Disallow copy and assignment in OGRFeatureDefn

[Kurt Schwehr]

This is a change I'd like to add to make sure that sneaky copy or assignment usages do not creep in on OGRFeatureDefn where reference counting is happening. Any reason not to add the pre-C++11 version of restriction?

ogr/ogr_feature.h

@@ -252 +252 @@
 
     static OGRFeatureDefn  *CreateFeatureDefn( const char *pszName = NULL );
     static void         DestroyFeatureDefn( OGRFeatureDefn * );
+
+  private:
+    // Disable copy and assignment to prevent reference counting problems.
+    OGRFeatureDefn( const OGRFeatureDefn &that );  // No implementation.
+    OGRFeatureDefn &operator=( const OGRFeatureDefn& );  // No implementation.
 };
 
 /************************************************************************/

Someday when C++11 is allowed, this would be

OGRFeatureDefn( const OGRFeatureDefn &that ) = delete;
OGRFeatureDefn &operator=( const OGRFeatureDefn& ) = delete;

Which could be behind an if:

#if __cplusplus >= 201103L
    OGRFeatureDefn( const OGRFeatureDefn &that ) = delete;
    OGRFeatureDefn &operator=( const OGRFeatureDefn & ) = delete;
#else
  private:
    // Disable copy and assignment to prevent reference counting problems.
    OGRFeatureDefn( const OGRFeatureDefn &that );  // No implementation.
    OGRFeatureDefn &operator=( const OGRFeatureDefn & );  // No implementation.
#endif

​http://stackoverflow.com/questions/6077143/disable-copy-constructor

[Kurt Schwehr]

Created in a disabled state: r30231

It would be great if people on non-linux platforms could give this a try. It should be cross platform.

Just flip the #if 0 to #if 1 to enable. At this point, no behavior should change.

port/cpl_port.h

@@ -632 +632 @@
    Must be placed in the private section of a class and should be at the end.
 */
 #ifdef __cplusplus
-#if 0 /* Initially disabled */
+#if 1
 
 #if __cplusplus >= 201103L
 #define CPL_DISALLOW_COPY_ASSIGN(ClassName) \

[Kurt Schwehr]

Enabled via r30264

[Even Rouault]

trunk r30277 "Avoid use of OGRFieldDefn (implicit) assignment operator"

trunk r30278 "Disable copy constructor and assignment operators in classes OGRFieldDefn, OGRGeomFieldDefn, OGRFeature, GDALMultiDomainMetadata, GDALDefaultOverviews, GDALOpenInfoGDALDataset, GDALRasterBlock, GDALRasterBand and GDALDriver (#6100)"

[Even Rouault]

Hum, there were linking errors due to r30278 with MSVC : ​https://ci.appveyor.com/project/rouault/gdal-coverage/build/1.0.512/job/a0mjcqyrub6g5i8w , ​http://build.gisinternals.com/sdk/build-output/vc9-20150912-2-30-37-10-vc9-dev.txt

Should be fixed with r30325 "Add CPL_DISALLOW_COPY_ASSIGN to various derived classes of GDALRasterBand and GDALDataset to fix linking error with MSVC" (tested locally with VC 10 & VC 12)

I'm not sure to have really understood why this was necessary. The reasons may be given at ​https://msdn.microsoft.com/en-us/library/dn457344%28v=vs.120%29.aspx