Fixed #8723: False negative: Same expression with methods

cfg/qt.cfg

@@ -945,6 +945,7 @@
   <function name="QString::compare">
     <noreturn>false</noreturn>
     <returnValue type="int"/>
+    <const/>
     <use-retval/>
     <leak-ignore/>
     <arg nr="1" direction="in">

test/cfg/qt.cpp

@@ -279,6 +279,13 @@ QVector<int>::iterator QVector2()
     return it;
 }
 
+void duplicateExpression_QString_Compare(QString style) //#8723
+{
+	// cppcheck-suppress duplicateExpression
+    if (style.compare( "x", Qt::CaseInsensitive ) == 0 || style.compare( "x", Qt::CaseInsensitive ) == 0)
+    {}
+}
+
 void QStack1(QStack<int> intStackArg)
 {
     for (int i = 0; i <= intStackArg.size(); ++i) {