Problem: cross-compiling czmq with fails

[sappo]

Hi,
when I cross-compile czmq with MXE to mingw32 the compilation fails.

I use the following setup to configure czmq. The libzmq build is at ~/workspace/zeromq/cross_x86_64

$ PKG_CONFIG_PATH_x86_64_w64_mingw32="~/workspace/zeromq/cross_x86_64/lib/pkgconfig" ./configure --host=x86_64-w64-mingw32 --prefix=~/workspace/zeromq/cross_x86_64  --with-libzmq=~/workspace/zeromq/cross_x86_64

This is the result when I run make now.

$ make
...
  CC     src/src_libczmq_la-zactor.lo
In file included from src/../include/czmq.h:19:0,
                 from src/zactor.c:34:
src/../include/czmq_prelude.h:459:1: error: unknown type name 'uint64_t'
src/zactor.c:100:1: error: 'zactor_new' redeclared without dllimport attribute: previous dllimport ignored [-Werror=attributes]
src/zactor.c:152:1: error: 'zactor_destroy' redeclared without dllimport attribute after being referenced with dll linkage [-Werror]
src/zactor.c:179:1: error: 'zactor_send' redeclared without dllimport attribute: previous dllimport ignored [-Werror=attributes]
src/zactor.c:191:1: error: 'zactor_recv' redeclared without dllimport attribute: previous dllimport ignored [-Werror=attributes]
src/zactor.c:201:1: error: 'zactor_is' redeclared without dllimport attribute after being referenced with dll linkage [-Werror]
src/zactor.c:214:1: error: 'zactor_resolve' redeclared without dllimport attribute: previous dllimport ignored [-Werror=attributes]
src/zactor.c:229:1: error: 'zactor_sock' redeclared without dllimport attribute: previous dllimport ignored [-Werror=attributes]
src/zactor.c:276:1: error: 'zactor_test' redeclared without dllimport attribute: previous dllimport ignored [-Werror=attributes]
cc1: all warnings being treated as errors
make[1]: *** [src/src_libczmq_la-zactor.lo] Error 1
make[1]: Leaving directory `/home/ksapper/Workspace/zeromq/czmq'
make: *** [all-recursive] Error 1

[evoskuil]

I just fixed up some issues in the VS builds. One of them might have been causing the dllimport errors on mingw. See f0b4801.

There remain two unresolved externals from the test build remaining in the VS builds. I can never seem to locate where the self-tests are exported.

czmq_selftest.obj : error LNK2019: unresolved external symbol _zgossip_test referenced in function _main
czmq_selftest.obj : error LNK2001: unresolved external symbol _zsys_allocs

Notice however that the second error is on zsys_allocs, which is in the same place as the first error you are seeing, on this line:

extern volatile uint64_t zsys_allocs;

Apparently uint64_t isn't defined in the mingw configuration, although it is in the VS build.

[sappo]

The uint64_t is only defined if mingw32 is not 428:# if (!defined (__MINGW32__)).

Sadly your pull request didn't fix the dllimport errror on mingw.

[evoskuil]

I've patched the VS unresolved externals mentioned above, see #821. I don't see anything wrong with zactor. Seems like there's something extraneous in the mingw build.

[pijyoi]

I got a bit further in the compilation, past the dllimport error:

CFLAGS=-DLIBCZMQ_EXPORTS PKG_CONFIG_PATH_i686_pc_mingw32=$HOME/mingw32/lib/pkgconfig ./configure --prefix=$HOME/mingw32 --host=i686-pc-mingw32

According to czmq_prelude.h, nowadays FD_SETSIZE is automatically set to 1024, so we no longer need to include it in CFLAGS.

[pijyoi]

Apart from fixing some warnings in ziflist.c, two more flags are needed before the ./configure line.
LDFLAGS="-L$HOME/mingw32/lib" LIBS="-lzmq"

Not sure why these aren't automatic anymore.

[sappo]

@pijyoi that is just awfully complicated :(

If I fix the warnings in ziflist.c I do get the following error:

  CCLD     src/libczmq.la
src/.libs/src_libczmq_la-zbeacon.o:zbeacon.c:(.text+0x2e0): undefined reference to `__imp_inet_addr'
src/.libs/src_libczmq_la-zbeacon.o:zbeacon.c:(.text+0x2fb): undefined reference to `__imp_inet_addr'
src/.libs/src_libczmq_la-zbeacon.o:zbeacon.c:(.text+0x38b): undefined reference to `__imp_htons'
src/.libs/src_libczmq_la-zbeacon.o:zbeacon.c:(.text+0x3e5): undefined reference to `__imp_bind'
src/.libs/src_libczmq_la-zbeacon.o:zbeacon.c:(.text+0x434): undefined reference to `__imp_getnameinfo'
/usr/bin/x86_64-w64-mingw32-ld: src/.libs/src_libczmq_la-zbeacon.o: bad reloc address 0x0 in section `.pdata'
collect2: error: ld returned 1 exit status
make[1]: *** [src/libczmq.la] Error 1
make[1]: Leaving directory `/mnt/DataStorage/workspace/zeromq/czmq'
make: *** [all-recursive] Error 1

Can you confirm this error or does czmq compile correctly with your configure modifications.

[pijyoi]

Yes, I got the same. There's another comment I left about the extra flags
needed. Even uglier.
On 22 Nov 2014 02:13, "Kevin Sapper" notifications@github.com wrote:

@pijyoi https://github.com/pijyoi that is just awfully complicated :(

If I fix the warnings in ziflist.c I do get the following error:

CCLD src/libczmq.la
src/.libs/src_libczmq_la-zbeacon.o:zbeacon.c:(.text+0x2e0): undefined reference to __imp_inet_addr' src/.libs/src_libczmq_la-zbeacon.o:zbeacon.c:(.text+0x2fb): undefined reference to__imp_inet_addr'
src/.libs/src_libczmq_la-zbeacon.o:zbeacon.c:(.text+0x38b): undefined reference to __imp_htons' src/.libs/src_libczmq_la-zbeacon.o:zbeacon.c:(.text+0x3e5): undefined reference to__imp_bind'
src/.libs/src_libczmq_la-zbeacon.o:zbeacon.c:(.text+0x434): undefined reference to __imp_getnameinfo' /usr/bin/x86_64-w64-mingw32-ld: src/.libs/src_libczmq_la-zbeacon.o: bad reloc address 0x0 in section.pdata'
collect2: error: ld returned 1 exit status
make[1]: *** [src/libczmq.la] Error 1
make[1]: Leaving directory `/mnt/DataStorage/workspace/zeromq/czmq'
make: *** [all-recursive] Error 1

Can you confirm this error or does czmq compile correctly with your
configure modifications.

Reply to this email directly or view it on GitHub
#819 (comment).

[sappo]

If I extend the LDFLAGS even further, it finally compiles:

LDFLAGS="-L$(MXE_HOME)/usr/x86_64-w64-mingw32/lib -lws2_32 -liphlpapi -lrpcrt4"

[pijyoi]

I thought master had since been patched so that LDFLAGS was no longer
required.

But even before the patch, the libs I need to add were only ws2_32 and zmq.
On 26 Nov 2014 01:07, "Kevin Sapper" notifications@github.com wrote:

If I extend the LDFLAGS even further, it finally compiles:

LDFLAGS="-L$(MXE_HOME)/usr/x86_64-w64-mingw32/lib -lws2_32 -liphlpapi -lrpcrt4"

Reply to this email directly or view it on GitHub
#819 (comment).

[sappo]

I guess this is due to the different hosts x86_64-w64-mingw32 vs i686_pc_mingw32.

[sappo]

@pijyoi are you currently able to cross compile libzmq with i686_pc_mingw32 because I do get the following error:

/home/ksapper/Workspace/zeromq/libzmq/tools/curve_keygen.cpp:42: undefined reference to `_imp__zmq_curve_keypair'
/home/ksapper/Workspace/zeromq/libzmq/tools/curve_keygen.cpp:43: undefined reference to `_imp__zmq_errno'

[pijyoi]

Yes, libzmq master compiles nicely.
./configure --prefix=$HOME/mingw32 --host=i686-pc-mingw32

For CZMQ, it's:
CFLAGS="-DLIBCZMQ_EXPORTS -D__USE_MINGW_ANSI_STDIO"
PKG_CONFIG_PATH_i686_pc_mingw32=$HOME/mingw32/lib/pkgconfig ./configure
--prefix=$HOME/mingw32 --host=i686-pc-mingw32

The __USE_MINGW_ANSI_STDIO allows the compilation to not warn (and fail)
when coming across C99 %zu format specifier that was used in ziflist.c

On Wed, Nov 26, 2014 at 8:09 PM, Kevin Sapper notifications@github.com
wrote:

@pijyoi https://github.com/pijyoi are you currently able to cross
compile libzmq with i686_pc_mingw32 because I do get the following error:

/home/ksapper/Workspace/zeromq/libzmq/tools/curve_keygen.cpp:42: undefined reference to _imp__zmq_curve_keypair' /home/ksapper/Workspace/zeromq/libzmq/tools/curve_keygen.cpp:43: undefined reference to_imp__zmq_errno'

Reply to this email directly or view it on GitHub
#819 (comment).

[pijyoi]

Looking at libtool, it has the following: pic_flag = " -DDLL_EXPORT -DPIC"
That explains why CZMQ needs -DLIBCZMQ_EXPORTS but libzmq doesn't.
i.e. As far as libtool is concerned, the standard define to use is DLL_EXPORT.

commit 5dc41fe dated 2013-04-08 changed testing against DLL_EXPORT to testing against LIBCZMQ_EXPORTS.

If the current behaviour is surprising for the unwary, perhaps we could do something like
#ifdef DLL_EXPORT
#define LIBCZMQ_EXPORTS
#endif