strange warning when importing template from namespace

[Simon Anders]

Hi,

just a little question:

I'm using the hash_set template from the GNU C++ standard library.
Because the hashed containers are not standard content of the library
but an extension taken over from SGI, the GNU people have put them into
a special namespace __gnu_cxx.

So I wrote:

#include <ext/hash_set>
using __gnu_cxx::hash_set;
[...]
typedef hash_set<VertexIndex>::iterator VtxIdxIter;
[...]

Although this works fine, I get a compiler warning, namely:

stabilizer.h:12: Warning(315): Nothing known about
'__gnu_cxx::hash_set'.

(with line 12 being the 'using' statement).

What is the compiler trying to warn me about, i.e. what would it like to
know? As all works fine, I wonder when it would not have worked.

TIA,
Simon

[Victor Bazarov]

Simon Anders wrote:

Hi,

just a little question:

I'm using the hash_set template from the GNU C++ standard library.
Because the hashed containers are not standard content of the library
but an extension taken over from SGI, the GNU people have put them into
a special namespace __gnu_cxx.

So I wrote:

#include <ext/hash_set>
using __gnu_cxx::hash_set;
[...]
typedef hash_set<VertexIndex>::iterator VtxIdxIter;
try

typedef typename hash_set<VertexIndex>::iterator VtxIdxIter;
[...]

Although this works fine, I get a compiler warning, namely:

stabilizer.h:12: Warning(315): Nothing known about
'__gnu_cxx::hash_set'.

(with line 12 being the 'using' statement).

What is the compiler trying to warn me about, i.e. what would it like to
know? As all works fine, I wonder when it would not have worked.

I am not sure what specifically that compiler is warning you about, you
would need to ask in gnu.g++.help. Does it know what 'VertexIndex' is
at the time when it sees the typedef?

Victor

[Jari Kalevi Savolainen]

On Tue, 4 Jan 2005, Simon Anders wrote:

Hi,

just a little question:

I'm using the hash_set template from the GNU C++ standard library.
Because the hashed containers are not standard content of the library
but an extension taken over from SGI, the GNU people have put them into
a special namespace __gnu_cxx.

So I wrote:

#include <ext/hash_set>
using __gnu_cxx::hash_set;
[...]
typedef hash_set<VertexIndex>::iterator VtxIdxIter;
[...]

Although this works fine, I get a compiler warning, namely:

stabilizer.h:12: Warning(315): Nothing known about
'__gnu_cxx::hash_set'.

(with line 12 being the 'using' statement).

What is the compiler trying to warn me about, i.e. what would it like to
know? As all works fine, I wonder when it would not have worked.

TIA,
Simon

Identifiers starting with ___s are often used internally by compilers. It
might warn about that.

Try and look for an alias for that namespace.