[CMake] CMAKE_EXE_LINKER_FLAGS for shared libraries?
David Cole
david.cole at kitware.com
Tue Dec 13 15:21:05 EST 2011
On Tue, Dec 13, 2011 at 2:09 PM, Robert Dailey <rcdailey at gmail.com> wrote:
> Thanks for the info. It's a bit disappointing that it doesn't work like I
> expect. The CMAKE_MFC_FLAG should work as you say the link flags should, but
> it does not. As long as CMAKE_MFC_FLAG is set before I create my target, it
> works. Since CMAKE_SHARED_LINK_FLAGS does not work the same, I consider this
> a bug. There is no reason for it to exist up to the end of the file... it
> should only exist up to the call to create the target. For example, if I
> want to have 2 calls to add_library() in the same file, but specify link
> flags differently for each, how am I expected to do this without using the
> target specific property?
You're not expected to do that. You should use the target property in
that case. That's what they're there for.
Or use sub-directory organization to have one target per sub-dir, and
then set the variable appropriately in each sub-dir's CMakeLists file.
And, there is a reason for it to exist up to the end of the file: it's
called backwards compatibility, and we take it pretty seriously.
The fact is that some variables are examined at configure-time, while
CMake is processing add_executable and add_library calls, and all the
other myriad commands that are affected by variables values, ...
... and some variables are examined later at generate-time, *after*
CMake is done processing the commands, (in other words, "at the end of
the file").
So: this particular case may be considered a bug by some, and a
feature by others. Personally, I'm not sure what side of that fence to
fall on.
However, the primary purpose of this mailing list is to try to show
you how you can do what you want to do with *existing* CMake. We also
like to discuss options and future plans here.
If you would like to report this as a bug, please feel free to add a
bug report to the bug tracker.
Thanks,
David
>
> ---------
> Robert Dailey
>
>
>
> On Mon, Dec 12, 2011 at 11:26 PM, Michael Wild <themiwi at gmail.com> wrote:
>>
>> It needs to exist **at the end** of the CMakeLists.txt file containing
>> the target. If you don't want to do that (or can't, as in your case),
>> you can use the LINK_FLAGS target property instead.
>>
>> HTH
>>
>> Michael
>>
>> On 12/12/2011 11:39 PM, Robert Dailey wrote:
>> > I have attached a small CMake project that reproduces the issue I'm
>> > referring to. Please take a look :)
>> >
>> > ---------
>> > Robert Dailey
>> >
>> >
>> > On Mon, Dec 12, 2011 at 4:11 PM, Robert Dailey <rcdailey at gmail.com
>> > <mailto:rcdailey at gmail.com>> wrote:
>> >
>> > I forgot to say that the main issue is that my /NODEFAULTLIB link
>> > flag isn't showing up in visual studio.
>> >
>> > ---------
>> > Robert Dailey
>> >
>> >
>> >
>> > On Mon, Dec 12, 2011 at 4:10 PM, Robert Dailey <rcdailey at gmail.com
>> > <mailto:rcdailey at gmail.com>> wrote:
>> >
>> > Another issue...
>> >
>> > At what point is it most important for the values of
>> > CMAKE_SHARED_LINK_FLAGS to exist? I set the value of this
>> > variable before my call to add_library(), however after that at
>> > some point the flags will get reverted because I'm stepping out
>> > of function scope. Does it need to exist up to the end of the
>> > current cmake script? My flow is basically this (pseudo call
>> > stack):
>> >
>> > Enter CMakeLists.txt
>> > - Call define_project() function (in a separate cmake module)
>> > - - Call ignore_libs() function
>> > - - - Set CMAKE_SHARED_LINK_FLAGS with PARENT_SCOPE
>> > - - Call create_target() function
>> > - - - Call add_library() command
>> > Leave CMakeLists.txt
>> >
>> > I've done some testing and I find that before the call to
>> > add_library(), my flags are setup properly in the
>> > CMAKE_SHARED_LINK_FLAGS variable.
>> >
>> > ---------
>> > Robert Dailey
>> >
>> >
>> >
>> > On Mon, Dec 12, 2011 at 2:20 PM, Michael Wild <themiwi at gmail.com
>> > <mailto:themiwi at gmail.com>> wrote:
>> >
>> > On 12/12/2011 09:13 PM, Robert Dailey wrote:
>> > > On Mon, Dec 12, 2011 at 2:10 PM, David Cole
>> > <david.cole at kitware.com <mailto:david.cole at kitware.com>
>> > > <mailto:david.cole at kitware.com
>> > <mailto:david.cole at kitware.com>>> wrote:
>> > >
>> > > Apparently, they are undocumented, but there are also:
>> > >
>> > > CMAKE_SHARED_LINKER_FLAGS and
>> > CMAKE_MODULE_LINKER_FLAGS (and their
>> > > per-config variants) for SHARED and MODULE library
>> > targets as well.
>> > >
>> > > Use CMAKE_SHARED_LINKER_FLAGS instead.
>> > >
>> > >
>> > > Thanks for the information guys. I'm having a minor
>> > problem with these
>> > > variables though.
>> > >
>> > > Here is how I use it:
>> > >
>> > > set( CMAKE_SHARED_LINKER_FLAGS
>> > ${CMAKE_SHARED_LINKER_FLAGS}
>> > > /NODEFAULTLIB:\"${lib}\" )
>> > >
>> > > Prior to calling the set above, the shared linker flags
>> > look like this:
>> > >
>> > > /STACK:10000000 /machine:X86
>> > >
>> > > After calling the set above, it looks like this:
>> > >
>> > > /STACK:10000000 /machine:X86 ;/NODEFAULTLIB:"LIBC"
>> > >
>> > > For some reason a semi-colon is being inserted prior to
>> > the
>> > > /NODEFAULTLIB part. I don't know why this is happening but
>> > visual studio
>> > > is complaining about it. Any reason why this is happening?
>> > Thanks.
>> > >
>> >
>> > That's how CMake works.
>> >
>> > set(VAR val1 val2 val3)
>> >
>> > defines a *list* where the elements are separated by a
>> > semi-colon (;).
>> > To prevent that, quote the assignment:
>> >
>> > set(VAR "val1 val2 val3")
>> >
>> >
>> > Michael
>> >
>> > --
>> >
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>> >
>> > Visit other Kitware open-source projects at
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>> >
>> > Please keep messages on-topic and check the CMake FAQ at:
>> > http://www.cmake.org/Wiki/CMake_FAQ
>> >
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>> >
>> >
>> >
>> >
>>
>
>
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