QChar: prepare relational operators for constexpr'ification

Make sure the relational operators are in a constexpr'able form
by removing the use of the const/non-const-overloaded unicode()
function, which in the relational operators is resolved to the
non-const version, which isn't constexpr'able.

Replaced with direct member access for op== and op< (required
making them friends) and reformulating the other operators in
terms of these two.

Since I managed to introduce a bug while doing this change,
add a simple test for QChar operators, too.

Change-Id: I69f3da849e71abc2a17152f797694950914adebc
Reviewed-by: Alex Trotsenko <alex1973tr@gmail.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 29 insertions, 0 deletions

diff --git a/tests/auto/corelib/tools/qchar/tst_qchar.cpp b/tests/auto/corelib/tools/qchar/tst_qchar.cpp
index a4350ea2fe..55c911a5fc 100644
--- a/tests/auto/corelib/tools/qchar/tst_qchar.cpp
+++ b/tests/auto/corelib/tools/qchar/tst_qchar.cpp
@@ -47,6 +47,8 @@ public slots:
     void init();
     void cleanup();
 private slots:
+    void operators_data();
+    void operators();
     void toUpper();
     void toLower();
     void toTitle();
@@ -99,6 +101,33 @@ void tst_QChar::cleanup()
 #endif
 }
 
+void tst_QChar::operators_data()
+{
+    QTest::addColumn<QChar>("lhs");
+    QTest::addColumn<QChar>("rhs");
+
+    for (int i = 0; i < 3; ++i) {
+        for (int j = 0; j < 3; ++j)
+            QTest::newRow(qPrintable(QString().sprintf("'\\%d' (op) '\\%d'", i, j)))
+                    << QChar(ushort(i)) << QChar(ushort(j));
+    }
+}
+
+void tst_QChar::operators()
+{
+    QFETCH(QChar, lhs);
+    QFETCH(QChar, rhs);
+
+#define CHECK(op) QCOMPARE((lhs op rhs), (lhs.unicode() op rhs.unicode()))
+    CHECK(==);
+    CHECK(!=);
+    CHECK(< );
+    CHECK(> );
+    CHECK(<=);
+    CHECK(>=);
+#undef CHECK
+}
+
 void tst_QChar::toUpper()
 {
     QVERIFY(QChar('a').toUpper() == 'A');