fix some comments

Author: nx2k3

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -165,8 +165,6 @@ enum IsStandalone {
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 enum IncOrDec {
     Inc,
-    // FIXME: `i--` recovery isn't implemented yet
-    // #[allow(dead_code)]
     Dec,
 }
 
@@ -1331,7 +1329,7 @@ impl<'a> Parser<'a> {
 
         Ok(())
     }
-    #[allow(dead_code)]
+
     pub(super) fn recover_from_prefix_increment(
         &mut self,
         operand_expr: P<Expr>,
@@ -1342,7 +1340,7 @@ impl<'a> Parser<'a> {
         let kind = IncDecRecovery { standalone, op: IncOrDec::Inc, fixity: UnaryFixity::Pre };
         self.recover_from_inc_dec(operand_expr, kind, op_span)
     }
-    #[allow(dead_code)]
+
     pub(super) fn recover_from_postfix_increment(
         &mut self,
         operand_expr: P<Expr>,

compiler/rustc_parse/src/parser/expr.rs

@@ -286,7 +286,7 @@ impl<'a> Parser<'a> {
                 && self.prev_token.span.between(self.token.span).is_empty()
             {
                 let op_span = self.prev_token.span.to(self.token.span);
-                // Eat the second `+`
+                // Eat the second `-`
                 self.bump();
                 lhs = self.recover_from_postfix_decrement(lhs, op_span, starts_stmt)?;
                 continue;
@@ -602,14 +602,14 @@ impl<'a> Parser<'a> {
                 let operand_expr = this.parse_dot_or_call_expr(Default::default())?;
                 this.recover_from_prefix_increment(operand_expr, pre_span, starts_stmt)
             }
-            // Recover from `++x`:
+            // Recover from `--x`:
             token::BinOp(token::Minus)
                 if this.look_ahead(1, |t| *t == token::BinOp(token::Minus)) =>
             {
                 let starts_stmt = this.prev_token == token::Semi
                     || this.prev_token == token::CloseDelim(Delimiter::Brace);
                 let pre_span = this.token.span.to(this.look_ahead(1, |t| t.span));
-                // Eat both `+`s.
+                // Eat both `-`s.
                 this.bump();
                 this.bump();