Check for word boundaries when looking for operators in ParamIterator

As found by Igor Kushnir during code review, the old code didn't
handle custom identifiers that ended with the string 'operator'.

kdevplatform/language/duchain/stringhelpers.cpp

@@ -76,6 +76,15 @@ int rStrip_impl(const T& str, T& from)
     return s - from.length();
 }
 
+bool endsWithWordBoundary(QStringView str)
+{
+    if (str.isEmpty()) {
+        return true;
+    }
+    const auto boundary = str.last();
+    return !boundary.isLetterOrNumber() && boundary != QLatin1Char('_');
+}
+
 bool isOperator(const QString& str, int pos)
 {
     const auto c = str[pos];
@@ -93,7 +102,14 @@ bool isOperator(const QString& str, int pos)
         --pos;
     }
 
-    return QStringView(str).mid(0, pos + 1).endsWith(QLatin1String("operator"));
+    auto prefix = QStringView(str).left(pos + 1);
+    const auto op = QLatin1String("operator");
+    if (!prefix.endsWith(op)) {
+        return false;
+    }
+
+    prefix.chop(op.size());
+    return endsWithWordBoundary(prefix);
 }
 
 int skipStringOrCharLiteral(const QString& str, int pos)

kdevplatform/language/duchain/tests/test_stringhelpers.cpp

@@ -157,6 +157,7 @@ void TestStringHelpers::testParamIterator_data()
             {"_Tp", "foo<bar>", "__void_t<decltype(std::declval<_Tp>().operator->(std::declval<_Up>()))>"});
     addTest("A<\">\\\">\">", {"\">\\\">\""});
     addTest("A<'>'>", {"'>'"});
+    addTest("myoperator<anoperator<anotheroperator>, my_operator>", {"anoperator<anotheroperator>", "my_operator"});
 }
 
 void TestStringHelpers::testParamIterator()