Merge branch 'main' of github.com:github/codeql into SharedDataflow_PostUpdateNodes

2026-04-29 18:55:14 +02:00 · 2020-08-28 13:01:14 +02:00
parent 9503c5d8bb 93e0bd9d85
commit 6b8d9f2a77
108 changed files with 2110 additions and 618 deletions
--- a/csharp/extractor/Semmle.Extraction.CIL/CachedFunction.cs
+++ b/csharp/extractor/Semmle.Extraction.CIL/CachedFunction.cs
@@ -9,7 +9,7 @@ namespace Semmle.Extraction.CIL
    /// </summary>
    /// <typeparam name="SrcType">The type of the source.</typeparam>
    /// <typeparam name="TargetType">The type of the generated object.</typeparam>
-    public class CachedFunction<SrcType, TargetType>
+    public class CachedFunction<SrcType, TargetType> where SrcType : notnull
    {
        readonly Func<SrcType, TargetType> generator;
        readonly Dictionary<SrcType, TargetType> cache;
--- a/csharp/extractor/Semmle.Extraction.CIL/Context.cs
+++ b/csharp/extractor/Semmle.Extraction.CIL/Context.cs
@@ -14,13 +14,19 @@ namespace Semmle.Extraction.CIL
    /// </summary>
    partial class Context : IDisposable
    {
-        public Extraction.Context cx;
        readonly FileStream stream;
-        public readonly MetadataReader mdReader;
-        public readonly PEReader peReader;
-        public readonly string assemblyPath;
-        public Entities.Assembly assembly;
-        public PDB.IPdb pdb;
+        Entities.Assembly? assemblyNull;
+
+        public Extraction.Context cx { get; }
+        public MetadataReader mdReader { get; }
+        public PEReader peReader { get; }
+        public string assemblyPath { get; }
+        public Entities.Assembly assembly
+        {
+            get { return assemblyNull!; }
+            set { assemblyNull = value; }
+        }
+        public PDB.IPdb? pdb { get; }

        public Context(Extraction.Context cx, string assemblyPath, bool extractPdbs)
        {
@@ -105,7 +111,7 @@ namespace Semmle.Extraction.CIL
        /// </summary>
        /// <param name="handle">The handle of the method.</param>
        /// <returns>The debugging information, or null if the information could not be located.</returns>
-        public PDB.IMethod GetMethodDebugInformation(MethodDefinitionHandle handle)
+        public PDB.IMethod? GetMethodDebugInformation(MethodDefinitionHandle handle)
        {
            return pdb == null ? null : pdb.GetMethod(handle.ToDebugInformationHandle());
        }
@@ -125,7 +131,8 @@ namespace Semmle.Extraction.CIL
        }

        /// <summary>
-        /// The list of generic type parameters.
+        /// The list of generic type parameters, including type parameters of
+        /// containing types.
        /// </summary>
        public abstract IEnumerable<Entities.Type> TypeParameters { get; }

--- a/csharp/extractor/Semmle.Extraction.CIL/Entities/Assembly.cs
+++ b/csharp/extractor/Semmle.Extraction.CIL/Entities/Assembly.cs
@@ -47,9 +47,9 @@ namespace Semmle.Extraction.CIL.Entities
            trapFile.Write(cx.assemblyPath.Replace("\\", "/"));
        }

-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
        {
-            return GetType() == obj.GetType() && Equals(file, ((Assembly)obj).file);
+            return GetType() == obj?.GetType() && Equals(file, ((Assembly)obj).file);
        }

        public override int GetHashCode() => 7 * file.GetHashCode();
@@ -63,7 +63,7 @@ namespace Semmle.Extraction.CIL.Entities
            get
            {
                yield return file;
-                yield return Tuples.assemblies(this, file, FullName, assemblyName.Name, assemblyName.Version.ToString());
+                yield return Tuples.assemblies(this, file, FullName, assemblyName.Name ?? string.Empty, assemblyName.Version?.ToString() ?? string.Empty);

                if (cx.pdb != null)
                {
@@ -75,7 +75,7 @@ namespace Semmle.Extraction.CIL.Entities

                foreach (var handle in cx.mdReader.TypeDefinitions)
                {
-                    IExtractionProduct product = null;
+                    IExtractionProduct? product = null;
                    try
                    {
                        product = cx.Create(handle);
@@ -92,7 +92,7 @@ namespace Semmle.Extraction.CIL.Entities

                foreach (var handle in cx.mdReader.MethodDefinitions)
                {
-                    IExtractionProduct product = null;
+                    IExtractionProduct? product = null;
                    try
                    {
                        product = cx.Create(handle);
--- a/csharp/extractor/Semmle.Extraction.CIL/Entities/Attribute.cs
+++ b/csharp/extractor/Semmle.Extraction.CIL/Entities/Attribute.cs
@@ -27,7 +27,7 @@ namespace Semmle.Extraction.CIL.Entities
            this.@object = @object;
        }

-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
        {
            return obj is Attribute attribute && handle.Equals(attribute.handle);
        }
@@ -58,13 +58,15 @@ namespace Semmle.Extraction.CIL.Entities
                for (int index = 0; index < decoded.FixedArguments.Length; ++index)
                {
                    object value = decoded.FixedArguments[index].Value;
-                    yield return Tuples.cil_attribute_positional_argument(this, index, value == null ? "null" : value.ToString());
+                    var stringValue = value?.ToString();
+                    yield return Tuples.cil_attribute_positional_argument(this, index, stringValue ?? "null");
                }

                foreach (var p in decoded.NamedArguments)
                {
                    object value = p.Value;
-                    yield return Tuples.cil_attribute_named_argument(this, p.Name, value == null ? "null" : value.ToString());
+                    var stringValue = value?.ToString();
+                    yield return Tuples.cil_attribute_named_argument(this, p.Name, stringValue ?? "null");
                }
            }
        }
--- a/csharp/extractor/Semmle.Extraction.CIL/Entities/Event.cs
+++ b/csharp/extractor/Semmle.Extraction.CIL/Entities/Event.cs
@@ -36,7 +36,7 @@ namespace Semmle.Extraction.CIL.Entities

        public override string IdSuffix => ";cil-event";

-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
        {
            return obj is Event e && handle.Equals(e.handle);
        }
--- a/csharp/extractor/Semmle.Extraction.CIL/Entities/ExceptionRegion.cs
+++ b/csharp/extractor/Semmle.Extraction.CIL/Entities/ExceptionRegion.cs
@@ -30,7 +30,7 @@ namespace Semmle.Extraction.CIL.Entities
        {
            get
            {
-                IInstruction try_start, try_end, handler_start;
+                IInstruction? try_start, try_end, handler_start;

                if (!jump_table.TryGetValue(r.TryOffset, out try_start))
                    throw new InternalError("Failed  to retrieve handler");
@@ -44,7 +44,7 @@ namespace Semmle.Extraction.CIL.Entities

                if (r.FilterOffset != -1)
                {
-                    IInstruction filter_start;
+                    IInstruction? filter_start;
                    if (!jump_table.TryGetValue(r.FilterOffset, out filter_start))
                        throw new InternalError("ExceptionRegion filter clause");

--- a/csharp/extractor/Semmle.Extraction.CIL/Entities/Field.cs
+++ b/csharp/extractor/Semmle.Extraction.CIL/Entities/Field.cs
@@ -91,7 +91,7 @@ namespace Semmle.Extraction.CIL.Entities
            fd = cx.mdReader.GetFieldDefinition(handle);
        }

-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
        {
            return obj is DefinitionField field && handle.Equals(field.handle);
        }
@@ -153,7 +153,7 @@ namespace Semmle.Extraction.CIL.Entities
            declType = (Type)cx.CreateGeneric(gc, mr.Parent);
        }

-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
        {
            return obj is MemberReferenceField field && Handle.Equals(field.Handle);
        }
--- a/csharp/extractor/Semmle.Extraction.CIL/Entities/File.cs
+++ b/csharp/extractor/Semmle.Extraction.CIL/Entities/File.cs
@@ -25,9 +25,9 @@ namespace Semmle.Extraction.CIL.Entities
            trapFile.Write(Semmle.Extraction.Entities.File.PathAsDatabaseId(path));
        }

-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
        {
-            return GetType() == obj.GetType() && path == ((File)obj).path;
+            return GetType() == obj?.GetType() && path == ((File)obj).path;
        }

        public override int GetHashCode() => 11 * path.GetHashCode();
@@ -36,7 +36,11 @@ namespace Semmle.Extraction.CIL.Entities
        {
            get
            {
-                var parent = cx.CreateFolder(System.IO.Path.GetDirectoryName(path));
+                var directoryName = System.IO.Path.GetDirectoryName(path);
+                if (directoryName is null)
+                    throw new InternalError($"Directory name for path '{path}' is null.");
+
+                var parent = cx.CreateFolder(directoryName);
                yield return parent;
                yield return Tuples.containerparent(parent, this);
                yield return Tuples.files(this, path, System.IO.Path.GetFileNameWithoutExtension(path), System.IO.Path.GetExtension(path).Substring(1));
--- a/csharp/extractor/Semmle.Extraction.CIL/Entities/Folder.cs
+++ b/csharp/extractor/Semmle.Extraction.CIL/Entities/Folder.cs
@@ -41,7 +41,7 @@ namespace Semmle.Extraction.CIL.Entities
            }
        }

-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
        {
            return obj is Folder folder && path == folder.path;
        }
--- a/csharp/extractor/Semmle.Extraction.CIL/Entities/Instruction.cs
+++ b/csharp/extractor/Semmle.Extraction.CIL/Entities/Instruction.cs
@@ -365,6 +365,11 @@ namespace Semmle.Extraction.CIL.Entities
            {
                int offset = Offset;

+                if (Method.Implementation is null)
+                {
+                    yield break;
+                }
+
                yield return Tuples.cil_instruction(this, (int)OpCode, Index, Method.Implementation);

                switch (PayloadType)
@@ -414,11 +419,17 @@ namespace Semmle.Extraction.CIL.Entities
                        break;
                    case Payload.Arg8:
                    case Payload.Arg16:
-                        yield return Tuples.cil_access(this, Method.Parameters[(int)UnsignedPayloadValue]);
+                        if (Method.Parameters is object)
+                        {
+                            yield return Tuples.cil_access(this, Method.Parameters[(int)UnsignedPayloadValue]);
+                        }
                        break;
                    case Payload.Local8:
                    case Payload.Local16:
-                        yield return Tuples.cil_access(this, Method.LocalVariables[(int)UnsignedPayloadValue]);
+                        if (Method.LocalVariables is object)
+                        {
+                            yield return Tuples.cil_access(this, Method.LocalVariables[(int)UnsignedPayloadValue]);
+                        }
                        break;
                    case Payload.None:
                    case Payload.Target8:
@@ -439,7 +450,7 @@ namespace Semmle.Extraction.CIL.Entities
        public IEnumerable<IExtractionProduct> JumpContents(Dictionary<int, IInstruction> jump_table)
        {
            int target;
-            IInstruction inst;
+            IInstruction? inst;

            switch (PayloadType)
            {
--- a/csharp/extractor/Semmle.Extraction.CIL/Entities/Method.cs
+++ b/csharp/extractor/Semmle.Extraction.CIL/Entities/Method.cs
@@ -23,25 +23,29 @@ namespace Semmle.Extraction.CIL.Entities
    /// </summary>
    abstract class Method : TypeContainer, IMethod
    {
+        protected MethodTypeParameter[]? genericParams;
+        protected GenericContext gc;
+        protected MethodSignature<ITypeSignature> signature;
+
        protected Method(GenericContext gc) : base(gc.cx)
        {
            this.gc = gc;
        }

-        public override IEnumerable<Type> TypeParameters => gc.TypeParameters.Concat(declaringType.TypeParameters);
+        public override IEnumerable<Type> TypeParameters => gc.TypeParameters.Concat(DeclaringType.TypeParameters);

        public override IEnumerable<Type> MethodParameters =>
            genericParams == null ? gc.MethodParameters : gc.MethodParameters.Concat(genericParams);

        public int GenericParameterCount => signature.GenericParameterCount;

-        public virtual Method SourceDeclaration => this;
+        public virtual Method? SourceDeclaration => this;

        public abstract Type DeclaringType { get; }
        public abstract string Name { get; }

-        public virtual IList<LocalVariable> LocalVariables => throw new NotImplementedException();
-        public IList<Parameter> Parameters { get; private set; }
+        public virtual IList<LocalVariable>? LocalVariables => throw new NotImplementedException();
+        public IList<Parameter>? Parameters { get; protected set; }

        public override void WriteId(TextWriter trapFile) => WriteMethodId(trapFile, DeclaringType, NameLabel);

@@ -70,19 +74,8 @@ namespace Semmle.Extraction.CIL.Entities
            trapFile.Write(')');
        }

-        protected MethodTypeParameter[] genericParams;
-        protected Type declaringType;
-        protected GenericContext gc;
-        protected MethodSignature<ITypeSignature> signature;
-        protected string name;
-
        public override string IdSuffix => ";cil-method";

-        protected void PopulateParameters(IEnumerable<Type> parameterTypes)
-        {
-            Parameters = MakeParameters(parameterTypes).ToArray();
-        }
-
        protected IEnumerable<IExtractionProduct> PopulateFlags
        {
            get
@@ -94,7 +87,7 @@ namespace Semmle.Extraction.CIL.Entities

        public abstract bool IsStatic { get; }

-        private IEnumerable<Parameter> MakeParameters(IEnumerable<Type> parameterTypes)
+        protected IEnumerable<Parameter> MakeParameters(IEnumerable<Type> parameterTypes)
        {
            int i = 0;

@@ -145,13 +138,15 @@ namespace Semmle.Extraction.CIL.Entities
    {
        readonly Handle handle;
        readonly MethodDefinition md;
-        readonly PDB.IMethod methodDebugInformation;
+        readonly PDB.IMethod? methodDebugInformation;
+        readonly Type declaringType;

-        LocalVariable[] locals;
+        readonly string name;
+        LocalVariable[]? locals;

-        public MethodImplementation Implementation { get; private set; }
+        public MethodImplementation? Implementation { get; private set; }

-        public override IList<LocalVariable> LocalVariables => locals;
+        public override IList<LocalVariable>? LocalVariables => locals;

        public DefinitionMethod(GenericContext gc, MethodDefinitionHandle handle) : base(gc)
        {
@@ -167,7 +162,7 @@ namespace Semmle.Extraction.CIL.Entities
            methodDebugInformation = cx.GetMethodDebugInformation(handle);
        }

-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
        {
            return obj is DefinitionMethod method && handle.Equals(method.handle);
        }
@@ -206,7 +201,7 @@ namespace Semmle.Extraction.CIL.Entities

                var typeSignature = md.DecodeSignature(cx.TypeSignatureDecoder, this);

-                PopulateParameters(typeSignature.ParameterTypes);
+                Parameters = MakeParameters(typeSignature.ParameterTypes).ToArray();

                foreach (var c in Parameters)
                    yield return c;
@@ -315,8 +310,8 @@ namespace Semmle.Extraction.CIL.Entities
            // The sequence point gives the location of each instruction.
            // The location of an instruction is given by the sequence point *after* the
            // instruction.
-            IEnumerator<PDB.SequencePoint> nextSequencePoint = null;
-            PdbSourceLocation instructionLocation = null;
+            IEnumerator<PDB.SequencePoint>? nextSequencePoint = null;
+            PdbSourceLocation? instructionLocation = null;

            if (methodDebugInformation != null)
            {
@@ -401,9 +396,9 @@ namespace Semmle.Extraction.CIL.Entities
    {
        readonly MemberReferenceHandle handle;
        readonly MemberReference mr;
-        readonly Type declType;
+        readonly Type declaringType;
        readonly GenericContext parent;
-        readonly Method sourceDeclaration;
+        readonly Method? sourceDeclaration;

        public MemberReferenceMethod(GenericContext gc, MemberReferenceHandle handle) : base(gc)
        {
@@ -416,22 +411,24 @@ namespace Semmle.Extraction.CIL.Entities
            parent = (GenericContext)cx.CreateGeneric(gc, mr.Parent);

            var parentMethod = parent as Method;
-            nameLabel = cx.GetString(mr.Name);

-            declType = parentMethod == null ? parent as Type : parentMethod.DeclaringType;
+            var declType = parentMethod is null ? parent as Type : parentMethod.DeclaringType;

            if (declType is null)
                throw new InternalError("Parent context of method is not a type");

-            var typeSourceDeclaration = declType.SourceDeclaration;
-            sourceDeclaration = typeSourceDeclaration == declType ? (Method)this : typeSourceDeclaration.LookupMethod(mr.Name, mr.Signature);
+            declaringType = declType;
+            nameLabel = cx.GetString(mr.Name);
+
+            var typeSourceDeclaration = declaringType.SourceDeclaration;
+            sourceDeclaration = typeSourceDeclaration == declaringType ? (Method)this : typeSourceDeclaration.LookupMethod(mr.Name, mr.Signature);
        }

        private readonly string nameLabel;

        public override string NameLabel => nameLabel;

-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
        {
            return obj is MemberReferenceMethod method && handle.Equals(method.handle);
        }
@@ -441,11 +438,11 @@ namespace Semmle.Extraction.CIL.Entities
            return handle.GetHashCode();
        }

-        public override Method SourceDeclaration => sourceDeclaration;
+        public override Method? SourceDeclaration => sourceDeclaration;

        public override bool IsStatic => !signature.Header.IsInstance;

-        public override Type DeclaringType => declType;
+        public override Type DeclaringType => declaringType;

        public override string Name => cx.ShortName(mr.Name);

@@ -464,7 +461,7 @@ namespace Semmle.Extraction.CIL.Entities

                var typeSignature = mr.DecodeMethodSignature(cx.TypeSignatureDecoder, this);

-                PopulateParameters(typeSignature.ParameterTypes);
+                Parameters = MakeParameters(typeSignature.ParameterTypes).ToArray();
                foreach (var p in Parameters) yield return p;

                foreach (var f in PopulateFlags) yield return f;
@@ -486,6 +483,7 @@ namespace Semmle.Extraction.CIL.Entities
        readonly MethodSpecification ms;
        readonly Method unboundMethod;
        readonly ImmutableArray<Type> typeParams;
+        readonly Type declaringType;

        public MethodSpecificationMethod(GenericContext gc, MethodSpecificationHandle handle) : base(gc)
        {
@@ -511,7 +509,7 @@ namespace Semmle.Extraction.CIL.Entities

        public override string NameLabel => throw new NotImplementedException();

-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
        {
            return obj is MethodSpecificationMethod method && handle.Equals(method.handle) && typeParams.SequenceEqual(method.typeParams);
        }
@@ -547,7 +545,7 @@ namespace Semmle.Extraction.CIL.Entities
                        throw new InternalError($"Unexpected constructed method handle kind {ms.Method.Kind}");
                }

-                PopulateParameters(constructedTypeSignature.ParameterTypes);
+                Parameters = MakeParameters(constructedTypeSignature.ParameterTypes).ToArray();
                foreach (var p in Parameters)
                    yield return p;

--- a/csharp/extractor/Semmle.Extraction.CIL/Entities/Namespace.cs
+++ b/csharp/extractor/Semmle.Extraction.CIL/Entities/Namespace.cs
@@ -17,10 +17,10 @@ namespace Semmle.Extraction.CIL.Entities
    /// </summary>
    public sealed class Namespace : TypeContainer, INamespace
    {
-        public Namespace ParentNamespace;
+        public Namespace? ParentNamespace;
        public readonly string Name;

-        public bool IsGlobalNamespace => ParentNamespace == null;
+        public bool IsGlobalNamespace => ParentNamespace is null;

        public override string IdSuffix => ";namespace";

@@ -35,7 +35,7 @@ namespace Semmle.Extraction.CIL.Entities
            trapFile.Write(Name);
        }

-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
        {
            if (obj is Namespace ns && Name == ns.Name)
            {
@@ -63,7 +63,7 @@ namespace Semmle.Extraction.CIL.Entities
            return i == -1 ? fqn : fqn.Substring(i + 1);
        }

-        static Namespace createParentNamespace(Context cx, string fqn)
+        static Namespace? createParentNamespace(Context cx, string fqn)
        {
            if (fqn == "") return null;
            var i = fqn.LastIndexOf('.');
@@ -74,7 +74,7 @@ namespace Semmle.Extraction.CIL.Entities
        {
        }

-        public Namespace(Context cx, string name, Namespace parent) : base(cx)
+        public Namespace(Context cx, string name, Namespace? parent) : base(cx)
        {
            Name = name;
            ParentNamespace = parent;
@@ -85,7 +85,7 @@ namespace Semmle.Extraction.CIL.Entities
            get
            {
                yield return Tuples.namespaces(this, Name);
-                if (!IsGlobalNamespace)
+                if (ParentNamespace is object)
                    yield return Tuples.parent_namespace(this, ParentNamespace);
            }
        }
--- a/csharp/extractor/Semmle.Extraction.CIL/Entities/Parameter.cs
+++ b/csharp/extractor/Semmle.Extraction.CIL/Entities/Parameter.cs
@@ -33,7 +33,7 @@ namespace Semmle.Extraction.CIL.Entities
            trapFile.Write(index);
        }

-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
        {
            return obj is Parameter param && method.Equals(param.method) && index == param.index;
        }
--- a/csharp/extractor/Semmle.Extraction.CIL/Entities/Property.cs
+++ b/csharp/extractor/Semmle.Extraction.CIL/Entities/Property.cs
@@ -48,7 +48,7 @@ namespace Semmle.Extraction.CIL.Entities
            trapFile.Write(")");
        }

-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
        {
            return obj is Property property && Equals(handle, property.handle);
        }
--- a/csharp/extractor/Semmle.Extraction.CIL/Entities/SourceLocation.cs
+++ b/csharp/extractor/Semmle.Extraction.CIL/Entities/SourceLocation.cs
@@ -32,7 +32,7 @@ namespace Semmle.Extraction.CIL.Entities
            trapFile.Write(location.EndColumn);
        }

-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
        {
            return obj is PdbSourceLocation l && location.Equals(l.location);
        }
--- a/csharp/extractor/Semmle.Extraction.CIL/Entities/Type.cs
+++ b/csharp/extractor/Semmle.Extraction.CIL/Entities/Type.cs
@@ -8,6 +8,7 @@ using System.Reflection;
 using Semmle.Util;
 using System.IO;
 using System.Text;
+using System.Diagnostics.CodeAnalysis;

 namespace Semmle.Extraction.CIL.Entities
 {
@@ -103,7 +104,7 @@ namespace Semmle.Extraction.CIL.Entities
        /// shortcut to comparing the signature bytes since handles are unique.
        /// </param>
        /// <returns>The method, or 'null' if not found or not supported.</returns>
-        internal virtual Method LookupMethod(StringHandle methodName, BlobHandle signature)
+        internal virtual Method? LookupMethod(StringHandle methodName, BlobHandle signature)
        {
            return null;
        }
@@ -160,7 +161,7 @@ namespace Semmle.Extraction.CIL.Entities
            get;
        }

-        public virtual TypeContainer Parent => (TypeContainer)ContainingType ?? Namespace;
+        public virtual TypeContainer Parent => (TypeContainer?)ContainingType ?? Namespace!;

        public override IEnumerable<IExtractionProduct> Contents
        {
@@ -177,9 +178,9 @@ namespace Semmle.Extraction.CIL.Entities

        public abstract string Name { get; }

-        public abstract Namespace Namespace { get; }
+        public abstract Namespace? Namespace { get; }

-        public abstract Type ContainingType { get; }
+        public abstract Type? ContainingType { get; }

        public abstract Type Construct(IEnumerable<Type> typeArguments);

@@ -233,7 +234,7 @@ namespace Semmle.Extraction.CIL.Entities
        /// </summary>
        /// <param name="t">The resulting primitive type, or null.</param>
        /// <returns>True if this type is a primitive type.</returns>
-        public bool TryGetPrimitiveType(out PrimitiveType t)
+        public bool TryGetPrimitiveType([NotNullWhen(true)] out PrimitiveType? t)
        {
            if (TryGetPrimitiveTypeCode(out var code))
            {
@@ -249,7 +250,7 @@ namespace Semmle.Extraction.CIL.Entities

        private bool TryGetPrimitiveTypeCode(out PrimitiveTypeCode code)
        {
-            if (ContainingType == null && Namespace.Name == cx.SystemNamespace.Name)
+            if (ContainingType == null && Namespace?.Name == cx.SystemNamespace.Name)
            {
                switch (Name)
                {
@@ -341,7 +342,7 @@ namespace Semmle.Extraction.CIL.Entities
            typeParams = new Lazy<IEnumerable<TypeTypeParameter>>(MakeTypeParameters);
        }

-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
        {
            return obj is TypeDefinitionType t && handle.Equals(t.handle);
        }
@@ -390,9 +391,9 @@ namespace Semmle.Extraction.CIL.Entities

        public override Namespace Namespace => cx.Create(td.NamespaceDefinition);

-        readonly Type declType;
+        readonly Type? declType;

-        public override Type ContainingType => declType;
+        public override Type? ContainingType => declType;

        public override int ThisTypeParameters
        {
@@ -562,18 +563,14 @@ namespace Semmle.Extraction.CIL.Entities
        readonly TypeReference tr;
        readonly Lazy<TypeTypeParameter[]> typeParams;

-        public TypeReferenceType(Context cx, TypeReferenceHandle handle) : this(cx, handle, cx.mdReader.GetTypeReference(handle))
-        {
-            typeParams = new Lazy<TypeTypeParameter[]>(MakeTypeParameters);
-        }
-
-        public TypeReferenceType(Context cx, TypeReferenceHandle handle, TypeReference tr) : base(cx)
+        public TypeReferenceType(Context cx, TypeReferenceHandle handle) : base(cx)
        {
+            this.typeParams = new Lazy<TypeTypeParameter[]>(MakeTypeParameters);
            this.handle = handle;
-            this.tr = tr;
+            this.tr = cx.mdReader.GetTypeReference(handle);
        }

-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
        {
            return obj is TypeReferenceType t && handle.Equals(t.handle);
        }
@@ -637,7 +634,7 @@ namespace Semmle.Extraction.CIL.Entities
            }
        }

-        public override Type ContainingType
+        public override Type? ContainingType
        {
            get
            {
@@ -654,7 +651,7 @@ namespace Semmle.Extraction.CIL.Entities
            switch (tr.ResolutionScope.Kind)
            {
                case HandleKind.TypeReference:
-                    ContainingType.WriteAssemblyPrefix(trapFile);
+                    ContainingType!.WriteAssemblyPrefix(trapFile);
                    break;
                case HandleKind.AssemblyReference:
                    var assemblyDef = cx.mdReader.GetAssemblyReference((AssemblyReferenceHandle)tr.ResolutionScope);
@@ -684,7 +681,7 @@ namespace Semmle.Extraction.CIL.Entities
            var ct = ContainingType;
            if (ct != null)
            {
-                ContainingType.GetId(trapFile, inContext);
+                ct.GetId(trapFile, inContext);
            }
            else
            {
@@ -719,9 +716,11 @@ namespace Semmle.Extraction.CIL.Entities
    public sealed class ConstructedType : Type
    {
        readonly Type unboundGenericType;
-        readonly Type[] thisTypeArguments;

-        public override IEnumerable<Type> ThisTypeArguments => thisTypeArguments;
+        // Either null or notEmpty
+        readonly Type[]? thisTypeArguments;
+
+        public override IEnumerable<Type> ThisTypeArguments => thisTypeArguments.EnumerateNull();

        public override IEnumerable<Type> ThisGenericArguments => thisTypeArguments.EnumerateNull();

@@ -751,7 +750,6 @@ namespace Semmle.Extraction.CIL.Entities

            unboundGenericType = unboundType;
            var thisParams = unboundType.ThisTypeParameters;
-            var parentParams = suppliedArgs - thisParams;

            if (typeArguments.Count() == thisParams)
            {
@@ -760,16 +758,19 @@ namespace Semmle.Extraction.CIL.Entities
            }
            else if (thisParams == 0)
            {
-                containingType = unboundType.ContainingType.Construct(typeArguments);
+                // all type arguments belong to containing type
+                containingType = unboundType.ContainingType!.Construct(typeArguments);
            }
            else
            {
-                containingType = unboundType.ContainingType.Construct(typeArguments.Take(parentParams));
+                // some type arguments belong to containing type
+                var parentParams = suppliedArgs - thisParams;
+                containingType = unboundType.ContainingType!.Construct(typeArguments.Take(parentParams));
                thisTypeArguments = typeArguments.Skip(parentParams).ToArray();
            }
        }

-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
        {
            if (obj is ConstructedType t && Equals(unboundGenericType, t.unboundGenericType) && Equals(containingType, t.containingType))
            {
@@ -788,12 +789,12 @@ namespace Semmle.Extraction.CIL.Entities
            return h;
        }

-        readonly Type containingType;
-        public override Type ContainingType => containingType;
+        readonly Type? containingType;
+        public override Type? ContainingType => containingType;

        public override string Name => unboundGenericType.Name;

-        public override Namespace Namespace => unboundGenericType.Namespace;
+        public override Namespace Namespace => unboundGenericType.Namespace!;

        public override int ThisTypeParameters => thisTypeArguments == null ? 0 : thisTypeArguments.Length;

@@ -851,7 +852,7 @@ namespace Semmle.Extraction.CIL.Entities
            typeCode = tc;
        }

-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
        {
            return obj is PrimitiveType pt && typeCode == pt.typeCode;
        }
@@ -871,7 +872,7 @@ namespace Semmle.Extraction.CIL.Entities

        public override Namespace Namespace => cx.SystemNamespace;

-        public override Type ContainingType => null;
+        public override Type? ContainingType => null;

        public override int ThisTypeParameters => 0;

@@ -894,19 +895,17 @@ namespace Semmle.Extraction.CIL.Entities
        readonly Type elementType;
        readonly int rank;

-        public ArrayType(Context cx, Type element, ArrayShape shape) : base(cx)
+        public ArrayType(Context cx, Type elementType, int rank) : base(cx)
        {
-            rank = shape.Rank;
-            elementType = element;
+            this.rank = rank;
+            this.elementType = elementType;
        }

-        public ArrayType(Context cx, Type element) : base(cx)
+        public ArrayType(Context cx, Type elementType) : this(cx, elementType, 1)
        {
-            rank = 1;
-            elementType = element;
        }

-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
        {
            return obj is ArrayType array && elementType.Equals(array.elementType) && rank == array.rank;
        }
@@ -929,7 +928,7 @@ namespace Semmle.Extraction.CIL.Entities

        public override Namespace Namespace => cx.SystemNamespace;

-        public override Type ContainingType => null;
+        public override Type? ContainingType => null;

        public override int ThisTypeParameters => elementType.ThisTypeParameters;

@@ -972,9 +971,9 @@ namespace Semmle.Extraction.CIL.Entities
            this.gc = gc;
        }

-        public override Namespace Namespace => null;
+        public override Namespace? Namespace => null;

-        public override Type ContainingType => null;
+        public override Type? ContainingType => null;

        public override int ThisTypeParameters => 0;

@@ -1034,7 +1033,7 @@ namespace Semmle.Extraction.CIL.Entities
            this.index = index;
        }

-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
        {
            return obj is MethodTypeParameter tp && method.Equals(tp.method) && index == tp.index;
        }
@@ -1072,7 +1071,7 @@ namespace Semmle.Extraction.CIL.Entities
            type = t;
        }

-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
        {
            return obj is TypeTypeParameter tp && type.Equals(tp.type) && index == tp.index;
        }
@@ -1089,7 +1088,7 @@ namespace Semmle.Extraction.CIL.Entities
            trapFile.Write(index);
        }

-        public override TypeContainer Parent => type ?? gc as TypeContainer;
+        public override TypeContainer Parent => type;
        public override string Name => "!" + index;

        public override IEnumerable<Type> TypeParameters => Enumerable.Empty<Type>();
@@ -1119,7 +1118,7 @@ namespace Semmle.Extraction.CIL.Entities
            this.pointee = pointee;
        }

-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
        {
            return obj is PointerType pt && pointee.Equals(pt.pointee);
        }
@@ -1138,9 +1137,9 @@ namespace Semmle.Extraction.CIL.Entities

        public override string Name => pointee.Name + "*";

-        public override Namespace Namespace => pointee.Namespace;
+        public override Namespace? Namespace => pointee.Namespace;

-        public override Type ContainingType => pointee.ContainingType;
+        public override Type? ContainingType => pointee.ContainingType;

        public override TypeContainer Parent => pointee.Parent;

@@ -1180,7 +1179,7 @@ namespace Semmle.Extraction.CIL.Entities

        public override Namespace Namespace => cx.GlobalNamespace;

-        public override Type ContainingType => null;
+        public override Type? ContainingType => null;

        public override int ThisTypeParameters => 0;

@@ -1202,8 +1201,15 @@ namespace Semmle.Extraction.CIL.Entities
    {
        struct Array : ITypeSignature
        {
-            public ITypeSignature elementType;
-            public ArrayShape shape;
+            private readonly ITypeSignature elementType;
+            private readonly ArrayShape shape;
+
+            public Array(ITypeSignature elementType, ArrayShape shape) : this()
+            {
+                this.elementType = elementType;
+                this.shape = shape;
+            }
+
            public void WriteId(TextWriter trapFile, GenericContext gc)
            {
                elementType.WriteId(trapFile, gc);
@@ -1216,7 +1222,12 @@ namespace Semmle.Extraction.CIL.Entities

        struct ByRef : ITypeSignature
        {
-            public ITypeSignature elementType;
+            private readonly ITypeSignature elementType;
+
+            public ByRef(ITypeSignature elementType)
+            {
+                this.elementType = elementType;
+            }

            public void WriteId(TextWriter trapFile, GenericContext gc)
            {
@@ -1227,7 +1238,12 @@ namespace Semmle.Extraction.CIL.Entities

        struct FnPtr : ITypeSignature
        {
-            public MethodSignature<ITypeSignature> signature;
+            private readonly MethodSignature<ITypeSignature> signature;
+
+            public FnPtr(MethodSignature<ITypeSignature> signature)
+            {
+                this.signature = signature;
+            }

            public void WriteId(TextWriter trapFile, GenericContext gc)
            {
@@ -1236,18 +1252,25 @@ namespace Semmle.Extraction.CIL.Entities
        }

        ITypeSignature IConstructedTypeProvider<ITypeSignature>.GetArrayType(ITypeSignature elementType, ArrayShape shape) =>
-            new Array { elementType = elementType, shape = shape };
+            new Array(elementType, shape);

        ITypeSignature IConstructedTypeProvider<ITypeSignature>.GetByReferenceType(ITypeSignature elementType) =>
-            new ByRef { elementType = elementType };
+            new ByRef(elementType);

        ITypeSignature ISignatureTypeProvider<ITypeSignature, object>.GetFunctionPointerType(MethodSignature<ITypeSignature> signature) =>
-            new FnPtr { signature = signature };
+            new FnPtr(signature);

        class Instantiation : ITypeSignature
        {
-            public ITypeSignature genericType;
-            public ImmutableArray<ITypeSignature> typeArguments;
+            private readonly ITypeSignature genericType;
+            private readonly ImmutableArray<ITypeSignature> typeArguments;
+
+            public Instantiation(ITypeSignature genericType, ImmutableArray<ITypeSignature> typeArguments)
+            {
+                this.genericType = genericType;
+                this.typeArguments = typeArguments;
+            }
+

            public void WriteId(TextWriter trapFile, GenericContext gc)
            {
@@ -1264,12 +1287,18 @@ namespace Semmle.Extraction.CIL.Entities
        }

        ITypeSignature IConstructedTypeProvider<ITypeSignature>.GetGenericInstantiation(ITypeSignature genericType, ImmutableArray<ITypeSignature> typeArguments) =>
-            new Instantiation { genericType = genericType, typeArguments = typeArguments };
+            new Instantiation(genericType, typeArguments);

        class GenericMethodParameter : ITypeSignature
        {
-            public object innerGc;
-            public int index;
+            private readonly object innerGc;
+            private readonly int index;
+
+            public GenericMethodParameter(object innerGc, int index)
+            {
+                this.innerGc = innerGc;
+                this.index = index;
+            }

            public void WriteId(TextWriter trapFile, GenericContext outerGc)
            {
@@ -1284,7 +1313,12 @@ namespace Semmle.Extraction.CIL.Entities

        class GenericTypeParameter : ITypeSignature
        {
-            public int index;
+            private readonly int index;
+
+            public GenericTypeParameter(int index)
+            {
+                this.index = index;
+            }

            public void WriteId(TextWriter trapFile, GenericContext gc)
            {
@@ -1294,16 +1328,23 @@ namespace Semmle.Extraction.CIL.Entities
        }

        ITypeSignature ISignatureTypeProvider<ITypeSignature, object>.GetGenericMethodParameter(object genericContext, int index) =>
-            new GenericMethodParameter { innerGc = genericContext, index = index };
+            new GenericMethodParameter(genericContext, index);

        ITypeSignature ISignatureTypeProvider<ITypeSignature, object>.GetGenericTypeParameter(object genericContext, int index) =>
-            new GenericTypeParameter { index = index };
+            new GenericTypeParameter(index);

        class Modified : ITypeSignature
        {
-            public ITypeSignature modifier;
-            public ITypeSignature unmodifiedType;
-            public bool isRequired;
+            private readonly ITypeSignature modifier;
+            private readonly ITypeSignature unmodifiedType;
+            private readonly bool isRequired;
+
+            public Modified(ITypeSignature modifier, ITypeSignature unmodifiedType, bool isRequired)
+            {
+                this.modifier = modifier;
+                this.unmodifiedType = unmodifiedType;
+                this.isRequired = isRequired;
+            }

            public void WriteId(TextWriter trapFile, GenericContext gc)
            {
@@ -1313,12 +1354,17 @@ namespace Semmle.Extraction.CIL.Entities

        ITypeSignature ISignatureTypeProvider<ITypeSignature, object>.GetModifiedType(ITypeSignature modifier, ITypeSignature unmodifiedType, bool isRequired)
        {
-            return new Modified { modifier = modifier, unmodifiedType = unmodifiedType, isRequired = isRequired };
+            return new Modified(modifier, unmodifiedType, isRequired);
        }

        class Pinned : ITypeSignature
        {
-            public ITypeSignature elementType;
+            private readonly ITypeSignature elementType;
+
+            public Pinned(ITypeSignature elementType)
+            {
+                this.elementType = elementType;
+            }

            public void WriteId(TextWriter trapFile, GenericContext gc)
            {
@@ -1329,12 +1375,17 @@ namespace Semmle.Extraction.CIL.Entities

        ITypeSignature ISignatureTypeProvider<ITypeSignature, object>.GetPinnedType(ITypeSignature elementType)
        {
-            return new Pinned { elementType = elementType };
+            return new Pinned(elementType);
        }

        class PointerType : ITypeSignature
        {
-            public ITypeSignature elementType;
+            private readonly ITypeSignature elementType;
+
+            public PointerType(ITypeSignature elementType)
+            {
+                this.elementType = elementType;
+            }

            public void WriteId(TextWriter trapFile, GenericContext gc)
            {
@@ -1345,12 +1396,17 @@ namespace Semmle.Extraction.CIL.Entities

        ITypeSignature IConstructedTypeProvider<ITypeSignature>.GetPointerType(ITypeSignature elementType)
        {
-            return new PointerType { elementType = elementType };
+            return new PointerType(elementType);
        }

        class Primitive : ITypeSignature
        {
-            public PrimitiveTypeCode typeCode;
+            private readonly PrimitiveTypeCode typeCode;
+
+            public Primitive(PrimitiveTypeCode typeCode)
+            {
+                this.typeCode = typeCode;
+            }

            public void WriteId(TextWriter trapFile, GenericContext gc)
            {
@@ -1360,12 +1416,18 @@ namespace Semmle.Extraction.CIL.Entities

        ITypeSignature ISimpleTypeProvider<ITypeSignature>.GetPrimitiveType(PrimitiveTypeCode typeCode)
        {
-            return new Primitive { typeCode = typeCode };
+            return new Primitive(typeCode);
        }

        class SzArrayType : ITypeSignature
        {
-            public ITypeSignature elementType;
+            private readonly ITypeSignature elementType;
+
+            public SzArrayType(ITypeSignature elementType)
+            {
+                this.elementType = elementType;
+            }
+
            public void WriteId(TextWriter trapFile, GenericContext gc)
            {
                elementType.WriteId(trapFile, gc);
@@ -1375,41 +1437,53 @@ namespace Semmle.Extraction.CIL.Entities

        ITypeSignature ISZArrayTypeProvider<ITypeSignature>.GetSZArrayType(ITypeSignature elementType)
        {
-            return new SzArrayType { elementType = elementType };
+            return new SzArrayType(elementType);
        }

        class TypeDefinition : ITypeSignature
        {
-            public TypeDefinitionHandle handle;
-            public byte rawTypeKind;
-            Type type;
+            private readonly TypeDefinitionHandle handle;
+            private readonly byte rawTypeKind;
+
+            public TypeDefinition(TypeDefinitionHandle handle, byte rawTypeKind)
+            {
+                this.handle = handle;
+                this.rawTypeKind = rawTypeKind;
+            }
+
            public void WriteId(TextWriter trapFile, GenericContext gc)
            {
-                type = (Type)gc.cx.Create(handle);
+                var type = (Type)gc.cx.Create(handle);
                type.WriteId(trapFile);
            }
        }

        ITypeSignature ISimpleTypeProvider<ITypeSignature>.GetTypeFromDefinition(MetadataReader reader, TypeDefinitionHandle handle, byte rawTypeKind)
        {
-            return new TypeDefinition { handle = handle, rawTypeKind = rawTypeKind };
+            return new TypeDefinition(handle, rawTypeKind);
        }

        class TypeReference : ITypeSignature
        {
-            public TypeReferenceHandle handle;
-            public byte rawTypeKind; // struct/class (not used)
-            Type type;
+            private readonly TypeReferenceHandle handle;
+            private readonly byte rawTypeKind; // struct/class (not used)
+
+            public TypeReference(TypeReferenceHandle handle, byte rawTypeKind)
+            {
+                this.handle = handle;
+                this.rawTypeKind = rawTypeKind;
+            }
+
            public void WriteId(TextWriter trapFile, GenericContext gc)
            {
-                type = (Type)gc.cx.Create(handle);
+                var type = (Type)gc.cx.Create(handle);
                type.WriteId(trapFile);
            }
        }

        ITypeSignature ISimpleTypeProvider<ITypeSignature>.GetTypeFromReference(MetadataReader reader, TypeReferenceHandle handle, byte rawTypeKind)
        {
-            return new TypeReference { handle = handle, rawTypeKind = rawTypeKind };
+            return new TypeReference(handle, rawTypeKind);
        }

        ITypeSignature ISignatureTypeProvider<ITypeSignature, object>.GetTypeFromSpecification(MetadataReader reader, object genericContext, TypeSpecificationHandle handle, byte rawTypeKind)
@@ -1433,7 +1507,7 @@ namespace Semmle.Extraction.CIL.Entities
        }

        Type IConstructedTypeProvider<Type>.GetArrayType(Type elementType, ArrayShape shape) =>
-            cx.Populate(new ArrayType(cx, elementType, shape));
+            cx.Populate(new ArrayType(cx, elementType, shape.Rank));

        Type IConstructedTypeProvider<Type>.GetByReferenceType(Type elementType) =>
            elementType;  // ??
--- a/csharp/extractor/Semmle.Extraction.CIL/Factories.cs
+++ b/csharp/extractor/Semmle.Extraction.CIL/Factories.cs
@@ -41,7 +41,7 @@ namespace Semmle.Extraction.CIL
                    e.WriteId(writer);
                    var id = writer.ToString();

-                    if (debugLabels.TryGetValue(id, out IExtractedEntity previousEntity))
+                    if (debugLabels.TryGetValue(id, out IExtractedEntity? previousEntity))
                    {
                        cx.Extractor.Message(new Message("Duplicate trap ID", id, null, severity: Util.Logging.Severity.Warning));
                    }
--- a/csharp/extractor/Semmle.Extraction.CIL/PDB/MetadataPdbReader.cs
+++ b/csharp/extractor/Semmle.Extraction.CIL/PDB/MetadataPdbReader.cs
@@ -25,7 +25,7 @@ namespace Semmle.Extraction.PDB

            public string Path { get; private set; }

-            public string Contents => File.Exists(Path) ? File.ReadAllText(Path, System.Text.Encoding.Default) : null;
+            public string? Contents => File.Exists(Path) ? File.ReadAllText(Path, System.Text.Encoding.Default) : null;
        }

        // Turns out to be very important to keep the MetadataReaderProvider live
@@ -41,7 +41,7 @@ namespace Semmle.Extraction.PDB

        public IEnumerable<ISourceFile> SourceFiles => reader.Documents.Select(handle => new SourceFile(reader, handle));

-        public IMethod GetMethod(MethodDebugInformationHandle handle)
+        public IMethod? GetMethod(MethodDebugInformationHandle handle)
        {
            var debugInfo = reader.GetMethodDebugInformation(handle);

@@ -51,10 +51,10 @@ namespace Semmle.Extraction.PDB
                Where(p => p.Location.File.Path != null).
                ToArray();

-            return sequencePoints.Any() ? new Method() { SequencePoints = sequencePoints } : null;
+            return sequencePoints.Any() ? new Method(sequencePoints) : null;
        }

-        public static MetadataPdbReader CreateFromAssembly(string assemblyPath, PEReader peReader)
+        public static MetadataPdbReader? CreateFromAssembly(string assemblyPath, PEReader peReader)
        {
            foreach (var provider in peReader.
                ReadDebugDirectory().
--- a/csharp/extractor/Semmle.Extraction.CIL/PDB/NativePdbReader.cs
+++ b/csharp/extractor/Semmle.Extraction.CIL/PDB/NativePdbReader.cs
@@ -23,7 +23,7 @@ namespace Semmle.Extraction.PDB
            public Document(ISymUnmanagedDocument doc)
            {
                document = doc;
-                contents = new Lazy<string>(() =>
+                contents = new Lazy<string?>(() =>
                {
                    bool isEmbedded;
                    if (document.HasEmbeddedSource(out isEmbedded) == 0 && isEmbedded)
@@ -38,7 +38,7 @@ namespace Semmle.Extraction.PDB
                });
            }

-            public override bool Equals(object obj)
+            public override bool Equals(object? obj)
            {
                var otherDoc = obj as Document;
                return otherDoc != null && Path.Equals(otherDoc.Path);
@@ -50,14 +50,14 @@ namespace Semmle.Extraction.PDB

            public override string ToString() => Path;

-            readonly Lazy<string> contents;
+            readonly Lazy<string?> contents;

-            public string Contents => contents.Value;
+            public string? Contents => contents.Value;
        }

        public IEnumerable<ISourceFile> SourceFiles => reader.GetDocuments().Select(d => new Document(d));

-        public IMethod GetMethod(MethodDebugInformationHandle h)
+        public IMethod? GetMethod(MethodDebugInformationHandle h)
        {
            int methodToken = MetadataTokens.GetToken(h.ToDefinitionHandle());
            var method = reader.GetMethod(methodToken);
@@ -72,7 +72,7 @@ namespace Semmle.Extraction.PDB
                    Select(sp => new SequencePoint(sp.Offset, new Location(new Document(sp.Document), sp.StartLine, sp.StartColumn, sp.EndLine, sp.EndColumn))).
                    ToArray();

-                return s.Any() ? new Method { SequencePoints = s } : null;
+                return s.Any() ? new Method(s) : null;
            }
            return null;
        }
@@ -87,7 +87,7 @@ namespace Semmle.Extraction.PDB
        readonly ISymUnmanagedReader5 reader;
        readonly FileStream pdbStream;

-        public static NativePdbReader CreateFromAssembly(string assemblyPath, PEReader peReader)
+        public static NativePdbReader? CreateFromAssembly(string assemblyPath, PEReader peReader)
        {
            // The Native PDB reader uses an unmanaged Windows DLL
            // so only works on Windows.
@@ -123,7 +123,7 @@ namespace Semmle.Extraction.PDB
        {
        }

-        public object GetMetadataImport() => null;
+        public object? GetMetadataImport() => null;

        public unsafe bool TryGetStandaloneSignature(int standaloneSignatureToken, out byte* signature, out int length) =>
            throw new NotImplementedException();
--- a/csharp/extractor/Semmle.Extraction.CIL/PDB/PdbReader.cs
+++ b/csharp/extractor/Semmle.Extraction.CIL/PDB/PdbReader.cs
@@ -55,7 +55,7 @@ namespace Semmle.Extraction.PDB
            return string.Format("({0},{1})-({2},{3})", StartLine, StartColumn, EndLine, EndColumn);
        }

-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
        {
            var otherLocation = obj as Location;

@@ -91,7 +91,12 @@ namespace Semmle.Extraction.PDB

    class Method : IMethod
    {
-        public IEnumerable<SequencePoint> SequencePoints { get; set; }
+        public IEnumerable<SequencePoint> SequencePoints { get; }
+
+        public Method(IEnumerable<SequencePoint> sequencePoints)
+        {
+            SequencePoints = sequencePoints;
+        }

        public Location Location => SequencePoints.First().Location;
    }
@@ -111,7 +116,7 @@ namespace Semmle.Extraction.PDB
        /// null if the contents are unavailable.
        /// E.g. if the PDB file exists but the corresponding source files are missing.
        /// </summary>
-        string Contents { get; }
+        string? Contents { get; }
    }

    /// <summary>
@@ -131,7 +136,7 @@ namespace Semmle.Extraction.PDB
        /// </summary>
        /// <param name="methodHandle">The handle to query.</param>
        /// <returns>The method information, or null if the method does not have debug information.</returns>
-        IMethod GetMethod(MethodDebugInformationHandle methodHandle);
+        IMethod? GetMethod(MethodDebugInformationHandle methodHandle);
    }

    class PdbReader
@@ -140,11 +145,11 @@ namespace Semmle.Extraction.PDB
        /// Returns the PDB information associated with an assembly.
        /// </summary>
        /// <param name="assemblyPath">The path to the assembly.</param>
-        /// <param name="peReader">The PE reader for the assembky.</param>
+        /// <param name="peReader">The PE reader for the assembly.</param>
        /// <returns>A PdbReader, or null if no PDB information is available.</returns>
-        public static IPdb Create(string assemblyPath, PEReader peReader)
+        public static IPdb? Create(string assemblyPath, PEReader peReader)
        {
-            return (IPdb)MetadataPdbReader.CreateFromAssembly(assemblyPath, peReader) ??
+            return (IPdb?)MetadataPdbReader.CreateFromAssembly(assemblyPath, peReader) ??
                NativePdbReader.CreateFromAssembly(assemblyPath, peReader);
        }
    }
--- a/csharp/extractor/Semmle.Extraction.CIL/Semmle.Extraction.CIL.csproj
+++ b/csharp/extractor/Semmle.Extraction.CIL/Semmle.Extraction.CIL.csproj
@@ -7,6 +7,7 @@
    <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
    <RuntimeIdentifiers>win-x64;linux-x64;osx-x64</RuntimeIdentifiers>
+    <Nullable>enable</Nullable>
  </PropertyGroup>

  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|AnyCPU'">
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/ArrayCreation.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/ArrayCreation.cs
@@ -1,4 +1,5 @@
 using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Semmle.Extraction.Kinds;
 using System.IO;
@@ -21,7 +22,7 @@ namespace Semmle.Extraction.CSharp.Entities.Expressions

        protected override void PopulateExpression(TextWriter trapFile)
        {
-            var child = 0;
+
            var explicitlySized = false;

            if (TypeSyntax is null)
@@ -29,38 +30,21 @@ namespace Semmle.Extraction.CSharp.Entities.Expressions
                cx.ModelError(Syntax, "Array has unexpected type syntax");
            }

-            foreach (var rank in TypeSyntax.RankSpecifiers.SelectMany(rs => rs.Sizes))
+            var firstLevelSizes = TypeSyntax.RankSpecifiers.First()?.Sizes ?? SyntaxFactory.SeparatedList<ExpressionSyntax>();
+
+            if (firstLevelSizes.OfType<ExpressionSyntax>().Any(s => s is OmittedArraySizeExpressionSyntax))
            {
-                if (rank is OmittedArraySizeExpressionSyntax)
-                {
-                    // Create an expression which simulates the explicit size of the array
-
-                    if (!(Initializer is null))
-                    {
-                        // An implicitly-sized array must have an initializer.
-                        // Guard it just in case.
-                        var size = Initializer.Expressions.Count;
-
-                        var info = new ExpressionInfo(
-                            cx,
-                            new AnnotatedType(Entities.Type.Create(cx, cx.Compilation.GetSpecialType(Microsoft.CodeAnalysis.SpecialType.System_Int32)), NullableAnnotation.None),
-                            Location,
-                            ExprKind.INT_LITERAL,
-                            this,
-                            child,
-                            true,
-                            size.ToString());
-
-                        new Expression(info);
-                    }
-                }
-                else
-                {
-                    Create(cx, rank, this, child);
-                    explicitlySized = true;
-                }
-                child++;
+                SetArraySizes(Initializer, firstLevelSizes.Count);
            }
+            else
+            {
+                for (var sizeIndex = 0; sizeIndex < firstLevelSizes.Count; sizeIndex++)
+                {
+                    Create(cx, firstLevelSizes[sizeIndex], this, sizeIndex);
+                }
+                explicitlySized = true;
+            }
+
            if (!(Initializer is null))
            {
                ArrayInitializer.Create(new ExpressionNodeInfo(cx, Initializer, this, -1));
@@ -69,6 +53,31 @@ namespace Semmle.Extraction.CSharp.Entities.Expressions
            if (explicitlySized)
                trapFile.explicitly_sized_array_creation(this);
        }
+
+        private void SetArraySizes(InitializerExpressionSyntax initializer, int rank)
+        {
+            for (var level = 0; level < rank; level++)
+            {
+                if (initializer is null)
+                {
+                    return;
+                }
+
+                var info = new ExpressionInfo(
+                    cx,
+                    new AnnotatedType(Entities.Type.Create(cx, cx.Compilation.GetSpecialType(Microsoft.CodeAnalysis.SpecialType.System_Int32)), NullableAnnotation.None),
+                    Location,
+                    ExprKind.INT_LITERAL,
+                    this,
+                    level,
+                    true,
+                    initializer.Expressions.Count.ToString());
+
+                new Expression(info);
+
+                initializer = initializer.Expressions.FirstOrDefault() as InitializerExpressionSyntax;
+            }
+        }
    }

    class NormalArrayCreation : ExplicitArrayCreation<ArrayCreationExpressionSyntax>
--- a/csharp/extractor/Semmle.Util/IEnumerableExtensions.cs
+++ b/csharp/extractor/Semmle.Util/IEnumerableExtensions.cs
@@ -64,7 +64,7 @@ namespace Semmle.Util
        /// Enumerates a possibly null enumerable.
        /// If the enumerable is null, the list is empty.
        /// </summary>
-        public static IEnumerable<T> EnumerateNull<T>(this IEnumerable<T> items)
+        public static IEnumerable<T> EnumerateNull<T>(this IEnumerable<T>? items)
        {
            if (items == null) yield break;
            foreach (var item in items) yield return item;
--- a/csharp/ql/src/Linq/Helpers.qll
+++ b/csharp/ql/src/Linq/Helpers.qll
@@ -6,18 +6,32 @@
 import csharp

 //#################### PREDICATES ####################
-Stmt firstStmt(ForeachStmt fes) {
+private Stmt firstStmt(ForeachStmt fes) {
  if fes.getBody() instanceof BlockStmt
  then result = fes.getBody().(BlockStmt).getStmt(0)
  else result = fes.getBody()
 }

+private int numStmts(ForeachStmt fes) {
+  if fes.getBody() instanceof BlockStmt
+  then result = count(fes.getBody().(BlockStmt).getAStmt())
+  else result = 1
+}
+
+/** Holds if the type's qualified name is "System.Linq.Enumerable" */
 predicate isEnumerableType(ValueOrRefType t) { t.hasQualifiedName("System.Linq.Enumerable") }

+/** Holds if the type's qualified name starts with "System.Collections.Generic.IEnumerable" */
 predicate isIEnumerableType(ValueOrRefType t) {
  t.getQualifiedName().matches("System.Collections.Generic.IEnumerable%")
 }

+/**
+ * Holds if `foreach` statement `fes` could be converted to a `.All()` call.
+ * That is, the `ForeachStmt` contains a single `if` with a condition that
+ * accesses the loop variable and with a body that assigns `false` to a variable
+ * and `break`s out of the `foreach`.
+ */
 predicate missedAllOpportunity(ForeachStmt fes) {
  exists(IfStmt is |
    // The loop contains an if statement with no else case, and nothing else.
@@ -36,6 +50,12 @@ predicate missedAllOpportunity(ForeachStmt fes) {
  )
 }

+/**
+ * Holds if `foreach` statement `fes` could be converted to a `.Cast()` call.
+ * That is, the loop variable is accessed only in the first statement of the
+ * block, and the access is a cast. The first statement needs to be a
+ * `LocalVariableDeclStmt`.
+ */
 predicate missedCastOpportunity(ForeachStmt fes, LocalVariableDeclStmt s) {
  s = firstStmt(fes) and
  forex(VariableAccess va | va = fes.getVariable().getAnAccess() |
@@ -47,6 +67,12 @@ predicate missedCastOpportunity(ForeachStmt fes, LocalVariableDeclStmt s) {
  )
 }

+/**
+ * Holds if `foreach` statement `fes` could be converted to an `.OfType()` call.
+ * That is, the loop variable is accessed only in the first statement of the
+ * block, and the access is a cast with the `as` operator. The first statement
+ * needs to be a `LocalVariableDeclStmt`.
+ */
 predicate missedOfTypeOpportunity(ForeachStmt fes, LocalVariableDeclStmt s) {
  s = firstStmt(fes) and
  forex(VariableAccess va | va = fes.getVariable().getAnAccess() |
@@ -58,6 +84,12 @@ predicate missedOfTypeOpportunity(ForeachStmt fes, LocalVariableDeclStmt s) {
  )
 }

+/**
+ * Holds if `foreach` statement `fes` could be converted to a `.Select()` call.
+ * That is, the loop variable is accessed only in the first statement of the
+ * block, and the access is not a cast. The first statement needs to be a
+ * `LocalVariableDeclStmt`.
+ */
 predicate missedSelectOpportunity(ForeachStmt fes, LocalVariableDeclStmt s) {
  s = firstStmt(fes) and
  forex(VariableAccess va | va = fes.getVariable().getAnAccess() |
@@ -66,6 +98,12 @@ predicate missedSelectOpportunity(ForeachStmt fes, LocalVariableDeclStmt s) {
  not s.getAVariableDeclExpr().getInitializer() instanceof Cast
 }

+/**
+ * Holds if `foreach` statement `fes` could be converted to a `.Where()` call.
+ * That is, first statement of the loop is an `if`, which accesses the loop
+ * variable, and the body of the `if` is either a `continue` or there's nothing
+ * else in the loop than the `if`.
+ */
 predicate missedWhereOpportunity(ForeachStmt fes, IfStmt is) {
  // The very first thing the foreach loop does is test its iteration variable.
  is = firstStmt(fes) and
@@ -82,12 +120,6 @@ predicate missedWhereOpportunity(ForeachStmt fes, IfStmt is) {
  )
 }

-int numStmts(ForeachStmt fes) {
-  if fes.getBody() instanceof BlockStmt
-  then result = count(fes.getBody().(BlockStmt).getAStmt())
-  else result = 1
-}
-
 //#################### CLASSES ####################
 /** A LINQ Any(...) call. */
 class AnyCall extends MethodCall {
--- a/csharp/ql/src/external/CodeDuplication.qll
+++ b/csharp/ql/src/external/CodeDuplication.qll
@@ -66,9 +66,9 @@ class SimilarBlock extends Copy, @similarity {
  }
 }

-Method sourceMethod() { method_location(result, _) and numlines(result, _, _, _) }
+private Method sourceMethod() { method_location(result, _) and numlines(result, _, _, _) }

-int numberOfSourceMethods(Class c) {
+private int numberOfSourceMethods(Class c) {
  result = count(Method m | m = sourceMethod() and m.getDeclaringType() = c)
 }

@@ -97,6 +97,7 @@ private predicate duplicateStatement(Method m1, Method m2, Stmt s1, Stmt s2) {
  )
 }

+/** Holds if `duplicate` number of statements are duplicated in the methods. */
 predicate duplicateStatements(Method m1, Method m2, int duplicate, int total) {
  duplicate = strictcount(Stmt s | duplicateStatement(m1, m2, s, _)) and
  total = strictcount(statementInMethod(m1))
@@ -109,7 +110,7 @@ predicate duplicateMethod(Method m, Method other) {
  exists(int total | duplicateStatements(m, other, total, total))
 }

-predicate similarLines(File f, int line) {
+private predicate similarLines(File f, int line) {
  exists(SimilarBlock b | b.sourceFile() = f and line in [b.sourceStartLine() .. b.sourceEndLine()])
 }

@@ -148,7 +149,7 @@ private predicate similarLinesCovered(File f, int coveredLines, File otherFile)
  )
 }

-predicate duplicateLines(File f, int line) {
+private predicate duplicateLines(File f, int line) {
  exists(DuplicateBlock b |
    b.sourceFile() = f and line in [b.sourceStartLine() .. b.sourceEndLine()]
  )
@@ -189,6 +190,7 @@ private predicate duplicateLinesCovered(File f, int coveredLines, File otherFile
  )
 }

+/** Holds if the two files are not duplicated but have more than 80% similar lines. */
 predicate similarFiles(File f, File other, int percent) {
  exists(int covered, int total |
    similarLinesCovered(f, covered, other) and
@@ -199,6 +201,7 @@ predicate similarFiles(File f, File other, int percent) {
  not duplicateFiles(f, other, _)
 }

+/** Holds if the two files have more than 70% duplicated lines. */
 predicate duplicateFiles(File f, File other, int percent) {
  exists(int covered, int total |
    duplicateLinesCovered(f, covered, other) and
@@ -209,7 +212,7 @@ predicate duplicateFiles(File f, File other, int percent) {
 }

 pragma[noopt]
-predicate duplicateAnonymousClass(AnonymousClass c, AnonymousClass other) {
+private predicate duplicateAnonymousClass(AnonymousClass c, AnonymousClass other) {
  exists(int numDup |
    numDup =
      strictcount(Method m1 |
@@ -248,6 +251,7 @@ private predicate mostlyDuplicateClassBase(Class c, Class other, int numDup, int
  not other instanceof AnonymousClass
 }

+/** Holds if the methods in the two classes are more than 80% duplicated. */
 predicate mostlyDuplicateClass(Class c, Class other, string message) {
  exists(int numDup, int total |
    mostlyDuplicateClassBase(c, other, numDup, total) and
@@ -272,19 +276,28 @@ predicate mostlyDuplicateClass(Class c, Class other, string message) {
  )
 }

+/** Holds if the two files are similar or duplicated. */
 predicate fileLevelDuplication(File f, File other) {
  similarFiles(f, other, _) or duplicateFiles(f, other, _)
 }

+/**
+ * Holds if the two classes are duplicated anonymous classes or more than 80% of
+ * their methods are duplicated.
+ */
 predicate classLevelDuplication(Class c, Class other) {
  duplicateAnonymousClass(c, other) or mostlyDuplicateClass(c, other, _)
 }

-Element whitelistedDuplicateElement() {
+private Element whitelistedDuplicateElement() {
  result instanceof UsingNamespaceDirective or
  result instanceof UsingStaticDirective
 }

+/**
+ * Holds if the `line` in the `file` contains an element, such as a `using`
+ * directive, that is not considered for code duplication.
+ */
 predicate whitelistedLineForDuplication(File file, int line) {
  exists(Location loc | loc = whitelistedDuplicateElement().getLocation() |
    line = loc.getStartLine() and file = loc.getFile()
--- a/csharp/ql/src/semmle/code/cil/Access.qll
+++ b/csharp/ql/src/semmle/code/cil/Access.qll
@@ -31,6 +31,7 @@ class ReadRefAccess extends ReadAccess, ReadRef { }

 /** An instruction that writes a variable. */
 class WriteAccess extends VariableAccess, @cil_write_access {
+  /** Gets the expression whose value is used in this variable write. */
  Expr getExpr() { none() }
 }

--- a/csharp/ql/src/semmle/code/csharp/Callable.qll
+++ b/csharp/ql/src/semmle/code/csharp/Callable.qll
@@ -437,6 +437,9 @@ class Operator extends Callable, Member, Attributable, @operator {

  override string getName() { operators(this, _, result, _, _, _) }

+  /**
+   * Gets the metadata name of the operator, such as `op_implicit` or `op_RightShift`.
+   */
  string getFunctionName() { none() }

  override ValueOrRefType getDeclaringType() { operators(this, _, _, result, _, _) }
--- a/csharp/ql/src/semmle/code/csharp/Conversion.qll
+++ b/csharp/ql/src/semmle/code/csharp/Conversion.qll
@@ -514,6 +514,11 @@ predicate convNullableType(ValueOrRefType fromType, NullableType toType) {
  )
 }

+/**
+ * Holds if `fromType` is `NullType`, and `toType` is a type that can represent
+ * the `null` value, such as a reference type, `Nullable<T>` or a type parameter
+ * with contraints that restrict it to a reference type.
+ */
 // This is a deliberate, small Cartesian product, so we have manually lifted it to force the
 // evaluator to evaluate it in its entirety, rather than trying to optimize it in context.
 pragma[noinline]
--- a/csharp/ql/src/semmle/code/csharp/dispatch/RuntimeCallable.qll
+++ b/csharp/ql/src/semmle/code/csharp/dispatch/RuntimeCallable.qll
@@ -26,6 +26,7 @@ class RuntimeMethod extends RuntimeCallable {
    this instanceof CIL::Method
  }

+  /** Holds if the method is `static`. */
  predicate isStatic() { this.(Method).isStatic() or this.(CIL::Method).isStatic() }
 }

--- a/csharp/ql/src/semmle/code/csharp/exprs/Expr.qll
+++ b/csharp/ql/src/semmle/code/csharp/exprs/Expr.qll
@@ -1011,6 +1011,7 @@ class RangeExpr extends Expr, @range_expr {

 /** An index expression, for example `^1` meaning "1 from the end". */
 class IndexExpr extends Expr, @index_expr {
+  /** Gets the sub expression of this index expression. */
  Expr getExpr() { result.getParent() = this }

  override string toString() { result = "^..." }
--- a/csharp/ql/src/semmle/code/csharp/frameworks/EntityFramework.qll
+++ b/csharp/ql/src/semmle/code/csharp/frameworks/EntityFramework.qll
@@ -8,7 +8,12 @@ private import semmle.code.csharp.frameworks.system.collections.Generic
 private import semmle.code.csharp.frameworks.Sql
 private import semmle.code.csharp.dataflow.LibraryTypeDataFlow

+/**
+ * Definitions relating to the `System.ComponentModel.DataAnnotations`
+ * namespace.
+ */
 module DataAnnotations {
+  /** Class for `NotMappedAttribute`. */
  class NotMappedAttribute extends Attribute {
    NotMappedAttribute() {
      this
@@ -18,6 +23,10 @@ module DataAnnotations {
  }
 }

+/**
+ * Definitions relating to the `Microsoft.EntityFrameworkCore` or
+ * `System.Data.Entity` namespaces.
+ */
 module EntityFramework {
  /** An EF6 or EFCore namespace. */
  class EFNamespace extends Namespace {
@@ -43,12 +52,14 @@ module EntityFramework {
  class DbContext extends EFClass {
    DbContext() { this.getName() = "DbContext" }

+    /** Gets a `Find` or `FindAsync` method in the `DbContext`. */
    Method getAFindMethod() {
      result = this.getAMethod("Find")
      or
      result = this.getAMethod("FindAsync")
    }

+    /** Gets an `Update` method in the `DbContext`. */
    Method getAnUpdateMethod() { result = this.getAMethod("Update") }
  }

@@ -119,6 +130,7 @@ module EntityFramework {
      preservesValue = false
    }

+    /** Gets a conversion operator from `string` to `RawSqlString`. */
    ConversionOperator getAConversionTo() {
      result = this.getAMember() and
      result.getTargetType() instanceof RawSqlStringStruct and
--- a/csharp/ql/src/semmle/code/csharp/frameworks/JsonNET.qll
+++ b/csharp/ql/src/semmle/code/csharp/frameworks/JsonNET.qll
@@ -135,8 +135,10 @@ module JsonNET {
  class JsonSerializerClass extends JsonClass, LibraryTypeDataFlow {
    JsonSerializerClass() { this.hasName("JsonSerializer") }

+    /** Gets the method for `JsonSerializer.Serialize`. */
    Method getSerializeMethod() { result = this.getAMethod("Serialize") }

+    /** Gets the method for `JsonSerializer.Deserialize`. */
    Method getDeserializeMethod() { result = this.getAMethod("Deserialize") }

    override predicate callableFlow(
--- a/csharp/ql/src/semmle/code/csharp/frameworks/NHibernate.qll
+++ b/csharp/ql/src/semmle/code/csharp/frameworks/NHibernate.qll
@@ -1,8 +1,13 @@
+/**
+ * Classes for modelling NHibernate.
+ */
+
 import csharp
 private import semmle.code.csharp.frameworks.System
 private import semmle.code.csharp.frameworks.system.Collections
 private import semmle.code.csharp.frameworks.Sql

+/** Definitions relating to the `NHibernate` package. */
 module NHibernate {
  /** A class that is mapped to the database. */
  abstract class MappedClass extends Class { }
--- a/csharp/ql/src/semmle/code/csharp/frameworks/system/Linq.qll
+++ b/csharp/ql/src/semmle/code/csharp/frameworks/system/Linq.qll
@@ -5,6 +5,7 @@
 private import csharp as csharp
 private import semmle.code.csharp.frameworks.System as System

+/** Definitions relating to the `System.Linq` namespace. */
 module SystemLinq {
  /** The `System.Linq` namespace. */
  class Namespace extends csharp::Namespace {
--- a/csharp/ql/src/semmle/code/csharp/frameworks/system/data/Common.qll
+++ b/csharp/ql/src/semmle/code/csharp/frameworks/system/data/Common.qll
@@ -5,6 +5,7 @@
 private import csharp as csharp
 private import semmle.code.csharp.frameworks.system.Data as Data

+/** Definitions relating to the `System.Data.Common` namespace. */
 module SystemDataCommon {
  /** The `System.Data.Common` namespace. */
  class Namespace extends csharp::Namespace {
--- a/csharp/ql/src/semmle/code/csharp/frameworks/system/data/Entity.qll
+++ b/csharp/ql/src/semmle/code/csharp/frameworks/system/data/Entity.qll
@@ -5,6 +5,7 @@
 private import csharp as csharp
 private import semmle.code.csharp.frameworks.system.Data as Data

+/** Definitions relating to the `System.Data.Entity` namespace. */
 module SystemDataEntity {
  /** The `System.Data.Entity` namespace. */
  class Namespace extends csharp::Namespace {
@@ -78,6 +79,7 @@ module SystemDataEntity {
  }
 }

+/** Definitions relating to the `System.Data.Entity.Infrastructure` namespace. */
 module SystemDataEntityInfrastructure {
  /** The `System.Data.Entity.Infrastructure` namespace. */
  class Namespace extends csharp::Namespace {
--- a/csharp/ql/src/semmle/code/csharp/frameworks/system/linq/Expressions.qll
+++ b/csharp/ql/src/semmle/code/csharp/frameworks/system/linq/Expressions.qll
@@ -5,6 +5,7 @@
 private import csharp as csharp
 private import semmle.code.csharp.frameworks.system.Linq

+/** Definitions relating to the `System.Linq.Expressions` namespace. */
 module SystemLinqExpressions {
  /** The `System.Linq.Expressions` namespace. */
  class Namespace extends csharp::Namespace {
--- a/csharp/ql/src/semmle/code/csharp/frameworks/system/text/RegularExpressions.qll
+++ b/csharp/ql/src/semmle/code/csharp/frameworks/system/text/RegularExpressions.qll
@@ -1,3 +1,7 @@
+/**
+ * Provides classes related to the namespace `System.Text.RegularExpressions`.
+ */
+
 import default
 import semmle.code.csharp.frameworks.system.Text

--- a/csharp/ql/src/semmle/code/csharp/frameworks/system/xml/XPath.qll
+++ b/csharp/ql/src/semmle/code/csharp/frameworks/system/xml/XPath.qll
@@ -3,6 +3,7 @@
 import csharp as csharp
 private import semmle.code.csharp.frameworks.system.Xml as xml

+/** Definitions relating to the `System.Xml.XPath` namespace. */
 module SystemXmlXPath {
  /** The `System.Xml.XPath` namespace. */
  class Namespace extends csharp::Namespace {
--- a/csharp/ql/src/semmle/code/csharp/metrics/Coupling.qll
+++ b/csharp/ql/src/semmle/code/csharp/metrics/Coupling.qll
@@ -222,6 +222,10 @@ predicate shareFieldOrProperty(ValueOrRefType t, Method m1, Method m2) {
  )
 }

+/**
+ * Holds if the declaring type of method `m` is `t` and `m` accesses declaration
+ * `d`, which is either a field or a property.
+ */
 predicate methodUsesFieldOrProperty(ValueOrRefType t, Method m, Declaration d) {
  m.getDeclaringType() = t and
  (
--- a/csharp/ql/src/semmle/code/csharp/serialization/Deserializers.qll
+++ b/csharp/ql/src/semmle/code/csharp/serialization/Deserializers.qll
@@ -8,6 +8,7 @@ import csharp
 /** An unsafe deserializer. */
 abstract class UnsafeDeserializer extends Callable { }

+/** An unsafe deserializer method in the `System.*` namespace. */
 class SystemDeserializer extends UnsafeDeserializer {
  SystemDeserializer() {
    this
@@ -48,12 +49,17 @@ class SystemDeserializer extends UnsafeDeserializer {
  }
 }

+/** An unsafe deserializer method in the `Microsoft.*` namespace. */
 class MicrosoftDeserializer extends UnsafeDeserializer {
  MicrosoftDeserializer() {
    this.hasQualifiedName("Microsoft.Web.Design.Remote.ProxyObject", "DecodeValue")
  }
 }

+/**
+ * An unsafe deserializer method that calls any unsafe deserializer on any of
+ * the parameters.
+ */
 class WrapperDeserializer extends UnsafeDeserializer {
  WrapperDeserializer() {
    exists(Call call |
--- a/csharp/ql/src/semmle/code/csharp/serialization/Serialization.qll
+++ b/csharp/ql/src/semmle/code/csharp/serialization/Serialization.qll
@@ -1,5 +1,14 @@
+/**
+ * Provides classes to identify any .Net serializable type such as types
+ * attributed with `SerializableAttribute` and types implementing the
+ * `ISerializable` interface.
+ */
+
 import csharp

+/**
+ * A constructor with `SerializationInfo` and `StreamingContext` parameters.
+ */
 class SerializationConstructor extends Constructor {
  SerializationConstructor() {
    this.getNumberOfParameters() = 2 and
@@ -91,16 +100,3 @@ class CustomBinarySerializableType extends BinarySerializableType {
    result.(SerializationConstructor).getDeclaringType() = this
  }
 }
-
-class DangerousCallable extends Callable {
-  DangerousCallable() {
-    //files
-    this.(Method).getQualifiedName().matches("System.IO.File.Write%") or
-    this.(Method).getQualifiedName().matches("System.IO.File.%Copy%") or
-    this.(Method).getQualifiedName().matches("System.IO.File.%Move%") or
-    this.(Method).getQualifiedName().matches("System.IO.File.%Append%") or
-    this.(Method).getQualifiedName().matches("System.IO.%.%Delete%") or
-    //assembly
-    this.(Method).getQualifiedName().matches("System.Reflection.Assembly.%Load%")
-  }
-}
--- a/csharp/ql/src/semmle/code/dotnet/Callable.qll
+++ b/csharp/ql/src/semmle/code/dotnet/Callable.qll
@@ -1,3 +1,8 @@
+/**
+ * Provides `Callable` classes, which are things that can be called
+ * such as methods and constructors.
+ */
+
 import Declaration
 import Variable
 import Expr
--- a/csharp/ql/src/semmle/code/dotnet/Variable.qll
+++ b/csharp/ql/src/semmle/code/dotnet/Variable.qll
@@ -1,3 +1,5 @@
+/** Provides classes for .Net variables, such as fields and parameters. */
+
 import Declaration
 import Callable

--- a/csharp/ql/test/library-tests/expressions/AnonymousMethod1.expected
+++ b/csharp/ql/test/library-tests/expressions/AnonymousMethod1.expected
@@ -1 +1 @@
-| expressions.cs:443:33:443:66 | delegate(...) { ... } |
+| expressions.cs:455:33:455:66 | delegate(...) { ... } |
--- a/csharp/ql/test/library-tests/expressions/AnonymousMethod2.expected
+++ b/csharp/ql/test/library-tests/expressions/AnonymousMethod2.expected
@@ -1 +1 @@
-| expressions.cs:443:33:443:66 | delegate(...) { ... } | expressions.cs:443:47:443:47 | x |
+| expressions.cs:455:33:455:66 | delegate(...) { ... } | expressions.cs:455:47:455:47 | x |
--- a/csharp/ql/test/library-tests/expressions/AnonymousMethod3.expected
+++ b/csharp/ql/test/library-tests/expressions/AnonymousMethod3.expected
@@ -1 +1 @@
-| expressions.cs:443:33:443:66 | delegate(...) { ... } |
+| expressions.cs:455:33:455:66 | delegate(...) { ... } |
--- a/csharp/ql/test/library-tests/expressions/AnonymousMethod4.expected
+++ b/csharp/ql/test/library-tests/expressions/AnonymousMethod4.expected
@@ -1 +1 @@
-| expressions.cs:445:28:445:53 | delegate(...) { ... } | expressions.cs:445:28:445:53 | delegate(...) { ... } |
+| expressions.cs:457:28:457:53 | delegate(...) { ... } | expressions.cs:457:28:457:53 | delegate(...) { ... } |
--- a/csharp/ql/test/library-tests/expressions/AnonymousMethod5.expected
+++ b/csharp/ql/test/library-tests/expressions/AnonymousMethod5.expected
@@ -1 +1 @@
-| expressions.cs:445:28:445:53 | delegate(...) { ... } | expressions.cs:445:46:445:46 | access to local variable j |
+| expressions.cs:457:28:457:53 | delegate(...) { ... } | expressions.cs:457:46:457:46 | access to local variable j |
--- a/csharp/ql/test/library-tests/expressions/ArrayCreation11.expected
+++ b/csharp/ql/test/library-tests/expressions/ArrayCreation11.expected
@@ -1,3 +1,27 @@
 | expressions.cs:168:27:168:44 | array creation of type Object[] | expressions.cs:168:27:168:44 | 1 | true |
+| expressions.cs:409:23:409:65 | array creation of type Int32[,] | expressions.cs:409:23:409:65 | 2 | true |
 | expressions.cs:409:23:409:65 | array creation of type Int32[,] | expressions.cs:409:23:409:65 | 3 | true |
-| expressions.cs:409:23:409:65 | array creation of type Int32[,] | expressions.cs:409:23:409:65 | 3 | true |
+| expressions.cs:437:24:437:66 | array creation of type Int32[,] | expressions.cs:437:24:437:66 | 2 | true |
+| expressions.cs:437:24:437:66 | array creation of type Int32[,] | expressions.cs:437:24:437:66 | 3 | true |
+| expressions.cs:438:17:438:93 | array creation of type Int32[,,] | expressions.cs:438:17:438:93 | 2 | true |
+| expressions.cs:438:17:438:93 | array creation of type Int32[,,] | expressions.cs:438:17:438:93 | 2 | true |
+| expressions.cs:438:17:438:93 | array creation of type Int32[,,] | expressions.cs:438:17:438:93 | 3 | true |
+| expressions.cs:439:17:443:13 | array creation of type Int32[,][,] | expressions.cs:439:17:443:13 | 2 | true |
+| expressions.cs:439:17:443:13 | array creation of type Int32[,][,] | expressions.cs:439:17:443:13 | 3 | true |
+| expressions.cs:441:19:441:45 | array creation of type Int32[,] | expressions.cs:441:19:441:45 | 2 | true |
+| expressions.cs:441:19:441:45 | array creation of type Int32[,] | expressions.cs:441:19:441:45 | 2 | true |
+| expressions.cs:441:48:441:82 | array creation of type Int32[,] | expressions.cs:441:48:441:82 | 2 | true |
+| expressions.cs:441:48:441:82 | array creation of type Int32[,] | expressions.cs:441:48:441:82 | 3 | true |
+| expressions.cs:441:85:441:122 | array creation of type Int32[,] | expressions.cs:441:85:441:122 | 2 | true |
+| expressions.cs:441:85:441:122 | array creation of type Int32[,] | expressions.cs:441:85:441:122 | 3 | true |
+| expressions.cs:442:19:442:45 | array creation of type Int32[,] | expressions.cs:442:19:442:45 | 2 | true |
+| expressions.cs:442:19:442:45 | array creation of type Int32[,] | expressions.cs:442:19:442:45 | 2 | true |
+| expressions.cs:442:48:442:82 | array creation of type Int32[,] | expressions.cs:442:48:442:82 | 2 | true |
+| expressions.cs:442:48:442:82 | array creation of type Int32[,] | expressions.cs:442:48:442:82 | 3 | true |
+| expressions.cs:442:85:442:122 | array creation of type Int32[,] | expressions.cs:442:85:442:122 | 2 | true |
+| expressions.cs:442:85:442:122 | array creation of type Int32[,] | expressions.cs:442:85:442:122 | 3 | true |
+| expressions.cs:444:17:444:123 | array creation of type Int32[,][] | expressions.cs:444:17:444:123 | 2 | true |
+| expressions.cs:444:32:444:54 | array creation of type Int32[,] | expressions.cs:444:32:444:54 | 1 | true |
+| expressions.cs:444:32:444:54 | array creation of type Int32[,] | expressions.cs:444:32:444:54 | 2 | true |
+| expressions.cs:444:57:444:121 | array creation of type Int32[,] | expressions.cs:444:57:444:121 | 3 | true |
+| expressions.cs:444:57:444:121 | array creation of type Int32[,] | expressions.cs:444:57:444:121 | 4 | true |
--- a/csharp/ql/test/library-tests/expressions/Lambda1.expected
+++ b/csharp/ql/test/library-tests/expressions/Lambda1.expected
@@ -1 +1 @@
-| expressions.cs:437:36:437:53 | (...) => ... |
+| expressions.cs:449:36:449:53 | (...) => ... |
--- a/csharp/ql/test/library-tests/expressions/Lambda2.expected
+++ b/csharp/ql/test/library-tests/expressions/Lambda2.expected
@@ -1 +1 @@
-| expressions.cs:438:38:438:59 | (...) => ... |
+| expressions.cs:450:38:450:59 | (...) => ... |
--- a/csharp/ql/test/library-tests/expressions/Lambda3.expected
+++ b/csharp/ql/test/library-tests/expressions/Lambda3.expected
@@ -1 +1 @@
-| expressions.cs:439:33:439:48 | (...) => ... |
+| expressions.cs:451:33:451:48 | (...) => ... |
--- a/csharp/ql/test/library-tests/expressions/Lambda4.expected
+++ b/csharp/ql/test/library-tests/expressions/Lambda4.expected
@@ -1 +1 @@
-| expressions.cs:440:36:440:64 | (...) => ... |
+| expressions.cs:452:36:452:64 | (...) => ... |
--- a/csharp/ql/test/library-tests/expressions/Lambda5.expected
+++ b/csharp/ql/test/library-tests/expressions/Lambda5.expected
@@ -1 +1 @@
-| expressions.cs:441:20:441:34 | (...) => ... |
+| expressions.cs:453:20:453:34 | (...) => ... |
--- a/csharp/ql/test/library-tests/expressions/Lambda6.expected
+++ b/csharp/ql/test/library-tests/expressions/Lambda6.expected
@@ -1 +1 @@
-| expressions.cs:442:23:442:47 | (...) => ... |
+| expressions.cs:454:23:454:47 | (...) => ... |
--- a/csharp/ql/test/library-tests/expressions/OperatorCall6.expected
+++ b/csharp/ql/test/library-tests/expressions/OperatorCall6.expected
@@ -1,4 +1,4 @@
-| expressions.cs:458:20:458:27 | addition | expressions.cs:460:26:460:26 | access to parameter a | expressions.cs:473:40:473:40 | + |
-| expressions.cs:458:20:458:27 | addition | expressions.cs:460:30:460:30 | access to parameter b | expressions.cs:473:40:473:40 | + |
-| expressions.cs:458:20:458:27 | addition | expressions.cs:461:13:461:18 | access to local variable result | expressions.cs:473:40:473:40 | + |
-| expressions.cs:458:20:458:27 | addition | expressions.cs:461:23:461:23 | access to parameter c | expressions.cs:473:40:473:40 | + |
+| expressions.cs:470:20:470:27 | addition | expressions.cs:472:26:472:26 | access to parameter a | expressions.cs:485:40:485:40 | + |
+| expressions.cs:470:20:470:27 | addition | expressions.cs:472:30:472:30 | access to parameter b | expressions.cs:485:40:485:40 | + |
+| expressions.cs:470:20:470:27 | addition | expressions.cs:473:13:473:18 | access to local variable result | expressions.cs:485:40:485:40 | + |
+| expressions.cs:470:20:470:27 | addition | expressions.cs:473:23:473:23 | access to parameter c | expressions.cs:485:40:485:40 | + |
--- a/csharp/ql/test/library-tests/expressions/OperatorCall7.expected
+++ b/csharp/ql/test/library-tests/expressions/OperatorCall7.expected
@@ -1,2 +1,2 @@
-| expressions.cs:452:21:452:35 | delegateCombine | expressions.cs:450:11:450:23 | OperatorCalls | expressions.cs:455:13:455:27 | access to local variable PropertyChanged | expressions.cs:479:30:479:39 | MyDelegate |
-| expressions.cs:452:21:452:35 | delegateCombine | expressions.cs:450:11:450:23 | OperatorCalls | expressions.cs:455:32:455:34 | access to parameter fun | expressions.cs:479:30:479:39 | MyDelegate |
+| expressions.cs:464:21:464:35 | delegateCombine | expressions.cs:462:11:462:23 | OperatorCalls | expressions.cs:467:13:467:27 | access to local variable PropertyChanged | expressions.cs:491:30:491:39 | MyDelegate |
+| expressions.cs:464:21:464:35 | delegateCombine | expressions.cs:462:11:462:23 | OperatorCalls | expressions.cs:467:32:467:34 | access to parameter fun | expressions.cs:491:30:491:39 | MyDelegate |
--- a/csharp/ql/test/library-tests/expressions/PrintAst.expected
+++ b/csharp/ql/test/library-tests/expressions/PrintAst.expected
@@ -1491,333 +1491,467 @@ expressions.cs:
 #  432|         0: [Parameter] x
 #  432|         1: [Parameter] y
 #  433|     7: [DelegateType] Unit
-#  435|     8: [Method] MainAnonymousFunctions
+#  435|     8: [Method] MultiDimensionalArrayCreations
 #  436|       4: [BlockStmt] {...}
 #  437|         0: [LocalVariableDeclStmt] ... ...;
-#  437|           0: [LocalVariableDeclAndInitExpr] Func<Int16,Byte> f1 = ...
-#  437|             0: [LambdaExpr] (...) => ...
-#  437|               0: [CastExpr] (...) ...
-#  437|                 0: [AddExpr] ... + ...
-#  437|                   0: [CastExpr] (...) ...
-#  437|                     0: [ParameterAccess] access to parameter x
-#  437|                   1: [IntLiteral] 1
-#  437|                 1: [TypeAccess] access to type Byte
+#  437|           0: [LocalVariableDeclAndInitExpr] Object o = ...
+#  437|             0: [ArrayCreation] array creation of type Int32[,]
+#  437|               -1: [ArrayInitializer] { ..., ... }
+#  437|                 0: [ArrayInitializer] { ..., ... }
+#  437|                   0: [IntLiteral] 1
+#  437|                   1: [IntLiteral] 2
+#  437|                 1: [ArrayInitializer] { ..., ... }
+#  437|                   0: [IntLiteral] 3
+#  437|                   1: [IntLiteral] 4
+#  437|                 2: [ArrayInitializer] { ..., ... }
+#  437|                   0: [IntLiteral] 5
+#  437|                   1: [IntLiteral] 6
+#  437|             1: [LocalVariableAccess] access to local variable o
+#  438|         1: [ExprStmt] ...;
+#  438|           0: [AssignExpr] ... = ...
+#  438|             0: [ArrayCreation] array creation of type Int32[,,]
+#  438|               -1: [ArrayInitializer] { ..., ... }
+#  438|                 0: [ArrayInitializer] { ..., ... }
+#  438|                   0: [ArrayInitializer] { ..., ... }
+#  438|                     0: [IntLiteral] 1
+#  438|                     1: [IntLiteral] 2
+#  438|                     2: [IntLiteral] 3
+#  438|                   1: [ArrayInitializer] { ..., ... }
+#  438|                     0: [IntLiteral] 4
+#  438|                     1: [IntLiteral] 5
+#  438|                     2: [IntLiteral] 6
+#  438|                 1: [ArrayInitializer] { ..., ... }
+#  438|                   0: [ArrayInitializer] { ..., ... }
+#  438|                     0: [IntLiteral] 7
+#  438|                     1: [IntLiteral] 8
+#  438|                     2: [IntLiteral] 9
+#  438|                   1: [ArrayInitializer] { ..., ... }
+#  438|                     0: [IntLiteral] 10
+#  438|                     1: [IntLiteral] 11
+#  438|                     2: [IntLiteral] 12
+#  438|             1: [LocalVariableAccess] access to local variable o
+#  439|         2: [ExprStmt] ...;
+#  439|           0: [AssignExpr] ... = ...
+#  439|             0: [ArrayCreation] array creation of type Int32[,][,]
+#  440|               -1: [ArrayInitializer] { ..., ... }
+#  441|                 0: [ArrayInitializer] { ..., ... }
+#  441|                   0: [ArrayCreation] array creation of type Int32[,]
+#  441|                     -1: [ArrayInitializer] { ..., ... }
+#  441|                       0: [ArrayInitializer] { ..., ... }
+#  441|                         0: [IntLiteral] 1
+#  441|                         1: [IntLiteral] 3
+#  441|                       1: [ArrayInitializer] { ..., ... }
+#  441|                         0: [IntLiteral] 5
+#  441|                         1: [IntLiteral] 7
+#  441|                   1: [ArrayCreation] array creation of type Int32[,]
+#  441|                     -1: [ArrayInitializer] { ..., ... }
+#  441|                       0: [ArrayInitializer] { ..., ... }
+#  441|                         0: [IntLiteral] 0
+#  441|                         1: [IntLiteral] 2
+#  441|                       1: [ArrayInitializer] { ..., ... }
+#  441|                         0: [IntLiteral] 4
+#  441|                         1: [IntLiteral] 6
+#  441|                       2: [ArrayInitializer] { ..., ... }
+#  441|                         0: [IntLiteral] 8
+#  441|                         1: [IntLiteral] 10
+#  441|                   2: [ArrayCreation] array creation of type Int32[,]
+#  441|                     -1: [ArrayInitializer] { ..., ... }
+#  441|                       0: [ArrayInitializer] { ..., ... }
+#  441|                         0: [IntLiteral] 11
+#  441|                         1: [IntLiteral] 22
+#  441|                       1: [ArrayInitializer] { ..., ... }
+#  441|                         0: [IntLiteral] 99
+#  441|                         1: [IntLiteral] 88
+#  441|                       2: [ArrayInitializer] { ..., ... }
+#  441|                         0: [IntLiteral] 0
+#  441|                         1: [IntLiteral] 9
+#  442|                 1: [ArrayInitializer] { ..., ... }
+#  442|                   0: [ArrayCreation] array creation of type Int32[,]
+#  442|                     -1: [ArrayInitializer] { ..., ... }
+#  442|                       0: [ArrayInitializer] { ..., ... }
+#  442|                         0: [IntLiteral] 1
+#  442|                         1: [IntLiteral] 3
+#  442|                       1: [ArrayInitializer] { ..., ... }
+#  442|                         0: [IntLiteral] 5
+#  442|                         1: [IntLiteral] 7
+#  442|                   1: [ArrayCreation] array creation of type Int32[,]
+#  442|                     -1: [ArrayInitializer] { ..., ... }
+#  442|                       0: [ArrayInitializer] { ..., ... }
+#  442|                         0: [IntLiteral] 0
+#  442|                         1: [IntLiteral] 2
+#  442|                       1: [ArrayInitializer] { ..., ... }
+#  442|                         0: [IntLiteral] 4
+#  442|                         1: [IntLiteral] 6
+#  442|                       2: [ArrayInitializer] { ..., ... }
+#  442|                         0: [IntLiteral] 8
+#  442|                         1: [IntLiteral] 10
+#  442|                   2: [ArrayCreation] array creation of type Int32[,]
+#  442|                     -1: [ArrayInitializer] { ..., ... }
+#  442|                       0: [ArrayInitializer] { ..., ... }
+#  442|                         0: [IntLiteral] 11
+#  442|                         1: [IntLiteral] 22
+#  442|                       1: [ArrayInitializer] { ..., ... }
+#  442|                         0: [IntLiteral] 99
+#  442|                         1: [IntLiteral] 88
+#  442|                       2: [ArrayInitializer] { ..., ... }
+#  442|                         0: [IntLiteral] 0
+#  442|                         1: [IntLiteral] 9
+#  439|             1: [LocalVariableAccess] access to local variable o
+#  444|         3: [ExprStmt] ...;
+#  444|           0: [AssignExpr] ... = ...
+#  444|             0: [ArrayCreation] array creation of type Int32[,][]
+#  444|               -1: [ArrayInitializer] { ..., ... }
+#  444|                 0: [ArrayCreation] array creation of type Int32[,]
+#  444|                   -1: [ArrayInitializer] { ..., ... }
+#  444|                     0: [ArrayInitializer] { ..., ... }
+#  444|                       0: [IntLiteral] 1
+#  444|                       1: [IntLiteral] 2
+#  444|                 1: [ArrayCreation] array creation of type Int32[,]
+#  444|                   -1: [ArrayInitializer] { ..., ... }
+#  444|                     0: [ArrayInitializer] { ..., ... }
+#  444|                       0: [IntLiteral] 1
+#  444|                       1: [IntLiteral] 2
+#  444|                       2: [IntLiteral] 3
+#  444|                     1: [ArrayInitializer] { ..., ... }
+#  444|                       0: [IntLiteral] 1
+#  444|                       1: [IntLiteral] 2
+#  444|                       2: [IntLiteral] 3
+#  444|                     2: [ArrayInitializer] { ..., ... }
+#  444|                       0: [IntLiteral] 1
+#  444|                       1: [IntLiteral] 2
+#  444|                       2: [IntLiteral] 3
+#  444|                     3: [ArrayInitializer] { ..., ... }
+#  444|                       0: [IntLiteral] 1
+#  444|                       1: [IntLiteral] 2
+#  444|                       2: [IntLiteral] 3
+#  444|             1: [LocalVariableAccess] access to local variable o
+#  447|     9: [Method] MainAnonymousFunctions
+#  448|       4: [BlockStmt] {...}
+#  449|         0: [LocalVariableDeclStmt] ... ...;
+#  449|           0: [LocalVariableDeclAndInitExpr] Func<Int16,Byte> f1 = ...
+#  449|             0: [LambdaExpr] (...) => ...
+#  449|               0: [CastExpr] (...) ...
+#  449|                 0: [AddExpr] ... + ...
+#  449|                   0: [CastExpr] (...) ...
+#  449|                     0: [ParameterAccess] access to parameter x
+#  449|                   1: [IntLiteral] 1
+#  449|                 1: [TypeAccess] access to type Byte
 #-----|               2: (Parameters)
-#  437|                 0: [Parameter] x
-#  437|             1: [LocalVariableAccess] access to local variable f1
-#  438|         1: [LocalVariableDeclStmt] ... ...;
-#  438|           0: [LocalVariableDeclAndInitExpr] Func<Int32,Double> f2 = ...
-#  438|             0: [LambdaExpr] (...) => ...
-#  438|               0: [BlockStmt] {...}
-#  438|                 0: [ReturnStmt] return ...;
-#  438|                   0: [CastExpr] (...) ...
-#  438|                     0: [AddExpr] ... + ...
-#  438|                       0: [ParameterAccess] access to parameter x
-#  438|                       1: [IntLiteral] 1
+#  449|                 0: [Parameter] x
+#  449|             1: [LocalVariableAccess] access to local variable f1
+#  450|         1: [LocalVariableDeclStmt] ... ...;
+#  450|           0: [LocalVariableDeclAndInitExpr] Func<Int32,Double> f2 = ...
+#  450|             0: [LambdaExpr] (...) => ...
+#  450|               0: [BlockStmt] {...}
+#  450|                 0: [ReturnStmt] return ...;
+#  450|                   0: [CastExpr] (...) ...
+#  450|                     0: [AddExpr] ... + ...
+#  450|                       0: [ParameterAccess] access to parameter x
+#  450|                       1: [IntLiteral] 1
 #-----|               2: (Parameters)
-#  438|                 0: [Parameter] x
-#  438|             1: [LocalVariableAccess] access to local variable f2
-#  439|         2: [LocalVariableDeclStmt] ... ...;
-#  439|           0: [LocalVariableDeclAndInitExpr] Func<Int32,Int32> f3 = ...
-#  439|             0: [LambdaExpr] (...) => ...
-#  439|               0: [AddExpr] ... + ...
-#  439|                 0: [ParameterAccess] access to parameter x
-#  439|                 1: [IntLiteral] 1
+#  450|                 0: [Parameter] x
+#  450|             1: [LocalVariableAccess] access to local variable f2
+#  451|         2: [LocalVariableDeclStmt] ... ...;
+#  451|           0: [LocalVariableDeclAndInitExpr] Func<Int32,Int32> f3 = ...
+#  451|             0: [LambdaExpr] (...) => ...
+#  451|               0: [AddExpr] ... + ...
+#  451|                 0: [ParameterAccess] access to parameter x
+#  451|                 1: [IntLiteral] 1
 #-----|               2: (Parameters)
-#  439|                 0: [Parameter] x
-#  439|             1: [LocalVariableAccess] access to local variable f3
-#  440|         3: [LocalVariableDeclStmt] ... ...;
-#  440|           0: [LocalVariableDeclAndInitExpr] Func<Int32,String> f4 = ...
-#  440|             0: [LambdaExpr] (...) => ...
-#  440|               0: [BlockStmt] {...}
-#  440|                 0: [ReturnStmt] return ...;
-#  440|                   0: [AddExpr] ... + ...
-#  440|                     0: [CastExpr] (...) ...
-#  440|                       0: [ParameterAccess] access to parameter x
-#  440|                     1: [StringLiteral] ""
+#  451|                 0: [Parameter] x
+#  451|             1: [LocalVariableAccess] access to local variable f3
+#  452|         3: [LocalVariableDeclStmt] ... ...;
+#  452|           0: [LocalVariableDeclAndInitExpr] Func<Int32,String> f4 = ...
+#  452|             0: [LambdaExpr] (...) => ...
+#  452|               0: [BlockStmt] {...}
+#  452|                 0: [ReturnStmt] return ...;
+#  452|                   0: [AddExpr] ... + ...
+#  452|                     0: [CastExpr] (...) ...
+#  452|                       0: [ParameterAccess] access to parameter x
+#  452|                     1: [StringLiteral] ""
 #-----|               2: (Parameters)
-#  440|                 0: [Parameter] x
-#  440|             1: [LocalVariableAccess] access to local variable f4
-#  441|         4: [LocalVariableDeclStmt] ... ...;
-#  441|           0: [LocalVariableDeclAndInitExpr] S f5 = ...
-#  441|             0: [LambdaExpr] (...) => ...
-#  441|               0: [MulExpr] ... * ...
-#  441|                 0: [ParameterAccess] access to parameter x
-#  441|                 1: [ParameterAccess] access to parameter y
+#  452|                 0: [Parameter] x
+#  452|             1: [LocalVariableAccess] access to local variable f4
+#  453|         4: [LocalVariableDeclStmt] ... ...;
+#  453|           0: [LocalVariableDeclAndInitExpr] S f5 = ...
+#  453|             0: [LambdaExpr] (...) => ...
+#  453|               0: [MulExpr] ... * ...
+#  453|                 0: [ParameterAccess] access to parameter x
+#  453|                 1: [ParameterAccess] access to parameter y
 #-----|               2: (Parameters)
-#  441|                 0: [Parameter] x
-#  441|                 1: [Parameter] y
-#  441|             1: [LocalVariableAccess] access to local variable f5
-#  442|         5: [LocalVariableDeclStmt] ... ...;
-#  442|           0: [LocalVariableDeclAndInitExpr] Unit f6 = ...
-#  442|             0: [LambdaExpr] (...) => ...
-#  442|               0: [MethodCall] call to method WriteLine
-#  442|                 -1: [TypeAccess] access to type Console
-#  442|             1: [LocalVariableAccess] access to local variable f6
-#  443|         6: [LocalVariableDeclStmt] ... ...;
-#  443|           0: [LocalVariableDeclAndInitExpr] Func<Int32,Int32> f7 = ...
-#  443|             0: [AnonymousMethodExpr] delegate(...) { ... }
-#  443|               0: [BlockStmt] {...}
-#  443|                 0: [ReturnStmt] return ...;
-#  443|                   0: [AddExpr] ... + ...
-#  443|                     0: [ParameterAccess] access to parameter x
-#  443|                     1: [IntLiteral] 1
+#  453|                 0: [Parameter] x
+#  453|                 1: [Parameter] y
+#  453|             1: [LocalVariableAccess] access to local variable f5
+#  454|         5: [LocalVariableDeclStmt] ... ...;
+#  454|           0: [LocalVariableDeclAndInitExpr] Unit f6 = ...
+#  454|             0: [LambdaExpr] (...) => ...
+#  454|               0: [MethodCall] call to method WriteLine
+#  454|                 -1: [TypeAccess] access to type Console
+#  454|             1: [LocalVariableAccess] access to local variable f6
+#  455|         6: [LocalVariableDeclStmt] ... ...;
+#  455|           0: [LocalVariableDeclAndInitExpr] Func<Int32,Int32> f7 = ...
+#  455|             0: [AnonymousMethodExpr] delegate(...) { ... }
+#  455|               0: [BlockStmt] {...}
+#  455|                 0: [ReturnStmt] return ...;
+#  455|                   0: [AddExpr] ... + ...
+#  455|                     0: [ParameterAccess] access to parameter x
+#  455|                     1: [IntLiteral] 1
 #-----|               2: (Parameters)
-#  443|                 0: [Parameter] x
-#  443|             1: [LocalVariableAccess] access to local variable f7
-#  444|         7: [LocalVariableDeclStmt] ... ...;
-#  444|           0: [LocalVariableDeclAndInitExpr] Int32 j = ...
-#  444|             0: [IntLiteral] 0
-#  444|             1: [LocalVariableAccess] access to local variable j
-#  445|         8: [LocalVariableDeclStmt] ... ...;
-#  445|           0: [LocalVariableDeclAndInitExpr] Func<Int32> f8 = ...
-#  445|             0: [AnonymousMethodExpr] delegate(...) { ... }
-#  445|               0: [BlockStmt] {...}
-#  445|                 0: [ReturnStmt] return ...;
-#  445|                   0: [AddExpr] ... + ...
-#  445|                     0: [LocalVariableAccess] access to local variable j
-#  445|                     1: [IntLiteral] 1
-#  445|             1: [LocalVariableAccess] access to local variable f8
-#  450|   18: [Class] OperatorCalls
-#  452|     5: [Method] delegateCombine
+#  455|                 0: [Parameter] x
+#  455|             1: [LocalVariableAccess] access to local variable f7
+#  456|         7: [LocalVariableDeclStmt] ... ...;
+#  456|           0: [LocalVariableDeclAndInitExpr] Int32 j = ...
+#  456|             0: [IntLiteral] 0
+#  456|             1: [LocalVariableAccess] access to local variable j
+#  457|         8: [LocalVariableDeclStmt] ... ...;
+#  457|           0: [LocalVariableDeclAndInitExpr] Func<Int32> f8 = ...
+#  457|             0: [AnonymousMethodExpr] delegate(...) { ... }
+#  457|               0: [BlockStmt] {...}
+#  457|                 0: [ReturnStmt] return ...;
+#  457|                   0: [AddExpr] ... + ...
+#  457|                     0: [LocalVariableAccess] access to local variable j
+#  457|                     1: [IntLiteral] 1
+#  457|             1: [LocalVariableAccess] access to local variable f8
+#  462|   18: [Class] OperatorCalls
+#  464|     5: [Method] delegateCombine
 #-----|       2: (Parameters)
-#  452|         0: [Parameter] fun
-#  453|       4: [BlockStmt] {...}
-#  454|         0: [LocalVariableDeclStmt] ... ...;
-#  454|           0: [LocalVariableDeclAndInitExpr] MyDelegate PropertyChanged = ...
-#  454|             0: [NullLiteral] null
-#  454|             1: [LocalVariableAccess] access to local variable PropertyChanged
-#  455|         1: [ExprStmt] ...;
-#  455|           0: [AssignAddExpr] ... += ...
-#  455|             0: [ParameterAccess] access to parameter fun
-#  455|             1: [LocalVariableAccess] access to local variable PropertyChanged
-#  458|     6: [Method] addition
+#  464|         0: [Parameter] fun
+#  465|       4: [BlockStmt] {...}
+#  466|         0: [LocalVariableDeclStmt] ... ...;
+#  466|           0: [LocalVariableDeclAndInitExpr] MyDelegate PropertyChanged = ...
+#  466|             0: [NullLiteral] null
+#  466|             1: [LocalVariableAccess] access to local variable PropertyChanged
+#  467|         1: [ExprStmt] ...;
+#  467|           0: [AssignAddExpr] ... += ...
+#  467|             0: [ParameterAccess] access to parameter fun
+#  467|             1: [LocalVariableAccess] access to local variable PropertyChanged
+#  470|     6: [Method] addition
 #-----|       2: (Parameters)
-#  458|         0: [Parameter] a
-#  458|         1: [Parameter] b
-#  458|         2: [Parameter] c
-#  459|       4: [BlockStmt] {...}
-#  460|         0: [LocalVariableDeclStmt] ... ...;
-#  460|           0: [LocalVariableDeclAndInitExpr] Num result = ...
-#  460|             0: [OperatorCall] call to operator +
-#  460|               0: [ParameterAccess] access to parameter a
-#  460|               1: [ParameterAccess] access to parameter b
-#  460|             1: [LocalVariableAccess] access to local variable result
-#  461|         1: [ExprStmt] ...;
-#  461|           0: [AssignAddExpr] ... += ...
-#  461|             0: [ParameterAccess] access to parameter c
-#  461|             1: [LocalVariableAccess] access to local variable result
-#  462|         2: [ReturnStmt] return ...;
-#  462|           0: [LocalVariableAccess] access to local variable result
-#  464|     7: [Class] Num
-#  466|       4: [Field] value
-#  468|       5: [InstanceConstructor] Num
+#  470|         0: [Parameter] a
+#  470|         1: [Parameter] b
+#  470|         2: [Parameter] c
+#  471|       4: [BlockStmt] {...}
+#  472|         0: [LocalVariableDeclStmt] ... ...;
+#  472|           0: [LocalVariableDeclAndInitExpr] Num result = ...
+#  472|             0: [OperatorCall] call to operator +
+#  472|               0: [ParameterAccess] access to parameter a
+#  472|               1: [ParameterAccess] access to parameter b
+#  472|             1: [LocalVariableAccess] access to local variable result
+#  473|         1: [ExprStmt] ...;
+#  473|           0: [AssignAddExpr] ... += ...
+#  473|             0: [ParameterAccess] access to parameter c
+#  473|             1: [LocalVariableAccess] access to local variable result
+#  474|         2: [ReturnStmt] return ...;
+#  474|           0: [LocalVariableAccess] access to local variable result
+#  476|     7: [Class] Num
+#  478|       4: [Field] value
+#  480|       5: [InstanceConstructor] Num
 #-----|         2: (Parameters)
-#  468|           0: [Parameter] value
-#  469|         4: [BlockStmt] {...}
-#  470|           0: [ExprStmt] ...;
-#  470|             0: [AssignExpr] ... = ...
-#  470|               0: [ParameterAccess] access to parameter value
-#  470|               1: [FieldAccess] access to field value
-#  470|                 -1: [ThisAccess] this access
-#  473|       6: [AddOperator] +
+#  480|           0: [Parameter] value
+#  481|         4: [BlockStmt] {...}
+#  482|           0: [ExprStmt] ...;
+#  482|             0: [AssignExpr] ... = ...
+#  482|               0: [ParameterAccess] access to parameter value
+#  482|               1: [FieldAccess] access to field value
+#  482|                 -1: [ThisAccess] this access
+#  485|       6: [AddOperator] +
 #-----|         2: (Parameters)
-#  473|           0: [Parameter] c1
-#  473|           1: [Parameter] c2
-#  474|         4: [BlockStmt] {...}
-#  475|           0: [ReturnStmt] return ...;
-#  475|             0: [ObjectCreation] object creation of type Num
-#  475|               0: [AddExpr] ... + ...
-#  475|                 0: [FieldAccess] access to field value
-#  475|                   -1: [ParameterAccess] access to parameter c1
-#  475|                 1: [FieldAccess] access to field value
-#  475|                   -1: [ParameterAccess] access to parameter c2
-#  479|     8: [DelegateType] MyDelegate
+#  485|           0: [Parameter] c1
+#  485|           1: [Parameter] c2
+#  486|         4: [BlockStmt] {...}
+#  487|           0: [ReturnStmt] return ...;
+#  487|             0: [ObjectCreation] object creation of type Num
+#  487|               0: [AddExpr] ... + ...
+#  487|                 0: [FieldAccess] access to field value
+#  487|                   -1: [ParameterAccess] access to parameter c1
+#  487|                 1: [FieldAccess] access to field value
+#  487|                   -1: [ParameterAccess] access to parameter c2
+#  491|     8: [DelegateType] MyDelegate
 #-----|       2: (Parameters)
-#  479|         0: [Parameter] e
-#  482|   19: [Class] ExpressionDepth
-#  484|     5: [Field] d
-#  484|       1: [AssignExpr] ... = ...
-#  484|         0: [AddExpr] ... + ...
-#  484|           0: [AddExpr] ... + ...
-#  484|             0: [AddExpr] ... + ...
-#  484|               0: [AddExpr] ... + ...
-#  484|                 0: [AddExpr] ... + ...
-#  484|                   0: [AddExpr] ... + ...
-#  484|                     0: [AddExpr] ... + ...
-#  484|                       0: [AddExpr] ... + ...
-#  484|                         0: [AddExpr] ... + ...
-#  484|                           0: [AddExpr] ... + ...
-#  484|                             0: [AddExpr] ... + ...
-#  484|                               0: [AddExpr] ... + ...
-#  484|                                 0: [AddExpr] ... + ...
-#  484|                                   0: [AddExpr] ... + ...
-#  484|                                     0: [AddExpr] ... + ...
-#  484|                                       0: [AddExpr] ... + ...
-#  484|                                         0: [AddExpr] ... + ...
-#  484|                                           0: [AddExpr] ... + ...
-#  484|                                             0: [AddExpr] ... + ...
-#  484|                                               0: [AddExpr] ... + ...
-#  484|                                                 0: [AddExpr] ... + ...
-#  484|                                                   0: [AddExpr] ... + ...
-#  484|                                                     0: [AddExpr] ... + ...
-#  484|                                                       0: [AddExpr] ... + ...
-#  484|                                                         0: [AddExpr] ... + ...
-#  484|                                                           0: [AddExpr] ... + ...
-#  484|                                                             0: [AddExpr] ... + ...
-#  484|                                                               0: [AddExpr] ... + ...
-#  484|                                                                 0: [AddExpr] ... + ...
-#  484|                                                                   0: [AddExpr] ... + ...
-#  484|                                                                     0: [AddExpr] ... + ...
-#  484|                                                                       0: [AddExpr] ... + ...
-#  484|                                                                         0: [AddExpr] ... + ...
-#  484|                                                                           0: [AddExpr] ... + ...
-#  484|                                                                             0: [AddExpr] ... + ...
-#  484|                                                                               0: [AddExpr] ... + ...
-#  484|                                                                                 0: [AddExpr] ... + ...
-#  484|                                                                                   0: [AddExpr] ... + ...
-#  484|                                                                                     0: [AddExpr] ... + ...
-#  484|                                                                                       0: [AddExpr] ... + ...
-#  484|                                                                                         0: [AddExpr] ... + ...
-#  484|                                                                                           0: [AddExpr] ... + ...
-#  484|                                                                                             0: [AddExpr] ... + ...
-#  484|                                                                                               0: [AddExpr] ... + ...
-#  484|                                                                                                 0: [AddExpr] ... + ...
-#  484|                                                                                                   0: [AddExpr] ... + ...
-#  484|                                                                                                     0: [AddExpr] ... + ...
-#  484|                                                                                                       0: [AddExpr] ... + ...
-#  484|                                                                                                         0: [AddExpr] ... + ...
-#  484|                                                                                                           0: [AddExpr] ... + ...
-#  484|                                                                                                             0: [AddExpr] ... + ...
-#  484|                                                                                                               0: [AddExpr] ... + ...
-#  484|                                                                                                                 0: [AddExpr] ... + ...
-#  484|                                                                                                                   0: [AddExpr] ... + ...
-#  484|                                                                                                                     0: [AddExpr] ... + ...
-#  484|                                                                                                                       0: [AddExpr] ... + ...
-#  484|                                                                                                                         0: [AddExpr] ... + ...
-#  484|                                                                                                                           0: [AddExpr] ... + ...
-#  484|                                                                                                                             0: [AddExpr] ... + ...
-#  484|                                                                                                                               0: [AddExpr] ... + ...
-#  484|                                                                                                                                 0: [AddExpr] ... + ...
-#  484|                                                                                                                                   0: [AddExpr] ... + ...
-#  484|                                                                                                                                     0: [AddExpr] ... + ...
-#  484|                                                                                                                                       0: [AddExpr] ... + ...
-#  484|                                                                                                                                         0: [AddExpr] ... + ...
-#  484|                                                                                                                                           0: [AddExpr] ... + ...
-#  484|                                                                                                                                             0: [AddExpr] ... + ...
-#  484|                                                                                                                                               0: [AddExpr] ... + ...
-#  484|                                                                                                                                                 0: [AddExpr] ... + ...
-#  484|                                                                                                                                                   0: [AddExpr] ... + ...
-#  484|                                                                                                                                                     0: [AddExpr] ... + ...
-#  484|                                                                                                                                                       0: [AddExpr] ... + ...
-#  484|                                                                                                                                                         0: [AddExpr] ... + ...
-#  484|                                                                                                                                                           0: [AddExpr] ... + ...
-#  484|                                                                                                                                                             0: [AddExpr] ... + ...
-#  484|                                                                                                                                                               0: [AddExpr] ... + ...
-#  484|                                                                                                                                                                 0: [AddExpr] ... + ...
-#  484|                                                                                                                                                                   0: [AddExpr] ... + ...
-#  484|                                                                                                                                                                     0: [AddExpr] ... + ...
-#  484|                                                                                                                                                                       0: [IntLiteral] 1
-#  484|                                                                                                                                                                       1: [IntLiteral] 1
-#  484|                                                                                                                                                                     1: [IntLiteral] 1
-#  484|                                                                                                                                                                   1: [IntLiteral] 1
-#  484|                                                                                                                                                                 1: [IntLiteral] 1
-#  484|                                                                                                                                                               1: [IntLiteral] 1
-#  484|                                                                                                                                                             1: [IntLiteral] 1
-#  484|                                                                                                                                                           1: [IntLiteral] 1
-#  484|                                                                                                                                                         1: [IntLiteral] 1
-#  484|                                                                                                                                                       1: [IntLiteral] 1
-#  484|                                                                                                                                                     1: [IntLiteral] 1
-#  484|                                                                                                                                                   1: [IntLiteral] 1
-#  484|                                                                                                                                                 1: [IntLiteral] 1
-#  484|                                                                                                                                               1: [IntLiteral] 1
-#  484|                                                                                                                                             1: [IntLiteral] 1
-#  484|                                                                                                                                           1: [IntLiteral] 1
-#  484|                                                                                                                                         1: [IntLiteral] 1
-#  484|                                                                                                                                       1: [IntLiteral] 1
-#  484|                                                                                                                                     1: [IntLiteral] 1
-#  484|                                                                                                                                   1: [IntLiteral] 1
-#  484|                                                                                                                                 1: [IntLiteral] 1
-#  484|                                                                                                                               1: [IntLiteral] 1
-#  484|                                                                                                                             1: [IntLiteral] 1
-#  484|                                                                                                                           1: [IntLiteral] 1
-#  484|                                                                                                                         1: [IntLiteral] 1
-#  484|                                                                                                                       1: [IntLiteral] 1
-#  484|                                                                                                                     1: [IntLiteral] 1
-#  484|                                                                                                                   1: [IntLiteral] 1
-#  484|                                                                                                                 1: [IntLiteral] 1
-#  484|                                                                                                               1: [IntLiteral] 1
-#  484|                                                                                                             1: [IntLiteral] 1
-#  484|                                                                                                           1: [IntLiteral] 1
-#  484|                                                                                                         1: [IntLiteral] 1
-#  484|                                                                                                       1: [IntLiteral] 1
-#  484|                                                                                                     1: [IntLiteral] 1
-#  484|                                                                                                   1: [IntLiteral] 1
-#  484|                                                                                                 1: [IntLiteral] 1
-#  484|                                                                                               1: [IntLiteral] 1
-#  484|                                                                                             1: [IntLiteral] 1
-#  484|                                                                                           1: [IntLiteral] 1
-#  485|                                                                                         1: [IntLiteral] 1
-#  485|                                                                                       1: [IntLiteral] 1
-#  485|                                                                                     1: [IntLiteral] 1
-#  485|                                                                                   1: [IntLiteral] 1
-#  485|                                                                                 1: [IntLiteral] 1
-#  485|                                                                               1: [IntLiteral] 1
-#  485|                                                                             1: [IntLiteral] 1
-#  485|                                                                           1: [IntLiteral] 1
-#  485|                                                                         1: [IntLiteral] 1
-#  485|                                                                       1: [IntLiteral] 1
-#  485|                                                                     1: [IntLiteral] 1
-#  485|                                                                   1: [IntLiteral] 1
-#  485|                                                                 1: [IntLiteral] 1
-#  485|                                                               1: [IntLiteral] 1
-#  485|                                                             1: [IntLiteral] 1
-#  485|                                                           1: [IntLiteral] 1
-#  485|                                                         1: [IntLiteral] 1
-#  485|                                                       1: [IntLiteral] 1
-#  485|                                                     1: [IntLiteral] 1
-#  485|                                                   1: [IntLiteral] 1
-#  485|                                                 1: [IntLiteral] 1
-#  485|                                               1: [IntLiteral] 1
-#  485|                                             1: [IntLiteral] 1
-#  485|                                           1: [IntLiteral] 1
-#  485|                                         1: [IntLiteral] 1
-#  485|                                       1: [IntLiteral] 1
-#  485|                                     1: [IntLiteral] 1
-#  485|                                   1: [IntLiteral] 1
-#  485|                                 1: [IntLiteral] 1
-#  485|                               1: [IntLiteral] 1
-#  485|                             1: [IntLiteral] 1
-#  485|                           1: [IntLiteral] 1
-#  485|                         1: [IntLiteral] 1
-#  485|                       1: [IntLiteral] 1
-#  485|                     1: [IntLiteral] 1
-#  485|                   1: [IntLiteral] 1
-#  485|                 1: [IntLiteral] 1
-#  485|               1: [IntLiteral] 1
-#  485|             1: [IntLiteral] 1
-#  485|           1: [IntLiteral] 1
-#  484|         1: [MemberConstantAccess] access to constant d
-#  488|   20: [Class] TupleExprs
-#  490|     5: [Method] Test
-#  491|       4: [BlockStmt] {...}
-#  492|         0: [LocalVariableDeclStmt] ... ...;
-#  492|           0: [LocalVariableDeclAndInitExpr] (Int32,String) a = ...
-#  492|             0: [DefaultValueExpr] default(...)
-#  492|               0: [TypeAccess] access to type (Int32,String)
-#  492|             1: [LocalVariableAccess] access to local variable a
-#  493|         1: [LocalVariableDeclStmt] ... ...;
-#  493|           0: [LocalVariableDeclAndInitExpr] (Boolean,Int32[],Object) b = ...
-#  493|             0: [DefaultValueExpr] default(...)
-#  493|               0: [TypeAccess] access to type (Boolean,Int32[],Object)
-#  493|             1: [LocalVariableAccess] access to local variable b
-#  494|         2: [LocalVariableDeclStmt] ... ...;
-#  494|           0: [LocalVariableDeclAndInitExpr] Type x = ...
-#  494|             0: [TypeofExpr] typeof(...)
-#  494|               0: [TypeAccess] access to type (Int32,String)
-#  494|             1: [LocalVariableAccess] access to local variable x
-#  495|         3: [LocalVariableDeclStmt] ... ...;
-#  495|           0: [LocalVariableDeclAndInitExpr] Type y = ...
-#  495|             0: [TypeofExpr] typeof(...)
-#  495|               0: [TypeAccess] access to type (Boolean,Int32[],dynamic)
-#  495|             1: [LocalVariableAccess] access to local variable y
+#  491|         0: [Parameter] e
+#  494|   19: [Class] ExpressionDepth
+#  496|     5: [Field] d
+#  496|       1: [AssignExpr] ... = ...
+#  496|         0: [AddExpr] ... + ...
+#  496|           0: [AddExpr] ... + ...
+#  496|             0: [AddExpr] ... + ...
+#  496|               0: [AddExpr] ... + ...
+#  496|                 0: [AddExpr] ... + ...
+#  496|                   0: [AddExpr] ... + ...
+#  496|                     0: [AddExpr] ... + ...
+#  496|                       0: [AddExpr] ... + ...
+#  496|                         0: [AddExpr] ... + ...
+#  496|                           0: [AddExpr] ... + ...
+#  496|                             0: [AddExpr] ... + ...
+#  496|                               0: [AddExpr] ... + ...
+#  496|                                 0: [AddExpr] ... + ...
+#  496|                                   0: [AddExpr] ... + ...
+#  496|                                     0: [AddExpr] ... + ...
+#  496|                                       0: [AddExpr] ... + ...
+#  496|                                         0: [AddExpr] ... + ...
+#  496|                                           0: [AddExpr] ... + ...
+#  496|                                             0: [AddExpr] ... + ...
+#  496|                                               0: [AddExpr] ... + ...
+#  496|                                                 0: [AddExpr] ... + ...
+#  496|                                                   0: [AddExpr] ... + ...
+#  496|                                                     0: [AddExpr] ... + ...
+#  496|                                                       0: [AddExpr] ... + ...
+#  496|                                                         0: [AddExpr] ... + ...
+#  496|                                                           0: [AddExpr] ... + ...
+#  496|                                                             0: [AddExpr] ... + ...
+#  496|                                                               0: [AddExpr] ... + ...
+#  496|                                                                 0: [AddExpr] ... + ...
+#  496|                                                                   0: [AddExpr] ... + ...
+#  496|                                                                     0: [AddExpr] ... + ...
+#  496|                                                                       0: [AddExpr] ... + ...
+#  496|                                                                         0: [AddExpr] ... + ...
+#  496|                                                                           0: [AddExpr] ... + ...
+#  496|                                                                             0: [AddExpr] ... + ...
+#  496|                                                                               0: [AddExpr] ... + ...
+#  496|                                                                                 0: [AddExpr] ... + ...
+#  496|                                                                                   0: [AddExpr] ... + ...
+#  496|                                                                                     0: [AddExpr] ... + ...
+#  496|                                                                                       0: [AddExpr] ... + ...
+#  496|                                                                                         0: [AddExpr] ... + ...
+#  496|                                                                                           0: [AddExpr] ... + ...
+#  496|                                                                                             0: [AddExpr] ... + ...
+#  496|                                                                                               0: [AddExpr] ... + ...
+#  496|                                                                                                 0: [AddExpr] ... + ...
+#  496|                                                                                                   0: [AddExpr] ... + ...
+#  496|                                                                                                     0: [AddExpr] ... + ...
+#  496|                                                                                                       0: [AddExpr] ... + ...
+#  496|                                                                                                         0: [AddExpr] ... + ...
+#  496|                                                                                                           0: [AddExpr] ... + ...
+#  496|                                                                                                             0: [AddExpr] ... + ...
+#  496|                                                                                                               0: [AddExpr] ... + ...
+#  496|                                                                                                                 0: [AddExpr] ... + ...
+#  496|                                                                                                                   0: [AddExpr] ... + ...
+#  496|                                                                                                                     0: [AddExpr] ... + ...
+#  496|                                                                                                                       0: [AddExpr] ... + ...
+#  496|                                                                                                                         0: [AddExpr] ... + ...
+#  496|                                                                                                                           0: [AddExpr] ... + ...
+#  496|                                                                                                                             0: [AddExpr] ... + ...
+#  496|                                                                                                                               0: [AddExpr] ... + ...
+#  496|                                                                                                                                 0: [AddExpr] ... + ...
+#  496|                                                                                                                                   0: [AddExpr] ... + ...
+#  496|                                                                                                                                     0: [AddExpr] ... + ...
+#  496|                                                                                                                                       0: [AddExpr] ... + ...
+#  496|                                                                                                                                         0: [AddExpr] ... + ...
+#  496|                                                                                                                                           0: [AddExpr] ... + ...
+#  496|                                                                                                                                             0: [AddExpr] ... + ...
+#  496|                                                                                                                                               0: [AddExpr] ... + ...
+#  496|                                                                                                                                                 0: [AddExpr] ... + ...
+#  496|                                                                                                                                                   0: [AddExpr] ... + ...
+#  496|                                                                                                                                                     0: [AddExpr] ... + ...
+#  496|                                                                                                                                                       0: [AddExpr] ... + ...
+#  496|                                                                                                                                                         0: [AddExpr] ... + ...
+#  496|                                                                                                                                                           0: [AddExpr] ... + ...
+#  496|                                                                                                                                                             0: [AddExpr] ... + ...
+#  496|                                                                                                                                                               0: [AddExpr] ... + ...
+#  496|                                                                                                                                                                 0: [AddExpr] ... + ...
+#  496|                                                                                                                                                                   0: [AddExpr] ... + ...
+#  496|                                                                                                                                                                     0: [AddExpr] ... + ...
+#  496|                                                                                                                                                                       0: [IntLiteral] 1
+#  496|                                                                                                                                                                       1: [IntLiteral] 1
+#  496|                                                                                                                                                                     1: [IntLiteral] 1
+#  496|                                                                                                                                                                   1: [IntLiteral] 1
+#  496|                                                                                                                                                                 1: [IntLiteral] 1
+#  496|                                                                                                                                                               1: [IntLiteral] 1
+#  496|                                                                                                                                                             1: [IntLiteral] 1
+#  496|                                                                                                                                                           1: [IntLiteral] 1
+#  496|                                                                                                                                                         1: [IntLiteral] 1
+#  496|                                                                                                                                                       1: [IntLiteral] 1
+#  496|                                                                                                                                                     1: [IntLiteral] 1
+#  496|                                                                                                                                                   1: [IntLiteral] 1
+#  496|                                                                                                                                                 1: [IntLiteral] 1
+#  496|                                                                                                                                               1: [IntLiteral] 1
+#  496|                                                                                                                                             1: [IntLiteral] 1
+#  496|                                                                                                                                           1: [IntLiteral] 1
+#  496|                                                                                                                                         1: [IntLiteral] 1
+#  496|                                                                                                                                       1: [IntLiteral] 1
+#  496|                                                                                                                                     1: [IntLiteral] 1
+#  496|                                                                                                                                   1: [IntLiteral] 1
+#  496|                                                                                                                                 1: [IntLiteral] 1
+#  496|                                                                                                                               1: [IntLiteral] 1
+#  496|                                                                                                                             1: [IntLiteral] 1
+#  496|                                                                                                                           1: [IntLiteral] 1
+#  496|                                                                                                                         1: [IntLiteral] 1
+#  496|                                                                                                                       1: [IntLiteral] 1
+#  496|                                                                                                                     1: [IntLiteral] 1
+#  496|                                                                                                                   1: [IntLiteral] 1
+#  496|                                                                                                                 1: [IntLiteral] 1
+#  496|                                                                                                               1: [IntLiteral] 1
+#  496|                                                                                                             1: [IntLiteral] 1
+#  496|                                                                                                           1: [IntLiteral] 1
+#  496|                                                                                                         1: [IntLiteral] 1
+#  496|                                                                                                       1: [IntLiteral] 1
+#  496|                                                                                                     1: [IntLiteral] 1
+#  496|                                                                                                   1: [IntLiteral] 1
+#  496|                                                                                                 1: [IntLiteral] 1
+#  496|                                                                                               1: [IntLiteral] 1
+#  496|                                                                                             1: [IntLiteral] 1
+#  496|                                                                                           1: [IntLiteral] 1
+#  497|                                                                                         1: [IntLiteral] 1
+#  497|                                                                                       1: [IntLiteral] 1
+#  497|                                                                                     1: [IntLiteral] 1
+#  497|                                                                                   1: [IntLiteral] 1
+#  497|                                                                                 1: [IntLiteral] 1
+#  497|                                                                               1: [IntLiteral] 1
+#  497|                                                                             1: [IntLiteral] 1
+#  497|                                                                           1: [IntLiteral] 1
+#  497|                                                                         1: [IntLiteral] 1
+#  497|                                                                       1: [IntLiteral] 1
+#  497|                                                                     1: [IntLiteral] 1
+#  497|                                                                   1: [IntLiteral] 1
+#  497|                                                                 1: [IntLiteral] 1
+#  497|                                                               1: [IntLiteral] 1
+#  497|                                                             1: [IntLiteral] 1
+#  497|                                                           1: [IntLiteral] 1
+#  497|                                                         1: [IntLiteral] 1
+#  497|                                                       1: [IntLiteral] 1
+#  497|                                                     1: [IntLiteral] 1
+#  497|                                                   1: [IntLiteral] 1
+#  497|                                                 1: [IntLiteral] 1
+#  497|                                               1: [IntLiteral] 1
+#  497|                                             1: [IntLiteral] 1
+#  497|                                           1: [IntLiteral] 1
+#  497|                                         1: [IntLiteral] 1
+#  497|                                       1: [IntLiteral] 1
+#  497|                                     1: [IntLiteral] 1
+#  497|                                   1: [IntLiteral] 1
+#  497|                                 1: [IntLiteral] 1
+#  497|                               1: [IntLiteral] 1
+#  497|                             1: [IntLiteral] 1
+#  497|                           1: [IntLiteral] 1
+#  497|                         1: [IntLiteral] 1
+#  497|                       1: [IntLiteral] 1
+#  497|                     1: [IntLiteral] 1
+#  497|                   1: [IntLiteral] 1
+#  497|                 1: [IntLiteral] 1
+#  497|               1: [IntLiteral] 1
+#  497|             1: [IntLiteral] 1
+#  497|           1: [IntLiteral] 1
+#  496|         1: [MemberConstantAccess] access to constant d
+#  500|   20: [Class] TupleExprs
+#  502|     5: [Method] Test
+#  503|       4: [BlockStmt] {...}
+#  504|         0: [LocalVariableDeclStmt] ... ...;
+#  504|           0: [LocalVariableDeclAndInitExpr] (Int32,String) a = ...
+#  504|             0: [DefaultValueExpr] default(...)
+#  504|               0: [TypeAccess] access to type (Int32,String)
+#  504|             1: [LocalVariableAccess] access to local variable a
+#  505|         1: [LocalVariableDeclStmt] ... ...;
+#  505|           0: [LocalVariableDeclAndInitExpr] (Boolean,Int32[],Object) b = ...
+#  505|             0: [DefaultValueExpr] default(...)
+#  505|               0: [TypeAccess] access to type (Boolean,Int32[],Object)
+#  505|             1: [LocalVariableAccess] access to local variable b
+#  506|         2: [LocalVariableDeclStmt] ... ...;
+#  506|           0: [LocalVariableDeclAndInitExpr] Type x = ...
+#  506|             0: [TypeofExpr] typeof(...)
+#  506|               0: [TypeAccess] access to type (Int32,String)
+#  506|             1: [LocalVariableAccess] access to local variable x
+#  507|         3: [LocalVariableDeclStmt] ... ...;
+#  507|           0: [LocalVariableDeclAndInitExpr] Type y = ...
+#  507|             0: [TypeofExpr] typeof(...)
+#  507|               0: [TypeAccess] access to type (Boolean,Int32[],dynamic)
+#  507|             1: [LocalVariableAccess] access to local variable y
--- a/csharp/ql/test/library-tests/expressions/QualifiableExpr.expected
+++ b/csharp/ql/test/library-tests/expressions/QualifiableExpr.expected
@@ -65,7 +65,7 @@
 | expressions.cs:377:43:377:46 | access to field name | expressions.cs:377:43:377:46 | this access |
 | expressions.cs:377:57:377:60 | access to field name | expressions.cs:377:57:377:60 | this access |
 | expressions.cs:378:57:378:68 | access to field phoneNumbers | expressions.cs:378:57:378:68 | this access |
-| expressions.cs:442:29:442:47 | call to method WriteLine | expressions.cs:442:29:442:35 | access to type Console |
-| expressions.cs:470:17:470:26 | access to field value | expressions.cs:470:17:470:20 | this access |
-| expressions.cs:475:32:475:39 | access to field value | expressions.cs:475:32:475:33 | access to parameter c1 |
-| expressions.cs:475:43:475:50 | access to field value | expressions.cs:475:43:475:44 | access to parameter c2 |
+| expressions.cs:454:29:454:47 | call to method WriteLine | expressions.cs:454:29:454:35 | access to type Console |
+| expressions.cs:482:17:482:26 | access to field value | expressions.cs:482:17:482:20 | this access |
+| expressions.cs:487:32:487:39 | access to field value | expressions.cs:487:32:487:33 | access to parameter c1 |
+| expressions.cs:487:43:487:50 | access to field value | expressions.cs:487:43:487:44 | access to parameter c2 |
--- a/csharp/ql/test/library-tests/expressions/StripCasts.expected
+++ b/csharp/ql/test/library-tests/expressions/StripCasts.expected
@@ -50,7 +50,7 @@
 | expressions.cs:334:30:334:30 | (...) ... | expressions.cs:334:30:334:30 | 8 |
 | expressions.cs:414:31:414:31 | (...) ... | expressions.cs:414:31:414:31 | 1 |
 | expressions.cs:414:39:414:39 | (...) ... | expressions.cs:414:39:414:39 | 2 |
-| expressions.cs:437:41:437:53 | (...) ... | expressions.cs:437:48:437:52 | ... + ... |
-| expressions.cs:437:48:437:48 | (...) ... | expressions.cs:437:48:437:48 | access to parameter x |
-| expressions.cs:438:52:438:56 | (...) ... | expressions.cs:438:52:438:56 | ... + ... |
-| expressions.cs:440:56:440:56 | (...) ... | expressions.cs:440:56:440:56 | access to parameter x |
+| expressions.cs:449:41:449:53 | (...) ... | expressions.cs:449:48:449:52 | ... + ... |
+| expressions.cs:449:48:449:48 | (...) ... | expressions.cs:449:48:449:48 | access to parameter x |
+| expressions.cs:450:52:450:56 | (...) ... | expressions.cs:450:52:450:56 | ... + ... |
+| expressions.cs:452:56:452:56 | (...) ... | expressions.cs:452:56:452:56 | access to parameter x |
--- a/csharp/ql/test/library-tests/expressions/Tuples1.expected
+++ b/csharp/ql/test/library-tests/expressions/Tuples1.expected
@@ -1,4 +1,4 @@
-| expressions.cs:492:29:492:41 | access to type (Int32,String) | expressions.cs:492:29:492:41 | (Int32,String) |
-| expressions.cs:493:29:493:49 | access to type (Boolean,Int32[],Object) | expressions.cs:493:29:493:49 | (Boolean,Int32[],Object) |
-| expressions.cs:494:28:494:40 | access to type (Int32,String) | expressions.cs:492:29:492:41 | (Int32,String) |
-| expressions.cs:495:28:495:49 | access to type (Boolean,Int32[],dynamic) | expressions.cs:495:28:495:49 | (Boolean,Int32[],dynamic) |
+| expressions.cs:504:29:504:41 | access to type (Int32,String) | expressions.cs:504:29:504:41 | (Int32,String) |
+| expressions.cs:505:29:505:49 | access to type (Boolean,Int32[],Object) | expressions.cs:505:29:505:49 | (Boolean,Int32[],Object) |
+| expressions.cs:506:28:506:40 | access to type (Int32,String) | expressions.cs:504:29:504:41 | (Int32,String) |
+| expressions.cs:507:28:507:49 | access to type (Boolean,Int32[],dynamic) | expressions.cs:507:28:507:49 | (Boolean,Int32[],dynamic) |
--- a/csharp/ql/test/library-tests/expressions/expressions.cs
+++ b/csharp/ql/test/library-tests/expressions/expressions.cs
@@ -432,6 +432,18 @@ namespace Expressions
        delegate int S(int x, int y);
        delegate void Unit();

+        void MultiDimensionalArrayCreations()
+        {
+            object o = new int[,] { { 1, 2 }, { 3, 4 }, { 5, 6 } };
+            o = new int[,,] { { { 1, 2, 3 }, { 4, 5, 6 } }, { { 7, 8, 9 }, { 10, 11, 12 } } };
+            o = new int[,][,]
+            {
+                { new int[,] { {1,3}, {5,7} }, new int[,] { {0,2}, {4,6}, {8,10} }, new int[,] { {11,22}, {99,88}, {0,9} } },
+                { new int[,] { {1,3}, {5,7} }, new int[,] { {0,2}, {4,6}, {8,10} }, new int[,] { {11,22}, {99,88}, {0,9} } }
+            };
+            o = new int[][,] { new int[,] { { 1, 2 } }, new int[,] { { 1, 2, 3 }, { 1, 2, 3 }, { 1, 2, 3 }, { 1, 2, 3 } } };
+        }
+
        void MainAnonymousFunctions()
        {
            Func<Int16, Byte> f1 = x => (byte)(x + 1); // Implicitly typed, expression body