Report diagnostic for BestFitMapping, ThrowOnUnmappableChar, and …

…`LCIDConversion` (dotnet/runtimelab#291)

Commit migrated from dotnet/runtimelab@633f08d

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

@@ -16,6 +16,8 @@ static class TypeNames
 
         public const string MarshalUsingAttribute = "System.Runtime.InteropServices.MarshalUsingAttribute";
 
+        public const string LCIDConversionAttribute = "System.Runtime.InteropServices.LCIDConversionAttribute";
+
         public const string System_Span_Metadata = "System.Span`1";
         public const string System_Span = "System.Span";
 

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

@@ -32,7 +32,6 @@ private TypePositionInfo()
         {
             this.ManagedIndex = UnsetIndex;
             this.NativeIndex = UnsetIndex;
-            this.UnmanagedLCIDConversionArgIndex = UnsetIndex;
         }
 #pragma warning restore
 
@@ -49,7 +48,6 @@ private TypePositionInfo()
 
         public int ManagedIndex { get; init; }
         public int NativeIndex { get; init; }
-        public int UnmanagedLCIDConversionArgIndex { get; init; }
 
         public MarshallingInfo MarshallingAttributeInfo { get; init; }
 

src/libraries/System.Runtime.InteropServices/gen/docs/design/libraries/DllImportGenerator/Compatibility.md

@@ -12,7 +12,9 @@ The default value of [`CharSet`](https://docs.microsoft.com/dotnet/api/system.ru
 
 The built-in system treats `CharSet.None` as `CharSet.Ansi`. The P/Invoke source generator will treat `CharSet.None` as if the `CharSet` was not set.
 
-### `char` marshaller
+[`BestFitMapping`](https://docs.microsoft.com/dotnet/api/system.runtime.interopservices.dllimportattribute.bestfitmapping) and [`ThrowOnUnmappableChar`](https://docs.microsoft.com/dotnet/api/system.runtime.interopservices.dllimportattribute.throwonunmappablechar) will not be supported for `GeneratedDllImportAttribute`. These values only have meaning on Windows when marshalling string data (`char`, `string`, `StringBuilder`) as [ANSI](https://docs.microsoft.com/windows/win32/intl/code-pages). As the general recommendation - including from Windows - is to move away from ANSI, the P/Invoke source generator will not support these fields.
+
+### `char` marshalling
 
 Marshalling of `char` will not be supported when configured with any of the following:
   - [`CharSet.Ansi`, `CharSet.Auto`, or `CharSet.None`](https://docs.microsoft.com/dotnet/api/system.runtime.interopservices.charset) will not be supported.
@@ -23,7 +25,7 @@ For `CharSet.Ansi` and `CharSet.None`, the built-in system used the [system defa
 
 For `CharSet.Auto`, the built-in system relied upon detection at runtime of the platform when determining the targeted encoding. Performing this check in generated code violates the "pay-for-play" principle. Given that there are no scenarios for this feature in `NetCoreApp` it will not be supported.
 
-### `string` marshaller
+### `string` marshalling
 
 Marshalling of `string` will not be supported when configured with any of the following:
   - [`CharSet.None`](https://docs.microsoft.com/dotnet/api/system.runtime.interopservices.charset)
@@ -44,7 +46,7 @@ On Windows, marshalling using `CharSet.Auto` is treated as UTF-16. When marshall
 
 Using a custom marshaller (i.e. [`ICustomMarshaler`](https://docs.microsoft.com/dotnet/api/system.runtime.interopservices.icustommarshaler)) with the `UnmanagedType.CustomMarshaler` value on `MarshalAsAttribute` is not supported. This also implies `MarshalAsAttribute` fields: [`MarshalTypeRef`](https://docs.microsoft.com/dotnet/api/system.runtime.interopservices.marshalasattribute.marshaltyperef), [`MarshalType`](https://docs.microsoft.com/dotnet/api/system.runtime.interopservices.marshalasattribute.marshaltype), and [`MarshalCookie`](https://docs.microsoft.com/dotnet/api/system.runtime.interopservices.marshalasattribute.marshalcookie) are unsupported.
 
-### Array marshaller support
+### Array marshalling
 
 Marshalling of arrays will not be supported when using [`UnmangedType.SafeArray`](https://docs.microsoft.com/dotnet/api/system.runtime.interopservices.unmanagedtype). This implies that the following `MarshalAsAttribute` fields are unsupported: [`SafeArraySubType`](https://docs.microsoft.com/dotnet/api/system.runtime.interopservices.marshalasattribute.safearraysubtype) and [`SafeArrayUserDefinedSubType`](https://docs.microsoft.com/dotnet/api/system.runtime.interopservices.marshalasattribute.safearrayuserdefinedsubtype)
 
@@ -54,6 +56,10 @@ Only single-dimensional arrays are supported for source generated marshalling.
 
 In the source-generated marshalling, arrays will be allocated on the stack (instead of through [`AllocCoTaskMem`](https://docs.microsoft.com/dotnet/api/system.runtime.interopservices.marshal.alloccotaskmem)) if they are passed by value or by read-only reference if they contain at most 256 bytes of data. The built-in system does not support this optimization for arrays.
 
+### `LCIDConversion` support
+
+[`LCIDConversionAttribute`](`https://docs.microsoft.com/dotnet/api/system.runtime.interopservices.lcidconversionattribute`) will not be supported for methods marked with `GeneratedDllImportAttribute`.
+
 ## Verison 0
 
 This version is the built-in IL Stub generation system that is triggered whenever a method marked with `DllImport` is invoked.

src/libraries/System.Runtime.InteropServices/tests/DllImportGenerator.UnitTests/CodeSnippets.cs

@@ -168,6 +168,24 @@ partial class Test
         ThrowOnUnmappableChar = true)]
     public static partial void Method();
 }
+";
+
+        /// <summary>
+        /// Declaration with all supported DllImport named arguments.
+        /// </summary>
+        public static readonly string AllSupportedDllImportNamedArguments = @"
+using System.Runtime.InteropServices;
+partial class Test
+{
+    [GeneratedDllImport(""DoesNotExist"",
+        CallingConvention = CallingConvention.Cdecl,
+        CharSet = CharSet.Unicode,
+        EntryPoint = ""UserDefinedEntryPoint"",
+        ExactSpelling = true,
+        PreserveSig = false,
+        SetLastError = true)]
+    public static partial void Method();
+}
 ";
 
         /// <summary>
@@ -180,17 +198,26 @@ partial class Test
     private const bool IsTrue = true;
     private const bool IsFalse = false;
     private const string EntryPointName = nameof(Test) + nameof(IsFalse);
+    private const int One = 1;
+    private const int Two = 2;
 
     [GeneratedDllImport(nameof(Test),
-        BestFitMapping = 0 != 1,
         CallingConvention = (CallingConvention)1,
         CharSet = (CharSet)2,
         EntryPoint = EntryPointName,
-        ExactSpelling = IsTrue,
+        ExactSpelling = 0 != 1,
         PreserveSig = IsFalse,
-        SetLastError = !IsFalse,
-        ThrowOnUnmappableChar = !IsTrue)]
-    public static partial void Method();
+        SetLastError = IsTrue)]
+    public static partial void Method1();
+
+    [GeneratedDllImport(nameof(Test),
+        CallingConvention = (CallingConvention)One,
+        CharSet = (CharSet)Two,
+        EntryPoint = EntryPointName,
+        ExactSpelling = One != Two,
+        PreserveSig = !IsFalse,
+        SetLastError = !IsTrue)]
+    public static partial void Method2();
 }
 ";
 
@@ -204,6 +231,19 @@ partial class Test
     [GeneratedDllImport(""DoesNotExist"")]
     public static partial void Method(int t = 0);
 }
+";
+
+        /// <summary>
+        /// Declaration with LCIDConversionAttribute.
+        /// </summary>
+        public static readonly string LCIDConversionAttribute = @"
+using System.Runtime.InteropServices;
+partial class Test
+{
+    [LCIDConversion(0)]
+    [GeneratedDllImport(""DoesNotExist"")]
+    public static partial void Method();
+}
 ";
 
         /// <summary>

src/libraries/System.Runtime.InteropServices/tests/DllImportGenerator.UnitTests/CompileFails.cs

@@ -35,6 +35,13 @@ public static IEnumerable<object[]> CodeSnippetsToCompile()
             // Unsupported MarshalAsAttribute usage
             //  * UnmanagedType.CustomMarshaler, MarshalTypeRef, MarshalType, MarshalCookie
             yield return new object[] { CodeSnippets.MarshalAsCustomMarshalerOnTypes, 16, 0 };
+
+            // Unsupported named arguments
+            //  * BestFitMapping, ThrowOnUnmappableChar
+            yield return new object[] { CodeSnippets.AllDllImportNamedArguments, 2, 0 };
+
+            // LCIDConversion
+            yield return new object[] { CodeSnippets.LCIDConversionAttribute, 1, 0 };
         }
 
         [Theory]

src/libraries/System.Runtime.InteropServices/tests/DllImportGenerator.UnitTests/Compiles.cs

@@ -17,7 +17,7 @@ public static IEnumerable<object[]> CodeSnippetsToCompile_NoDiagnostics()
             yield return new[] { CodeSnippets.NestedNamespace };
             yield return new[] { CodeSnippets.NestedTypes };
             yield return new[] { CodeSnippets.UserDefinedEntryPoint };
-            yield return new[] { CodeSnippets.AllDllImportNamedArguments };
+            yield return new[] { CodeSnippets.AllSupportedDllImportNamedArguments };
             yield return new[] { CodeSnippets.DefaultParameters };
             yield return new[] { CodeSnippets.UseCSharpFeaturesForConstants };
             yield return new[] { CodeSnippets.BasicParametersAndModifiers<byte>() };