Can't include:

	#include <string>

in php/functions/foo.cc because <string> in libstdc++ distributed with
gcc-2.95.1 includes an alloc.h.  Since php distribution includes an
alloc.h, and compiling foo.cc required -Iphp in the compile command
line <string> ends up including php's alloc.h.  Which gets it awfully
confused about the class alloc.

One solution would be to rename alloc.h to phpalloc.h.   Otherwise
writing php functions in C++ involves solving a minor inconvenience.