Refactor kube-derive using darling

kube-derive/Cargo.toml

@@ -17,6 +17,7 @@ quote = "1.0.8"
 syn = { version = "1.0.57", features = ["extra-traits"] }
 Inflector = "0.11.4"
 serde_json = "1.0.61"
+darling = "0.12.1"
 
 [lib]
 proc-macro = true
@@ -31,3 +32,4 @@ serde_yaml = "0.8.14"
 k8s-openapi = { version = "0.11.0", default-features = false, features = ["v1_20"] }
 schemars = { version = "0.8.0", features = ["chrono"] }
 chrono = "0.4.19"
+trybuild = "1.0"

kube-derive/src/lib.rs

@@ -4,46 +4,8 @@
 #![recursion_limit = "1024"]
 extern crate proc_macro;
 #[macro_use] extern crate quote;
-use proc_macro::TokenStream;
-use syn::Result;
 
-trait CustomDerive: Sized {
-    fn parse(input: syn::DeriveInput, tokens: proc_macro2::TokenStream) -> Result<Self>;
-    fn emit(self) -> Result<proc_macro2::TokenStream>;
-}
-
-fn run_custom_derive<T>(input: TokenStream) -> TokenStream
-where
-    T: CustomDerive,
-{
-    let input: proc_macro2::TokenStream = input.into();
-    let tokens = input.clone();
-    let token_stream = match syn::parse2(input)
-        .and_then(|input| <T as CustomDerive>::parse(input, tokens))
-        .and_then(<T as CustomDerive>::emit)
-    {
-        Ok(token_stream) => token_stream,
-        Err(err) => err.to_compile_error(),
-    };
-    token_stream.into()
-}
-
-trait ResultExt<T> {
-    fn spanning(self, spanned: impl quote::ToTokens) -> Result<T>;
-}
-
-impl<T, E> ResultExt<T> for std::result::Result<T, E>
-where
-    E: std::fmt::Display,
-{
-    fn spanning(self, spanned: impl quote::ToTokens) -> Result<T> {
-        self.map_err(|err| syn::Error::new_spanned(spanned, err))
-    }
-}
-
-// #[derive(CustomResource)]
 mod custom_resource;
-use custom_resource::CustomResource;
 
 /// A custom derive for kubernetes custom resource definitions.
 ///
@@ -214,5 +176,5 @@ use custom_resource::CustomResource;
 /// [`k8s_openapi::Resource`]: https://docs.rs/k8s-openapi/*/k8s_openapi/trait.Resource.html
 #[proc_macro_derive(CustomResource, attributes(kube))]
 pub fn derive_custom_resource(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
-    run_custom_derive::<CustomResource>(input)
+    custom_resource::derive(proc_macro2::TokenStream::from(input)).into()
 }

kube-derive/tests/test_ui.rs

@@ -0,0 +1,10 @@
+// Test that `kube-derive` outputs helpful error messages.
+// If you make a change, remove `tests/ui/*.stderr` and run `cargo test`.
+// Then copy the files that appear under `wip/` if it's what you expected.
+// Alternatively, run `TRYBUILD=overwrite cargo test`.
+// See /~https://github.com/dtolnay/trybuild
+#[test]
+fn test_failures() {
+    let t = trybuild::TestCases::new();
+    t.compile_fail("tests/ui/*.rs");
+}

kube-derive/tests/ui/enum_fails.rs

@@ -0,0 +1,10 @@
+use kube_derive::CustomResource;
+use schemars::JsonSchema;
+use serde::{Deserialize, Serialize};
+
+#[derive(CustomResource, Serialize, Deserialize, Debug, Clone, JsonSchema)]
+enum FooSpec {
+    Foo,
+}
+
+fn main() {}

kube-derive/tests/ui/enum_fails.stderr

@@ -0,0 +1,5 @@
+error: Enums or Unions can not #[derive(CustomResource)]
+ --> $DIR/enum_fails.rs:6:6
+  |
+6 | enum FooSpec {
+  |      ^^^^^^^

kube-derive/tests/ui/fail_with_suggestion.rs

@@ -0,0 +1,11 @@
+use kube_derive::CustomResource;
+use schemars::JsonSchema;
+use serde::{Deserialize, Serialize};
+
+#[derive(CustomResource, Serialize, Deserialize, Debug, Clone, JsonSchema)]
+#[kube(group = "clux.dev", version = "v1", kind = "Foo", shortnames = "foo")]
+struct FooSpec {
+    foo: String,
+}
+
+fn main() {}

kube-derive/tests/ui/fail_with_suggestion.stderr

@@ -0,0 +1,5 @@
+error: Unknown field: `shortnames`. Did you mean `shortname`?
+ --> $DIR/fail_with_suggestion.rs:6:58
+  |
+6 | #[kube(group = "clux.dev", version = "v1", kind = "Foo", shortnames = "foo")]
+  |                                                          ^^^^^^^^^^

kube-derive/tests/ui/missing_required.rs

@@ -0,0 +1,10 @@
+use kube_derive::CustomResource;
+use schemars::JsonSchema;
+use serde::{Deserialize, Serialize};
+
+#[derive(CustomResource, Serialize, Deserialize, Debug, Clone, JsonSchema)]
+struct FooSpec {
+    foo: String,
+}
+
+fn main() {}

kube-derive/tests/ui/missing_required.stderr

@@ -0,0 +1,23 @@
+error: Missing field `group`
+ --> $DIR/missing_required.rs:5:10
+  |
+5 | #[derive(CustomResource, Serialize, Deserialize, Debug, Clone, JsonSchema)]
+  |          ^^^^^^^^^^^^^^
+  |
+  = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: Missing field `version`
+ --> $DIR/missing_required.rs:5:10
+  |
+5 | #[derive(CustomResource, Serialize, Deserialize, Debug, Clone, JsonSchema)]
+  |          ^^^^^^^^^^^^^^
+  |
+  = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: Missing field `kind`
+ --> $DIR/missing_required.rs:5:10
+  |
+5 | #[derive(CustomResource, Serialize, Deserialize, Debug, Clone, JsonSchema)]
+  |          ^^^^^^^^^^^^^^
+  |
+  = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)