[CMake] Weird linking error while cross compiling

Tue Nov 1 10:35:39 EDT 2011

On 10/28/2011 06:20 PM, Jose wrote:
> I give up. [...]

Never say die. ;)

> [...] I solved the problem with the solution Michael gave me. Actually
> this linking flag : -Bstatic
> was the causant of the troubles.

Out of curiosity: We've seen the failing link line; how does the
successful one look alike? Do you still use the -Bstatic flag?

> Nevertheless now I get undefined references to functions defined in the
> library "portablexdr" .
> 
> I have been trying to fix it for two days without success. The library is
> being linked and I have checked the content of the library with
> mingw32-nm and it has all the functions defined.
> 
> I have to say that I modified and rebuilt the library to include some
> functions that were not present ( portableXDR does not follow the Sun XDR
> standard). So I guess this is what it is
> causing me the troubles but It should not since I rebuilt it without
> problems and when I check the content of the library with nm the functions
> are there.
> 
> Any help??

Could you provide some more information, i.e. excerpts from the "make
VERBOSE=1" output and the concerned CMakeLists.txt files, especially
the latters' TARGET_LINK_LIBRARIES() commands? Ideally, you should
post a small self-contained example which demonstrates the issue.

Regards,

Michael

> 2011/10/26 Michael Hertling <mhertling at online.de>
> 
>> On 10/26/2011 10:28 AM, Andreas Pakulat wrote:
>>> On 26.10.11 03:54:02, Jose wrote:
>>>> Sorry for not being very specific.
>>>>
>>>> This is the command that Cmake is running while linking :
>>>>
>>>> /usr/bin/i686-pc-mingw32-g++  -O3 -O3    -Wl,-Bstatic -static-libgcc
>>>> -Wl,--whole-archive CMakeFiles/sqt2pin.dir/objects.a
>> -Wl,--no-whole-archive
>>>> -o sqt2pin.exe -Wl,--out-implib,libsqt2pin.dll.a
>>>> -Wl,--major-image-version,0,--minor-image-version,0
>>>> -L/home/fedora/percolator/percolator/src/converters/../../src
>>>> libconverters.a libperclibrary_part.a MSToolkit/libMSToolkit.a
>>>> MSToolkit/RAMP/libRAMP.a -lxerces-c -lportablexdr
>>>>
>> /home/fedora/percolator/percolator/src/converters/libs/dll/libtokyocabinet.a
>>>> -lz -lsqlite3 -Wl,-Bstatic -lkernel32 -luser32 -lgdi32 -lwinspool
>> -lshell32
>>>> -lole32 -loleaut32 -luuid -lcomdlg32 -ladvapi32
>>>> /usr/lib/gcc/i686-pc-mingw32/4.5.3/../../../../i686-pc-mingw32/bin/ld:
>>>> cannot find -lxerces-c
>>>> /usr/lib/gcc/i686-pc-mingw32/4.5.3/../../../../i686-pc-mingw32/bin/ld:
>>>> cannot find -lportablexdr
>>>> /usr/lib/gcc/i686-pc-mingw32/4.5.3/../../../../i686-pc-mingw32/bin/ld:
>>>> cannot find -lz
>>>> /usr/lib/gcc/i686-pc-mingw32/4.5.3/../../../../i686-pc-mingw32/bin/ld:
>>>> cannot find -lsqlite3
>>>>
>>>> That is weird cos I "load" all the libraries in the same way and they
>> all
>>>> the variables content the right paths to the libraries : (for example)
>>>>
>>>> Xercesc : /usr/i686-pc-mingw32/sys-root/mingw/lib/libxerces-c.dll.a ,
>> XDR :
>>>> /usr/i686-pc-mingw32/sys-root/mingw/lib/libportablexdr.dll.a
>>>>
>>>> This is how I link :
>>>>
>>>> #COMPILING SQT2PIN
>>>> include_directories(. MSToolkit/RAMP MSToolkit )
>>>> add_executable(sqt2pin Sqt2Pin.cpp )
>>>> IF(STATIC AND MINGW)
>>>>   set_property(TARGET sqt2pin PROPERTY LINK_SEARCH_END_STATIC ON)
>>>>   set_target_properties(sqt2pin PROPERTIES LINK_FLAGS "-Wl,-Bstatic
>>>> -static-libgcc")
>>>> ENDIF()
>>>> message(STATUS "Xercesc : ${XERCESC_LIBRARIES} , XDR :
>>>> ${PORTABLEXDR_LIBRARIES}")
>>>> target_link_libraries(sqt2pin converters perclibrary_part  MSToolkit
>> RAMP
>>>> ${XERCESC_LIBRARIES} ${PORTABLEXDR_LIBRARIES} ${TOKYOCABINET_LIBRARIES}
>> )
>>>>
>>>> I might  be missing something very stupid because I use the same
>> prodecure
>>>> to search for the librarys....the FindXXX.cmake macros that are tested
>> and
>>>> working with other programs.
>>>>
>>>> Could it be the include_directories("library include dir") which is
>> messing
>>>> this up? it looks like the linker disregard the path of the library that
>> Im
>>>> pasinng and looks for -lxerces-c instead. Is that xerces-c defined
>> somehow
>>>> before?
>>>
>>> This happens if the library is considered to be in a 'system path' since
>>> in that case specifying the path is not necessary for the linker to find
>>> it. However in your specific case it seems like cmake does this even for
>>> static libraries, which is of course wrong. I'd suggest to file a
>>> bugreport for this with a small self-contained example.
>>>
>>> Andreas
>>
>> The -l switch of ld is not related to the library's type, i.e.
>> shared or static; see ld's manpage and the following example:
>>
>> CMAKE_MINIMUM_REQUIRED(VERSION 2.8 FATAL_ERROR)
>> PROJECT(STATIC C)
>> SET(CMAKE_VERBOSE_MAKEFILE ON)
>> FILE(WRITE ${CMAKE_BINARY_DIR}/f.c "int f(void){return 0;}\n")
>> EXECUTE_PROCESS(COMMAND ${CMAKE_C_COMPILER} -c f.c)
>> EXECUTE_PROCESS(COMMAND ${CMAKE_AR} cr libf.a f.o)
>> FILE(WRITE ${CMAKE_BINARY_DIR}/main.c "int main(void){return f();}\n")
>> ADD_EXECUTABLE(main main.c)
>> TARGET_LINK_LIBRARIES(main -L${CMAKE_BINARY_DIR} f /usr/lib/libz.a)
>>
>> The executable "main" is linked against the static libf.a via the -l
>> switch. Usually, in particular on ELF systems, ld just prefers shared
>> libraries with -l unless it is told to not do so, e.g. using -Bstatic.
>> However, MinGW's ld behaves differently in this regard; IIRC, it even
>> prefers static and import libraries to shared ones with the -l switch.
>>
>> BTW, /usr/lib/libz.a is converted into -Wl,-Bstatic -lz -Wl,-Bdynamic
>> due to /usr/lib being a system directory, i.e. CMake performs this -l
>> conversion of full paths in system directories for static libraries,
>> too; why should it be called wrong?
>>
>> Jose, could you find out which directories CMake considers as system
>> directories and if these are actually searched implicitly by ld? If
>> CMake takes /usr/i686-pc-mingw32/sys-root/mingw/lib as system dir,
>> thus libxerces-c.dll.a --> -lxerces-c, but ld does not search it
>> without a proper -L switch, the issue would be quite clear. As
>> a quick workaround, you might use imported targets for the
>> concerned libraries to avoid the -l conversion, i.e.:
>>
>> ADD_LIBRARY(xerces-c STATIC IMPORTED)
>> SET_TARGET_PROPERTIES(xerces-c PROPERTIES IMPORTED_LOCATION
>>    /usr/i686-pc-mingw32/sys-root/mingw/lib/libxerces-c.dll.a)
>> TARGET_LINK_LIBRARIES(... xerces-c ...)
>>
>> 'hope that helps.
>>
>> Regards,
>>
>> Michael