From f783a0e2ae7990b6527653b7732c5756feed082e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marcel=20M=C3=BCller?= <neikos@neikos.email>
Date: Fri, 13 May 2022 17:19:05 +0200
Subject: [PATCH] Allow using smartpointers with source_diagnostic (#169)

* Add more tests for diagnostic_source

* Use Borrow::borrow instead of AsRef

AsRef is not reflexive, meaning that it is not implemented as &T for all
T. Borrow is though, so we use that to make sure that we always get a
reference that is correct, even in the presence of smart pointers.
---
 miette-derive/src/diagnostic_source.rs |  4 +--
 tests/test_diagnostic_source_macro.rs  | 45 ++++++++++++++++++++++++--
 2 files changed, 45 insertions(+), 4 deletions(-)

diff --git a/miette-derive/src/diagnostic_source.rs b/miette-derive/src/diagnostic_source.rs
index 949defe..46a8a64 100644
--- a/miette-derive/src/diagnostic_source.rs
+++ b/miette-derive/src/diagnostic_source.rs
@@ -59,7 +59,7 @@ impl DiagnosticSource {
                     };
                     quote! {
                         Self::#ident #display_pat => {
-                            std::option::Option::Some(#rel.as_ref())
+                            std::option::Option::Some(std::borrow::Borrow::borrow(#rel))
                         }
                     }
                 })
@@ -71,7 +71,7 @@ impl DiagnosticSource {
         let rel = &self.0;
         Some(quote! {
             fn diagnostic_source<'a>(&'a self) -> std::option::Option<&'a dyn miette::Diagnostic> {
-                std::option::Option::Some(&self.#rel)
+                std::option::Option::Some(std::borrow::Borrow::borrow(&self.#rel))
             }
         })
     }
diff --git a/tests/test_diagnostic_source_macro.rs b/tests/test_diagnostic_source_macro.rs
index d7c5d2d..8af2e88 100644
--- a/tests/test_diagnostic_source_macro.rs
+++ b/tests/test_diagnostic_source_macro.rs
@@ -6,15 +6,56 @@ struct AnErr;
 
 #[derive(Debug, miette::Diagnostic, thiserror::Error)]
 #[error("TestError")]
-struct TestError {
+struct TestStructError {
     #[diagnostic_source]
     asdf_inner_foo: AnErr,
 }
 
+#[derive(Debug, miette::Diagnostic, thiserror::Error)]
+#[error("TestError")]
+enum TestEnumError {
+    Without,
+    WithTuple(#[diagnostic_source] AnErr),
+    WithStruct {
+        #[diagnostic_source]
+        inner: AnErr,
+    },
+}
+
+#[derive(Debug, miette::Diagnostic, thiserror::Error)]
+#[error("TestError")]
+struct TestTupleError(#[diagnostic_source] AnErr);
+
+#[derive(Debug, miette::Diagnostic, thiserror::Error)]
+#[error("TestError")]
+struct TestBoxedError(#[diagnostic_source] Box<dyn Diagnostic>);
+
+#[derive(Debug, miette::Diagnostic, thiserror::Error)]
+#[error("TestError")]
+struct TestArcedError(#[diagnostic_source] std::sync::Arc<dyn Diagnostic>);
+
 #[test]
 fn test_diagnostic_source() {
-    let error = TestError {
+    let error = TestStructError {
         asdf_inner_foo: AnErr,
     };
     assert!(error.diagnostic_source().is_some());
+
+    let error = TestEnumError::Without;
+    assert!(error.diagnostic_source().is_none());
+
+    let error = TestEnumError::WithTuple(AnErr);
+    assert!(error.diagnostic_source().is_some());
+
+    let error = TestEnumError::WithStruct { inner: AnErr };
+    assert!(error.diagnostic_source().is_some());
+
+    let error = TestTupleError(AnErr);
+    assert!(error.diagnostic_source().is_some());
+
+    let error = TestBoxedError(Box::new(AnErr));
+    assert!(error.diagnostic_source().is_some());
+
+    let error = TestArcedError(std::sync::Arc::new(AnErr));
+    assert!(error.diagnostic_source().is_some());
 }