QMetaMethod: Store method constness in metaobject system

[ChangeLog][QtCore][QMetaMethod] It is now possible to query the
constness of a method with QMetaMethod::isConst.

Change-Id: I8a94480b8074ef5b30555aeccd64937c4c6d97d4
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

5 files changed, 47 insertions, 1 deletions

diff --git a/src/corelib/kernel/qmetaobject.cpp b/src/corelib/kernel/qmetaobject.cpp
index a574bec179..b09fe933e6 100644
--- a/src/corelib/kernel/qmetaobject.cpp
+++ b/src/corelib/kernel/qmetaobject.cpp
@@ -2140,6 +2140,23 @@ int QMetaMethod::revision() const
 }
 
 /*!
+    \since 6.2
+
+    Returns whether the method is const qualified.
+
+    \note This method might errorneously return \false for a const method
+    if it belongs to a library compiled against an older version of Qt.
+ */
+bool QMetaMethod::isConst() const
+{
+    if (!mobj)
+        return false;
+    if (QMetaObjectPrivate::get(mobj)->revision < 10)
+        return false;
+    return data.flags() & MethodIsConst;
+}
+
+/*!
     Returns the access specification of this method (private,
     protected, or public).
 
diff --git a/src/corelib/kernel/qmetaobject.h b/src/corelib/kernel/qmetaobject.h
index 1e9a0097fb..6fe259868f 100644
--- a/src/corelib/kernel/qmetaobject.h
+++ b/src/corelib/kernel/qmetaobject.h
@@ -77,6 +77,7 @@ public:
     int methodIndex() const;
     int relativeMethodIndex() const;
     int revision() const;
+    bool isConst() const;
 
     inline const QMetaObject *enclosingMetaObject() const { return mobj; }
 
diff --git a/src/corelib/kernel/qmetaobject_p.h b/src/corelib/kernel/qmetaobject_p.h
index e35d0b5e0c..35aa6ea6b9 100644
--- a/src/corelib/kernel/qmetaobject_p.h
+++ b/src/corelib/kernel/qmetaobject_p.h
@@ -98,7 +98,9 @@ enum MethodFlags {
     MethodCompatibility = 0x10,
     MethodCloned = 0x20,
     MethodScriptable = 0x40,
-    MethodRevisioned = 0x80
+    MethodRevisioned = 0x80,
+
+    MethodIsConst = 0x100, // no use case for volatile so far
 };
 
 enum MetaObjectFlag {
@@ -173,6 +175,7 @@ struct QMetaObjectPrivate
     // revision 8 is Qt 5.12: It adds the enum name to QMetaEnum
     // revision 9 is Qt 6.0: It adds the metatype of properties and methods
     // revision 10 is Qt 6.2: The metatype of the metaobject is stored in the metatypes array
+    //                        and metamethods store a flag stating whether they are const
     enum { OutputRevision = 10 }; // Used by moc, qmetaobjectbuilder and qdbus
     enum { IntsPerMethod = QMetaMethod::Data::Size };
     enum { IntsPerEnum = QMetaEnum::Data::Size };
diff --git a/src/corelib/kernel/qmetaobjectbuilder.cpp b/src/corelib/kernel/qmetaobjectbuilder.cpp
index d46adf05fb..8513805ef4 100644
--- a/src/corelib/kernel/qmetaobjectbuilder.cpp
+++ b/src/corelib/kernel/qmetaobjectbuilder.cpp
@@ -1743,6 +1743,28 @@ void QMetaMethodBuilder::setAttributes(int value)
 }
 
 /*!
+    Returns true if the method is const qualified.
+ */
+int QMetaMethodBuilder::isConst() const
+{
+    QMetaMethodBuilderPrivate *d = d_func();
+    if (!d)
+        return false;
+    return (d->attributes & MethodIsConst);
+}
+
+void QMetaMethodBuilder::setConst(bool methodIsConst)
+{
+    QMetaMethodBuilderPrivate *d = d_func();
+    if (!d)
+        return;
+    if (methodIsConst)
+        d->attributes |= MethodIsConst;
+    else
+        d->attributes &= ~MethodIsConst;
+}
+
+/*!
     Returns the revision of this method.
 
     \sa setRevision()
diff --git a/src/corelib/kernel/qmetaobjectbuilder_p.h b/src/corelib/kernel/qmetaobjectbuilder_p.h
index 0435e9cd97..429a05238e 100644
--- a/src/corelib/kernel/qmetaobjectbuilder_p.h
+++ b/src/corelib/kernel/qmetaobjectbuilder_p.h
@@ -204,6 +204,9 @@ public:
     int attributes() const;
     void setAttributes(int value);
 
+    int isConst() const;
+    void setConst(bool methodIsConst=true);
+
     int revision() const;
     void setRevision(int revision);