Fix clippy issues.

src/intermediate/registry.rs

@@ -52,9 +52,9 @@ impl<'orig, 'parse> Registry<'orig, 'parse> {
 pub(crate) async fn get_footnote_reference_id<'orig, 'parse>(
     intermediate_context: IntermediateContext<'orig, 'parse>,
     label: Option<&'parse str>,
-    definition: &'orig Vec<Object<'parse>>,
+    definition: &'orig [Object<'parse>],
 ) -> Result<(usize, usize), CustomError> {
-    if let None = label {
+    if label.is_none() {
         // If it has no label then it must always get a new ID.
         let contents = convert_reference_contents(intermediate_context.clone(), definition).await?;
         let pos = {
@@ -148,7 +148,7 @@ pub(crate) async fn register_footnote_definition<'orig, 'parse>(
 
 async fn convert_reference_contents<'orig, 'parse>(
     intermediate_context: IntermediateContext<'orig, 'parse>,
-    contents: &'orig Vec<Object<'parse>>,
+    contents: &'orig [Object<'parse>],
 ) -> Result<Vec<IAstNode>, CustomError> {
     let children = {
         let mut ret = Vec::new();
@@ -159,23 +159,19 @@ async fn convert_reference_contents<'orig, 'parse>(
     };
     let containing_paragraph =
         IParagraph::artificial(intermediate_context.clone(), children, 0).await?;
-    let contents = {
-        let mut ret = Vec::new();
-        ret.push(IAstNode::Paragraph(containing_paragraph));
-        ret
-    };
+    let contents = vec![IAstNode::Paragraph(containing_paragraph)];
 
     Ok(contents)
 }
 
 async fn convert_definition_contents<'orig, 'parse>(
     intermediate_context: IntermediateContext<'orig, 'parse>,
-    contents: &'orig Vec<Element<'parse>>,
+    contents: &'orig [Element<'parse>],
 ) -> Result<Vec<IAstNode>, CustomError> {
     let contents = {
         let mut ret = Vec::new();
         for obj in contents.iter() {
-            ret.push(obj.into_ast_node(intermediate_context.clone()).await?);
+            ret.push(obj.as_ast_node(intermediate_context.clone()).await?);
         }
         ret
     };
@@ -190,8 +186,7 @@ pub(crate) async fn promote_footnote_definition<'orig, 'parse>(
 ) -> Result<(), CustomError> {
     let definition = {
         let mut registry = intermediate_context.registry.lock().unwrap();
-        let definition = registry.on_deck_footnote_ids.remove(label);
-        definition
+        registry.on_deck_footnote_ids.remove(label)
     };
     if let Some(elements) = definition {
         let existing_id = {