Re: [Libmesh-users] problems with "using" in anonymous namespace

[John Peterson]

On Thu, May 8, 2014 at 8:24 AM, Michael Povolotskyi <mpovo...@purdue.edu>wrote:

> Hello everybody,
>
> In a file parallel_implementation.h there are lines:
> 173 // Anonymous namespace for helper functions
> 174 namespace {
> 175
> 176 // Safe to use this here since it won't "infect" anything outside the
> 177 // anonymous namespace
> 178 using namespace libMesh;
> 179
>
> However,
> the following resource
>
> http://stackoverflow.com/questions/8775563/using-namespace-statement-inside-an-anonymous-namespace
>
> tells that that "using" inside an anonymous namespace is not safe.
>

I tried the same thing but with 2 separate files:

// X.h
namespace X
{
int f() { return 1; }
}

// Anonymous namespace with using declaration inside
namespace
{
using namespace X;
}


// main.C
#include "X.h"

int main()
{
  // Does the 'using' declaration apply to us?
  f();

  return 0;
}

and it compiles for me, so it seems that the using declaration inside an
anonymous namespace does still pollute the namespace of any file that
includes it, Roy's comment notwithstanding...

This should be pretty easy to fix though, I'll push a patch hopefully
shortly, that does that.

-- 
John
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