[cfe-dev] Clang (3.1 and 3.2): __attribute__((overloadable)) and enum types.

[Ólafur Waage]

// bleh.cpp
#include <iostream>

enum class One : int {DUMMY_1 = 1};
enum class Two : unsigned int {DUMMY_2 = 1};
enum class Three : char {DUMMY_3 = 1};

void foo(One)
{
    std::cout << "One" << std::endl;
}
void foo(Two)
{
    std::cout << "Two" << std::endl;
}
void foo(Three)
{
    std::cout << "Three" << std::endl;
}

int main()
{
    foo(One::DUMMY_1);
    foo(Two::DUMMY_2);
    foo(Three::DUMMY_3);
    return 0;
}

//

$ clang++ -std=c++11 bleh.cpp -o bleh
$ ./bleh
One
Two
Three


On Fri, Aug 2, 2013 at 12:57 PM, Ólafur Waage <olafurw at gmail.com> wrote:

> Since enums in C are just named integers, they are all of the same type.
> So it would be the same as doing three functions with int as the argument.
>
>
>
>
> On Fri, Aug 2, 2013 at 12:29 PM, Lizunov, Andrey E <
> andrey.e.lizunov at intel.com> wrote:
>
>>   Hello,****
>>
>> ** **
>>
>> I was trying to use  __attribute__((overloadable)) for functions
>> accepting enumerated types but hadn’t succeeded so far.****
>>
>> Clang 3.1 and 3.2 failed to compile the following example.****
>>
>> /* clang -x c foo.cpp */****
>>
>> typedef enum __One {DUMMY_1} One;****
>>
>> typedef enum {DUMMY_2} Two;****
>>
>> enum Three {DUMMY_3};****
>>
>> ** **
>>
>> __attribute__((overloadable)) void foo(One);****
>>
>> __attribute__((overloadable)) void foo(Two);****
>>
>> __attribute__((overloadable)) void foo(enum Three);****
>>
>> ** **
>>
>> int main()****
>>
>> {****
>>
>>   foo(DUMMY_1);****
>>
>>   return 0;****
>>
>> } ****
>>
>> Providing me with the following error message:****
>>
>> $ clang -x c foo.cpp****
>>
>> foo.cpp:22:3: error: call to 'foo' is ambiguous****
>>
>>   foo(DUMMY_1);****
>>
>>   ^~~****
>>
>> foo.cpp:16:36: note: candidate function****
>>
>> __attribute__((overloadable)) void foo(One);****
>>
>>                                    ^****
>>
>> foo.cpp:17:36: note: candidate function****
>>
>> __attribute__((overloadable)) void foo(Two);****
>>
>>                                    ^****
>>
>> foo.cpp:18:36: note: candidate function****
>>
>> __attribute__((overloadable)) void foo(enum Three);****
>>
>>                                    ^****
>>
>> 1 error generated.****
>>
>> While with “-x c++” both versions of Clang compiled it successfully
>> (failed to link though).****
>>
>> ** **
>>
>> According to
>> http://clang.llvm.org/docs/LanguageExtensions.html#function-overloading-in-coverloadable attribute is an analogue for C++ function overloading in C.
>> ****
>>
>> So, is it a bug in the Clang or I didn’t understand/consider something?**
>> **
>>
>> ** **
>>
>> ** **
>>
>> BR,****
>>
>> Andrey Lizunov****
>>
>> ** **
>>
>>
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