Rollup merge of #56820 - ljedrz:format_tweaks, r=alexcrichton

format-related tweaks

- remove an unreachable condition
- inline one-liners related to `parse_expr` (called in succession)
- refactor `report_invalid_references`
- refactor `verify_arg_type`
- minor stylistic improvements

src/libsyntax/parse/parser.rs

@@ -3062,6 +3062,7 @@ impl<'a> Parser<'a> {
     ///
     /// This parses an expression accounting for associativity and precedence of the operators in
     /// the expression.
+    #[inline]
     fn parse_assoc_expr(&mut self,
                             already_parsed_attrs: Option<ThinVec<Attribute>>)
                             -> PResult<'a, P<Expr>> {
@@ -3722,6 +3723,7 @@ impl<'a> Parser<'a> {
     }
 
     /// Parse an expression
+    #[inline]
     pub fn parse_expr(&mut self) -> PResult<'a, P<Expr>> {
         self.parse_expr_res(Restrictions::empty(), None)
     }
@@ -3741,6 +3743,7 @@ impl<'a> Parser<'a> {
     }
 
     /// Parse an expression, subject to the given restrictions
+    #[inline]
     fn parse_expr_res(&mut self, r: Restrictions,
                           already_parsed_attrs: Option<ThinVec<Attribute>>)
                           -> PResult<'a, P<Expr>> {