This relies heavily on the documented fact that we only support trusted
QML/JS content, meaning most files are only significant, not critical.
This also extends to the handling of qmlc files (as in
compilationunitmapper), as we store them in a user owned, non-shared
cache directory – so any vulnerability there would already mean that an
attacker has write-priviledges on user data.

An exception is ArrayBuffer, which can be used with arbitrary user data,
and should create a valid QBA.

Fixes: QTBUG-136970
Pick-to: 6.10 6.9 6.8
QUIP: 23
Change-Id: I22033fe6ab4acf8362a8183e25b92331d45cb32c
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

WeakValue::set shold normally not mark objects, given that a weak value
is not supposed to keep an object alive.
However, if we are past GCState::HandleQObjectWrappers, nothing will
reset weak values referencing unmarked values, even if sweep collects
the referenced value.
That leads to stale pointers, and then most likely to crashes.
To avoid this, we mark the objects under this special condition.

The test is written in a way that would also allow for resetting the new
weak values instead, but the current implementation treats memory usage
for throughput and doesn't revisit weak values to reset them.

Change-Id: I789f63c1d8609957711c2253d2e76b4bd3f9810a
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

This unifies the operation when the gc is running with the normal mode,
avoiding a potentially costly iteration over all pages for allocations
during an ongoing gc cycle.

Change-Id: I39e8990c303149e3bc458b10522cc1487e62a401
Reviewed-by: Olivier De Cannière <olivier.decanniere@qt.io>
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

silence gcc's -Wextra-semi. the private headers are pulled in via the
type compiler

Pick-to: 6.4
Change-Id: I5291d007c379f522c2dae9d814c4f4cc6a7d118a
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

Replace the current license disclaimer in files by
a SPDX-License-Identifier.
Files that have to be modified by hand are modified.
License files are organized under LICENSES directory.

Pick-to: 6.4
Task-number: QTBUG-67283
Change-Id: I63563bbeb6f60f89d2c99660400dca7fab78a294
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

qSwap() is a monster that looks for ADL overloads of swap() and also
detects the noexcept of the wrapped swap() function, so it should only
be used when the argument type is unknown. In the vast majority of
cases, the type is known to be efficiently std::swap()able or to have
a member-swap. Call either of these.

For the common case of pointer types, circumvent the expensive trait
checks on std::swap() by using our hand-rolled qt_ptr_swap() template,
the advantage being that it can be unconditionally noexcept, removing
all type traits instantiations.

In QQmlPropertyCacheAliasCreator, replace the qSwap() with std::move().

Task-number: QTBUG-97601
Pick-to: 6.3 6.2 5.15
Change-Id: I8b78a3ad287ce8565ca258ff38261e4d2cf0be63
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

Code checker complains about the absence of move ctors and operators.
While we're at it, make ctors default where possible, do not use const
rvalue refs, add noexcept where possible, properly disable moving and
copying of QQmlBindEntryContent, and inline the null check of
QV4::PersistentValueStorage::free().

Change-Id: I11b6511f39f3d84479dbacee7f3e3552a5fb2b5a
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

Being careful, we can now save primitive values inline. We use the heap
pointer of QV4::Value as either QString* or QV4::Value* for complex
types. We cannot store persistent managed QV4::Value without the double
indirection as those need to be allocated in a special place.

The generic QVariant case is not supported anymore. The only place where
it was actually needed were the stream operators for QJSValue. Those
were fundamentally broken:

* A managed QJSValue saved and loaded from a stream was converted to a
  QVariant-type QJSValue
* QVariant-type QJSValues were not callable, could not be objects or
  arrays, or any of the special types.
* Cyclic references were forcibly broken when saving to a data stream.

In general the support for saving and loading of managed types to/from
a data stream was so abysmally bad that we don't lose much by dropping
it.

[ChangeLog][QML][Important Behavior Changes] When saving a QJSValue to a
QDataStream only primitive values or strings will be retained. Support
for objects and arrays was incomplete and unreliable already before. It
cannot work correctly as we don't necessarily have a JavaScript heap
when loading a QJSValue from a stream. Therefore, we don't have a proper
place to keep any managed values. Using QVariant to keep them instead is
a bad idea because QVariant cannot represent everything a QJSValue can
contain.

Fixes: QTBUG-75174
Change-Id: I75697670639bca8d4b1668763d7020c4cf871bda
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

clang-tidy -p compile_commands.json $file -checks='-*,modernize-use-default-member-init,readability-redundant-member-init'
 -config='{CheckOptions: [{key: modernize-use-default-member-init.UseAssignment, value: "1"}]}' -header-filter='qtdeclarative' -fix

Change-Id: I705f3235ff129ba68b0d8dad54a083e29fcead5f
Reviewed-by: Johan Helsing <johan.helsing@qt.io>

From now on we prefer nullptr instead of 0 to clarify cases where
we are assigning or testing a pointer rather than a numeric zero.

Also, replaced cases where 0 was passed as Qt::KeyboardModifiers
with Qt::NoModifier (clang-tidy replaced them with nullptr, which
waas wrong, so it was just as well to make the tests more readable
rather than to revert those lines).

Change-Id: I4735d35e4d9f42db5216862ce091429eadc6e65d
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>