Re: [Boost-users] Boost 1.54.0 Header Warnings: Shadowed Variables

Subject: Re: [Boost-users] Boost 1.54.0 Header Warnings: Shadowed Variables
From: Jeff Flinn (Jeffrey.Flinn_at_[hidden])
Date: 2013-11-13 09:06:37

On 11/8/2013 7:31 PM, Tom Browder wrote:
> I am trying to use Boost 1.54.0 to replace a previous version (1.47)
> and am using g++ 4.7 with  most warnings turned on.  I am getting many
> -Wshadow errors and wonder why they exist.  Surely the developers test
> for such.
>
> Here is one example from xpressive/detail/utility/hash_peek_bitset.hpp:
>
> Both 'icase' and 'count' are reported to shadow members of 'this'.
>
> Note that the bool arg is named 'icase' but the compiler reports
> 'this' has a member named 'icase' (as can be plainly seen below).  In
> this example it's fairly clear what is intended, but then again maybe
> not (and it doesn't give the user much confidence in the code).  It
> isn't good practice IMHO to do such so that is why I like to use some
> prefix or suffix to disambiguate the two variables.
>
>      // Make sure all sub-expressions being merged have the same case-sensitivity
>      bool test_icase_(bool icase)
>      {
>          std::size_t count = this->bset_.count();
>
>          if(256 == count)
>          {
>              return false; // all set already, nothing to do
>          }
>          else if(0 != count && this->icase_ != icase)
>          {
>              this->set_all(); // icase mismatch! set all and bail
>              return false;
>          }
>
>          this->icase_ = icase;
>          return true;
>      }
>
> I could file many bugs but it begs the question of why the warnings
> are allowed in the first place.

Maybe I don't see all of the context but how does icase shadow icase_ in 
the code above? Also std::size_t count = this->bset_.count(); seems 
perfectly fine to me - less of an issue than picking a less suitable 
variable name.

Jeff