Re: [PATCH v6] C++ify gdb/common/environ.c

[Simon Marchi <simon.marchi@polymtl.ca>]

On 2017-06-19 06:51, Sergio Durigan Junior wrote:
> On Monday, June 19 2017, I wrote:
> 
>> [...]
>> -struct gdb_environ *
>> -make_environ (void)
>> +gdb_environ &
>> +gdb_environ::operator= (gdb_environ &&e)
>>  {
>> -  struct gdb_environ *e;
>> -
>> -  e = XNEW (struct gdb_environ);
>> -
>> -  e->allocated = 10;
>> -  e->vector = (char **) xmalloc ((e->allocated + 1) * sizeof (char 
>> *));
>> -  e->vector[0] = 0;
>> -  return e;
>> -}
>> -
>> -/* Free an environment and all the strings in it.  */
>> -
>> -void
>> -free_environ (struct gdb_environ *e)
>> -{
>> -  char **vector = e->vector;
>> -
>> -  while (*vector)
>> -    xfree (*vector++);
>> -
>> -  xfree (e->vector);
>> -  xfree (e);
>> +  clear ();
>> +  m_environ_vector = std::move (e.m_environ_vector);
>> +  return *this;
>>  }
> 
> I should probably do an m_environ_vector.clear () before doing the
> std::move, because the vector will contain the NULL element.  I'll make
> sure to do this before I push the patch.

 From what I saw stepping in the STL code, the previous content of the 
moved-to vector is cleared, as if you called .clear().  In 
_M_move_assign, it moves the old content to a temporary, stack allocated 
vector, which gets cleared when exiting that function.  So I think it's 
not necessary.

Simon