Uninitialized value when copying QSharedPointer with structured binding

[jhasse]

Bugzilla Link	43042
Version	unspecified
OS	All
CC	@devincoughlin,@haoNoQ

Extended Description

The following example code:

#include

QPair<int, QSharedPointer> foo() {
return {42, nullptr};
}

int main() {
auto [x, p] = foo();
auto p2 = p;
}

produces the following warning:

QtCore.framework/Headers/qsharedpointer_impl.h:460:7: warning: 1st function call argument is an uninitialized value [clang-analyzer-core.CallAndMessage]
{ deref(d); }
^
test.cpp:9:12: note: Uninitialized value stored to '.second.d'
auto p2 = p;
^
test.cpp:10:1: note: Calling implicit destructor for 'QPair<int, QSharedPointer>'
}
^
test.cpp:10:1: note: Calling '~QSharedPointer'
QtCore.framework/Headers/qsharedpointer_impl.h:315:25: note: Calling 'QSharedPointer::deref'
~QSharedPointer() { deref(); }
^
QtCore.framework/Headers/qsharedpointer_impl.h:460:7: note: 1st function call argument is an uninitialized value
{ deref(d); }
^

Which is weird, since QSharedPointer's copy constructor initializes d. Is this a false-positive?

See related Qt bug report: https://bugreports.qt.io/browse/QTBUG-77641

[jhasse]

assigned to @haoNoQ

[haoNoQ]

clang++ -std=c++17 --analyze repro.ii
Yeah, it's most likely false positive, looks like incomplete support for c++17 structured bindings in the static analyzer is causing that.

I attached a preprocessed reproducer for the reference. I'll take a look when i have time.

[isuckatcs]

The issue no longer persists. See it on godbolt.