Add StringMarshallingCustomType to GeneratedDllImportAttribute (#…

…65855)

src/coreclr/nativeaot/Test.CoreLib/src/Test.CoreLib.csproj

@@ -5,9 +5,9 @@
     <TargetFramework>netstandard2.0</TargetFramework>
     <EnableDllImportGenerator>true</EnableDllImportGenerator>
     <!--
-      DLLIMPORTGEN003: DllImportGenerator Target Framework Not Supported.
+      DLLIMPORTGEN004: DllImportGenerator Target Framework Not Supported.
      -->
-    <NoWarn>$(NoWarn);DLLIMPORTGEN003</NoWarn>
+    <NoWarn>$(NoWarn);DLLIMPORTGEN004</NoWarn>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)' == 'Debug'">
     <DefineConstants>FEATURE_GC_STRESS;$(DefineConstants)</DefineConstants>

src/libraries/Common/src/System/Runtime/InteropServices/GeneratedDllImportAttribute.cs

@@ -22,6 +22,7 @@ sealed class GeneratedDllImportAttribute : Attribute
         public string? EntryPoint { get; set; }
         public bool SetLastError { get; set; }
         public StringMarshalling StringMarshalling { get; set; }
+        public Type? StringMarshallingCustomType { get; set; }
 
         public GeneratedDllImportAttribute(string dllName)
         {

src/libraries/System.Runtime.InteropServices/gen/DllImportGenerator/DllImportGenerator.cs

@@ -357,6 +357,7 @@ private static TargetFramework DetermineTargetFramework(Compilation compilation,
             bool setLastError = false;
 
             StringMarshalling stringMarshalling = StringMarshalling.Custom;
+            INamedTypeSymbol? stringMarshallingCustomType = null;
 
             // All other data on attribute is defined as NamedArguments.
             foreach (KeyValuePair<string, TypedConstant> namedArg in attrData.NamedArguments)
@@ -369,16 +370,6 @@ private static TargetFramework DetermineTargetFramework(Compilation compilation,
                         // Return null here to indicate invalid attribute data.
                         Debug.WriteLine($"An unknown member '{namedArg.Key}' was found on {attrData.AttributeClass}");
                         return null;
-                    case nameof(GeneratedDllImportData.StringMarshalling):
-                        userDefinedValues |= DllImportMember.StringMarshalling;
-                        // TypedConstant's Value property only contains primitive values.
-                        if (namedArg.Value.Value is not int)
-                        {
-                            return null;
-                        }
-                        // A boxed primitive can be unboxed to an enum with the same underlying type.
-                        stringMarshalling = (StringMarshalling)namedArg.Value.Value!;
-                        break;
                     case nameof(GeneratedDllImportData.EntryPoint):
                         userDefinedValues |= DllImportMember.EntryPoint;
                         if (namedArg.Value.Value is not string)
@@ -395,6 +386,24 @@ private static TargetFramework DetermineTargetFramework(Compilation compilation,
                         }
                         setLastError = (bool)namedArg.Value.Value!;
                         break;
+                    case nameof(GeneratedDllImportData.StringMarshalling):
+                        userDefinedValues |= DllImportMember.StringMarshalling;
+                        // TypedConstant's Value property only contains primitive values.
+                        if (namedArg.Value.Value is not int)
+                        {
+                            return null;
+                        }
+                        // A boxed primitive can be unboxed to an enum with the same underlying type.
+                        stringMarshalling = (StringMarshalling)namedArg.Value.Value!;
+                        break;
+                    case nameof(GeneratedDllImportData.StringMarshallingCustomType):
+                        userDefinedValues |= DllImportMember.StringMarshallingCustomType;
+                        if (namedArg.Value.Value is not INamedTypeSymbol)
+                        {
+                            return null;
+                        }
+                        stringMarshallingCustomType = (INamedTypeSymbol)namedArg.Value.Value;
+                        break;
                 }
             }
 
@@ -406,9 +415,10 @@ private static TargetFramework DetermineTargetFramework(Compilation compilation,
             return new GeneratedDllImportData(attrData.ConstructorArguments[0].Value!.ToString())
             {
                 IsUserDefined = userDefinedValues,
-                StringMarshalling = stringMarshalling,
                 EntryPoint = entryPoint,
                 SetLastError = setLastError,
+                StringMarshalling = stringMarshalling,
+                StringMarshallingCustomType = stringMarshallingCustomType,
             };
         }
 
@@ -462,6 +472,23 @@ private static IncrementalStubGenerationContext CalculateStubInformation(IMethod
                 stubDllImportData = new GeneratedDllImportData("INVALID_CSHARP_SYNTAX");
             }
 
+            if (stubDllImportData.IsUserDefined.HasFlag(DllImportMember.StringMarshalling))
+            {
+                // User specified StringMarshalling.Custom without specifying StringMarshallingCustomType
+                if (stubDllImportData.StringMarshalling == StringMarshalling.Custom && stubDllImportData.StringMarshallingCustomType is null)
+                {
+                    generatorDiagnostics.ReportInvalidStringMarshallingConfiguration(
+                        generatedDllImportAttr, symbol.Name, Resources.InvalidStringMarshallingConfigurationMissingCustomType);
+                }
+
+                // User specified something other than StringMarshalling.Custom while specifying StringMarshallingCustomType
+                if (stubDllImportData.StringMarshalling != StringMarshalling.Custom && stubDllImportData.StringMarshallingCustomType is not null)
+                {
+                    generatorDiagnostics.ReportInvalidStringMarshallingConfiguration(
+                        generatedDllImportAttr, symbol.Name, Resources.InvalidStringMarshallingConfigurationNotCustom);
+                }
+            }
+
             if (lcidConversionAttr is not null)
             {
                 // Using LCIDConversion with GeneratedDllImport is not supported
@@ -543,13 +570,22 @@ private MemberDeclarationSyntax PrintForwarderStub(MethodDeclarationSyntax userD
                 && targetDllImportData.StringMarshalling != StringMarshalling.Utf16)
             {
                 diagnostics.ReportCannotForwardToDllImport(
+                    userDeclaredMethod,
                     $"{nameof(TypeNames.GeneratedDllImportAttribute)}{Type.Delimiter}{nameof(StringMarshalling)}",
-                    $"{nameof(StringMarshalling)}{Type.Delimiter}{targetDllImportData.StringMarshalling}",
-                    userDeclaredMethod);
+                    $"{nameof(StringMarshalling)}{Type.Delimiter}{targetDllImportData.StringMarshalling}");
 
                 targetDllImportData = targetDllImportData with { IsUserDefined = targetDllImportData.IsUserDefined & ~DllImportMember.StringMarshalling };
             }
 
+            if (targetDllImportData.IsUserDefined.HasFlag(DllImportMember.StringMarshallingCustomType))
+            {
+                diagnostics.ReportCannotForwardToDllImport(
+                    userDeclaredMethod,
+                    $"{nameof(TypeNames.GeneratedDllImportAttribute)}{Type.Delimiter}{nameof(DllImportMember.StringMarshallingCustomType)}");
+
+                targetDllImportData = targetDllImportData with { IsUserDefined = targetDllImportData.IsUserDefined & ~DllImportMember.StringMarshallingCustomType };
+            }
+
             SyntaxTokenList modifiers = StripTriviaFromModifiers(userDeclaredMethod.Modifiers);
             modifiers = AddToModifiers(modifiers, SyntaxKind.ExternKeyword);
             // Create stub function

src/libraries/System.Runtime.InteropServices/gen/DllImportGenerator/DllImportStubContext.cs

@@ -163,8 +163,12 @@ private static (ImmutableArray<TypePositionInfo>, IMarshallingGeneratorFactory)
                     _ => CharEncoding.Undefined, // [Compat] Do not assume a specific value
                 };
             }
+            else if (dllImportData.IsUserDefined.HasFlag(DllImportMember.StringMarshallingCustomType))
+            {
+                defaultEncoding = CharEncoding.Custom;
+            }
 
-            var defaultInfo = new DefaultMarshallingInfo(defaultEncoding);
+            var defaultInfo = new DefaultMarshallingInfo(defaultEncoding, dllImportData.StringMarshallingCustomType);
 
             var marshallingAttributeParser = new MarshallingAttributeInfoParser(env.Compilation, diagnostics, defaultInfo, method);
 

src/libraries/System.Runtime.InteropServices/gen/DllImportGenerator/GeneratedDllImportData.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Runtime.InteropServices;
+using Microsoft.CodeAnalysis;
 
 namespace Microsoft.Interop
 {
@@ -16,6 +17,7 @@ public enum DllImportMember
         EntryPoint = 1 << 0,
         SetLastError = 1 << 1,
         StringMarshalling = 1 << 2,
+        StringMarshallingCustomType = 1 << 3,
         All = ~None
     }
 
@@ -32,8 +34,9 @@ internal sealed record GeneratedDllImportData(string ModuleName)
         /// Value set by the user on the original declaration.
         /// </summary>
         public DllImportMember IsUserDefined { get; init; }
-        public StringMarshalling StringMarshalling { get; init; }
         public string? EntryPoint { get; init; }
         public bool SetLastError { get; init; }
+        public StringMarshalling StringMarshalling { get; init; }
+        public INamedTypeSymbol? StringMarshallingCustomType { get; init; }
     }
 }

src/libraries/System.Runtime.InteropServices/gen/DllImportGenerator/GeneratorDiagnostics.cs

@@ -19,14 +19,25 @@ public class GeneratorDiagnostics : IGeneratorDiagnostics
         public class Ids
         {
             public const string Prefix = "DLLIMPORTGEN";
-            public const string TypeNotSupported = Prefix + "001";
-            public const string ConfigurationNotSupported = Prefix + "002";
-            public const string TargetFrameworkNotSupported = Prefix + "003";
-            public const string CannotForwardToDllImport = Prefix + "004";
+            public const string InvalidGeneratedDllImportAttributeUsage = Prefix + "001";
+            public const string TypeNotSupported = Prefix + "002";
+            public const string ConfigurationNotSupported = Prefix + "003";
+            public const string TargetFrameworkNotSupported = Prefix + "004";
+            public const string CannotForwardToDllImport = Prefix + "005";
         }
 
         private const string Category = "SourceGeneration";
 
+        public static readonly DiagnosticDescriptor InvalidStringMarshallingConfiguration =
+            new DiagnosticDescriptor(
+            Ids.InvalidGeneratedDllImportAttributeUsage,
+            GetResourceString(nameof(Resources.InvalidLibraryImportAttributeUsageTitle)),
+            GetResourceString(nameof(Resources.InvalidStringMarshallingConfigurationMessage)),
+            Category,
+            DiagnosticSeverity.Error,
+            isEnabledByDefault: true,
+            description: GetResourceString(nameof(Resources.InvalidStringMarshallingConfigurationDescription)));
+
         public static readonly DiagnosticDescriptor ParameterTypeNotSupported =
             new DiagnosticDescriptor(
                 Ids.TypeNotSupported,
@@ -141,6 +152,24 @@ public class Ids
 
         public IEnumerable<Diagnostic> Diagnostics => _diagnostics;
 
+        /// <summary>
+        /// Report diagnostic for invalid configuration for string marshalling.
+        /// </summary>
+        /// <param name="attributeData">Attribute specifying the invalid configuration</param>
+        /// <param name="methodName">Name of the method</param>
+        /// <param name="detailsMessage">Specific reason the configuration is invalid</param>
+        public void ReportInvalidStringMarshallingConfiguration(
+            AttributeData attributeData,
+            string methodName,
+            string detailsMessage)
+        {
+            _diagnostics.Add(
+                attributeData.CreateDiagnostic(
+                    GeneratorDiagnostics.InvalidStringMarshallingConfiguration,
+                    methodName,
+                    detailsMessage));
+        }
+
         /// <summary>
         /// Report diagnostic for configuration that is not supported by the DLL import source generator
         /// </summary>
@@ -287,17 +316,16 @@ public void ReportTargetFrameworkNotSupported(Version minimumSupportedVersion)
         /// <summary>
         /// Report diagnostic for configuration that cannot be forwarded to <see cref="DllImportAttribute" />
         /// </summary>
+        /// <param name="method">Method with the configuration that cannot be forwarded</param>
         /// <param name="name">Configuration name</param>
         /// <param name="value">Configuration value</param>
-        /// <param name="method">Method with the arguments that cannot be forwarded</param>
-        public void ReportCannotForwardToDllImport(string name, string value, MethodDeclarationSyntax method)
+        public void ReportCannotForwardToDllImport(MethodDeclarationSyntax method, string name, string? value = null)
         {
             _diagnostics.Add(
                 Diagnostic.Create(
                     CannotForwardToDllImport,
                     Location.Create(method.SyntaxTree, method.Identifier.Span),
-                    name,
-                    value));
+                    value is null ? name : $"{name}={value}"));
         }
 
         private static LocalizableResourceString GetResourceString(string resourceName)

src/libraries/System.Runtime.InteropServices/gen/DllImportGenerator/Resources.resx

@@ -136,12 +136,10 @@
     <value>Native type '{0}' has a constructor taking a caller-allocated buffer, but does not support marshalling in scenarios where using a caller-allocated buffer is impossible</value>
   </data>
   <data name="CannotForwardToDllImportDescription" xml:space="preserve">
-    <value>The generated 'DllImportAttribute' will not have a value corresponding to '{0}={1}'.</value>
-    <comment>{0} and {1} are the name and value of an attribute argument</comment>
+    <value>The generated 'DllImportAttribute' will not have a value corresponding to '{0}'.</value>
   </data>
   <data name="CannotForwardToDllImportMessage" xml:space="preserve">
-    <value>'{0}={1}' has no equivalent in 'DllImportAtttribute' and will not be forwarded</value>
-    <comment>{0} and {1} are the name and value of an attribute argument</comment>
+    <value>'{0}' has no equivalent in 'DllImportAtttribute' and will not be forwarded</value>
   </data>
   <data name="CannotForwardToDllImportTitle" xml:space="preserve">
     <value>Specified 'GeneratedDllImportAttribute' arguments cannot be forwarded to 'DllImportAttribute'</value>
@@ -240,6 +238,22 @@
   <data name="GetPinnableReferenceShouldSupportAllocatingMarshallingFallbackMessage" xml:space="preserve">
     <value>Type '{0}' has a 'GetPinnableReference' method but its native type does not support marshalling in scenarios where pinning is impossible</value>
   </data>
+  <data name="InvalidLibraryImportAttributeUsageTitle" xml:space="preserve">
+    <value>Invalid 'LibraryImportAttribute' usage</value>
+  </data>
+  <data name="InvalidStringMarshallingConfigurationDescription" xml:space="preserve">
+    <value>The configuration of 'StringMarshalling' and 'StringMarshallingCustomType' is invalid.</value>
+  </data>
+  <data name="InvalidStringMarshallingConfigurationMessage" xml:space="preserve">
+    <value>The configuration of 'StringMarshalling' and 'StringMarshallingCustomType' on method '{0}' is invalid. {1}</value>
+    <comment>{1} is a message containing additional details about what is not valid</comment>
+  </data>
+  <data name="InvalidStringMarshallingConfigurationMissingCustomType" xml:space="preserve">
+    <value>'StringMarshallingCustomType' must be specified when 'StringMarshalling' is set to 'StringMarshalling.Custom'.</value>
+  </data>
+  <data name="InvalidStringMarshallingConfigurationNotCustom" xml:space="preserve">
+    <value>'StringMarshalling' should be set to 'StringMarshalling.Custom' when 'StringMarshallingCustomType' is specified.</value>
+  </data>
   <data name="MarshallerGetPinnableReferenceRequiresValuePropertyDescription" xml:space="preserve">
     <value>The use cases for 'GetPinnableReference' are not applicable in any scenarios where a 'Value' property is not also required.</value>
   </data>