Strange warning with ld

Question

I received this warning from ld whe I was buliding my program:

ld: warning: direct access in global constructors keyed to _ZN12_GLOBAL__N_143ensure_log_is_created_before_maing_l_filterEto global weak symbol vtable for cs::ObjectFactoryAliasInstantiation<cs::DefaultCommandDispatcher> means the weak symbol cannot be overridden at runtime. This was likely caused by different translation units being compiled with different visibility settings.

The code witch refer the error is this:

class ObjectFactory {
        public :
        ObjectFactory(const char *alias):sAlias(alias){};
        std::string sAlias;
        virtual void* createInstance() = 0;
    };

template <class T>
class ObjectFactoryAliasInstantiation : public ObjectFactory{
public:
    ObjectFactoryAliasInstantiation(const char *alias):ObjectFactory(alias){};
    void* createInstance() { return (void*)new T(&sAlias); };
};`

and this:

        /*
         Class for register the dispatcher for the command
         */
    class CommandDispatcherRegister {  
    public:
        CommandDispatcherRegister(ObjectFactory *commandFactory);
    };

    /*
     Macro for help the Command Dispatcher classes registration
     */
#define REGISTER_AND_DEFINE_COMMAND_DISPATCHER_CLASS(CMD_CLASS_NAME)  class CMD_CLASS_NAME;\
static const CommandDispatcherRegister CMD_CLASS_NAME ## CommandDispatcherRegister(new ObjectFactoryAliasInstantiation<CMD_CLASS_NAME>(#CMD_CLASS_NAME));\
class CMD_CLASS_NAME : public CommandDispatcher\

end this:

 REGISTER_AND_DEFINE_COMMAND_DISPATCHER_CLASS(DefaultCommandDispatcher) {
        bool deinitialized;

And `This was likely caused by different translation units being compiled with different visibility settings` is not hinting to what to check? — PlasmaHH, Oct 16 '11 at 17:52
the first thing i have i had think was the #pragma GCC visibility but i don't have this. — Claudio Bisegni, Oct 16 '11 at 18:26
@ClaudioBisegni: And thats the only way to influence visibility? — PlasmaHH, Oct 16 '11 at 18:30
not also the public, protected and private on class derivation syntax — Claudio Bisegni, Oct 16 '11 at 18:31
public/protected/private doesn't influence weakness of symbols, just accessibilty at compile time — bdonlan, Oct 16 '11 at 18:33
Can you show any of the code for `ensure_log_is_created_before_maing_l_filter` or `cs::ObjectFactoryAliasInstantiation`? — bdonlan, Oct 16 '11 at 18:35
@ClaudioBisegni, basically just templates and explicit annotations, really — bdonlan, Oct 16 '11 at 18:35
gcc version 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2336.1.00) — Claudio Bisegni, Oct 16 '11 at 18:40
hmm, gcc-llvm? interesting. Try compiling this on the same settings, see if it gives the same warning: http://codepad.org/AlYrfxuN If it does, please post the assembly code output (ie, build with `-S -o test.s`, plus any other flags you pass to the main compile, and post the contents of `test.s`) — bdonlan, Oct 16 '11 at 18:41
@ClaudioBisegni, C++ code must be built using `g++`, not `gcc` — bdonlan, Oct 16 '11 at 18:49
@ClaudioBisegni, are you building your main program as a shared library? — bdonlan, Oct 16 '11 at 19:19
i build a static library that contain the code showed upper. Then i compiled a main with that library. anyway i try to compile the code on linux machine with gcc version 4.1.2 20080704 (Red Hat 4.1.2-50) and i get no warning with the same scons script — Claudio Bisegni, Oct 16 '11 at 19:46

score -2 · Answer 1 · answered Oct 16 '11 at 17:13

-2

This was likely caused by different translation units being compiled with different visibility settings.

i.e. you changed some headers and didn't do a full re-build of your whole project. Do that now.

answered Oct 16 '11 at 17:13

Lightness Races in Orbit

378,754
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1,055

i used also scons to be my project(i work with Xcode but distribute it with scons) and i receive this warning also if i run scons -c and then scones. Anyway i'll try again – Claudio Bisegni Oct 16 '11 at 17:24
1

that's not the warning you'd get from changing a header but from compiling targets with non-matching -fvisibility settings. see http://stackoverflow.com/a/9954259/48125 – nevyn Jul 03 '12 at 12:58

Strange warning with ld

1 Answers1