src/ObjCBindings/BindFromAttribute.cs

@@ -0,0 +1,35 @@
+using System;
+using System.Reflection;
+using System.Diagnostics.CodeAnalysis;
+using ObjCRuntime;
+
+#nullable enable
+
+namespace ObjCBindings {
+
+	/// <summary>
+	/// Attribute to bind from a specific type.
+	/// </summary>
+	[Experimental ("APL0003")]
+	[AttributeUsage (AttributeTargets.ReturnValue | AttributeTargets.Property | AttributeTargets.Parameter, AllowMultiple = false)]
+	public class BindFromAttribute : Attribute {
+
+		/// <summary>
+		/// Initializes a new instance of the <see cref="BindFromAttribute"/> class.
+		/// </summary>
+		public BindFromAttribute (Type type)
+		{
+			Type = type;
+		}
+
+		/// <summary>
+		/// The type to bind from.
+		/// </summary>
+		public Type Type { get; set; }
+
+		/// <summary>
+		/// The original type that was bound from.
+		/// </summary>
+		public Type? OriginalType { get; set; } = null;
+	}
+}

src/frameworks.sources

@@ -1935,6 +1935,7 @@ SHARED_CORE_SOURCES = \
 	DotNetGlobals.cs \
 	MinimumVersions.cs \
 	MonoPInvokeCallbackAttribute.cs \
+	ObjCBindings/BindFromAttribute.cs \
 	ObjCBindings/BindingTypeAttribute.cs \
 	ObjCBindings/BindingTypeTag.cs \
 	ObjCBindings/ExportAttribute.cs \

src/rgen/Microsoft.Macios.Bindings.Analyzer/Microsoft.Macios.Bindings.Analyzer.csproj

@@ -39,6 +39,9 @@
         <Compile Include="../Microsoft.Macios.Generator/DictionaryComparer.cs" >
             <Link>Generator/DictionaryComparer.cs</Link>
         </Compile>
+        <Compile Include="../Microsoft.Macios.Generator/Attributes/BindFromData.cs" >
+            <Link>Generator/Attributes/BindFromData.cs</Link>
+        </Compile>
         <Compile Include="../Microsoft.Macios.Generator/Attributes/FieldData.cs" >
             <Link>Generator/Attributes/FieldData.cs</Link>
         </Compile>

src/rgen/Microsoft.Macios.Generator/Attributes/BindFromData.cs

@@ -0,0 +1,98 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using System;
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.CodeAnalysis;
+
+namespace Microsoft.Macios.Generator.Attributes;
+
+readonly struct BindFromData : IEquatable<BindFromData> {
+
+	public string Type { get; }
+	public string? OriginalType { get; }
+
+	public BindFromData (string type)
+	{
+		Type = type;
+	}
+
+	public BindFromData (string type, string? originalType)
+	{
+		Type = type;
+		OriginalType = originalType;
+	}
+
+
+	public static bool TryParse (AttributeData attributeData,
+		[NotNullWhen (true)] out BindFromData? data)
+	{
+		data = null;
+		var count = attributeData.ConstructorArguments.Length;
+		string? type;
+		string? originalType = null;
+
+		switch (count) {
+		case 1:
+			type = ((INamedTypeSymbol) attributeData.ConstructorArguments [0].Value!).ToDisplayString ();
+			break;
+		default:
+			// no other constructors are available
+			return false;
+		}
+
+		if (attributeData.NamedArguments.Length == 0) {
+			data = new (type);
+			return true;
+		}
+
+		foreach (var (name, value) in attributeData.NamedArguments) {
+			switch (name) {
+			case "Type":
+				type = ((INamedTypeSymbol) value.Value!).ToDisplayString ();
+				break;
+			case "OriginalType":
+				originalType = ((INamedTypeSymbol) value.Value!).ToDisplayString ();
+				break;
+			default:
+				data = null;
+				return false;
+			}
+		}
+		data = new (type, originalType);
+		return true;
+	}
+
+	/// <inheritdoc />
+	public bool Equals (BindFromData other)
+	{
+		return Type == other.Type && OriginalType == other.OriginalType;
+	}
+
+	/// <inheritdoc />
+	public override bool Equals (object? obj)
+	{
+		return obj is BindFromData other && Equals (other);
+	}
+
+	/// <inheritdoc />
+	public override int GetHashCode ()
+	{
+		return HashCode.Combine (Type, OriginalType);
+	}
+
+	public static bool operator == (BindFromData x, BindFromData y)
+	{
+		return x.Equals (y);
+	}
+
+	public static bool operator != (BindFromData x, BindFromData y)
+	{
+		return !(x == y);
+	}
+
+	public override string ToString ()
+	{
+		return $"{{ Type: '{Type}', OriginalType: '{OriginalType ?? "null"}' }}";
+	}
+}

src/rgen/Microsoft.Macios.Generator/Attributes/FieldData.cs

@@ -137,6 +137,6 @@ public override int GetHashCode ()
 	/// <inheritdoc />
 	public override string ToString ()
 	{
-		return $"{{ SymbolName: '{SymbolName}' LibraryName: '{LibraryName ?? "null"}', Flags: '{Flags}' }}";
+		return $"{{ SymbolName: '{SymbolName}', LibraryName: '{LibraryName ?? "null"}', Flags: '{Flags}' }}";
 	}
 }

src/rgen/Microsoft.Macios.Generator/AttributesNames.cs

@@ -12,6 +12,7 @@ static class AttributesNames {
 	public const string BindingAttribute = "ObjCBindings.BindingTypeAttribute";
 	public const string BindingCategoryAttribute = "ObjCBindings.BindingTypeAttribute<ObjCBindings.Category>";
 	public const string BindingClassAttribute = "ObjCBindings.BindingTypeAttribute<ObjCBindings.Class>";
+	public const string BindFromAttribute = "ObjCBindings.BindFromAttribute";
 	public const string BindingProtocolAttribute = "ObjCBindings.BindingTypeAttribute<ObjCBindings.Protocol>";
 	public const string BindingStrongDictionaryAttribute = "ObjCBindings.BindingTypeAttribute<ObjCBindings.StrongDictionary>";
 	public const string FieldAttribute = "ObjCBindings.FieldAttribute";

src/rgen/Microsoft.Macios.Generator/DataModel/Accessor.Generator.cs

@@ -2,8 +2,6 @@
 // Licensed under the MIT License.
 
 using System.Collections.Immutable;
-using System.Linq;
-using System.Text;
 using Microsoft.CodeAnalysis;
 using Microsoft.Macios.Generator.Attributes;
 using Microsoft.Macios.Generator.Availability;
@@ -17,9 +15,6 @@ readonly partial struct Accessor {
 	/// </summary>
 	public ExportData<ObjCBindings.Property>? ExportPropertyData { get; init; }
 
-	/// <summary>
-	/// State if we should marshal native exceptions when generating the accessor.
-	/// </summary>
 	public bool MarshalNativeExceptions
 		=> ExportPropertyData is not null && ExportPropertyData.Value.Flags.HasFlag (ObjCBindings.Property.MarshalNativeExceptions);
 
@@ -77,16 +72,4 @@ public Accessor (AccessorKind accessorKind,
 	public bool ShouldMarshalNativeExceptions (in Property property)
 		=> MarshalNativeExceptions || property.MarshalNativeExceptions;
 
-	/// <inheritdoc />
-	public override string ToString ()
-	{
-		var sb = new StringBuilder ($"{{ Kind: {Kind}, ");
-		sb.Append ($"Supported Platforms: {SymbolAvailability}, ");
-		sb.Append ($"ExportData: {ExportPropertyData?.ToString () ?? "null"} Modifiers: [");
-		sb.AppendJoin (",", Modifiers.Select (x => x.Text));
-		sb.Append ("], Attributes: [");
-		sb.AppendJoin (", ", Attributes);
-		sb.Append ("] }");
-		return sb.ToString ();
-	}
 }

src/rgen/Microsoft.Macios.Generator/DataModel/Accessor.cs

@@ -25,7 +25,7 @@ namespace Microsoft.Macios.Generator.DataModel;
 	/// <summary>
 	/// List of attribute code changes of the accessor.
 	/// </summary>
-	public ImmutableArray<AttributeCodeChange> Attributes { get; } = [];
+	public ImmutableArray<AttributeCodeChange> Attributes { get; }
 
 	/// <summary>
 	/// List of modifiers of the accessor.
@@ -70,4 +70,15 @@ public override int GetHashCode ()
 	{
 		return !left.Equals (right);
 	}
+
+	/// <inheritdoc />
+	public override string ToString ()
+	{
+		var sb = new StringBuilder ($"{{ Kind: {Kind}, Supported Platforms: {SymbolAvailability}, ExportData: {ExportPropertyData?.ToString () ?? "null"} Modifiers: [");
+		sb.AppendJoin (",", Modifiers.Select (x => x.Text));
+		sb.Append ("], Attributes: [");
+		sb.AppendJoin (", ", Attributes);
+		sb.Append ("] }");
+		return sb.ToString ();
+	}
 }

src/rgen/Microsoft.Macios.Generator/DataModel/Method.Generator.cs

@@ -20,6 +20,11 @@ readonly partial struct Method {
 	/// </summary>
 	public ExportData<ObjCBindings.Method> ExportMethodData { get; }
 
+	/// <summary>
+	/// Returns the bind from data if present in the binding.
+	/// </summary>
+	public BindFromData? BindAs { get; init; }
+
 	/// <summary>
 	/// Returns if the method was marked as thread safe.
 	/// </summary>
@@ -79,7 +84,9 @@ public static bool TryCreate (MethodDeclarationSyntax declaration, RootBindingCo
 			exportMethodData: exportData,
 			attributes: attributes,
 			modifiers: [.. declaration.Modifiers],
-			parameters: parametersBucket.ToImmutableArray ());
+			parameters: parametersBucket.ToImmutableArray ()) {
+			BindAs = method.GetBindFromData (),
+		};
 
 		return true;
 	}

src/rgen/Microsoft.Macios.Generator/DataModel/Method.cs

@@ -61,6 +61,8 @@ public bool Equals (Method other)
 			return false;
 		if (ExportMethodData != other.ExportMethodData)
 			return false;
+		if (BindAs != other.BindAs)
+			return false;
 
 		var attrsComparer = new AttributesEqualityComparer ();
 		if (!attrsComparer.Equals (Attributes, other.Attributes))
@@ -86,6 +88,7 @@ public override int GetHashCode ()
 		hashCode.Add (Type);
 		hashCode.Add (Name);
 		hashCode.Add (ReturnType);
+		hashCode.Add (BindAs);
 		foreach (var modifier in Modifiers) {
 			hashCode.Add (modifier);
 		}
@@ -119,6 +122,7 @@ public override string ToString ()
 		sb.Append ($"ReturnType: {ReturnType}, ");
 		sb.Append ($"SymbolAvailability: {SymbolAvailability}, ");
 		sb.Append ($"ExportMethodData: {ExportMethodData}, ");
+		sb.Append ($"BindAs: {BindAs}, ");
 		sb.Append ("Attributes: [");
 		sb.AppendJoin (", ", Attributes);
 		sb.Append ("], Modifiers: [");

src/rgen/Microsoft.Macios.Generator/DataModel/Parameter.Generator.cs

@@ -4,6 +4,7 @@
 using System.Diagnostics.CodeAnalysis;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.Macios.Generator.Attributes;
 using Microsoft.Macios.Generator.Extensions;
 
 namespace Microsoft.Macios.Generator.DataModel;
@@ -19,7 +20,12 @@ public enum VariableType {
 		PrimitivePointer,
 		StringPointer,
 	}
-
+
+	/// <summary>
+	/// Returns the bind from data if present in the binding.
+	/// </summary>
+	public BindFromData? BindAs { get; init; }
+
 	public static bool TryCreate (IParameterSymbol symbol, ParameterSyntax declaration, SemanticModel semanticModel,
 		[NotNullWhen (true)] out Parameter? parameter)
 	{
@@ -30,6 +36,7 @@ public static bool TryCreate (IParameterSymbol symbol, ParameterSyntax declarati
 		}
 
 		parameter = new (symbol.Ordinal, new (symbol.Type), symbol.Name) {
+			BindAs = symbol.GetBindFromData (),
 			IsOptional = symbol.IsOptional,
 			IsParams = symbol.IsParams,
 			IsThis = symbol.IsThis,

src/rgen/Microsoft.Macios.Generator/DataModel/Parameter.cs

@@ -78,7 +78,7 @@ public Parameter (int position, TypeInfo type, string name)
 		Type = type;
 		Name = name;
 	}
-	
+
 	/// <inheritdoc/>
 	public bool Equals (Parameter other)
 	{
@@ -98,6 +98,8 @@ public bool Equals (Parameter other)
 			return false;
 		if (ReferenceKind != other.ReferenceKind)
 			return false;
+		if (BindAs != other.BindAs)
+			return false;
 		if (Delegate != other.Delegate)
 			return false;
 
@@ -124,6 +126,7 @@ public override int GetHashCode ()
 		hashCode.Add (DefaultValue);
 		hashCode.Add ((int) ReferenceKind);
 		hashCode.Add (Delegate);
+		hashCode.Add (BindAs);
 		return hashCode.ToHashCode ();
 	}
 
@@ -144,13 +147,14 @@ public override string ToString ()
 		sb.Append ($"Position: {Position}, ");
 		sb.Append ($"Type: {Type}, ");
 		sb.Append ($"Name: {Name}, ");
-		sb.Append ("Attributes: ");
+		sb.Append ("Attributes: [");
 		sb.AppendJoin (", ", Attributes);
-		sb.Append ($" IsOptional: {IsOptional}, ");
+		sb.Append ($"] IsOptional: {IsOptional}, ");
 		sb.Append ($"IsParams: {IsParams}, ");
 		sb.Append ($"IsThis: {IsThis}, ");
 		sb.Append ($"DefaultValue: {DefaultValue}, ");
 		sb.Append ($"ReferenceKind: {ReferenceKind}, ");
+		sb.Append ($"BindAs: {BindAs?.ToString () ?? "null"}, ");
 		sb.Append ($"Delegate: {Delegate?.ToString () ?? "null"} }}");
 		return sb.ToString ();
 	}