PublicApiGenerator · sungam3r · Jan 11, 2025 · Jan 8, 2025 · Jan 11, 2025 · Jan 11, 2025
diff --git a/src/PublicApiGenerator/DynamicContext.cs b/src/PublicApiGenerator/DynamicContext.cs
@@ -0,0 +1,41 @@
+using System.CodeDom;
+
+namespace PublicApiGenerator;
+
+internal sealed class DynamicContext
+{
+    private readonly bool[]? _transformFlags;
+    private int _index;
+
+    public DynamicContext(CodeAttributeDeclarationCollection attributes)
+    {
+        for (int i = 0; i < attributes.Count; ++i)
+        {
+            var attribute = attributes[i];
+            // return: System.Runtime.CompilerServices.DynamicAttribute is a workaround for CecilEx.MakeReturn.
+            if (attribute.Name == "System.Runtime.CompilerServices.DynamicAttribute" || attribute.Name == "return: System.Runtime.CompilerServices.DynamicAttribute")
+            {
+                if (attribute.Arguments.Count > 0)
+                {
+                    // https://learn.microsoft.com/en-us/dotnet/api/system.runtime.compilerservices.dynamicattribute.-ctor
+                    var expression = (CodeArrayCreateExpression)attribute.Arguments[0].Value;
+                    _transformFlags = new bool[expression.Initializers.Count];
+                    for (int j = 0; j < _transformFlags.Length; ++j)
+                    {
+                        _transformFlags[j] = (bool)((CodePrimitiveExpression)expression.Initializers[j]).Value;
+                    }
+                }
+                else
+                {
+                    _transformFlags = [];
+                }
+
+                break;
+            }
+        }
+    }
+
+    public void Move() => ++_index;
+
+    public bool IsDynamic => _transformFlags != null && (_transformFlags.Length == 0 || _transformFlags[_index]);
+}
diff --git a/src/PublicApiGenerator/System.CodeDom/CSharpCodeGenerator.cs b/src/PublicApiGenerator/System.CodeDom/CSharpCodeGenerator.cs
@@ -1,4 +1,4 @@
-// Licensed to the .NET Foundation under one or more agreements.
+// Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
 #pragma warning disable
@@ -216,7 +216,7 @@
 
         private void OutputIdentifier(string ident) => Output.Write(CreateEscapedIdentifier(ident));
 
-        private void OutputType(CodeTypeReference typeRef) => Output.Write(GetTypeOutput(typeRef));
+        private void OutputType(CodeTypeReference typeRef, DynamicContext dynamicContext = null) => Output.Write(GetTypeOutput(typeRef, dynamicContext));
 
         private void GenerateArrayCreateExpression(CodeArrayCreateExpression e)
         {
@@ -1305,7 +1305,7 @@
             }
 
             OutputDirection(e.Direction);
-            OutputTypeNamePair(e.Type, e.Name);
+            OutputTypeNamePair(e.Type, e.Name, new DynamicContext(e.CustomAttributes));
         }
 
         private void GenerateEntryPointMethod(CodeEntryPointMethod e)
@@ -1390,7 +1390,7 @@
                 // interfaces still need "new"
                 OutputVTableModifier(e.Attributes);
             }
-            OutputType(e.ReturnType);
+            OutputType(e.ReturnType, new DynamicContext(e.ReturnTypeCustomAttributes));
             Output.Write(' ');
             if (e.PrivateImplementationType != null)
             {
@@ -1989,7 +1989,7 @@
 
                 CodeTypeDelegate del = (CodeTypeDelegate)e;
                 Output.Write("delegate ");
-                OutputType(del.ReturnType);
+                OutputType(del.ReturnType, new DynamicContext(del.CustomAttributes));
                 Output.Write(' ');
                 OutputIdentifier(e.Name);
                 Output.Write('(');
@@ -2004,6 +2004,7 @@
                 OutputTypeParameters(e.TypeParameters);
 
                 bool first = true;
+                var dynamicContext = new DynamicContext(e.CustomAttributes);
                 foreach (CodeTypeReference typeRef in e.BaseTypes)
                 {
                     if (first)
@@ -2015,7 +2016,7 @@
                     {
                         Output.Write(", ");
                     }
-                    OutputType(typeRef);
+                    OutputType(typeRef, dynamicContext);
                 }
 
                 OutputTypeParameterConstraints(e.TypeParameters);
@@ -2309,9 +2310,9 @@
             }
         }
 
-        private void OutputTypeNamePair(CodeTypeReference typeRef, string name)
+        private void OutputTypeNamePair(CodeTypeReference typeRef, string name, DynamicContext dynamicContext = null)
         {
-            OutputType(typeRef);
+            OutputType(typeRef, dynamicContext);
             Output.Write(' ');
             OutputIdentifier(name);
         }
@@ -2687,6 +2688,13 @@
                     continue;
                 }
 
+                // Do not print DynamicAttribute, use dynamic keyword instead of object.
+                // return: System.Runtime.CompilerServices.DynamicAttribute is a workaround for CecilEx.MakeReturn.
+                if (current.Name.Equals("System.Runtime.CompilerServices.DynamicAttribute") || current.Name.Equals("return: System.Runtime.CompilerServices.DynamicAttribute"))
+                {
+                    continue;
+                }
+
                 GenerateAttributeDeclarationsStart();
                 if (prefix != null)
                 {
@@ -2825,7 +2833,7 @@
         }
 
         // returns the type name without any array declaration.
-        private string GetBaseTypeOutput(CodeTypeReference typeRef, bool preferBuiltInTypes = true)
+        private string GetBaseTypeOutput(CodeTypeReference typeRef, bool preferBuiltInTypes = true, DynamicContext dynamicContext = null)
         {
             string s = typeRef.BaseType;
 
@@ -2849,7 +2857,9 @@
                     case "system.string":
                         return "string";
                     case "system.object":
-                        return "object";
+                        return dynamicContext?.IsDynamic == true ? "dynamic" : "object";
+                    case "object?":
+                        return dynamicContext?.IsDynamic == true ? "dynamic?" : "object?";
                     case "system.boolean":
                         return "bool";
                     case "system.void":
@@ -2909,7 +2919,7 @@
                             i++;
                         }
 
-                        GetTypeArgumentsOutput(typeRef.TypeArguments, currentTypeArgStart, numTypeArgs, sb);
+                        GetTypeArgumentsOutput(typeRef.TypeArguments, currentTypeArgStart, numTypeArgs, sb, dynamicContext);
                         currentTypeArgStart += numTypeArgs;
 
                         // Arity can be in the middle of a nested type name, so we might have a . or + after it.
@@ -2934,11 +2944,11 @@
         private string GetTypeArgumentsOutput(CodeTypeReferenceCollection typeArguments)
         {
             var sb = new StringBuilder(128);
-            GetTypeArgumentsOutput(typeArguments, 0, typeArguments.Count, sb);
+            GetTypeArgumentsOutput(typeArguments, 0, typeArguments.Count, sb, null);
             return sb.ToString();
         }
 
-        private void GetTypeArgumentsOutput(CodeTypeReferenceCollection typeArguments, int start, int length, StringBuilder sb)
+        private void GetTypeArgumentsOutput(CodeTypeReferenceCollection typeArguments, int start, int length, StringBuilder sb, DynamicContext dynamicContext)
         {
             sb.Append('<');
             bool first = true;
@@ -2956,12 +2966,17 @@
                 // it's possible that we call GetTypeArgumentsOutput with an empty typeArguments collection.  This is the case
                 // for open types, so we want to just output the brackets and commas.
                 if (i < typeArguments.Count)
-                    sb.Append(GetTypeOutput(typeArguments[i]));
+                {
+                    dynamicContext?.Move();
+                    sb.Append(GetTypeOutput(typeArguments[i], dynamicContext));
+                }
             }
             sb.Append('>');
         }
 
-        public string GetTypeOutput(CodeTypeReference typeRef)
+        public string GetTypeOutput(CodeTypeReference typeRef) => GetTypeOutput(typeRef, null);
+
+        public string GetTypeOutput(CodeTypeReference typeRef, DynamicContext dynamicContext)
         {
             string s = string.Empty;
 
@@ -2970,7 +2985,7 @@
             {
                 baseTypeRef = baseTypeRef.ArrayElementType;
             }
-            s += GetBaseTypeOutput(baseTypeRef);
+            s += GetBaseTypeOutput(baseTypeRef, dynamicContext: dynamicContext);
 
             while (typeRef != null && typeRef.ArrayRank > 0)
             {
@@ -3182,4 +3197,4 @@
             }
         }
     }
-}
+}
diff --git a/src/PublicApiGeneratorTests/Delegate_types.cs b/src/PublicApiGeneratorTests/Delegate_types.cs
@@ -4,6 +4,16 @@ namespace PublicApiGeneratorTests
 {
     public class Delegate_types : ApiGeneratorTestsBase
     {
+        [Fact]
+        public void Should_output_dynamic_delegate()
+        {
+            AssertPublicApi<DynamicDelegate>(
+@"namespace PublicApiGeneratorTests.Examples
+{
+    public delegate dynamic DynamicDelegate(dynamic v);
+}");
+        }
+
         [Fact]
         public void Should_output_void_delegate()
         {
@@ -57,6 +67,7 @@ public void Should_output_generic_type_parameters()
 
     namespace Examples
     {
+        public delegate dynamic DynamicDelegate(dynamic v);
         public delegate void VoidDelegate();
         public delegate int DelegateWithPrimitiveParameters(int v1, string v2);
         public delegate ComplexType DelegateWithComplexParameters(ComplexType v1);

diff --git a/src/PublicApiGeneratorTests/Dynamics.cs b/src/PublicApiGeneratorTests/Dynamics.cs
@@ -4,24 +4,33 @@ namespace PublicApiGeneratorTests
 {
     public class Dynamics : ApiGeneratorTestsBase
     {
-        [Fact(Skip = "Needs investigation")]
+        [Fact]
         public void Should_output_dynamic()
         {
             AssertPublicApi<ClassWithDynamic>(
 @"namespace PublicApiGeneratorTests.Examples
 {
     public class ClassWithDynamic : System.Collections.Generic.List<dynamic>
     {
-        public class ClassWithDynamic2 : System.Collections.Generic.List<dynamic?> { }
         public ClassWithDynamic() { }
         public dynamic DoIt1(dynamic p) { }
         public dynamic? DoIt2(dynamic? p) { }
+        public System.Collections.Generic.Dictionary<dynamic, object> DoIt3(System.Collections.Generic.Dictionary<dynamic, object>? p) { }
+        public class ClassWithDynamic2 : System.Collections.Generic.List<dynamic?>
+        {
+            public ClassWithDynamic2() { }
+        }
+        public class ClassWithDynamic3 : System.Collections.Generic.Dictionary<dynamic, object>
+        {
+            public ClassWithDynamic3() { }
+        }
+        public class ClassWithDynamic4 : System.Collections.Generic.Dictionary<object, dynamic>
+        {
+            public ClassWithDynamic4() { }
+        }
     }
 }");
         }
-
-        // TODO: Enum with flags + undefined value
-        // Not supported by Cecil?
     }
 
     namespace Examples
@@ -30,9 +39,15 @@ public class ClassWithDynamic : List<dynamic>
         {
             public class ClassWithDynamic2 : List<dynamic?> { }
 
+            public class ClassWithDynamic3 : Dictionary<dynamic, object> { }
+
+            public class ClassWithDynamic4 : Dictionary<object, dynamic> { }
+
             public dynamic DoIt1(dynamic p) { throw null; }
 
             public dynamic? DoIt2(dynamic? p) { throw null; }
+
+            public Dictionary<dynamic, object> DoIt3(Dictionary<dynamic, object>? p) { throw null; }
         }
     }
 }