llvm dev - May 2016 - Non-void function does not return value

Hi Chandler,
I scanned the LLVM source code, and found some potential code issues, take the
piece of code in file './include/llvm/Support/Allocator.h' for example:


80

  /// \brief Deallocate space for a sequence of objects without constructing
them.

81

  template <typename T>

82

  typename std::enable_if<

83

      !std::is_same<typename std::remove_cv<T>::type, void>::value,
void>::type

84

[https://otckw.jf.intel.com:8080/review/review/images/folding/collapse_top.png]

  Deallocate(T *Ptr, size_t Num = 1) {

85

    Deallocate(static_cast<const void *>(Ptr), Num * sizeof(T));

86

[https://otckw.jf.intel.com:8080/review/review/images/folding/collapse_bottom.png]

  }



If the typename T is void, the std::is_same will be FALSE, which means the
std::enable_if::type is UNDEFIED.
So do you think it need a fix?
Thanks.


Luo Xionghu
Best Regards

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I think this is the intended use of enable_if, no?

http://en.cppreference.com/w/cpp/types/enable_if
"This metafunction is a convenient way to leverage SFINAE to conditionally
remove functions from overload resolution based on type traits and to
provide separate function overloads and specializations for different type
traits"

-- Sean Silva

On Tue, May 10, 2016 at 11:07 PM, Luo, Xionghu via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> Hi Chandler,
>
> I scanned the LLVM source code, and found some potential code issues, take
> the piece of code in file ‘./include/llvm/Support/Allocator.h’ for example:
>
>
>
>
>
> 80
>
>   /// \brief Deallocate space for a sequence of objects without
> constructing them.
>
> 81
>
>   *template* <*typename* T>
>
> 82
>
>   *typename* std::enable_if<
>
> 83
>
>       !std::is_same<*typename* std::remove_cv<T>::type,
*void*>::value,
> *void*>::type
>
> 84
>
> [image:
>
https://otckw.jf.intel.com:8080/review/review/images/folding/collapse_top.png]
>
>   Deallocate(T *Ptr, size_t Num = 1) {
>
> 85
>
>     Deallocate(*static_cast*<*const* *void* *>(Ptr), Num *
*sizeof*(T));
>
> 86
>
> [image:
>
https://otckw.jf.intel.com:8080/review/review/images/folding/collapse_bottom.png]
>
>   }
>
>
>
>
>
> If the typename T is void, the std::is_same will be FALSE, which means the
> std::enable_if::type is UNDEFIED.
>
> So do you think it need a fix?
>
> Thanks.
>
>
>
>
>
> Luo Xionghu
>
> Best Regards
>
>
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
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