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[handle] guard self-assign on owning-handle assignments #130

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[handle] guard self-assign on owning-handle assignments #130

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12 changes: 9 additions & 3 deletions c++/nda/mem/handle.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -169,9 +169,11 @@ namespace nda::mem {
* @brief Move assignment operator first releases the resources held by the current handle and then moves the
* resources from the source to the current handle.
*
* @param h Source handle.
* @param h Source handle. Must not alias `*this`.
*/
handle_heap &operator=(handle_heap &&h) noexcept {
EXPECTS(this != &h);

// release current resources if they are not shared and not null
if (not sptr and not(is_null())) destruct({_data, _size});

Expand Down Expand Up @@ -206,6 +208,7 @@ namespace nda::mem {
* @param h Source handle.
*/
handle_heap &operator=(handle_heap const &h) {
if (this == &h) return *this;
*this = handle_heap{h};
return *this;
}
Expand Down Expand Up @@ -382,9 +385,10 @@ namespace nda::mem {
/**
* @brief Move assignment operator simply calls the copy assignment operator.
* @details If an exception occurs in the constructor of `T`, the program terminates.
* @param h Source handle.
* @param h Source handle. Must not alias `*this`.
*/
handle_stack &operator=(handle_stack &&h) noexcept {
EXPECTS(this != &h);
operator=(h);
return *this;
}
Expand All @@ -401,6 +405,7 @@ namespace nda::mem {
* @param h Source handle.
*/
handle_stack &operator=(handle_stack const &h) {
if (this == &h) return *this;
for (size_t i = 0; i < Size; ++i) new (data() + i) T(h[i]);
return *this;
}
Expand Down Expand Up @@ -545,9 +550,10 @@ namespace nda::mem {
*
* @details In both cases, it resets the source handle to a null state.
*
* @param h Source handle.
* @param h Source handle. Must not alias `*this`.
*/
handle_sso &operator=(handle_sso &&h) noexcept {
EXPECTS(this != &h);
clean();
_size = h._size;
if (on_heap()) {
Expand Down
7 changes: 5 additions & 2 deletions test/c++/nda_mem.cpp
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Expand Up @@ -121,18 +121,21 @@ H check_handle() {
move2 = std::move(copy1);
EXPECT_EQ(handle.size(), move1.size());
EXPECT_EQ(handle.size(), move2.size());
std::swap(handle, handle); // check self swap
#ifdef NDEBUG // self-swap violates the handle move-assign precondition; release-only.
std::swap(handle, handle);
#endif
for (int i = 0; i < handle.size(); ++i) {
EXPECT_EQ(handle[i], static_cast<value_t>(i));
EXPECT_EQ(move1[i], static_cast<value_t>(i));
EXPECT_EQ(move2[i], static_cast<value_t>(i));
}

// check self move assignment (see https://stackoverflow.com/questions/9322174/move-assignment-operator-and-if-this-rhs)
#ifdef NDEBUG // self-move-assign violates the handle move-assign precondition; release-only.
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wself-move"
move1 = std::move(move1);
#pragma GCC diagnostic pop
#endif

return handle;
}
Expand Down