C#: Extract init only accessors and custom modifiers

csharp/extractor/Semmle.Extraction.CIL/Entities/DefinitionMethod.cs

@@ -76,9 +76,10 @@ namespace Semmle.Extraction.CIL.Entities
 
                 var typeSignature = md.DecodeSignature(Cx.TypeSignatureDecoder, this);
 
-                Parameters = MakeParameters(typeSignature.ParameterTypes).ToArray();
+                var parameters = GetParameterExtractionProducts(typeSignature.ParameterTypes).ToArray();
+                Parameters = parameters.OfType<Parameter>().ToArray();
 
-                foreach (var c in Parameters)
+                foreach (var c in parameters)
                     yield return c;
 
                 foreach (var c in PopulateFlags)
@@ -95,7 +96,12 @@ namespace Semmle.Extraction.CIL.Entities
                 }
 
                 yield return Tuples.metadata_handle(this, Cx.Assembly, MetadataTokens.GetToken(handle));
-                yield return Tuples.cil_method(this, Name, declaringType, typeSignature.ReturnType);
+
+                foreach (var m in GetMethodExtractionProducts(Name, declaringType, typeSignature.ReturnType))
+                {
+                    yield return m;
+                }
+
                 yield return Tuples.cil_method_source_declaration(this, this);
                 yield return Tuples.cil_method_location(this, Cx.Assembly);
 

csharp/extractor/Semmle.Extraction.CIL/Entities/Field.cs

@@ -8,7 +8,7 @@ namespace Semmle.Extraction.CIL.Entities
     /// <summary>
     /// An entity representing a field.
     /// </summary>
-    internal abstract class Field : GenericContext, IMember
+    internal abstract class Field : GenericContext, IMember, ICustomModifierReceiver
     {
         protected Field(Context cx) : base(cx)
         {
@@ -45,7 +45,13 @@ namespace Semmle.Extraction.CIL.Entities
         {
             get
             {
-                yield return Tuples.cil_field(this, DeclaringType, Name, Type);
+                var t = Type;
+                if (t is ModifiedType mt)
+                {
+                    t = mt.Unmodified;
+                    yield return Tuples.cil_custom_modifiers(this, mt.Modifier, mt.IsRequired);
+                }
+                yield return Tuples.cil_field(this, DeclaringType, Name, t);
             }
         }
 

csharp/extractor/Semmle.Extraction.CIL/Entities/MemberReferenceMethod.cs

@@ -76,12 +76,16 @@ namespace Semmle.Extraction.CIL.Entities
 
                 var typeSignature = mr.DecodeMethodSignature(Cx.TypeSignatureDecoder, this);
 
-                Parameters = MakeParameters(typeSignature.ParameterTypes).ToArray();
+                var parameters = GetParameterExtractionProducts(typeSignature.ParameterTypes).ToArray();
-                foreach (var p in Parameters) yield return p;
+                Parameters = parameters.OfType<Parameter>().ToArray();
+                foreach (var p in parameters) yield return p;
 
                 foreach (var f in PopulateFlags) yield return f;
 
-                yield return Tuples.cil_method(this, Name, DeclaringType, typeSignature.ReturnType);
+                foreach (var m in GetMethodExtractionProducts(Name, DeclaringType, typeSignature.ReturnType))
+                {
+                    yield return m;
+                }
 
                 if (SourceDeclaration != null)
                     yield return Tuples.cil_method_source_declaration(this, SourceDeclaration);

csharp/extractor/Semmle.Extraction.CIL/Entities/Method.cs

@@ -3,14 +3,13 @@ using System.Reflection.Metadata;
 using System.Collections.Generic;
 using System.Linq;
 using System.IO;
-using Semmle.Util;
 
 namespace Semmle.Extraction.CIL.Entities
 {
     /// <summary>
     /// A method entity.
     /// </summary>
-    internal abstract class Method : TypeContainer, IMember
+    internal abstract class Method : TypeContainer, IMember, ICustomModifierReceiver
     {
         protected MethodTypeParameter[]? genericParams;
         protected GenericContext gc;
@@ -21,6 +20,8 @@ namespace Semmle.Extraction.CIL.Entities
             this.gc = gc;
         }
 
+        public ITypeSignature ReturnType => signature.ReturnType;
+
         public override IEnumerable<Type> TypeParameters => gc.TypeParameters.Concat(DeclaringType.TypeParameters);
 
         public override IEnumerable<Type> MethodParameters =>
@@ -76,7 +77,7 @@ namespace Semmle.Extraction.CIL.Entities
 
         public abstract bool IsStatic { get; }
 
-        protected IEnumerable<Parameter> MakeParameters(IEnumerable<Type> parameterTypes)
+        protected IEnumerable<IExtractionProduct> GetParameterExtractionProducts(IEnumerable<Type> parameterTypes)
         {
             var i = 0;
 
@@ -86,7 +87,26 @@ namespace Semmle.Extraction.CIL.Entities
             }
 
             foreach (var p in parameterTypes)
-                yield return Cx.Populate(new Parameter(Cx, this, i++, p));
+            {
+                var t = p;
+                if (t is ModifiedType mt)
+                {
+                    t = mt.Unmodified;
+                    yield return Tuples.cil_custom_modifiers(this, mt.Modifier, mt.IsRequired);
+                }
+                yield return Cx.Populate(new Parameter(Cx, this, i++, t));
+            }
+        }
+
+        protected IEnumerable<IExtractionProduct> GetMethodExtractionProducts(string name, Type declaringType, Type returnType)
+        {
+            var t = returnType;
+            if (t is ModifiedType mt)
+            {
+                t = mt.Unmodified;
+                yield return Tuples.cil_custom_modifiers(this, mt.Modifier, mt.IsRequired);
+            }
+            yield return Tuples.cil_method(this, name, declaringType, t);
         }
     }
 }

csharp/extractor/Semmle.Extraction.CIL/Entities/MethodSpecificationMethod.cs

@@ -77,14 +77,19 @@ namespace Semmle.Extraction.CIL.Entities
                         throw new InternalError($"Unexpected constructed method handle kind {ms.Method.Kind}");
                 }
 
-                Parameters = MakeParameters(constructedTypeSignature.ParameterTypes).ToArray();
+                var parameters = GetParameterExtractionProducts(constructedTypeSignature.ParameterTypes).ToArray();
-                foreach (var p in Parameters)
+                Parameters = parameters.OfType<Parameter>().ToArray();
+                foreach (var p in parameters)
                     yield return p;
 
                 foreach (var f in PopulateFlags)
                     yield return f;
 
-                yield return Tuples.cil_method(this, Name, DeclaringType, constructedTypeSignature.ReturnType);
+                foreach (var m in GetMethodExtractionProducts(Name, DeclaringType, constructedTypeSignature.ReturnType))
+                {
+                    yield return m;
+                }
+
                 yield return Tuples.cil_method_source_declaration(this, SourceDeclaration);
 
                 if (typeParams.Length != unboundMethod.GenericParameterCount)

csharp/extractor/Semmle.Extraction.CIL/Entities/ModifiedType.cs

@@ -0,0 +1,49 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+
+namespace Semmle.Extraction.CIL.Entities
+{
+    /// <summary>
+    /// Modified types are not written directly to trap files. Instead, the modifiers are stored
+    /// on the modifiable entity (field type, property/method/function pointer parameter or return types).
+    /// </summary>
+    internal sealed class ModifiedType : Type
+    {
+        public ModifiedType(Context cx, Type unmodified, Type modifier, bool isRequired) : base(cx)
+        {
+            Unmodified = unmodified;
+            Modifier = modifier;
+            IsRequired = isRequired;
+        }
+
+        public Type Unmodified { get; }
+        public Type Modifier { get; }
+        public bool IsRequired { get; }
+
+        public override CilTypeKind Kind => throw new NotImplementedException();
+
+        public override Namespace? ContainingNamespace => throw new NotImplementedException();
+
+        public override Type? ContainingType => throw new NotImplementedException();
+
+        public override IEnumerable<Type> TypeParameters => throw new NotImplementedException();
+
+        public override int ThisTypeParameterCount => throw new NotImplementedException();
+
+        public override Type Construct(IEnumerable<Type> typeArguments) => throw new NotImplementedException();
+
+        public override string Name => Unmodified.Name + (IsRequired ? " modreq" : " modopt") + $"({Modifier.Name})";
+
+        public override void WriteAssemblyPrefix(TextWriter trapFile) => Unmodified.WriteAssemblyPrefix(trapFile);
+
+        public override void WriteId(TextWriter trapFile, bool inContext)
+        {
+            Unmodified.WriteId(trapFile, inContext);
+            trapFile.Write(IsRequired ? " modreq" : " modopt");
+            trapFile.Write("(");
+            Modifier.WriteId(trapFile, inContext);
+            trapFile.Write(")");
+        }
+    }
+}

csharp/extractor/Semmle.Extraction.CIL/Entities/Property.cs

@@ -8,7 +8,7 @@ namespace Semmle.Extraction.CIL.Entities
     /// <summary>
     /// A property.
     /// </summary>
-    internal sealed class Property : LabelledEntity
+    internal sealed class Property : LabelledEntity, ICustomModifierReceiver
     {
         private readonly Handle handle;
         private readonly Type type;
@@ -54,7 +54,15 @@ namespace Semmle.Extraction.CIL.Entities
                 yield return Tuples.metadata_handle(this, Cx.Assembly, MetadataTokens.GetToken(handle));
                 var sig = pd.DecodeSignature(Cx.TypeSignatureDecoder, type);
 
-                yield return Tuples.cil_property(this, type, Cx.ShortName(pd.Name), sig.ReturnType);
+                var name = Cx.ShortName(pd.Name);
+
+                var t = sig.ReturnType;
+                if (t is ModifiedType mt)
+                {
+                    t = mt.Unmodified;
+                    yield return Tuples.cil_custom_modifiers(this, mt.Modifier, mt.IsRequired);
+                }
+                yield return Tuples.cil_property(this, type, name, t);
 
                 var accessors = pd.GetAccessors();
                 if (!accessors.Getter.IsNil)

csharp/extractor/Semmle.Extraction.CIL/Entities/SignatureDecoder.cs

@@ -1,6 +1,7 @@
 using System.Reflection.Metadata;
 using System.Collections.Immutable;
 using System.IO;
+using System.Linq;
 
 namespace Semmle.Extraction.CIL.Entities
 {
@@ -138,21 +139,28 @@ namespace Semmle.Extraction.CIL.Entities
         private class Modified : ITypeSignature
         {
             private readonly ITypeSignature unmodifiedType;
+            private readonly ITypeSignature modifier;
+            private readonly bool isRequired;
 
-            public Modified(ITypeSignature unmodifiedType)
+            public Modified(ITypeSignature unmodifiedType, ITypeSignature modifier, bool isRequired)
             {
                 this.unmodifiedType = unmodifiedType;
+                this.modifier = modifier;
+                this.isRequired = isRequired;
             }
 
             public void WriteId(TextWriter trapFile, GenericContext gc)
             {
                 unmodifiedType.WriteId(trapFile, gc);
+                trapFile.Write(isRequired ? " modreq(" : " modopt(");
+                modifier.WriteId(trapFile, gc);
+                trapFile.Write(")");
             }
         }
 
         ITypeSignature ISignatureTypeProvider<ITypeSignature, object>.GetModifiedType(ITypeSignature modifier, ITypeSignature unmodifiedType, bool isRequired)
         {
-            return new Modified(unmodifiedType);
+            return new Modified(unmodifiedType, modifier, isRequired);
         }
 
         private class Pinned : ITypeSignature

csharp/extractor/Semmle.Extraction.CIL/Entities/TypeSignatureDecoder.cs

@@ -35,7 +35,7 @@ namespace Semmle.Extraction.CIL.Entities
             genericContext.GetGenericTypeParameter(index);
 
         Type ISignatureTypeProvider<Type, GenericContext>.GetModifiedType(Type modifier, Type unmodifiedType, bool isRequired) =>
-            unmodifiedType; // !! Not implemented properly
+            new ModifiedType(cx, unmodifiedType, modifier, isRequired);
 
         Type ISignatureTypeProvider<Type, GenericContext>.GetPinnedType(Type elementType) =>
             cx.Populate(new PointerType(cx, elementType));

csharp/extractor/Semmle.Extraction.CIL/ICustomModifierReceiver.cs

@@ -0,0 +1,6 @@
+namespace Semmle.Extraction.CIL
+{
+    internal interface ICustomModifierReceiver
+    {
+    }
+}

csharp/extractor/Semmle.Extraction.CIL/Tuples.cs

@@ -188,6 +188,9 @@ namespace Semmle.Extraction.CIL
         internal static Tuple cil_virtual(Method method) =>
             new Tuple("cil_virtual", method);
 
+        internal static Tuple cil_custom_modifiers(ICustomModifierReceiver receiver, Type modifier, bool isRequired) =>
+            new Tuple("cil_custom_modifiers", receiver, modifier, isRequired ? 1 : 0);
+
         internal static Tuple containerparent(Folder parent, IFileOrFolder child) =>
             new Tuple("containerparent", parent, child);
 

csharp/ql/src/semmle/code/cil/Method.qll

@@ -247,8 +247,12 @@ class Setter extends Accessor {
 
   override Property getProperty() { cil_setter(result, this) }
 
-  /** Holds if this setter is an `init`-only accessor. */
+  /** Holds if this setter is an `init` accessor. */
-  predicate isInitOnly() { none() }
+  predicate isInitOnly() {
+    exists(Type t | t.getQualifiedName() = "System.Runtime.CompilerServices.IsExternalInit" |
+      cil_custom_modifiers(this, t, 1)
+    )
+  }
 }
 
 /**

csharp/ql/src/semmlecode.csharp.dbscheme

@@ -1712,6 +1712,7 @@ cil_field(
 @cil_variable = @cil_field | @cil_stack_variable;
 @cil_stack_variable = @cil_local_variable | @cil_parameter;
 @cil_member = @cil_method | @cil_type | @cil_field | @cil_property | @cil_event;
+@cil_custom_modifier_receiver = @cil_method | @cil_property | @cil_parameter | @cil_field; // todo: add function pointer type
 
 #keyset[method, index]
 cil_parameter(
@@ -1726,6 +1727,12 @@ cil_parameter_out(unique int id: @cil_parameter ref);
 cil_setter(unique int prop: @cil_property ref,
   int method: @cil_method ref);
 
+#keyset[id, modifier]
+cil_custom_modifiers(
+  int id: @cil_custom_modifier_receiver ref,
+  int modifier: @cil_type ref,
+  int kind: int ref); // modreq: 1, modopt: 0
+
 cil_getter(unique int prop: @cil_property ref,
   int method: @cil_method ref);
 

csharp/ql/test/library-tests/cil/init-only-prop/setters.expected

@@ -1,2 +1,2 @@
 | cil-init-prop.dll:0:0:0:0 | set_Prop1 | set |
-| cil-init-prop.dll:0:0:0:0 | set_Prop2 | set |
+| cil-init-prop.dll:0:0:0:0 | set_Prop2 | init |