MSVC功能分解

Question

I have next functions:

namespace TEST {
    class TEST {
        int a;
        int b;
    };
}

namespace UNION_TEST {
    union UNION_TEST {
        int a;
        int b;
    };
}

union UNION_TEST_NEW {
    int a;
    int b;
};

namespace NAMESPACE_1 {
    namespace NAMESPACE_2 {
        union UNION_NAMESPACE_2 {
            int a, b;
        };
    }
}


void f1(UNION_TEST::UNION_TEST t, UNION_TEST::UNION_TEST t1) {
    return;
}

void f2(UNION_TEST::UNION_TEST t, TEST::TEST c, UNION_TEST::UNION_TEST t1) {
    return;
}

void f3(UNION_TEST_NEW u) {
    return;
}

void f4(NAMESPACE_1::NAMESPACE_2::UNION_NAMESPACE_2 u, TEST::TEST c, UNION_TEST::UNION_TEST t1) {
    return;
}

And correspond mangled symbols are:

0x000034e0  2  .text  ?f1@@YAXTUNION_TEST@1@0@Z
0x00003500  2  .text  ?f2@@YAXTUNION_TEST@1@VTEST@2@0@Z
0x00003520  2  .text  ?f3@@YAXTUNION_TEST_NEW@@@Z
0x00003530  2  .text  ?f4@@YAXTUNION_NAMESPACE_2@NAMESPACE_2@NAMESPACE_1@@VTEST@4@TUNION_TEST@5@@Z

Accroding to this http://www.agner.org/optimize/calling_conventions.pdf (page 27) we have that union X -> TX@@, so why for the function f1, f2 there is no @@ at the end and how than distiguish when union with namespace is end and start next argument?

Thank U for attention and help.

Answer 1

As you observed, the claim that a union name X is transformed to TX@@ is not a correct description of the name mangling used by your MSVC version. Note that "agner.org" is not associated with Microsoft, and doesn't provide official documentation.

As for your question how the different parts of a mangled name are separated, it appears that a single @ is sufficient.