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QList: remove yet another iterator->pointer implicit conversion

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The ranged constructor for QList has an optimization when the
iterators are QList's own iterators. In that case, it uses a
"contiguous append" shortcut by converting the iterators to pointers.
Avoid that conversion by extracting the pointers from the iterators.

Note that this is an optimization for C++17 only; in C++20
appendIteratorRange will deal with this case as well. Leave a note.

Change-Id: I761c36ff500dee95b4ae1b0a4479d22db0c8e3de
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
This commit is contained in:
Giuseppe D'Angelo 2021-10-13 09:43:45 +02:00
parent 507be11303
commit 9422dd0e19
1 changed files with 5 additions and 1 deletions
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6
src/corelib/tools/qlist.h
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@ -130,6 +130,7 @@ public:
#endif #endif
class iterator { class iterator {
friend class QList<T>;
T *i = nullptr; T *i = nullptr;
public: public:
using difference_type = qsizetype; using difference_type = qsizetype;
@ -178,6 +179,7 @@ public:
}; };
class const_iterator { class const_iterator {
friend class QList<T>;
const T *i = nullptr; const T *i = nullptr;
public: public:
using difference_type = qsizetype; using difference_type = qsizetype;
@ -282,9 +284,11 @@ public:
const auto distance = std::distance(i1, i2); const auto distance = std::distance(i1, i2);
if (distance) { if (distance) {
d = DataPointer(Data::allocate(distance)); d = DataPointer(Data::allocate(distance));
// appendIteratorRange can deal with contiguous iterators on its own,
// this is an optimization for C++17 code.
if constexpr (std::is_same_v<std::decay_t<InputIterator>, iterator> || if constexpr (std::is_same_v<std::decay_t<InputIterator>, iterator> ||
std::is_same_v<std::decay_t<InputIterator>, const_iterator>) { std::is_same_v<std::decay_t<InputIterator>, const_iterator>) {
d->copyAppend(i1, i2); d->copyAppend(i1.i, i2.i);
} else { } else {
d->appendIteratorRange(i1, i2); d->appendIteratorRange(i1, i2);
} }