Implement new C# index syntax

crates/bindings-csharp/BSATN.Codegen/Type.cs

@@ -65,9 +65,9 @@ public abstract record BaseTypeDeclaration<M>
     public readonly string ShortName;
     public readonly string FullName;
     public readonly TypeKind Kind;
-    public EquatableArray<M> Members { get; init; }
+    public readonly EquatableArray<M> Members;
 
-    protected abstract M ConvertMember(IFieldSymbol field, DiagReporter diag);
+    protected abstract M ConvertMember(int index, IFieldSymbol field, DiagReporter diag);
 
     public BaseTypeDeclaration(GeneratorAttributeSyntaxContext context, DiagReporter diag)
     {
@@ -134,10 +134,12 @@ public BaseTypeDeclaration(GeneratorAttributeSyntaxContext context, DiagReporter
         Scope = new(typeSyntax);
         ShortName = type.Name;
         FullName = SymbolToName(type);
-        Members = new(fields.Select(field => ConvertMember(field, diag)).ToImmutableArray());
+        Members = new(
+            fields.Select((field, index) => ConvertMember(index, field, diag)).ToImmutableArray()
+        );
     }
 
-    public virtual Scope.Extensions ToExtensions()
+    public Scope.Extensions ToExtensions()
     {
         string read,
             write;
@@ -261,8 +263,11 @@ record TypeDeclaration : BaseTypeDeclaration<MemberDeclaration>
     public TypeDeclaration(GeneratorAttributeSyntaxContext context, DiagReporter diag)
         : base(context, diag) { }
 
-    protected override MemberDeclaration ConvertMember(IFieldSymbol field, DiagReporter diag) =>
-        new(field, diag);
+    protected override MemberDeclaration ConvertMember(
+        int index,
+        IFieldSymbol field,
+        DiagReporter diag
+    ) => new(field, diag);
 }
 
 [Generator]

crates/bindings-csharp/Codegen.Tests/fixtures/diag/Lib.cs

@@ -362,12 +362,14 @@ public partial struct TestDuplicateTableName { }
 }
 
 [SpacetimeDB.Table]
-[SpacetimeDB.Index]
-public partial struct TestIndexWithoutColumns { }
-
-[SpacetimeDB.Table]
-[SpacetimeDB.Index(BTree = [])]
-public partial struct TestIndexWithEmptyColumns { }
+[SpacetimeDB.Index.BTree(Name = "TestIndexWithoutColumns")]
+[SpacetimeDB.Index.BTree(Name = "TestIndexWithEmptyColumns", Columns = [])]
+[SpacetimeDB.Index.BTree(Name = "TestUnknownColumns", Columns = ["UnknownColumn"])]
+public partial struct TestIndexIssues
+{
+    [SpacetimeDB.Index.BTree(Name = "TestUnexpectedColumns", Columns = ["UnexpectedColumn"])]
+    public int SelfIndexingColumn;
+}
 
 [SpacetimeDB.Table(
     Name = "TestScheduleWithoutPrimaryKey",
@@ -385,6 +387,11 @@ public partial struct TestIndexWithEmptyColumns { }
     Scheduled = "DummyScheduledReducer",
     ScheduledAt = nameof(ScheduleAtWrongType)
 )]
+[SpacetimeDB.Table(
+    Name = "TestScheduleWithMissingScheduleAtField",
+    Scheduled = "DummyScheduledReducer",
+    ScheduledAt = "MissingField"
+)]
 public partial struct TestScheduleIssues
 {
     [SpacetimeDB.PrimaryKey(Table = "TestScheduleWithWrongPrimaryKeyType")]