The code below asserts when being compiled with gcc in c++11 mode:
----------------------------------------------------------------------
#include <cassert>
typedef char yes_type;
struct no_type
{
char padding[8];
};
template
<
class enclosing_type,
class static_type
>
struct has_static_member_function_StaticFunction
{
template<static_type *> struct helper;
template<class internal_enclosing_type> static yes_type
chkt(helper<&internal_enclosing_type::StaticFunction> *);
template<class internal_enclosing_type> static no_type chkt(...);
static const bool
value=(sizeof(chkt<enclosing_type>(0))==sizeof(yes_type));
};
class AClass
{
public:
static void StaticFunction()
{
}
};
int main()
{
class ANestedClass
{
public:
static void StaticFunction()
{
}
};
assert((has_static_member_function_StaticFunction<ANestedClass,void
()>::value));
return 0;
}
-------------------------------------------------------------------------
If the 'assert" line instead is:
assert((has_static_member_function_StaticFunction<AClass,void ()>::value));
the assert does not occur. In other words the class template's 'value'
is false when passing the local class and true when passing the
non-local class.
The code is a simplified version of my Boost tti's library code for
checking if a static member function of a given name exists within a class.
Is this a gcc bug or is my code wrong for local classes in c++11 mode,
as opposed to non-local classes ?
I am fully aware that instantiating a template with a local class type
is forbidden prior to c++11.
The compile and link lines, for gcc 7.1 as an example, are:
somepath/g++ -ftemplate-depth-128 -Wno-unused-local-typedefs
-ftrack-macro-expansion=0 -Wno-unused-variable -std=c++11 -O0
-fno-inline -Wall -pedantic -g -march=i686 -m32 -c -o somepath/example.o
example.cpp
somepath/g++ -o example.exe -Wl,--start-group somepath/example.o
-Wl,-Bstatic -Wl,-Bdynamic -Wl,--end-group -g -march=i686 -m32
If this is a bug in gcc I will be happy to report it on the bug tracker
if it has not already been reported.
