C#: Fix typementions of arrays.

Author: calumgrant

csharp/extractor/Semmle.Extraction.CSharp/Entities/TypeMention.cs

@@ -22,6 +22,18 @@ class TypeMention : FreshEntity
             Loc = loc;
         }
 
+        static TypeSyntax GetArrayElementType(ArrayTypeSyntax array)
+        {
+            return array.ElementType is ArrayTypeSyntax a ? 
+                GetArrayElementType(a) :
+                array.ElementType;
+        }
+
+        static Type GetArrayElementType(Type t)
+        {
+            return t is ArrayType a ? GetArrayElementType(a.ElementType.Type) : t;
+        }
+
         void Populate()
         {
             switch (Syntax.Kind())
@@ -30,7 +42,7 @@ void Populate()
                     var ats = (ArrayTypeSyntax)Syntax;
                     var at = (ArrayType)Type;
                     Emit(Loc ?? Syntax.GetLocation(), Parent, Type);
-                    Create(cx, ats.ElementType, this, at.ElementType);
+                    Create(cx, GetArrayElementType(ats), this, GetArrayElementType(at));
                     return;
                 case SyntaxKind.NullableType:
                     var nts = (NullableTypeSyntax)Syntax;

csharp/ql/test/library-tests/regressions/Program.cs

@@ -159,4 +159,9 @@ class EmbeddedTypesManager<
     }
 }
 
+unsafe class ArrayTypesTest
+{
+  int*[][] field;
+}
+
 // semmle-extractor-options: /r:System.Dynamic.Runtime.dll

csharp/ql/test/library-tests/regressions/TypeMentions.expected

@@ -76,3 +76,6 @@
 | Program.cs:157:31:157:50 | EmbeddedTypesManager<,> |
 | Program.cs:157:52:157:72 | TEmbeddedTypesManager |
 | Program.cs:157:75:157:87 | TEmbeddedType |
+| Program.cs:164:3:164:5 | Int32 |
+| Program.cs:164:3:164:6 | Int32* |
+| Program.cs:164:3:164:10 | Int32*[][] |