github · hvitved · Aug 28, 2020 · Aug 19, 2020 · Aug 25, 2020 · Aug 27, 2020
@@ -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;

@@ -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 @@ public Entities.Type ErrorType
         /// </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 @@ public GenericContext(Context cx)
         }
 
         /// <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; }
 

@@ -47,9 +47,9 @@ public override void WriteId(TextWriter trapFile)
             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 @@ public override IEnumerable<IExtractionProduct> Contents
             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 @@ public override IEnumerable<IExtractionProduct> Contents
 
                 foreach (var handle in cx.mdReader.TypeDefinitions)
                 {
-                    IExtractionProduct product = null;
+                    IExtractionProduct? product = null;
                     try
                     {
                         product = cx.Create(handle);
@@ -92,7 +92,7 @@ public override IEnumerable<IExtractionProduct> Contents
 
                 foreach (var handle in cx.mdReader.MethodDefinitions)
                 {
-                    IExtractionProduct product = null;
+                    IExtractionProduct? product = null;
                     try
                     {
                         product = cx.Create(handle);

@@ -27,7 +27,7 @@ public Attribute(Context cx, IEntity @object, CustomAttributeHandle handle) : ba
             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 @@ public override IEnumerable<IExtractionProduct> Contents
                 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");
                 }
             }
         }

@@ -36,7 +36,7 @@ public override void WriteId(TextWriter trapFile)
 
         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);
         }

@@ -30,7 +30,7 @@ public override IEnumerable<IExtractionProduct> Contents
         {
             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 @@ public override IEnumerable<IExtractionProduct> Contents
 
                 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");
 

@@ -91,7 +91,7 @@ public DefinitionField(GenericContext gc, FieldDefinitionHandle handle) : base(g
             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 @@ public MemberReferenceField(GenericContext gc, MemberReferenceHandle handle) : b
             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);
         }

@@ -25,9 +25,9 @@ public override void WriteId(TextWriter trapFile)
             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 @@ public override IEnumerable<IExtractionProduct> Contents
         {
             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));

@@ -41,7 +41,7 @@ public override IEnumerable<IExtractionProduct> Contents
             }
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             return obj is Folder folder && path == folder.path;
         }

@@ -365,6 +365,11 @@ public override IEnumerable<IExtractionProduct> Contents
             {
                 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 @@ public override IEnumerable<IExtractionProduct> Contents
                         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 @@ public override IEnumerable<IExtractionProduct> Contents
         public IEnumerable<IExtractionProduct> JumpContents(Dictionary<int, IInstruction> jump_table)
         {
             int target;
-            IInstruction inst;
+            IInstruction? inst;
 
             switch (PayloadType)
             {
-Original file line number
+Diff line change
@@ Expand Up / @@ -41,7 +41,7 @@ public override IEnumerable<IExtractionProduct> Contents @@
                 }
             }
-            public override bool Equals(object obj)
+            public override bool Equals(object? obj)
             {
                 return obj is Folder folder && path == folder.path;
             }
@@ Expand Down @@