chore: checkpoint before Python removal

vendor/darling/examples/supports_struct.rs

@@ -0,0 +1,61 @@
+// The use of fields in debug print commands does not count as "used",
+// which causes the fields to trigger an unwanted dead code warning.
+#![allow(dead_code)]
+
+use darling::{ast, util, FromDeriveInput, FromField};
+use syn::{Ident, Type};
+
+#[derive(Debug, FromField)]
+#[darling(attributes(lorem))]
+pub struct LoremField {
+    ident: Option<Ident>,
+    ty: Type,
+    #[darling(default)]
+    skip: bool,
+}
+
+#[derive(Debug, FromDeriveInput)]
+#[darling(attributes(lorem), supports(struct_named))]
+pub struct Lorem {
+    ident: Ident,
+    data: ast::Data<util::Ignored, LoremField>,
+}
+
+fn main() {
+    let good_input = r#"#[derive(Lorem)]
+pub struct Foo {
+    #[lorem(skip)]
+    bar: bool,
+
+    baz: i64,
+}"#;
+
+    let bad_input = r#"#[derive(Lorem)]
+    pub struct BadFoo(String, u32);"#;
+
+    let parsed = syn::parse_str(good_input).unwrap();
+    let receiver = Lorem::from_derive_input(&parsed).unwrap();
+    let wrong_shape_parsed = syn::parse_str(bad_input).unwrap();
+    let wrong_shape = Lorem::from_derive_input(&wrong_shape_parsed).expect_err("Shape was wrong");
+
+    println!(
+        r#"
+INPUT:
+
+{}
+
+PARSED AS:
+
+{:?}
+
+BAD INPUT:
+
+{}
+
+PRODUCED ERROR:
+
+{}
+    "#,
+        good_input, receiver, bad_input, wrong_shape
+    );
+}