feat(derive): allow `Report` in `related` (#121)

Fixes: #119

miette-derive/src/related.rs

@@ -69,7 +69,10 @@ impl Related {
         let rel = &self.0;
         Some(quote! {
             fn related<'a>(&'a self) -> std::option::Option<std::boxed::Box<dyn std::iter::Iterator<Item = &'a dyn miette::Diagnostic> + 'a>> {
-                std::option::Option::Some(std::boxed::Box::new(self.#rel.iter().map(|x| -> &(dyn miette::Diagnostic) { &*x })))
+                use ::core::borrow::Borrow;
+                std::option::Option::Some(std::boxed::Box::new(
+                        self.#rel.iter().map(|x| -> &(dyn miette::Diagnostic) { &*x.borrow() })
+                ))
             }
         })
     }

src/eyreish/error.rs

@@ -727,3 +727,9 @@ impl AsRef<dyn Diagnostic> for Report {
         &**self
     }
 }
+
+impl std::borrow::Borrow<dyn Diagnostic> for Report {
+    fn borrow(&self) -> &(dyn Diagnostic + 'static) {
+        self.as_ref()
+    }
+}

tests/derive.rs

@@ -1,4 +1,4 @@
-use miette::{Diagnostic, Severity, SourceSpan};
+use miette::{Diagnostic, Report, Severity, SourceSpan};
 use thiserror::Error;
 
 #[test]
@@ -32,6 +32,17 @@ fn related() {
     struct Baz;
 }
 
+#[test]
+fn related_report() {
+    #[derive(Error, Debug, Diagnostic)]
+    #[error("welp")]
+    #[diagnostic(code(foo::bar::baz))]
+    struct Foo {
+        #[related]
+        related: Vec<Report>,
+    }
+}
+
 #[test]
 fn basic_struct() {
     #[derive(Debug, Diagnostic, Error)]