It's the declaration of a function taking a variable argument list and returning a reference to an array of 2 char
.
Note that if define a function like this the parameters are inaccessible (via standard means) as the <cstdarg>
macros require a variable argument list to follow a named parameter.
If you like, you can defined a function with this declaration and return a reference to suitable array. You can call it with any parameters, subject to the restrictions for ...
parameters which include the restrictions that passing non-POD class types causes undefined behaviour.
E.g.
namespace
{
char samplearray[2];
}
char (& test(...))[2]
{
return samplearray;
}