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Fix QtFuture::when{All,Any}() overload resolution 

Both whenAll() and whenAny() have two overloads:
* an overload taking two input iterators, e.g.
  whenAll(IntpuIt begin, InputIt end)
* an overload taking an arbitrary number of future objects, e.g.
  whenAll(Futures &&... futures)

The public APIs are properly constrained, but internally they call
QtPrivate::when*Impl() template functions, that have the same two
overloads, but do not have any constraints.

As a result, passing exactly two QFuture<T>{} objects was leading to
the compiler picking the Impl overload that takes a pair of iterators.

Fix it by applying a subset of constraints from the public API to
the private implementation as well.

Amends 102f7d31c4 which was introduced
for Qt 6.3, so picking down to Qt 6.5.

Fixes: QTBUG-131959
Pick-to: 6.9 6.8 6.5
Change-Id: Ide29ac9a494d07870e92957c40c1f614e56825f8
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
This commit is contained in:
Ivan Solovev 2024-12-19 16:02:14 +01:00
parent 3cb87d891b
commit 8aef5b0d8f
2 changed files with 15 additions and 2 deletions
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8
src/corelib/thread/qfuture_impl.h
View File

@ -1106,7 +1106,9 @@ void addCompletionHandlers(const std::shared_ptr<ContextType> &context, const st
addCompletionHandlersImpl<size - 1, ContextType, Ts...>(context, t);
}
template<typename OutputSequence, typename InputIt, typename ValueType>
template<typename OutputSequence, typename InputIt, typename ValueType,
std::enable_if_t<std::conjunction_v<IsForwardIterable<InputIt>, isQFuture<ValueType>>,
bool> = true>
QFuture<OutputSequence> whenAllImpl(InputIt first, InputIt last)
{
const qsizetype size = std::distance(first, last);
@ -1142,7 +1144,9 @@ QFuture<OutputSequence> whenAllImpl(Futures &&... futures)
return context->promise.future();
}
template<typename InputIt, typename ValueType>
template<typename InputIt, typename ValueType,
std::enable_if_t<std::conjunction_v<IsForwardIterable<InputIt>, isQFuture<ValueType>>,
bool> = true>
QFuture<QtFuture::WhenAnyResult<typename Future<ValueType>::type>> whenAnyImpl(InputIt first,
InputIt last)
{

9
tests/auto/corelib/thread/qfuture/tst_qfuture.cpp
View File

@ -233,6 +233,7 @@ private slots:
void getFutureInterface();
void convertQMetaType();
void whenAllwhenAnyOverloadResolution();
void whenAllIterators();
void whenAllIteratorsWithCanceled();
void whenAllIteratorsWithFailed();
@ -4447,6 +4448,14 @@ void tst_QFuture::convertQMetaType()
QVERIFY(voidFuture.isFinished());
}
void tst_QFuture::whenAllwhenAnyOverloadResolution()
{
// Compile-only test. These could fail to compile due to picking a wrong
// overload of *Impl() methods. See QTBUG-131959
[[maybe_unused]] auto f = QtFuture::whenAll(QFuture<void>{}, QFuture<void>{});
[[maybe_unused]] auto ff = QtFuture::whenAny(QFuture<void>{}, QFuture<void>{});
}
template<class OutputContainer>
void testWhenAllIterators()
{