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

[Simon Marchi <simon dot marchi at polymtl dot 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