[CMake] How to link shared lib on windows (visual studio 2014).

[J Decker]

On Apr 25, 2016 6:41 PM, "J. Caleb Wherry" <calebwherry at gmail.com> wrote:
>
> (1)
>
> You typically want to define the entry point in the source itself. You
can use the 'CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS' in CMake but you usually do
something like this in the source:
>
> #ifdef WIN32
> #define PUBLIC_API __declspec(dllexport)
> #else
> #define PUBLIC_API
> #endif
>
> PUBLIC_API void HelloFunc();
>
> That way when you are building a shared lib on windows it will export
those symbols which in turn creates the .lib. Without the exported symbols,
you will not have an import lib.
>
> (2)
>
> The missing DLL is a pain that you are just going to have to deal with
unless you want to do a bunch of voodoo with the registry or copy the DLLs.
Typically, there are POST_BUILD steps that copy the needed DLLs into the
same directory as the exe. There are many stackoverflow questions dealing
with this, first one googled here:
>

Could just set the path environment variable... No registry hack.. Or
include install rules and just build install before running.
>
http://stackoverflow.com/questions/5765986/how-can-i-run-an-exe-with-dlls-in-separate-directory
>
> -Caleb
>
>
> On Mon, Apr 25, 2016 at 9:01 PM, Chaos Zhang <zcsd2012 at gmail.com> wrote:
>>
>> Hi,
>>
>> I faced this problem when i try built a shared lib  and linked it on
>> windows. The structure of my project as below:
>> -test_dir/
>>      -sub_hello/
>>            CMakeLists.txt
>>            hello.c
>>      -top/
>>            main.c
>>            CMakeLists.txt
>>      CMakeLists.txt
>>
>> The content of each file:
>> ①test_dir/CMakeLists.txt:
>> PROJECT(TESTLIB)
>> add_subdirectory(sub_hello sub_hello)
>> add_subdirectory(top top)
>>
>> ②test_dir/sub_hello/CMakeLists.txt:
>> message("message from sub_hello")
>> add_library(hello_lib  SHARED hello.c)
>>
>> ③test_dir/top/CMakeLists.txt:
>> include_directories(../sub_hello)
>> add_executable(main main.c)
>> target_link_libraries(main hello_lib)
>>
>> ④test_dir/sub_hello/hello.c：
>> #include <stdio.h>
>> void HelloFunc()
>> {
>>         printf("###hello###\n");
>> }
>>
>> ⑤test_dir/top/main.c:
>> int main()
>> {
>>         HelloFunc();
>>         return 0;
>> }
>>
>> After i cmake this project, generated .sln and .proj files, then i built
it
>> and i get an error in vs:
>>
>> Error   LNK1104 can't open file "..\sub_hello\Debug\hello_lib.lib"
>>
>> In folder ..\sub_hello\Debug\ , there was not a hello_lib.lib existed.
>> Then i look thorough and found a solution:
>>
>> Add "set(CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS YES)" in file
>> test_dir/sub_hello/hello.c
>>
>> Then i built this solution again, this time it success, and hello_lib.lib
>> and main.exe was generated. But when i try to run main.exe, an error
>> occured: "lose hello_lib.dll". And i moved hello_lib.dll into the folder
of
>> main.exe, and it worked well.
>>
>> There are two questions i could not figure out:
>> ①Is this "..\sub_hello\Debug\hello_lib.lib" associates with
>> "..\sub_hello\Debug\hello_lib.dll"? For windows can not use .dll
directly,
>> and use a .lib to record the .dll's  entrance and location.
>> ②How to solve the problem of main.exe can not find .dll file.
>>
>> Best regards,
>> Chao Zhang
>>
>>
>>
>>
>>
>> --
>> View this message in context:
http://cmake.3232098.n2.nabble.com/How-to-link-shared-lib-on-windows-visual-studio-2014-tp7593346.html
>> Sent from the CMake mailing list archive at Nabble.com.
>> --
>>
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>
>
>
>
> --
> J. Caleb Wherry
> Scientific Software Engineer
>
> http://www.calebwherry.com
> +1 (615) 708-5651
> calebwherry at gmail.com
>
> --
>
> 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:
>
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>
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