'Re: [CMake] OBJECT libraries and INTERFACE_SOURCES'

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List:       cmake
Subject:    Re: [CMake] OBJECT libraries and INTERFACE_SOURCES
From:       Giovanni Funchal <gio () cloudnc ! co ! uk>
Date:       2016-12-12 9:44:04
Message-ID: CACs7uvbnUoWxx36CiU7L8mwC3AzEh1ahF_zb6xvEtpVaj3MuUA () mail ! gmail ! com
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Hello,

Can someone confirm please if this is a bug and whether I should file a bug
report?

Also, the "PRIVATE" workaround doesn't suit me (because it breaks
transitivity of includes). Is there any other workaround I can use? I
assume reverting to static libraries is the best thing to do in the
meanwhile?

Thanks,
-- Giovanni

On Fri, Dec 9, 2016 at 4:25 PM, Giovanni Funchal <gio@cloudnc.co.uk> wrote:

> Hello,
>
> PRIVATE works, but I don't understand why (the only difference between the
> two examples is using a subdirectory).
>
> Using ${CMAKE_CURRENT_SOURCE_DIR} does not work.
>
> Thanks,
> -- Giovanni
>
>
> On Fri, Dec 9, 2016 at 4:17 PM, Chuck Atkins <chuck.atkins@kitware.com>
> wrote:
>
>> Hi Giovanni,
>> Does it work if you add lib1 as a private dependency of lib2?  i.e.:
>> target_link_libraries(lib2 PRIVATE lib1)
>>
>> Also, it shouldn't matter but what about in your original example if you
>> use the full path to the source file instead while still keeping the public
>> link dependency?  i.e.:
>> add_library(lib1-obj OBJECT $(CMAKE_CURRENT_SOURCE_DIR}/lib1.cpp).
>>
>> ----------
>> Chuck Atkins
>> Staff R&D Engineer, Scientific Computing
>> Kitware, Inc.
>>
>>
>> On Fri, Dec 9, 2016 at 5:26 AM, Giovanni Funchal <gio@cloudnc.co.uk>
>> wrote:
>>
>>> Hi,
>>>
>>> Apologies, the problem wasn't properly minimised because I had some
>>> trouble wrapping my head around it. Here's two complete examples which I
>>> hope can explain the problem better this time.
>>>
>>> 1) This works:
>>>
>>> [CMakeLists.txt]
>>>     cmake_minimum_required(VERSION 3.6)
>>>     project(Test)
>>>     add_library(lib1-obj OBJECT lib1.cpp)
>>>     add_library(lib1 INTERFACE)
>>>     set_target_properties(lib1 PROPERTIES INTERFACE_SOURCES
>>> $<TARGET_OBJECTS:lib1-obj>)
>>>     add_library(lib2 lib2.cpp)
>>>     target_link_libraries(lib2 lib1)
>>>     add_executable(main main.cpp)
>>>     target_link_libraries(main lib2)
>>>
>>> 2) But this does not:
>>>
>>> [CMakeLists.txt]
>>>     cmake_minimum_required(VERSION 3.6)
>>>     project(Test)
>>>     add_library(lib1-obj OBJECT lib1.cpp)
>>>     add_library(lib1 INTERFACE)
>>>     set_target_properties(lib1 PROPERTIES INTERFACE_SOURCES
>>> $<TARGET_OBJECTS:lib1-obj>)
>>>     add_library(lib2 lib2.cpp)
>>>     target_link_libraries(lib2 lib1)
>>>     add_subdirectory(main)
>>>
>>> [main/CMakeLists.txt]
>>>     add_executable(main main.cpp)
>>>     target_link_libraries(main lib2)
>>>
>>> With the second example, I get an error "cannot find source file
>>> lib1.cpp.o tried extensions...".
>>>
>>> Thanks,
>>> -- Giovanni
>>>
>>>
>>> On Thu, Dec 8, 2016 at 9:56 PM, Stephen Kelly <steveire@gmail.com>
>>> wrote:
>>>
>>>> Giovanni Funchal wrote:
>>>>
>>>> > Hi,
>>>> >
>>>> > The help page [1] mentions that:
>>>> >
>>>> >> Although object libraries may not be named directly in calls to the
>>>> >> target_link_libraries() command, they can be "linked" indirectly by
>>>> >> using an Interface Library whose INTERFACE_SOURCES target property
>>>> >> is set to name $<TARGET_OBJECTS:objlib>.
>>>> >
>>>> > However, I was unable to get this to work. Doing this:
>>>> >
>>>> > add_library(lib-obj OBJECT test.cpp)
>>>> > add_library(lib INTERFACE)
>>>> > add_dependencies(lib lib-obj)
>>>> > set_target_properties(lib PROPERTIES INTERFACE_SOURCES
>>>> > $<TARGET_OBJECTS:lib-obj>)
>>>> >
>>>> > And then trying to specify lib in link_libraries of an executable
>>>> yields
>>>> > an error message "Cannot find source file: ... Tried extensions:... ".
>>>> >
>>>> > Am I doing something wrong?
>>>>
>>>> This works for me:
>>>>
>>>>     cmake_minimum_required(VERSION 3.3)
>>>>
>>>>     project(testit CXX)
>>>>
>>>>     add_library(lib-obj OBJECT foo.cpp)
>>>>     add_library(lib-iface INTERFACE)
>>>>     set_target_properties(lib-iface PROPERTIES
>>>>       INTERFACE_SOURCES $<TARGET_OBJECTS:lib-obj>
>>>>     )
>>>>     add_executable(main foo-user.cpp)
>>>>     target_link_libraries(main lib-iface)
>>>>
>>>>
>>>> Thanks,
>>>>
>>>> Steve.
>>>>
>>>>
>>>> --
>>>>
>>>> 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:
>>>> http://public.kitware.com/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:
>>> http://public.kitware.com/mailman/listinfo/cmake
>>>
>>
>>
>

[Attachment #5 (text/html)]

<div dir="ltr">Hello,<div><br></div><div>Can someone confirm please if this is a bug \
and whether I should file a bug report?</div><div><br></div><div>Also, the \
&quot;PRIVATE&quot; workaround doesn&#39;t suit me (because it breaks transitivity of \
includes). Is there any other workaround I can use? I assume reverting to static \
libraries is the best thing to do in the \
meanwhile?<br></div><div><br></div><div>Thanks,</div><div>-- \
Giovanni</div><div><br></div><div class="gmail_extra"><br><div class="gmail_quote">On \
Fri, Dec 9, 2016 at 4:25 PM, Giovanni Funchal <span dir="ltr">&lt;<a \
href="mailto:gio@cloudnc.co.uk" target="_blank">gio@cloudnc.co.uk</a>&gt;</span> \
wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px \
#ccc solid;padding-left:1ex"><div dir="ltr">Hello,<div><br></div><div>PRIVATE works, \
but I don&#39;t understand why (the only difference between the two examples is using \
a subdirectory).</div><div><br></div><div>Using ${CMAKE_CURRENT_SOURCE_DIR} does not \
work.</div><div><br></div><div>Thanks,</div><div>-- Giovanni</div><div><div \
class="h5"><div><br></div><div class="gmail_extra"><br><div class="gmail_quote">On \
Fri, Dec 9, 2016 at 4:17 PM, Chuck Atkins <span dir="ltr">&lt;<a \
href="mailto:chuck.atkins@kitware.com" \
target="_blank">chuck.atkins@kitware.com</a>&gt;</span> wrote:<br><blockquote \
class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc \
solid;padding-left:1ex"><div dir="ltr"><div>Hi Giovanni,<br>Does it work if you add \
lib1 as a private dependency of lib2?   i.e.:<br><span \
style="font-family:monospace,monospace">target_link_libraries(lib2 PRIVATE \
lib1)</span><br><br>Also, it shouldn&#39;t matter but what about in your original \
example if you use the full path to the source file instead while still keeping the \
public link dependency?   i.e.:<br><span \
style="font-family:monospace,monospace">add_library(lib1-obj OBJECT \
$(CMAKE_CURRENT_SOURCE_DIR}/li<wbr>b1.cpp).</span><br></div><div \
class="gmail_extra"><br clear="all"><div><div \
class="m_-6185478862421270697m_5844174973165701670m_-5799557117749818928gmail_signature" \
data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div \
dir="ltr">----------<br>Chuck Atkins<br>Staff R&amp;D Engineer, Scientific \
Computing<br>Kitware, Inc.<br><br></div></div></div></div></div></div></div><div><div \
class="m_-6185478862421270697h5"> <br><div class="gmail_quote">On Fri, Dec 9, 2016 at \
5:26 AM, Giovanni Funchal <span dir="ltr">&lt;<a href="mailto:gio@cloudnc.co.uk" \
target="_blank">gio@cloudnc.co.uk</a>&gt;</span> wrote:<br><blockquote \
class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc \
solid;padding-left:1ex"><div dir="ltr">Hi,<div><br></div><div>Apologies, the problem \
wasn&#39;t properly minimised because I had some trouble wrapping my head around it. \
Here&#39;s two complete examples which I hope can explain the problem better this \
time.</div><div><br></div><div>1) This \
works:</div><div><br></div><div>[CMakeLists.txt]</div><div><div>      \
cmake_minimum_required(VERSION 3.6)</div><div>      project(Test)</div><div>      \
add_library(lib1-obj OBJECT lib1.cpp)<br></div><div>      add_library(lib1 \
INTERFACE)<br></div><div>      set_target_properties(lib1 PROPERTIES \
INTERFACE_SOURCES $&lt;TARGET_OBJECTS:lib1-obj&gt;)</div><div>      add_library(lib2 \
lib2.cpp)<br></div><div>      target_link_libraries(lib2 lib1)</div><div>      \
add_executable(main main.cpp)<br></div><div>      target_link_libraries(main \
lib2)</div></div><div><br></div><div>2) But this does \
not:</div><div><br></div><div><div>[CMakeLists.txt]</div><div></div><div>      \
cmake_minimum_required(VERSION 3.6)</div><div>      project(Test)</div><div>      \
add_library(lib1-obj OBJECT lib1.cpp)<br></div><div>      add_library(lib1 \
INTERFACE)<br></div><div>      set_target_properties(lib1 PROPERTIES \
INTERFACE_SOURCES $&lt;TARGET_OBJECTS:lib1-obj&gt;)</div><div>      add_library(lib2 \
lib2.cpp)<br></div><div>      target_link_libraries(lib2 lib1)</div><div>      \
add_subdirectory(main)<br></div></div><div><br></div><div>[main/CMakeLists.txt]</div><div><div> \
add_executable(main main.cpp)<br></div><div>      target_link_libraries(main \
lib2)</div></div><div><br></div><div>With the second example, I get an error \
&quot;cannot find source file lib1.cpp.o tried \
extensions...&quot;.</div><div><br></div><div>Thanks,</div><div>-- \
Giovanni</div><div><div \
class="m_-6185478862421270697m_5844174973165701670m_-5799557117749818928h5"><div><br></div><div \
class="gmail_extra"><br><div class="gmail_quote">On Thu, Dec 8, 2016 at 9:56 PM, \
Stephen Kelly <span dir="ltr">&lt;<a href="mailto:steveire@gmail.com" \
target="_blank">steveire@gmail.com</a>&gt;</span> wrote:<br><blockquote \
class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid \
rgb(204,204,204);padding-left:1ex"><span \
class="m_-6185478862421270697m_5844174973165701670m_-5799557117749818928m_3387639873968406080gmail-">Giovanni \
Funchal wrote:<br> <br>
&gt; Hi,<br>
&gt;<br>
&gt; The help page [1] mentions that:<br>
&gt;<br>
&gt;&gt; Although object libraries may not be named directly in calls to the<br>
&gt;&gt; target_link_libraries() command, they can be "linked" indirectly by<br>
&gt;&gt; using an Interface Library whose INTERFACE_SOURCES target property<br>
&gt;&gt; is set to name $&lt;TARGET_OBJECTS:objlib&gt;.<br>
&gt;<br>
&gt; However, I was unable to get this to work. Doing this:<br>
&gt;<br>
&gt; add_library(lib-obj OBJECT test.cpp)<br>
&gt; add_library(lib INTERFACE)<br>
&gt; add_dependencies(lib lib-obj)<br>
&gt; set_target_properties(lib PROPERTIES INTERFACE_SOURCES<br>
&gt; $&lt;TARGET_OBJECTS:lib-obj&gt;)<br>
&gt;<br>
&gt; And then trying to specify lib in link_libraries of an executable yields<br>
&gt; an error message &quot;Cannot find source file: ... Tried extensions:... \
&quot;.<br> &gt;<br>
&gt; Am I doing something wrong?<br>
<br>
</span>This works for me:<br>
<br>
      cmake_minimum_required(VERSION 3.3)<br>
<br>
      project(testit CXX)<br>
<br>
      add_library(lib-obj OBJECT foo.cpp)<br>
      add_library(lib-iface INTERFACE)<br>
      set_target_properties(lib-ifac<wbr>e PROPERTIES<br>
<span class="m_-6185478862421270697m_5844174973165701670m_-5799557117749818928m_3387639873968406080gmail-"> \
INTERFACE_SOURCES $&lt;TARGET_OBJECTS:lib-obj&gt;<br>  )<br>
</span>      add_executable(main foo-user.cpp)<br>
      target_link_libraries(main lib-iface)<br>
<br>
<br>
Thanks,<br>
<br>
Steve.<br>
<br>
<br>
--<br>
<br>
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 <br>--<br>
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 </blockquote></div><br></div></div></div></div>
</blockquote></div><br></div></div>

-- 

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