C#: Teach unification library about tuple types

Author: hvitved

csharp/ql/src/semmle/code/csharp/Type.qll

@@ -941,6 +941,8 @@ class TupleType extends ValueType, @tuple_type {
   }
 
   override string getLabel() { result = getUnderlyingType().getLabel() }
+
+  override Type getChild(int i) { result = this.getUnderlyingType().getChild(i) }
 }
 
 /**

csharp/ql/src/semmle/code/csharp/Unification.qll

@@ -70,6 +70,8 @@ private module Gvn {
     or
     result = TConstructedType(t.(ConstructedType).getUnboundGeneric())
     or
+    result = TConstructedType(t.(TupleType).getUnderlyingType().getUnboundGeneric())
+    or
     result = TConstructedType(t)
   }
 

csharp/ql/test/library-tests/unification/Unification.expected

@@ -243,6 +243,21 @@ subsumes
 | Unification.cs:11:7:11:28 | C6<C2<S2>,Tm,C3<Tm>,S2> | Unification.cs:11:7:11:28 | C6<C2<S2>,C2<S2>,C3<C2<S2>>,S2> |
 | Unification.cs:11:7:11:28 | C6<C2<S2>,Tm,C3<Tm>,S2> | Unification.cs:11:7:11:28 | C6<C2<S2>,Tm,C3<Tm>,S2> |
 | Unification.cs:26:7:26:20 | Tuples<,> | Unification.cs:26:7:26:20 | Tuples<,> |
+| Unification.cs:28:12:28:20 | (T8,Int32) | Unification.cs:28:12:28:20 | (T8,Int32) |
+| Unification.cs:28:12:28:20 | (T8,Int32) | Unification.cs:29:12:29:24 | (String,Int32) |
+| Unification.cs:29:12:29:24 | (String,Int32) | Unification.cs:29:12:29:24 | (String,Int32) |
+| Unification.cs:30:12:30:23 | (String,T9) | Unification.cs:29:12:29:24 | (String,Int32) |
+| Unification.cs:30:12:30:23 | (String,T9) | Unification.cs:30:12:30:23 | (String,T9) |
+| Unification.cs:31:12:31:19 | (T8,T9) | Unification.cs:28:12:28:20 | (T8,Int32) |
+| Unification.cs:31:12:31:19 | (T8,T9) | Unification.cs:29:12:29:24 | (String,Int32) |
+| Unification.cs:31:12:31:19 | (T8,T9) | Unification.cs:30:12:30:23 | (String,T9) |
+| Unification.cs:31:12:31:19 | (T8,T9) | Unification.cs:31:12:31:19 | (T8,T9) |
+| Unification.cs:31:12:31:19 | (T8,T9) | Unification.cs:32:12:32:23 | (T8,T9) |
+| Unification.cs:32:12:32:23 | (T8,T9) | Unification.cs:28:12:28:20 | (T8,Int32) |
+| Unification.cs:32:12:32:23 | (T8,T9) | Unification.cs:29:12:29:24 | (String,Int32) |
+| Unification.cs:32:12:32:23 | (T8,T9) | Unification.cs:30:12:30:23 | (String,T9) |
+| Unification.cs:32:12:32:23 | (T8,T9) | Unification.cs:31:12:31:19 | (T8,T9) |
+| Unification.cs:32:12:32:23 | (T8,T9) | Unification.cs:32:12:32:23 | (T8,T9) |
 subsumptionImpliesUnification
 unifiable
 | Unification.cs:6:7:6:12 | C1<C0> | Unification.cs:6:7:6:12 | C1<> |
@@ -271,3 +286,13 @@ unifiable
 | Unification.cs:11:7:11:28 | C6<C2<S2>,C2<S2>,C3<C2<S2>>,S2> | Unification.cs:11:7:11:28 | C6<,,,> |
 | Unification.cs:11:7:11:28 | C6<C2<S2>,C2<S2>,C3<C2<S2>>,S2> | Unification.cs:11:7:11:28 | C6<C2<S2>,Tm,C3<Tm>,S2> |
 | Unification.cs:11:7:11:28 | C6<C2<S2>,Tm,C3<Tm>,S2> | Unification.cs:11:7:11:28 | C6<,,,> |
+| Unification.cs:28:12:28:20 | (T8,Int32) | Unification.cs:30:12:30:23 | (String,T9) |
+| Unification.cs:28:12:28:20 | (T8,Int32) | Unification.cs:31:12:31:19 | (T8,T9) |
+| Unification.cs:28:12:28:20 | (T8,Int32) | Unification.cs:32:12:32:23 | (T8,T9) |
+| Unification.cs:29:12:29:24 | (String,Int32) | Unification.cs:28:12:28:20 | (T8,Int32) |
+| Unification.cs:29:12:29:24 | (String,Int32) | Unification.cs:30:12:30:23 | (String,T9) |
+| Unification.cs:29:12:29:24 | (String,Int32) | Unification.cs:31:12:31:19 | (T8,T9) |
+| Unification.cs:29:12:29:24 | (String,Int32) | Unification.cs:32:12:32:23 | (T8,T9) |
+| Unification.cs:30:12:30:23 | (String,T9) | Unification.cs:28:12:28:20 | (T8,Int32) |
+| Unification.cs:30:12:30:23 | (String,T9) | Unification.cs:31:12:31:19 | (T8,T9) |
+| Unification.cs:30:12:30:23 | (String,T9) | Unification.cs:32:12:32:23 | (T8,T9) |