[CMake] How to add -fPIC to a static library?

[Steve Lorimer]

Thanks Nicholas, you are indeed correct!

On 28 August 2016 at 17:35, Nicholas Braden <nicholas11braden at gmail.com>
wrote:

> Have you tried set_property(TARGET cpp-netlib_pic PROPERTY
> POSITION_INDEPENDENT_CODE ON)? I think you must specify the value ON
> for it to work.
>
> On Sun, Aug 28, 2016 at 4:28 PM, Steve Lorimer <steve.lorimer at gmail.com>
> wrote:
> > I'm trying to create a static library with -fPIC specified.
> >
> > add_library(cpp-netlib_pic
> >     STATIC
> >     ${SRCS})
> > set_property(TARGET cpp-netlib_pic PROPERTY POSITION_INDEPENDENT_CODE)
> >
> > This doesn't work.
> >
> > The library (cpp-netlib_pic) is built without the -fPIC flags.
> >
> > Other targets which link against cpp-netlib_pic have -fPIC added to their
> > compiler flags, but the linking fails because cpp-netlib_pic didn't.
> >
> > Here foo will have -fPIC added:
> >
> > add_library(foo
> >     SHARED
> >     ${SRCS})
> > target_link_libraries(foo cpp-netlib_pic)
> >
> >
> > I've proved this to myself with make VERBOSE=1
> >
> > [ 87%] Building CXX object
> > third_party/cpp-netlib/CMakeFiles/cpp-netlib_pic.dir/
> src/server_request_parsers_impl.cpp.o
> >
> > /usr/bin/c++   ... -std=c++14 -Werror -Wall -Wextra ... -o
> > CMakeFiles/cpp-netlib_pic.dir/src/server_request_parsers_impl.cpp.o -c
> > .../third_party/cpp-netlib/src/server_request_parsers_impl.cpp
> >
> > Note no -fPIC here.
> >
> > When building a target which uses cpp-netlib_pic -fPIC appears:
> >
> > [ 93%] Building CXX object foo.cc.o
> > /usr/bin/c++  ... -std=c++14 -Werror -Wall -Wextra ... -fPIC ... -o
> > CMakeFiles/foo_shared_lib.dir/foo.cc.o -c .../foo/foo.cc
> >
> > How can I configure CMake to build the 1st library (cpp-netlib_pic) with
> > -fPIC?
> >
> > --
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