Stash WIP of future potential use of #[diagnostic::on_unimplemented]

examples/dynamic_watcher.rs

@@ -8,6 +8,9 @@ use tracing::*;
 
 use std::{env, fmt::Debug};
 
+#[derive(Clone, Debug)]
+struct MyStruct {}
+
 #[tokio::main]
 async fn main() -> anyhow::Result<()> {
     tracing_subscriber::fmt::init();
@@ -27,7 +30,7 @@ async fn main() -> anyhow::Result<()> {
     let (ar, _caps) = kube::discovery::pinned_kind(&client, &gvk).await?;
 
     // Use the full resource info to create an Api with the ApiResource as its DynamicType
-    let api = Api::<DynamicObject>::all_with(client, &ar);
+    let api = Api::<MyStruct>::all_with(client, &ar);
     let wc = watcher::Config::default();
 
     // Start a metadata or a full resource watch

kube-core/src/lib.rs

@@ -7,6 +7,7 @@
 //! Everything in this crate is re-exported from [`kube`](https://crates.io/crates/kube)
 //! (even with zero features) under [`kube::core`]((https://docs.rs/kube/*/kube/core/index.html)).
 #![cfg_attr(docsrs, feature(doc_cfg))]
+#![feature(diagnostic_namespace)]
 #![deny(missing_docs)]
 #![forbid(unsafe_code)]
 

kube-core/src/resource.rs

@@ -24,6 +24,12 @@ impl ResourceScope for DynamicResourceScope {}
 /// - `.metadata.resource_version`
 ///
 /// This avoids a bunch of the unnecessary unwrap mechanics for apps.
+#[diagnostic::on_unimplemented(
+    message = "The `kube::Resource` trait is not implemented for `{Self}`",
+    label = "Is this type a `k8s-openapi` top level Kubernetes type, or a dynamic type created via `CustomResource`",
+    note = "If this is a CustomResource, please use the generated top level struct (not the spec struct) for `Api`",
+    note = "If this is a fully typed openapi struct, ensure you use the top-level resource type (e.g. `Pod` over `PodSpec`) for `Api`"
+)]
 pub trait Resource {
     /// Type information for types that do not know their resource information at compile time.
     ///