g++ 6 auto_ptr

[rsbivand]

The use of auto_ptr throws warnings in g++ 6 in Fedora 24, chiefly in XMLTester:

In file included from ../../include/geos/geom/Geometry.h:27:0,
                 from ../../include/geos/geom/Point.h:26,
                 from XMLTester.cpp:27:
../../include/geos/geom/Envelope.h: At global scope:
../../include/geos/geom/Envelope.h:57:15: warning: ‘template<class> class std::auto_ptr’ is deprecated [-Wdeprecated-declarations]
  typedef std::auto_ptr<Envelope> AutoPtr;
               ^~~~~~~~
In file included from /usr/include/c++/6.1.1/memory:81:0,
                 from ../../include/geos/geom/Envelope.h:29,
                 from ../../include/geos/geom/Geometry.h:27,
                 from ../../include/geos/geom/Point.h:26,
                 from XMLTester.cpp:27:
/usr/include/c++/6.1.1/bits/unique_ptr.h:49:28: note: declared here
   template<typename> class auto_ptr;
                            ^~~~~~~~

There are other wanings for other types of -W, such as the following, so it looks as though g++ 6 is stricter in checking:

WKTWriter.cpp: In member function ‘void geos::io::WKTWriter::appendPointTaggedText(const geos::geom::Coordinate*, int, geos::io::Writer*)’:
WKTWriter.cpp:239:5: warning: this ‘if’ clause does not guard... [-Wmisleading-indentation]
     if( outputDimension == 3 && !old3D && coordinate != NULL )
     ^~
WKTWriter.cpp:242:2: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the ‘if’
  appendPointText(coordinate, level, writer);
  ^~~~~~~~~~~~~~~

[strk]

I'm afraid we are not ready to deprecate auto_ptr yet.

[rouault]

auto_ptr and unique_ptr have very similar behaviour and API and can be used equivalently if you make basic uses of them (check the differences to see if you're not running into them)

In GDAL there's a driver making use of auto_ptr, and I've finally done

#if __cplusplus >= 201103L
#define UNIQUEPTR       std::unique_ptr
#else
#define UNIQUEPTR       std::auto_ptr
#endif

A bit ugly, but works fine.

[mloskot]

Replying to rouault:

In GDAL there's a driver making use of auto_ptr, and I've finally done

#if __cplusplus >= 201103L
#define UNIQUEPTR       std::unique_ptr
#else
#define UNIQUEPTR       std::auto_ptr
#endif

For sake, typedef!

[strk]

An uniqueptr typedef sounds like a good idea. Patches welcome !

[mloskot]

I'd rather leave it as it is and wait until we can switch to c++0x/11 compilers and to std::unique_ptr only.

If GEOS switches to C++11, I will actively participate in the 'upgrade' refactoring.

[strk]

Ticket retargeted after milestone closed

[dbaston]

I think this can be considered closed now that current GEOS uses C++11, and we aren't going to backport C++11 features into stable branches.