qmllint: check default properties

Implement the check for default properties

Default aliases are not included in this patch

[ChangeLog][QML][qmllint] Add support for default properties

Change-Id: I2d0330e32c1f49c83d3a4ed602250b6bfd4ec674
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

2 files changed, 62 insertions, 0 deletions

diff --git a/tools/qmllint/findwarnings.cpp b/tools/qmllint/findwarnings.cpp
index 437b32ede3..01c5f30ef7 100644
--- a/tools/qmllint/findwarnings.cpp
+++ b/tools/qmllint/findwarnings.cpp
@@ -153,6 +153,60 @@ void FindWarningVisitor::flushPendingSignalParameters()
     m_pendingSingalHandler = QQmlJS::SourceLocation();
 }
 
+void FindWarningVisitor::checkDefaultProperty(const QQmlJSScope::ConstPtr &scope)
+{
+    if (scope == m_exportedRootScope) // inapplicable
+        return;
+
+    const QQmlJSScope *scopeOfDefaultProperty = nullptr;
+    QString defaultPropertyName;
+    // NB: start looking for default property in parent scope (because this
+    // scope is not suitable), but progress through baseType()
+    for (auto s = scope->parentScope(); s; s = s->baseType()) {
+        defaultPropertyName = s->defaultPropertyName();
+        if (!defaultPropertyName.isEmpty()) {
+            scopeOfDefaultProperty = s.data();
+            break;
+        }
+    }
+    if (defaultPropertyName.isEmpty()) {
+        m_errors.append({ QStringLiteral("Cannot assign to non-existent default property"),
+                          QtWarningMsg, scope->sourceLocation() });
+        m_visitFailed = true;
+        return;
+    }
+
+    Q_ASSERT(scopeOfDefaultProperty);
+    Q_ASSERT(scope->parentScope());
+    QQmlJSMetaProperty defaultProp = scopeOfDefaultProperty->property(defaultPropertyName);
+
+    // abuse QHash feature to construct default value through
+    // operator[]. default bool is false, which is what's needed
+    if (m_scopeHasDefaultPropertyAssignment[scopeOfDefaultProperty] && !defaultProp.isList()) {
+        // already has some object assigned to a default property and
+        // this default property is not a list property
+        m_errors.append(
+                { QStringLiteral("Cannot assign multiple objects to a default non-list property"),
+                  QtWarningMsg, scope->sourceLocation() });
+        m_visitFailed = true;
+    }
+    m_scopeHasDefaultPropertyAssignment[scopeOfDefaultProperty] = true;
+
+    auto propType = defaultProp.type().data();
+    if (!propType) // should be an error somewhere else
+        return;
+
+    // scope's type hierarchy has to have property type
+    for (const QQmlJSScope *type = scope.data(); type; type = type->baseType().data()) {
+        if (type == propType)
+            return;
+    }
+
+    m_errors.append({ QStringLiteral("Cannot assign to default property of incompatible type"),
+                      QtWarningMsg, scope->sourceLocation() });
+    m_visitFailed = true;
+}
+
 void FindWarningVisitor::throwRecursionDepthError()
 {
     QQmlJSImportVisitor::throwRecursionDepthError();
@@ -524,6 +578,9 @@ bool FindWarningVisitor::visit(QQmlJS::AST::UiObjectDefinition *uiod)
                 m_currentScope->addOwnMethod(method);
         }
     }
+
+    checkDefaultProperty(m_currentScope);
+
     return true;
 }
 
diff --git a/tools/qmllint/findwarnings.h b/tools/qmllint/findwarnings.h
index 30ee47705e..21ebb0825d 100644
--- a/tools/qmllint/findwarnings.h
+++ b/tools/qmllint/findwarnings.h
@@ -90,9 +90,14 @@ private:
 
     QVarLengthArray<OutstandingConnection, 3> m_outstandingConnections; // Connections whose target we have not encountered
 
+    // records of whether a default property has object assigned to it. for
+    // correctness, the scope that defines the default property acts as a key
+    QHash<const QQmlJSScope *, bool> m_scopeHasDefaultPropertyAssignment;
+
     void checkInheritanceCycle(QQmlJSScope::ConstPtr scope);
     void checkGroupedAndAttachedScopes(QQmlJSScope::ConstPtr scope);
     void flushPendingSignalParameters();
+    void checkDefaultProperty(const QQmlJSScope::ConstPtr &scope);
 
     void throwRecursionDepthError() override;