Make sure QML type "real" always maps to C++ type "double"

The type "real" was documented to be a single-precision float, but
that's incorrect. It's always been double.

However, signal parameters of type "real" would be mapped to the C++
type "qreal", which can be either float or double depending on the
platform.

Since JavaScript floating point numbers have double precision, QML
should use the same, to avoid potential loss of precision.

With this change, "real" behaves the same as the QML "double" type
(which already guaranteed double precision). Even though it's
redundant, "double" is kept to preserve compatibility.

Added tests for the "double" type to the QML meta-object autotest,
and a test for the "real" type that ensures there's no loss of
precision.

Change-Id: I1a77f1fd45082ff670684a935e17d1a46ea75d84
Reviewed-by: Aaron Kennedy <aaron.kennedy@nokia.com>

6 files changed, 64 insertions, 5 deletions

diff --git a/tests/auto/qml/qqmlecmascript/data/realTypePrecision.qml b/tests/auto/qml/qqmlecmascript/data/realTypePrecision.qml
new file mode 100644
index 0000000000..524478887e
--- /dev/null
+++ b/tests/auto/qml/qqmlecmascript/data/realTypePrecision.qml
@@ -0,0 +1,22 @@
+import Qt.test 1.0
+import QtQuick 2.0
+
+QtObject {
+    property real test: 1234567890
+    property real test2
+    property real test3
+    property real test4: test3
+    property real test5: func()
+    property real test6: test2 + test3
+
+    signal sig(real arg)
+
+    Component.onCompleted: {
+        test2 = 1234567890;
+        sig(1234567890)
+    }
+
+    onSig: { test3 = arg; }
+
+    function func() { return 1234567890; }
+}
diff --git a/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp b/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
index 676557a81c..0dc0e5aca8 100644
--- a/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
+++ b/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
@@ -236,6 +236,7 @@ private slots:
     void revisionErrors();
     void revision();
     void invokableWithQObjectDerived();
+    void realTypePrecision();
 
     void automaticSemicolon();
     void unaryExpression();
@@ -6092,6 +6093,20 @@ void tst_qqmlecmascript::invokableWithQObjectDerived()
     }
 }
 
+void tst_qqmlecmascript::realTypePrecision()
+{
+    // Properties and signal parameters of type real should have double precision.
+    QQmlComponent component(&engine, testFileUrl("realTypePrecision.qml"));
+    QScopedPointer<QObject> object(component.create());
+    QVERIFY(object != 0);
+    QCOMPARE(object->property("test").toDouble(), 1234567890.);
+    QCOMPARE(object->property("test2").toDouble(), 1234567890.);
+    QCOMPARE(object->property("test3").toDouble(), 1234567890.);
+    QCOMPARE(object->property("test4").toDouble(), 1234567890.);
+    QCOMPARE(object->property("test5").toDouble(), 1234567890.);
+    QCOMPARE(object->property("test6").toDouble(), 1234567890.*2);
+}
+
 QTEST_MAIN(tst_qqmlecmascript)
 
 #include "tst_qqmlecmascript.moc"
diff --git a/tests/auto/qml/qqmlmetaobject/data/property.double.qml b/tests/auto/qml/qqmlmetaobject/data/property.double.qml
new file mode 100644
index 0000000000..65da1889e4
--- /dev/null
+++ b/tests/auto/qml/qqmlmetaobject/data/property.double.qml
@@ -0,0 +1,5 @@
+import QtQuick 2.0
+
+QtObject {
+    property double test: 1234567890
+}
diff --git a/tests/auto/qml/qqmlmetaobject/data/property.real.qml b/tests/auto/qml/qqmlmetaobject/data/property.real.qml
index de2baf5be2..2268aac8c2 100644
--- a/tests/auto/qml/qqmlmetaobject/data/property.real.qml
+++ b/tests/auto/qml/qqmlmetaobject/data/property.real.qml
@@ -1,5 +1,5 @@
 import QtQuick 2.0
 
 QtObject {
-    property real test: 21
+    property real test: 1234567890
 }
diff --git a/tests/auto/qml/qqmlmetaobject/data/signal.6.qml b/tests/auto/qml/qqmlmetaobject/data/signal.6.qml
new file mode 100644
index 0000000000..a4ec6c0eaa
--- /dev/null
+++ b/tests/auto/qml/qqmlmetaobject/data/signal.6.qml
@@ -0,0 +1,5 @@
+import QtQuick 2.0
+
+QtObject {
+    signal testSignal(double foo)
+}
diff --git a/tests/auto/qml/qqmlmetaobject/tst_qqmlmetaobject.cpp b/tests/auto/qml/qqmlmetaobject/tst_qqmlmetaobject.cpp
index 6cadc3524b..f2c50ddbef 100644
--- a/tests/auto/qml/qqmlmetaobject/tst_qqmlmetaobject.cpp
+++ b/tests/auto/qml/qqmlmetaobject/tst_qqmlmetaobject.cpp
@@ -92,12 +92,18 @@ void tst_QQmlMetaObject::property_data()
             << QByteArray("bool") << int(QMetaType::Bool)
             << true // default
             << QVariant(true) << true << QVariant(false);
+    QTest::newRow("double") << "property.double.qml"
+             << QByteArray("double") << int(QMetaType::Double)
+             << false // default
+             << QVariant(double(1234567890.))
+             << true // writable
+             << QVariant(double(1.23456789));
     QTest::newRow("real") << "property.real.qml"
             << QByteArray("double") << int(QMetaType::Double)
             << false // default
-            << QVariant(double(21))
+            << QVariant(double(1234567890.))
             << true // writable
-            << QVariant(double(37));
+            << QVariant(double(1.23456789));
     QTest::newRow("string") << "property.string.qml"
             << QByteArray("QString") << int(QMetaType::QString)
             << true // default
@@ -306,10 +312,10 @@ void tst_QQmlMetaObject::method_data()
             << (QList<QByteArray>() << "QString")
             << (QList<QByteArray>() << "foo");
     QTest::newRow("testSignal(int foo, bool bar, real baz)") << "signal.3.qml"
-            << "testSignal(int,bool,qreal)"
+            << "testSignal(int,bool,double)"
             << QMetaMethod::Signal
             << ""
-            << (QList<QByteArray>() << "int" << "bool" << "qreal")
+            << (QList<QByteArray>() << "int" << "bool" << "double")
             << (QList<QByteArray>() << "foo" << "bar" << "baz");
     QTest::newRow("testSignal(variant foo, var bar)") << "signal.4.qml"
             << "testSignal(QVariant,QVariant)"
@@ -323,6 +329,12 @@ void tst_QQmlMetaObject::method_data()
             << ""
             << (QList<QByteArray>() << "QColor" << "QDateTime" << "QUrl")
             << (QList<QByteArray>() << "foo" << "bar" << "baz");
+    QTest::newRow("testSignal(double foo)") << "signal.6.qml"
+            << "testSignal(double)"
+            << QMetaMethod::Signal
+            << ""
+            << (QList<QByteArray>() << "double")
+            << (QList<QByteArray>() << "foo");
 }
 
 void tst_QQmlMetaObject::method()