On Thu, 24 Nov 2016, Even Rouault wrote:
Hi,
I've a branch where I've added the 'override' keyword to virtual methods that
are an override of a virtual method declared in a base class.
https://github.com/OSGeo/gdal/compare/trunk...rouault:add_override?expand=1
Of course, not completely manually, but at >90% with the help of clang-tidy.
GCC >= 5.1 has a -Wsuggest-override warning that I've enabled
in configure to find all places missed by tidy-clang (at least with the drivers
I've
enabled in that branch). And recent clang versions have a less powerful
-Winconsistent-missing-override (enabled with -Wall I think) that warns when
you have explicitly tagged an overriden method with 'override' but neglected
to do so for other overriden methods of the same class. So new code should
be override friendly.
As we still support C++03 compilers, the following tricks are used :
1) If the compiler doesn't advertize C++11 support, we #define override to
empty in
cpl_port.h. But that only if -DGDAL_COMPILATION is defined (which is the case
in the Unix and Windows makefiles used to build GDAL), so as to avoid messing
the
namespace of code that includes GDAL.
2) As we don't want 'override' to leak into installed headers to keep C++03
compat, then CPL_OVERRIDE is used in those files, instead of plain 'override'.
It is a #define to override is the compiler is C++11 enabled, or #define to
empty otherwise.
As words may poorly reflect the reality of the code, here's the code:
{{{
#ifdef __cplusplus
#if HAVE_CXX11 || _MSC_VER >= 1600
/** To be used in public headers only. For non-public headers or .cpp files,
* use override directly. */
# define CPL_OVERRIDE override
#else
/** To be used in public headers only. For non-public headers or .cpp files,
* use override directly. */
# define CPL_OVERRIDE
We need an extra "#endif"
#endif /* HAVE_CXX11 || _MSC_VER >= 1600 */
I think it goes here ?
/* For GDAL source compilation only, ignore override if non C++11 compiler */
#ifdef GDAL_COMPILATION
# define override
#endif
#endif /* __cpluscplus */
}}}
So in summary: use override in all .cpp files and non-installed .h headers.
Use CPL_OVERRIDE in installed .h headers. Will make C++11 compilers enforce
overriding, and C++03 ones ignore it.
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