Re: [PATCH, libstdc++] More

["François Dumont" <frs.dumont@gmail.com>]

I have a patch for the same location so here is my remark that might 
make my patch useless.

Maybe you can even merge it with yours Ed, here it is:

https://gcc.gnu.org/ml/libstdc++/2019-10/msg00072.html

On 11/25/19 10:15 PM, Jonathan Wakely wrote:
> On 15/11/19 22:17 -0500, Ed Smith-Rowland via libstdc++ wrote:
>> Index: include/bits/stl_algobase.h
>> ===================================================================
>> --- include/bits/stl_algobase.h    (revision 278318)
>> +++ include/bits/stl_algobase.h    (working copy)
>> @@ -107,6 +107,50 @@
>>     }
>>
>>   /*
>> +   * A constexpr wrapper for __builtin_memmove.
>
> This should say __builtin_memcpy.
>
>> +   * @param __num The number of elements of type _Tp (not bytes).
>> +   */
>> +  template<typename _Tp>
>> +    _GLIBCXX14_CONSTEXPR
>> +    inline void*
>> +    __memcpy(_Tp* __dst, const _Tp* __src, size_t __num)
>> +    {
>> +#ifdef __cpp_lib_is_constant_evaluated
>> +      if (std::is_constant_evaluated())
>> +    {
>> +      for(; __num > 0; --__num)

for (; __num != 0; --__num)

and make __num prtdiff_t.

would be better here as this way the compiler is able to report bad 
usages rather than silently do nothing.


>> +        *__dst++ = *__src++;
>> +      return __dst;
>> +    }
>> +      else
>> +#endif
>> +    return __builtin_memcpy(__dst, __src, sizeof(_Tp) * __num);
>> +      return __dst;
>> +    }
>> +
>> +  /*
>> +   * A constexpr wrapper for __builtin_memmove.
>
> And this should say __builtin_memset.
>
>> +   * @param __num The number of elements of type _Tp (not bytes).
>> +   */
>> +  template<typename _Tp>
>> +    _GLIBCXX14_CONSTEXPR
>> +    inline void*
>> +    __memset(_Tp* __dst, _Tp __a, size_t __num)
>> +    {
>> +#ifdef __cpp_lib_is_constant_evaluated
>> +      if (std::is_constant_evaluated())
>> +    {
>> +      for(; __num > 0; --__num)
>> +        *__dst = __a;
>> +      return __dst;
>> +    }
>> +      else
>> +#endif
>> +    return __builtin_memset(__dst, __a, sizeof(_Tp) * __num);
>> +      return __dst;
>> +    }
>
> OK for trunk with those two comment fixes. Thanks.
>
>
>