[CMake] Link order (Ubuntu)

[Giorgio Scorzelli]

Thanks for you help.

They are really shared lib, not static. I know it sounds weird: it's a
python extension which must not link the ${PYTHON_LIBRARY}  (according to
official docs; in fact If I do so I get a segmentation fault) but finally
in my executable,a sort of custom/home made  ${PYTHON_EXECUTABLE}, I have
to link the ${PYTHON_LIBRARY}.

About the "B;A;ImportedExtLib;B;A" order. I agree too: it SHOULD work.
Let's say I do:

target_link_libraries(MyExe B A ImpLib)

in command line (make VERBOSE=1) I;m getting

g++ .... -o MyExe B A ImpLib A

The last "A" is coming from target_link_libraries(B PUBLIC A) and the
linker  is complaining that this last "A" has undefined symbols.

Thanks.Giorgio.








Il giorno mar 6 nov 2018 alle ore 06:59 Robert Maynard <
robert.maynard at kitware.com> ha scritto:

> You have order dependent static libraries which can be solved by
> constructing a cycle. As Bo stated by constructing the cycle
> B;A;ImportedExtLib;B;A each library can see each other.
>
> Looking at your original code example it looks like you are importing
> the libraries as SHARED, but I think these are actually static
> libraries and should be imported as such so that CMake does the
> automatic cycle creation. In general CMake doesn't do cycle creation
> for shared libraries as they are not link order dependent.
> On Tue, Nov 6, 2018 at 8:51 AM Giorgio Scorzelli <scrgiorgio at gmail.com>
> wrote:
> >
> > I read the docs about  LINK_INTERFACE_MULTIPLICITY    too.
> > But I'm not in the situation of a "cyclic dependency" so I 'm not sure
> if it solve my problem.
> > In my case (with B A and ImpLib) what would be the syntax?
> >
> > Il giorno mar 6 nov 2018 alle ore 06:30 Robert Maynard <
> robert.maynard at kitware.com> ha scritto:
> >>
> >> The target_link_libraries has a property called
> >> LINK_INTERFACE_MULTIPLICITY that should help you out.
> >>
> https://cmake.org/cmake/help/v3.13/command/target_link_libraries.html#cyclic-dependencies-of-static-libraries
> >>
> >>
> >> On Tue, Nov 6, 2018 at 8:24 AM scrgiorgio <scrgiorgio at gmail.com> wrote:
> >> >
> >> > Thanks for the help,
> >> >
> >> > trying this (or any combination):
> >> >
> >> > target_link_libraries(MyExe B)
> >> > target_link_libraries(MyExe A )
> >> > target_link_libraries(MyExe ImpLib)
> >> >
> >> > I get this order:
> >> >
> >> > 'B;...whatever...;A;ImpLib"
> >> >
> >> > and the last past is causing the problem. Apparently there is no way
> to
> >> > change the right part (-Wl,--start-group -Wl,--end-groun sometimes
> work,
> >> > sometimes not).
> >> > Any advice?
> >> >
> >> >
> >> >
> >> >
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