Generated tests can contain cast to union of unnamed type

[IDKWNTCMF]

Description
If struct contains union of unnamed type, then in some cases generated tests can contain cast to union of unnamed type. Thus tests cannot be run.

Example

struct StructWithUnionOfUnnamedType {
    union {
        int x;
        struct {
            char c;
            double d;
        } ds;
        long long *ptr;
    } un;
};

struct StructWithUnionOfUnnamedType struct_with_union_of_unnamed_type_as_return_type(int a, int b) {
    struct StructWithUnionOfUnnamedType ans;
    if (a > b) {
        ans.un.ptr = 0;
    } else if (a < b) {
        ans.un.x = 153;
    } else {
        ans.un.ds.c = 'k';
        ans.un.ds.d = 1.0101;
    }
    return ans;
}

To Reproduce
Steps to reproduce the behavior:

1. Copy the example above in your project.
2. Generate tests for function struct_with_union_of_unnamed_type_as_return_type.
3. Try to run generated tests.

Expected behavior
Tests are supposed to be executed successfully.

Actual behavior
An error test is generated with information about errors.

Generated test

TEST(regression, struct_with_union_of_unnamed_type_as_return_type_test1)
{
    struct StructWithUnionOfUnnamedType actual = struct_with_union_of_unnamed_type_as_return_type(0, 0);
    struct StructWithUnionOfUnnamedType expected = {
        .un = from_bytes<StructWithUnionOfUnnamedType::StructWithUnionOfUnnamedType::(anonymous union at /home/utbot/UTBotCpp/integration-tests/c-example/lib/structures/structs/simple_structs.h:89:5)>({107, -85, -85, -85, -85, -85, -85, -85, -102, 8, 27, -98, 94, 41, -16, 63})
    };
}

Logs

/home/utbot/UTBotCpp/integration-tests/c-example/utbot_tests/makefiles/lib/structures/structs/../../../../../utbot_tests/lib/structures/structs/simple_structs_dot_c_test.cpp:17:86: error: expected unqualified-id
        .un = from_bytes<StructWithUnionOfUnnamedType::StructWithUnionOfUnnamedType::(anonymous union at /home/utbot/UTBotCpp/integration-tests/c-example/lib/structures/structs/simple_structs.h:89:5)>({107, -85, -85, -85, -85, -85, -85, -85, -102, 8, 27, -98, 94, 41, -16, 63})
                                                                                     ^
/home/utbot/UTBotCpp/integration-tests/c-example/utbot_tests/makefiles/lib/structures/structs/../../../../../utbot_tests/lib/structures/structs/simple_structs_dot_c_test.cpp:17:87: error: use of undeclared identifier 'anonymous'
        .un = from_bytes<StructWithUnionOfUnnamedType::StructWithUnionOfUnnamedType::(anonymous union at /home/utbot/UTBotCpp/integration-tests/c-example/lib/structures/structs/simple_structs.h:89:5)>({107, -85, -85, -85, -85, -85, -85, -85, -102, 8, 27, -98, 94, 41, -16, 63})
                                                                                      ^
2 errors generated.