How to remove mangling in C++

Question

I tried to create a function which is returning a vector in C++. But when it built to dll, the function name seems to be mangled.

I tried to use the extern C but the problem is return type vector cannot support if I use extern C

Error : C Linkage function cannot return C++ class std:: Vector

Below is the code I am using

class __declspec(dllexport) TestClass
        {
        public:
            string sClassName;
            string sName;
            string sDescription;


        };


extern "C"
{
    vector<TestClass> __declspec(dllexport) GetInfoList();
}

C does not support a `vector`. Try removing the `extern "C"` part. — Eljay, Nov 19 '19 at 13:02
Why it is problem that C++ function names are mangled for linker? — Öö Tiib, Nov 19 '19 at 13:10
Removing extern c will result in name mangling. I am loading a dll dynamically and I want to call the function GetInfoList(). — Hari Sankar v m, Nov 19 '19 at 13:11
What compiler/platform are you using/targetting? Why do you need non-mangled names? — Adrian Mole, Nov 19 '19 at 13:12
Since I am dynamically loading he DLL, i have to access the function using function name GetProcAddress(hGetProcIDDLL, "GetInfoList"); — Hari Sankar v m, Nov 19 '19 at 13:13
You could try to mangle the names you pass to GetProcAddress instead of demangling your DLL. — gan_, Nov 19 '19 at 13:35
See https://stackoverflow.com/questions/16016732/is-there-a-way-to-find-the-c-mangled-name-to-use-in-getprocaddress — WilliamClements, Nov 19 '19 at 15:03
It smells that you are over-optimistic about what you can dream of cross-platforming. The std::vector using code in dll compiled with one compiler (say Visual Studio 2019) is not guaranteed to be compatible with std::vector compiled with some other compiler (say gcc of mingw-w64). Most likely it is not compatible at all. — Öö Tiib, Nov 19 '19 at 15:24
Which compiler are you using? Under MSVC 14.1, this is just a warning that can be silenced with `#pragma warning (suppress: 4190)` above your declaration. — Quentin, Nov 19 '19 at 15:27

score 2 · Answer 1 · answered Nov 19 '19 at 15:16

We see it is not problem with easy solution. Here's an involved solution. Use a non-mangled name (extern "C") with GetProcAddress to access a special function in the higher level DLL. . Define all the functions you want to call, as virtuals, in an abstract base class. Call that function above to retrieve the pointer P to a lazily instantiated concrete class with virtuals overriden. Invoke desired method through the pointer P.

score 1 · Accepted Answer · answered Jan 09 '20 at 09:45

vector is C++ type and so cannot be directly given under extern "C". Give the function inside a class and export the class as C Type.

extern "C"
{
    class __declspec(dllexport) ClassToExport
    {
        vector<TestClass> GetInfoList();
    };
}

Now use this class object to axcess the function.

How to remove mangling in C++

2 Answers2