On 8 February 2016 at 13:54, H.J. Lu <hjl.to...@gmail.com> wrote: > On Sun, Feb 7, 2016 at 12:52 PM, H.J. Lu <hjl.to...@gmail.com> wrote: > > The standard-layout POD is well defined: > > https://en.wikipedia.org/wiki/C%2B%2B11#Modification_to_the_definition_of_plain_old_data > > Here is the updated proposal for Intel386, x86-64 and IA MCU psABIs: > > 1. "collection". A collection is a structure, union or C++ class.
These are all "class types". Why invent a new term? > 2. "empty collection". An empty collection is: > a. A collection without member. Or What about base classes? What about bit-fields of length 0? > b. A collection with only empty collections. Or What does "with" mean? Only members, or bases too? > c. An array of empty collections. > 3. "empty record". An empty record is Plain Old Data (POD) for the purpose > of standard-layout and "For the purposes of standard-layout" doesn't mean anything. A type is a standard-layout type, or it isn't. Do you mean "An empty record is a standard-layout type and..." > a. A collection without member. Or > b. A collection with only empty collections. ? The C++ standard defines the std::is_empty<T> trait as true when: "T is a class type, but not a union type, with no non-static data members other than bit-fields of length 0, no virtual member functions, no virtual base classes, and no base class B for which is_empty<B>::value is false." > 4. No memory slot nor register should be used to pass or return an object of > empty record.
