by www.kitware.com > > > > Please keep messages on-topic and check the CMake FAQ at: > > http://www.cmake.org/Wiki/CMake_FAQ > > > > Kitware offers various services to support the CMake community. For > > more information on each offering, please visit: > > > > CMake Support: http://cmake.org/cmake/help/support.html > > CMake Consulting: http://cmake.org/cmake/help/consulting.html > > CMake Training Courses: http://cmake.org/cmake/help/training.html > > > > Visit other Kitware open-source projects at > > http://www.kitware.com/opensource/opensource.html > > > > Follow this link to subscribe/unsubscribe: > > https://cmake.org/mailman/listinfo/cmake -- Powered by www.kitware.com Please keep messages on-topic and check the CMake FAQ at: http://www.cmake.org/Wiki/CMake_FAQ Kitware offers various services to support the CMake community. For more information on each offering, please visit: CMake Support: http://cmake.org/cmake/help/support.html CMake Consulting: http://cmake.org/cmake/help/consulting.html CMake Training Courses: http://cmake.org/cmake/help/training.html Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Follow this link to subscribe/unsubscribe: https://cmake.org/mailman/listinfo/cmake
Re: [CMake] Get linker flags / include directories for a library target
You can ask a CMake build target for its properties using get_target_property(). For instance, to retrieve the linker flags for a given target foo, you’d write: get_target_prooperty(foo_linker_flags foo LINK_FLAGS) See [1] for a list of valid parameters. Greetings, Kai [1] https://cmake.org/cmake/help/latest/manual/cmake-properties.7.html#properties-on-targets http://kai-wolf.me http://effective-cmake.com > Am 20.12.2018 um 23:14 schrieb Unknown : > > Dear community, > > I have been wondering on multiple occasions about how to get the > linker flags (i.e. all -llib -Ldir) and include flags (-Idir) > for a library (i.e. a target added to the project using > add_library) within a cmake. > > There are many cases in which the flags are required, noticeably > generating a suitable pkg-config file or creating a wrappers around > C/C++ libraries. > > I think that it should be possible to derive the flags from > some of the target properties of the library, but I don't > know exactly how. > > Could you give me a hand? > > ax487 > > -- > > Powered by www.kitware.com > > Please keep messages on-topic and check the CMake FAQ at: > http://www.cmake.org/Wiki/CMake_FAQ > > Kitware offers various services to support the CMake community. For more > information on each offering, please visit: > > CMake Support: http://cmake.org/cmake/help/support.html > CMake Consulting: http://cmake.org/cmake/help/consulting.html > CMake Training Courses: http://cmake.org/cmake/help/training.html > > Visit other Kitware open-source projects at > http://www.kitware.com/opensource/opensource.html > > Follow this link to subscribe/unsubscribe: > https://cmake.org/mailman/listinfo/cmake signature.asc Description: Message signed with OpenPGP -- Powered by www.kitware.com Please keep messages on-topic and check the CMake FAQ at: http://www.cmake.org/Wiki/CMake_FAQ Kitware offers various services to support the CMake community. For more information on each offering, please visit: CMake Support: http://cmake.org/cmake/help/support.html CMake Consulting: http://cmake.org/cmake/help/consulting.html CMake Training Courses: http://cmake.org/cmake/help/training.html Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Follow this link to subscribe/unsubscribe: https://cmake.org/mailman/listinfo/cmake
[CMake] Get linker flags / include directories for a library target
Dear community, I have been wondering on multiple occasions about how to get the linker flags (i.e. all -llib -Ldir) and include flags (-Idir) for a library (i.e. a target added to the project using add_library) within a cmake. There are many cases in which the flags are required, noticeably generating a suitable pkg-config file or creating a wrappers around C/C++ libraries. I think that it should be possible to derive the flags from some of the target properties of the library, but I don't know exactly how. Could you give me a hand? ax487 -- Powered by www.kitware.com Please keep messages on-topic and check the CMake FAQ at: http://www.cmake.org/Wiki/CMake_FAQ Kitware offers various services to support the CMake community. For more information on each offering, please visit: CMake Support: http://cmake.org/cmake/help/support.html CMake Consulting: http://cmake.org/cmake/help/consulting.html CMake Training Courses: http://cmake.org/cmake/help/training.html Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Follow this link to subscribe/unsubscribe: https://cmake.org/mailman/listinfo/cmake
