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cirosantillicirosantilli
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pod
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‎cpp/README.md‎

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1. [explicit](explicit.cpp)
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1. [class](class.cpp)
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1. Constructor
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1. [Most vexing parse](most_vexing_parse.cpp)
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1. [Delegating constructor](delegating_constructor.cpp)
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1. [Implicitly deleted constructor](implicitly_deleted_constructor.cpp)
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1. [Constructor init object member](constructor_init_object_member.cpp)
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1. [Initializer list constructor](initializer_list_constructor.cpp)
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1. [static](static.cpp)
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1. [Most vexing parse](most_vexing_parse.cpp)
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1. [Delegating constructor](delegating_constructor.cpp)
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1. [Implicitly deleted constructor](implicitly_deleted_constructor.cpp)
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1. [Constructor init object member](constructor_init_object_member.cpp)
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1. [Initializer list constructor](initializer_list_constructor.cpp)
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1. [static](static.cpp)
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1. [POD](pod.cpp)
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1. Inheritance
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1. [Inheritance override](inheritance_override.cpp)
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1. [Inherit overload_hide](inherit_overload_hide.cpp)

‎cpp/class.cpp‎

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# Aggregate initialization
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http://en.cppreference.com/w/cpp/language/aggregate_initialization
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# POD
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Plain old data:
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https://stackoverflow.com/questions/146452/what-are-pod-types-in-c
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http://stackoverflow.com/questions/4178175/what-are-aggregates-and-pods-and-how-why-are-they-special
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*/
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{
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// Syntax with new.

‎cpp/common.hpp‎

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Prefer `.hpp` which indicates that the header is C++ specific, and not pure C.
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*/
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#include <atomic>
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#include <algorithm> // copy, erase, lower_bound, remove_if, swap, transform
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#include <bitset>
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#include <exception> // bad_alloc, bad_cast, bad_exception, bad_typeid, exception, ios_base::failure
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#include <numeric> // partial sums, differences on std::vectors of numbers
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#include <ostream> // ostream
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#include <queue> // priority_queue
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#include <ratio> // ratio, nano
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#include <random>
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#include <set> // multiset, set
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#include <string> // getline, string
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#include <sstream> // stringstream
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#include <typeinfo> // typeid, bad_typeid, bad_typecast
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#include <tuple> // tuple
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#include <unordered_set>
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#include <unordered_map> // unordered_map, unordered_multimap
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#include <utility> // forward, get, pair, size_t, type_info, declval
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#include <vector> // vector
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#include <valarray>
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#if __cplusplus >= 201103L
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#include <array> // array
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#include <atomic>
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#include <cassert>
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#include <chrono> // nanoseconds
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#include <mutex> // mutex
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#include <random>
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#include <ratio> // ratio, nano
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#include <regex> // regex
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#include <thread> // thread
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#include <tuple>
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#include <type_traits> // is_pod, is_trivial, is_trivially_copyable, etc. etc.
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#include <typeindex> // type_index
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#include <unordered_set>
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#include <unordered_map> // unordered_map, unordered_multimap
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#endif
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/*
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http://stackoverflow.com/questions/32606023/when-using-c-headers-in-c-should-we-use-functions-from-std-or-the-global-na
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*/
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#include <cassert>
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#include <cmath>
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#include <cstdlib>
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#include <cstring>
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// Global thread parameters.
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const int NUM_THREADS = 1000;
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const int NUM_ITERS = 1000;
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const int NUM_OPS = NUM_THREADS * NUM_ITERS;
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// Misc.
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bool odd(int i){ return (i % 2) == 1; }
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#if __cplusplus >= 201103L
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// Keeps a list of functions that called it for testing purposes.
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std::vector<std::string> callStack;
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void printCallStack() {
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std::cout << "END callStack" << std::endl;
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}
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// Global thread parameters.
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const int NUM_THREADS = 1000;
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const int NUM_ITERS = 1000;
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const int NUM_OPS = NUM_THREADS * NUM_ITERS;
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// Misc.
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bool odd(int i){ return (i % 2) == 1; }
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/**
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* Simple instrumented class for tests on constructor destructor order.
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*
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~NoBaseNoMember1(){callStack.push_back("NoBaseNoMember1::~NoBaseNoMember1()");}
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void method(){callStack.push_back("NoBaseNoMember1::method()");}
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};
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#endif

‎cpp/pod.cpp‎

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/* # POD
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*
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* Plain old data:
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*
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* - https://en.cppreference.com/w/cpp/named_req/PODType
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* - https://stackoverflow.com/questions/146452/what-are-pod-types-in-c
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* - http://stackoverflow.com/questions/4178175/what-are-aggregates-and-pods-and-how-why-are-they-special
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* - https://github.com/gcc-mirror/gcc/blob/gcc-8_2_0-release/libstdc%2B%2B-v3/testsuite/20_util/is_pod/value.cc a few tests, but nothing awesome
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*/
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#include <type_traits>
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int main() {
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/* POD restrictions have become more and more relaxed as the standard evolved.
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*
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* std::is_pod was added in C++11, so let's consider that standard onwards for now.
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*/
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#if __cplusplus >= 201103L
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/* Non-POD examples. Let's just walk all non-recursive non-POD branches of cppreference. */
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{
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/* Non-trivial implies non-POD.
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* https://en.cppreference.com/w/cpp/named_req/TrivialType
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*/
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{
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/* Not trivial because we removed the default constructor
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* by using our own custom non-default constructor.
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*/
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{
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struct C {
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C(int i) {}
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};
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static_assert(std::is_trivially_copyable<C>());
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static_assert(!std::is_trivial<C>());
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static_assert(!std::is_pod<C>());
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}
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/* Not trivial because not trivially copyable. */
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{
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struct C {
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C(C& c) {}
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};
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static_assert(!std::is_trivially_copyable<C>());
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static_assert(!std::is_trivial<C>());
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static_assert(!std::is_pod<C>());
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}
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}
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/* Non-standard layout implies non-POD.
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* https://en.cppreference.com/w/cpp/named_req/StandardLayoutType
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*/
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{
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/* Non static members with different access control:
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* i is public and j is private.
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*/
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{
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struct C {
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public:
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int i;
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private:
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int j;
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};
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static_assert(!std::is_standard_layout<C>());
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static_assert(!std::is_pod<C>());
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}
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/* virtual function */
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{
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struct C {
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virtual void f() = 0;
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};
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static_assert(!std::is_standard_layout<C>());
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static_assert(!std::is_pod<C>());
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}
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/* Non-static member that is reference. */
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{
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struct C {
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int &i;
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};
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static_assert(!std::is_standard_layout<C>());
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static_assert(!std::is_pod<C>());
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}
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/* Neither:
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*
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* - has no base classes with non-static data members, or
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* - has no non-static data members in the most derived class
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* and at most one base class with non-static data members
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*/
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{
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/* Non POD because has two base classes with non-static data members. */
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{
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struct Base1 {
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int i;
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};
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struct Base2 {
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int j;
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};
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struct C : Base1, Base2 {};
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static_assert(!std::is_standard_layout<C>());
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static_assert(!std::is_pod<C>());
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}
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/* POD: has just one base class with non-static member. */
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{
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struct Base1 {
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int i;
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};
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struct C : Base1 {};
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static_assert(std::is_standard_layout<C>());
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static_assert(std::is_pod<C>());
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}
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}
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/* Base classes of the same type as the first non-static data member.
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* TODO failing on GCC 8.1 -std=c++11, 14 and 17.
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*/
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{
119+
struct C {};
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struct D : C {
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C c;
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};
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//static_assert(!std::is_standard_layout<C>());
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//static_assert(!std::is_pod<C>());
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};
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/* C++14 standard layout new rules, yay! */
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{
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/* Has two (possibly indirect) base class subobjects of the same type.
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* Here C has two base classes which are indirectly "Base".
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*
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* TODO failing on GCC 8.1 -std=c++11, 14 and 17.
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* even though the example was copy pasted from cppreference.
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*/
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{
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struct Q {};
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struct S : Q { };
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struct T : Q { };
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struct U : S, T { }; // not a standard-layout class: two base class subobjects of type Q
140+
//static_assert(!std::is_standard_layout<U>());
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//static_assert(!std::is_pod<U>());
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}
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/* Has all non-static data members and bit-fields declared in the same class
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* (either all in the derived or all in some base).
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*/
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{
148+
struct Base { int i; };
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struct Middle : Base {};
150+
struct C : Middle { int j; };
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static_assert(!std::is_standard_layout<C>());
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static_assert(!std::is_pod<C>());
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}
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/* None of the base class subobjects has the same type as
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* for non-union types, as the first non-static data member
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*
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* TODO: similar to the C++11 for which we could not make a proper example,
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* but with recursivity added.
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*/
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/* TODO come up with an example that is POD in C++14 but not in C++11. */
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}
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}
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}
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/* POD examples. Everything that does not fall in the non-POD examples. */
168+
{
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/* Can't get more POD than this. */
170+
{
171+
struct C {};
172+
static_assert(std::is_pod<C>());
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}
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/* Private member: became POD in C++11
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* https://stackoverflow.com/questions/4762788/can-a-class-with-all-private-members-be-a-pod-class/4762944#4762944
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*/
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{
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struct C {
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private:
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int i;
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};
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#if __cplusplus >= 201103L
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static_assert(std::is_pod<C>());
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#else
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static_assert(!std::is_pod<C>());
187+
#endif
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}
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/* Derived.
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* https://stackoverflow.com/questions/4762788/can-a-class-with-all-private-members-be-a-pod-class/4762944#4762944
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*/
193+
{
194+
struct C {};
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struct D : C {};
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static_assert(std::is_pod<D>());
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}
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}
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#endif
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}

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