C#: Roll back changes for tuples in default to string.

Author: michaelnebel

csharp/ql/src/Useless code/DefaultToStringQuery.qll

@@ -46,7 +46,6 @@ private predicate alwaysInvokesToString(ParameterRead pr) {
  * method from `System.Object` or `System.ValueType`.
  */
 predicate alwaysDefaultToString(ValueOrRefType t) {
-  not t instanceof TupleType and
   exists(ToStringMethod m | t.hasMethod(m) |
     m.getDeclaringType() instanceof SystemObjectClass or
     m.getDeclaringType() instanceof SystemValueTypeClass
@@ -56,11 +55,6 @@ predicate alwaysDefaultToString(ValueOrRefType t) {
     overriding.getABaseType+() = t
   ) and
   ((t.isAbstract() or t instanceof Interface) implies not t.isEffectivelyPublic())
-  or
-  exists(ValueOrRefType elem |
-    elem = t.(TupleType).getElementType(_) and
-    alwaysDefaultToString(elem)
-  )
 }
 
 class DefaultToStringType extends ValueOrRefType {