C# bindings for views

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

@@ -483,6 +483,15 @@ public partial struct TestScheduleIssues
     public static void DummyScheduledReducer(ReducerContext ctx, TestScheduleIssues table) { }
 }
 
+[SpacetimeDB.Table]
+public partial struct Player
+{
+    [Unique]
+    public Identity Identity;
+}
+
+public struct NotSpacetimeType { }
+
 public partial class Module
 {
 #pragma warning disable STDB_UNSTABLE // Enable ClientVisibilityFilter
@@ -506,4 +515,84 @@ public partial class Module
     public static readonly Filter MY_FOURTH_FILTER = new Filter.Sql(
         "SELECT * FROM TestAutoIncNotInteger"
     );
+
+    // Invalid: View definition missing Public=true
+    [SpacetimeDB.View(Name = "view_def_no_public")]
+    public static List<Player> ViewDefNoPublic(ViewContext ctx)
+    {
+        return new List<Player>();
+    }
+
+    // Invalid: View definition with missing context type
+    [SpacetimeDB.View(Name = "view_def_no_context", Public = true)]
+    public static List<Player> ViewDefNoContext()
+    {
+        return new List<Player>();
+    }
+
+    // Invalid: View definition with wrong context type
+    [SpacetimeDB.View(Name = "view_def_wrong_context", Public = true)]
+    public static List<Player> ViewDefWrongContext(ReducerContext ctx)
+    {
+        return new List<Player>();
+    }
+
+    // Invalid: View that performs Insert
+    [SpacetimeDB.View(Name = "view_no_insert", Public = true)]
+    public static Player? ViewNoInsert(ViewContext ctx)
+    {
+        ctx.Db.Player.Insert(new Player { Identity = new() });
+        return new Player { Identity = new() };
+    }
+
+    // Invalid: View that performs Delete
+    [SpacetimeDB.View(Name = "view_no_delete", Public = true)]
+    public static Player? ViewNoDelete(ViewContext ctx)
+    {
+        ctx.Db.Player.Delete(new Player { Identity = new() });
+        return null;
+    }
+
+    // TODO: Investigate why void return breaks the FFI generation
+    // // Invalid: Void return type is not Vec<T> or Option<T>
+    // [SpacetimeDB.View(Name = "view_def_no_return", Public = true)]
+    // public static void ViewDefNoReturn(ViewContext ctx)
+    // {
+    //     return;
+    // }
+
+    // Invalid: Wrong return type is not Vec<T> or Option<T>
+    [SpacetimeDB.View(Name = "view_def_wrong_return", Public = true)]
+    public static Player ViewDefWrongReturn(ViewContext ctx)
+    {
+        return new Player { Identity = new() };
+    }
+
+    // Invalid: Returns type that is not a SpacetimeType
+    [SpacetimeDB.View(Name = "view_def_returns_not_a_spacetime_type", Public = true)]
+    public static NotSpacetimeType? ViewDefReturnsNotASpacetimeType(AnonymousViewContext ctx)
+    {
+        return new NotSpacetimeType();
+    }
+
+    [SpacetimeDB.View(Name = "view_def_no_anon_identity", Public = true)]
+    public static Player? ViewDefNoAnonIdentity(AnonymousViewContext ctx)
+    {
+        ctx.GetIdentity();
+        return null;
+    }
+
+    [SpacetimeDB.View(Name = "view_def_no_iter", Public = true)]
+    public static Player? ViewDefNoIter(AnonymousViewContext ctx)
+    {
+        ctx.Db.Player.Iter();
+        return null;
+    }
+
+    [SpacetimeDB.View(Name = "view_def_index_no_mutation", Public = true)]
+    public static Player? ViewDefIndexNoMutation(AnonymousViewContext ctx)
+    {
+        ctx.Db.Player.Identity.Delete(0);
+        return null;
+    }
 }

crates/bindings-csharp/Codegen.Tests/fixtures/diag/snapshots/ExtraCompilationErrors.verified.txt

@@ -1,4 +1,27 @@
 [
+  {/*
+    {
+        ctx.GetIdentity();
+            ^^^^^^^^^^^
+        return null;
+*/
+    Message: 'AnonymousViewContext' does not contain a definition for 'GetIdentity' and no accessible extension method 'GetIdentity' accepting a first argument of type 'AnonymousViewContext' could be found (are you missing a using directive or an assembly reference?),
+    Severity: Error,
+    Descriptor: {
+      Id: CS1061,
+      Title: ,
+      HelpLink: https://msdn.microsoft.com/query/roslyn.query?appId=roslyn&k=k(CS1061),
+      MessageFormat: '{0}' does not contain a definition for '{1}' and no accessible extension method '{1}' accepting a first argument of type '{0}' could be found (are you missing a using directive or an assembly reference?),
+      Category: Compiler,
+      DefaultSeverity: Error,
+      IsEnabledByDefault: true,
+      CustomTags: [
+        Compiler,
+        Telemetry,
+        NotConfigurable
+      ]
+    }
+  },
   {/*
 SpacetimeDB.Internal.Module.RegisterTable<global::TestUniqueNotEquatable, SpacetimeDB.Internal.TableHandles.TestUniqueNotEquatable>();
         SpacetimeDB.Internal.Module.RegisterClientVisibilityFilter(global::Module.MY_FILTER);
@@ -22,6 +45,98 @@ SpacetimeDB.Internal.Module.RegisterClientVisibilityFilter(global::Module.MY_FOU
       ]
     }
   },
+  {/*
+    {
+        ctx.Db.Player.Identity.Delete(0);
+                               ^^^^^^
+        return null;
+*/
+    Message: 'PlayerReadOnly.IdentityIndex' does not contain a definition for 'Delete' and no accessible extension method 'Delete' accepting a first argument of type 'PlayerReadOnly.IdentityIndex' could be found (are you missing a using directive or an assembly reference?),
+    Severity: Error,
+    Descriptor: {
+      Id: CS1061,
+      Title: ,
+      HelpLink: https://msdn.microsoft.com/query/roslyn.query?appId=roslyn&k=k(CS1061),
+      MessageFormat: '{0}' does not contain a definition for '{1}' and no accessible extension method '{1}' accepting a first argument of type '{0}' could be found (are you missing a using directive or an assembly reference?),
+      Category: Compiler,
+      DefaultSeverity: Error,
+      IsEnabledByDefault: true,
+      CustomTags: [
+        Compiler,
+        Telemetry,
+        NotConfigurable
+      ]
+    }
+  },
+  {/*
+    {
+        ctx.Db.Player.Delete(new Player { Identity = new() });
+                      ^^^^^^
+        return null;
+*/
+    Message: 'PlayerReadOnly' does not contain a definition for 'Delete' and no accessible extension method 'Delete' accepting a first argument of type 'PlayerReadOnly' could be found (are you missing a using directive or an assembly reference?),
+    Severity: Error,
+    Descriptor: {
+      Id: CS1061,
+      Title: ,
+      HelpLink: https://msdn.microsoft.com/query/roslyn.query?appId=roslyn&k=k(CS1061),
+      MessageFormat: '{0}' does not contain a definition for '{1}' and no accessible extension method '{1}' accepting a first argument of type '{0}' could be found (are you missing a using directive or an assembly reference?),
+      Category: Compiler,
+      DefaultSeverity: Error,
+      IsEnabledByDefault: true,
+      CustomTags: [
+        Compiler,
+        Telemetry,
+        NotConfigurable
+      ]
+    }
+  },
+  {/*
+    {
+        ctx.Db.Player.Insert(new Player { Identity = new() });
+                      ^^^^^^
+        return new Player { Identity = new() };
+*/
+    Message: 'PlayerReadOnly' does not contain a definition for 'Insert' and no accessible extension method 'Insert' accepting a first argument of type 'PlayerReadOnly' could be found (are you missing a using directive or an assembly reference?),
+    Severity: Error,
+    Descriptor: {
+      Id: CS1061,
+      Title: ,
+      HelpLink: https://msdn.microsoft.com/query/roslyn.query?appId=roslyn&k=k(CS1061),
+      MessageFormat: '{0}' does not contain a definition for '{1}' and no accessible extension method '{1}' accepting a first argument of type '{0}' could be found (are you missing a using directive or an assembly reference?),
+      Category: Compiler,
+      DefaultSeverity: Error,
+      IsEnabledByDefault: true,
+      CustomTags: [
+        Compiler,
+        Telemetry,
+        NotConfigurable
+      ]
+    }
+  },
+  {/*
+    {
+        ctx.Db.Player.Iter();
+                      ^^^^
+        return null;
+*/
+    Message: 'PlayerReadOnly' does not contain a definition for 'Iter' and no accessible extension method 'Iter' accepting a first argument of type 'PlayerReadOnly' could be found (are you missing a using directive or an assembly reference?),
+    Severity: Error,
+    Descriptor: {
+      Id: CS1061,
+      Title: ,
+      HelpLink: https://msdn.microsoft.com/query/roslyn.query?appId=roslyn&k=k(CS1061),
+      MessageFormat: '{0}' does not contain a definition for '{1}' and no accessible extension method '{1}' accepting a first argument of type '{0}' could be found (are you missing a using directive or an assembly reference?),
+      Category: Compiler,
+      DefaultSeverity: Error,
+      IsEnabledByDefault: true,
+      CustomTags: [
+        Compiler,
+        Telemetry,
+        NotConfigurable
+      ]
+    }
+  },
   {/*
     // Valid Filter, but [ClientVisibilityFilter] is disabled
     [SpacetimeDB.ClientVisibilityFilter]
@@ -114,6 +229,29 @@ public partial struct TestDefaultFieldValues
       ]
     }
   },
+  {/*
+
+            var returnValue = Module.ViewDefWrongContext((SpacetimeDB.ViewContext)ctx);
+                                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+            using var output = new System.IO.MemoryStream();
+*/
+    Message: Argument 1: cannot convert from 'SpacetimeDB.ViewContext' to 'SpacetimeDB.ReducerContext',
+    Severity: Error,
+    Descriptor: {
+      Id: CS1503,
+      Title: ,
+      HelpLink: https://msdn.microsoft.com/query/roslyn.query?appId=roslyn&k=k(CS1503),
+      MessageFormat: Argument {0}: cannot convert from '{1}' to '{2}',
+      Category: Compiler,
+      DefaultSeverity: Error,
+      IsEnabledByDefault: true,
+      CustomTags: [
+        Compiler,
+        Telemetry,
+        NotConfigurable
+      ]
+    }
+  },
   {/*
 SpacetimeDB.Internal.Module.RegisterClientVisibilityFilter(global::Module.MY_SECOND_FILTER);
 SpacetimeDB.Internal.Module.RegisterClientVisibilityFilter(global::Module.MY_THIRD_FILTER);
@@ -137,6 +275,75 @@ SpacetimeDB.Internal.Module.RegisterClientVisibilityFilter(global::Module.MY_THI
       ]
     }
   },
+  {/*
+
+            var returnValue = Module.ViewDefNoContext((SpacetimeDB.ViewContext)ctx);
+                                     ^^^^^^^^^^^^^^^^
+            using var output = new System.IO.MemoryStream();
+*/
+    Message: No overload for method 'ViewDefNoContext' takes 1 arguments,
+    Severity: Error,
+    Descriptor: {
+      Id: CS1501,
+      Title: ,
+      HelpLink: https://msdn.microsoft.com/query/roslyn.query?appId=roslyn&k=k(CS1501),
+      MessageFormat: No overload for method '{0}' takes {1} arguments,
+      Category: Compiler,
+      DefaultSeverity: Error,
+      IsEnabledByDefault: true,
+      CustomTags: [
+        Compiler,
+        Telemetry,
+        NotConfigurable
+      ]
+    }
+  },
+  {/*
+
+    private static readonly SpacetimeDB.BSATN.ValueOption<NotSpacetimeType, NotSpacetimeType.BSATN> returnRW = new();
+                                                                                             ^^^^^
+
+*/
+    Message: The type name 'BSATN' does not exist in the type 'NotSpacetimeType',
+    Severity: Error,
+    Descriptor: {
+      Id: CS0426,
+      Title: ,
+      HelpLink: https://msdn.microsoft.com/query/roslyn.query?appId=roslyn&k=k(CS0426),
+      MessageFormat: The type name '{0}' does not exist in the type '{1}',
+      Category: Compiler,
+      DefaultSeverity: Error,
+      IsEnabledByDefault: true,
+      CustomTags: [
+        Compiler,
+        Telemetry,
+        NotConfigurable
+      ]
+    }
+  },
+  {/*
+    Params: [],
+    ReturnType: new SpacetimeDB.BSATN.ValueOption<NotSpacetimeType, NotSpacetimeType.BSATN>().GetAlgebraicType(registrar)
+                                                                                     ^^^^^
+);
+*/
+    Message: The type name 'BSATN' does not exist in the type 'NotSpacetimeType',
+    Severity: Error,
+    Descriptor: {
+      Id: CS0426,
+      Title: ,
+      HelpLink: https://msdn.microsoft.com/query/roslyn.query?appId=roslyn&k=k(CS0426),
+      MessageFormat: The type name '{0}' does not exist in the type '{1}',
+      Category: Compiler,
+      DefaultSeverity: Error,
+      IsEnabledByDefault: true,
+      CustomTags: [
+        Compiler,
+        Telemetry,
+        NotConfigurable
+      ]
+    }
+  },
   {/*
     {
         internal static readonly TRW FieldRW = new();