Fix "Expression depends on non-NOTIFYable properties" regression

CONSTANT properties are by nature non-NOTIFYable.

The issue behind the regression is caused by the fact that we were
capturing a property regardless of whether or not it was const.
There were two states that captureRequired was expressing:

true: We're reading the property of a QObject, and we're not quite sure
where the QObject comes from or what it is. So, when reading that
property at run-time, make sure that we capture where we read that
property so that if it changes we can re-evaluate the entire
expression.

false: We're reading the property of a QObject, and we know that it's
the scope object or context object, which we know very well. Instead of
registering a property capture every time, we can do that ahead of time
and then register all those captures in one shot in
registerQmlDependencies().

There is a third state that is only relevant when captureRequired is
false: We're reading a property from the scope or context object, but
it's a CONSTANT property, so we don't need to register a dependency
at all.

This patch adds replaces captureRequired with the PropertyCapturePolicy
enum, which accounts for the third state and, as a bonus, makes the
code easier to understand.

Task-number: QTBUG-66361
Change-Id: I6cef1deb76538fbdacf1324b4467403dd40dd7de
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 14 insertions, 6 deletions

diff --git a/src/qml/compiler/qqmlirbuilder.cpp b/src/qml/compiler/qqmlirbuilder.cpp
index 6de0ed6f7d..6c8ca4bbfc 100644
--- a/src/qml/compiler/qqmlirbuilder.cpp
+++ b/src/qml/compiler/qqmlirbuilder.cpp
@@ -2231,20 +2231,28 @@ QV4::Compiler::Codegen::Reference JSCodeGen::fallbackNameLookup(const QString &n
         QQmlPropertyData *data = lookupQmlCompliantProperty(_scopeObject, name);
         if (!data)
             return Reference::fromName(this, name);
+
         Reference base = Reference::fromStackSlot(this, _qmlContextSlot);
-        bool captureRequired = !data->isConstant() && !data->isQmlBinding();
-        return Reference::fromQmlScopeObject(base, data->coreIndex(), data->notifyIndex(),
-                                             captureRequired);
+        Reference::PropertyCapturePolicy capturePolicy;
+        if (!data->isConstant() && !data->isQmlBinding())
+            capturePolicy = Reference::CaptureAtRuntime;
+        else
+            capturePolicy = data->isConstant() ? Reference::DontCapture : Reference::CaptureAheadOfTime;
+        return Reference::fromQmlScopeObject(base, data->coreIndex(), data->notifyIndex(), capturePolicy);
     }
 
     if (_contextObject) {
         QQmlPropertyData *data = lookupQmlCompliantProperty(_contextObject, name);
         if (!data)
             return Reference::fromName(this, name);
+
         Reference base = Reference::fromStackSlot(this, _qmlContextSlot);
-        bool captureRequired = !data->isConstant() && !data->isQmlBinding();
-        return Reference::fromQmlContextObject(base, data->coreIndex(), data->notifyIndex(),
-                                               captureRequired);
+        Reference::PropertyCapturePolicy capturePolicy;
+        if (!data->isConstant() && !data->isQmlBinding())
+            capturePolicy = Reference::CaptureAtRuntime;
+        else
+            capturePolicy = data->isConstant() ? Reference::DontCapture : Reference::CaptureAheadOfTime;
+        return Reference::fromQmlContextObject(base, data->coreIndex(), data->notifyIndex(), capturePolicy);
     }
 
     if (m_globalNames.contains(name)) {