Add implementation comments

Signed-off-by: Sasha Pourcelot <[email protected]>

Author: scrabsha

compiler/rustc_parse/src/parser/expr.rs

@@ -981,13 +981,14 @@ impl<'a> Parser<'a> {
                 self.eat_noexpect(&token::Dot)
             } else if self.token.kind == TokenKind::RArrow
                 && self.prev_token.span.overlaps_or_adjacent(self.token.span)
+                && self.may_recover()
             {
                 // Recovery for `expr->suffix`.
                 //
                 // We make sure the `expr` and `->` are adjacent because we don't want to trigger the
                 // recovery for function signature.
-                let span = self.token.span;
-                self.eat_noexpect(&TokenKind::RArrow);
+                self.bump();
+                let span = self.prev_token.span;
                 self.dcx().emit_err(errors::ExprRArrowCall { span });
                 true
             } else {