fix(miri): remove or mark as dead_code unused internal structs

- Mark as dead_code the structs uses in testing
- Remove unused code inherited from Eyre for converting `Option` into
  `Result`

src/eyreish/context.rs

@@ -213,5 +213,4 @@ pub(crate) mod private {
     pub trait Sealed {}
 
     impl<T, E> Sealed for Result<T, E> where E: ext::Diag {}
-    impl<T> Sealed for Option<T> {}
 }

src/eyreish/wrapper.rs

@@ -6,35 +6,9 @@ use crate::{Diagnostic, LabeledSpan, Report, SourceCode};
 
 use crate as miette;
 
-#[repr(transparent)]
-pub(crate) struct DisplayError<M>(pub(crate) M);
-
 #[repr(transparent)]
 pub(crate) struct MessageError<M>(pub(crate) M);
 
-pub(crate) struct NoneError;
-
-impl<M> Debug for DisplayError<M>
-where
-    M: Display,
-{
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        Display::fmt(&self.0, f)
-    }
-}
-
-impl<M> Display for DisplayError<M>
-where
-    M: Display,
-{
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        Display::fmt(&self.0, f)
-    }
-}
-
-impl<M> StdError for DisplayError<M> where M: Display + 'static {}
-impl<M> Diagnostic for DisplayError<M> where M: Display + 'static {}
-
 impl<M> Debug for MessageError<M>
 where
     M: Display + Debug,
@@ -56,21 +30,6 @@ where
 impl<M> StdError for MessageError<M> where M: Display + Debug + 'static {}
 impl<M> Diagnostic for MessageError<M> where M: Display + Debug + 'static {}
 
-impl Debug for NoneError {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        Debug::fmt("Option was None", f)
-    }
-}
-
-impl Display for NoneError {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        Display::fmt("Option was None", f)
-    }
-}
-
-impl StdError for NoneError {}
-impl Diagnostic for NoneError {}
-
 #[repr(transparent)]
 pub(crate) struct BoxedError(pub(crate) Box<dyn Diagnostic + Send + Sync>);
 

tests/derive.rs

@@ -6,12 +6,14 @@ fn related() {
     #[derive(Error, Debug, Diagnostic)]
     #[error("welp")]
     #[diagnostic(code(foo::bar::baz))]
+    #[allow(dead_code)]
     struct Foo {
         #[related]
         related: Vec<Baz>,
     }
 
     #[derive(Error, Debug, Diagnostic)]
+    #[allow(dead_code)]
     enum Bar {
         #[error("variant1")]
         #[diagnostic(code(foo::bar::baz))]
@@ -29,6 +31,7 @@ fn related() {
 
     #[derive(Error, Debug, Diagnostic)]
     #[error("welp2")]
+    #[allow(dead_code)]
     struct Baz;
 }
 
@@ -37,6 +40,7 @@ fn related_report() {
     #[derive(Error, Debug, Diagnostic)]
     #[error("welp")]
     #[diagnostic(code(foo::bar::baz))]
+    #[allow(dead_code)]
     struct Foo {
         #[related]
         related: Vec<Report>,
@@ -288,6 +292,7 @@ fn test_snippet_named_struct() {
     #[derive(Debug, Diagnostic, Error)]
     #[error("welp")]
     #[diagnostic(code(foo::bar::baz))]
+    #[allow(dead_code)]
     struct Foo<'a> {
         #[source_code]
         src: &'a str,
@@ -310,6 +315,7 @@ fn test_snippet_unnamed_struct() {
     #[derive(Debug, Diagnostic, Error)]
     #[error("welp")]
     #[diagnostic(code(foo::bar::baz))]
+    #[allow(dead_code)]
     struct Foo<'a>(
         #[source_code] &'a str,
         #[label("{0}")] SourceSpan,