From 505a2a23fc883d9fd2c87555f5ce316227c33661 Mon Sep 17 00:00:00 2001
From: Jeremy Koritzinsky <jekoritz@microsoft.com>
Date: Fri, 14 May 2021 16:17:48 -0700
Subject: [PATCH] Remove from hashtable as we return from
 HasOnlyBlittableFields to make sure we're handling our recursion check
 correctly.

---
 .../TypeSymbolExtensions.cs                   | 38 ++++++++++---------
 1 file changed, 21 insertions(+), 17 deletions(-)

diff --git a/DllImportGenerator/DllImportGenerator/TypeSymbolExtensions.cs b/DllImportGenerator/DllImportGenerator/TypeSymbolExtensions.cs
index 1db9eb33336c..4d854c904463 100644
--- a/DllImportGenerator/DllImportGenerator/TypeSymbolExtensions.cs
+++ b/DllImportGenerator/DllImportGenerator/TypeSymbolExtensions.cs
@@ -29,26 +29,30 @@ private static bool HasOnlyBlittableFields(this ITypeSymbol type, HashSet<ITypeS
             seenTypes.Add(type);
             foreach (var field in type.GetMembers().OfType<IFieldSymbol>())
             {
-                bool? fieldBlittable = field switch
+                if (!field.IsStatic)
                 {
-                    { IsStatic: true } => null,
-                    { Type: { IsReferenceType: true } } => false,
-                    { Type: IPointerTypeSymbol ptr } => IsConsideredBlittable(ptr.PointedAtType),
-                    { Type: IFunctionPointerTypeSymbol } => true,
-                    not { Type: { SpecialType: SpecialType.None } } => IsSpecialTypeBlittable(field.Type.SpecialType),
-                    // Assume that type parameters that can be blittable are blittable.
-                    // We'll re-evaluate blittability for generic fields of generic types at instantation time.
-                    { Type: ITypeParameterSymbol } => true,
-                    { Type: { IsValueType: false } } => false,
-                    _ => IsConsideredBlittable(field.Type, seenTypes)
-                };
-
-                if (fieldBlittable is false)
-                {
-                    return false;
+                    bool fieldBlittable = field switch
+                    {
+                        { Type: { IsReferenceType: true } } => false,
+                        { Type: IPointerTypeSymbol ptr } => IsConsideredBlittable(ptr.PointedAtType),
+                        { Type: IFunctionPointerTypeSymbol } => true,
+                        not { Type: { SpecialType: SpecialType.None } } => IsSpecialTypeBlittable(field.Type.SpecialType),
+                        // Assume that type parameters that can be blittable are blittable.
+                        // We'll re-evaluate blittability for generic fields of generic types at instantation time.
+                        { Type: ITypeParameterSymbol } => true,
+                        { Type: { IsValueType: false } } => false,
+                        _ => IsConsideredBlittable(field.Type, seenTypes)
+                    };
+
+                    if (!fieldBlittable)
+                    {
+                        seenTypes.Remove(type);
+                        return false;
+                    }
                 }
             }
 
+            seenTypes.Remove(type);
             return true;
         }
 
@@ -98,7 +102,7 @@ private static bool IsConsideredBlittable(this ITypeSymbol type, HashSet<ITypeSy
 
             if (type is INamedTypeSymbol { TypeKind: TypeKind.Enum, EnumUnderlyingType: ITypeSymbol underlyingType })
             {
-                return underlyingType!.IsConsideredBlittable(seenTypes);
+                return underlyingType.IsConsideredBlittable(seenTypes);
             }
 
             bool hasNativeMarshallingAttribute = false;