Emil Dotchevski wrote:
How is failure to allocate an exception object handled in various compilers? 15.1.4 says that "the memory for the temporary copy of the exception being thrown is allocated in an unspecified way" but I don't think it specifies behavior for the case when the allocation fails. I know that some compilers allocate exceptions from the heap, so does this mean that an attempt to throw any exception could, in theory, result in a std::bad_alloc being thrown instead? As far as I can tell such behavior wouldn't violate the C++ standard, but I'm not sure my interpretation is correct. Anyone?
GCC allocates exceptions on the heap. If that fails, it will allocate them in the emergency storage instead. The emergency storage is a small buffer (64 slots of a few kB each - used to be 16 slots, but I changed that when I implemented exception propagation) allocated statically. If allocation in emergency storage fails, GCC aborts the process. The way the common C++ ABI is specified, I think every compiler that follows it will have to do a very similar thing. There's a __cxa_allocate_exception function specified. So Sun, IBM and HP's compilers probably do the same thing. But I can't vouch for it. http://www.codesourcery.com/public/cxx-abi/abi-eh.html#cxx-throw MSVC allocates on the stack. Sebastian