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, 6 insertions, 6 deletions

diff --git a/src/qml/compiler/qv4codegen.cpp b/src/qml/compiler/qv4codegen.cpp
index 5f0d7395f7..b2808784a0 100644
--- a/src/qml/compiler/qv4codegen.cpp
+++ b/src/qml/compiler/qv4codegen.cpp
@@ -3087,7 +3087,7 @@ Codegen::Reference &Codegen::Reference::operator =(const Reference &other)
         qmlBase = other.qmlBase;
         qmlCoreIndex = other.qmlCoreIndex;
         qmlNotifyIndex = other.qmlNotifyIndex;
-        captureRequired = other.captureRequired;
+        capturePolicy = other.capturePolicy;
         break;
     }
 
@@ -3124,7 +3124,7 @@ bool Codegen::Reference::operator==(const Codegen::Reference &other) const
     case QmlScopeObject:
     case QmlContextObject:
         return qmlCoreIndex == other.qmlCoreIndex && qmlNotifyIndex == other.qmlNotifyIndex
-                && captureRequired == other.captureRequired;
+                && capturePolicy == other.capturePolicy;
     }
     return true;
 }
@@ -3453,18 +3453,18 @@ QT_WARNING_POP
         Instruction::LoadScopeObjectProperty load;
         load.base = qmlBase;
         load.propertyIndex = qmlCoreIndex;
-        load.captureRequired = captureRequired;
+        load.captureRequired = capturePolicy == CaptureAtRuntime;
         codegen->bytecodeGenerator->addInstruction(load);
-        if (!captureRequired)
+        if (capturePolicy == CaptureAheadOfTime)
             codegen->_context->scopeObjectPropertyDependencies.insert(qmlCoreIndex, qmlNotifyIndex);
     } return;
     case QmlContextObject: {
         Instruction::LoadContextObjectProperty load;
         load.base = qmlBase;
         load.propertyIndex = qmlCoreIndex;
-        load.captureRequired = captureRequired;
+        load.captureRequired = capturePolicy == CaptureAtRuntime;
         codegen->bytecodeGenerator->addInstruction(load);
-        if (!captureRequired)
+        if (capturePolicy == CaptureAheadOfTime)
             codegen->_context->contextObjectPropertyDependencies.insert(qmlCoreIndex, qmlNotifyIndex);
     } return;
     case Invalid: