Simplify Parser::parse_expr_dot_or_call.

The call in `parse_expr_prefix` for the `++` case passes an empty
`attrs`, but it doesn' need to. This commit changes it to pass the
parsed `attrs`, which doesn't change any behaviour. As a result,
`parse_expr_dot_or_call` no longer needs an `Option` argument, and no
longer needs to call `parse_or_use_outer_attributes`.

Author: nnethercote

compiler/rustc_parse/src/parser/expr.rs

@@ -629,7 +629,7 @@ impl<'a> Parser<'a> {
                 this.bump();
                 this.bump();
 
-                let operand_expr = this.parse_expr_dot_or_call(Default::default())?;
+                let operand_expr = this.parse_expr_dot_or_call(attrs)?;
                 this.recover_from_prefix_increment(operand_expr, pre_span, starts_stmt)
             }
             token::Ident(..) if this.token.is_keyword(kw::Box) => {
@@ -638,7 +638,7 @@ impl<'a> Parser<'a> {
             token::Ident(..) if this.may_recover() && this.is_mistaken_not_ident_negation() => {
                 make_it!(this, attrs, |this, _| this.recover_not_expr(lo))
             }
-            _ => return this.parse_expr_dot_or_call(Some(attrs)),
+            _ => return this.parse_expr_dot_or_call(attrs),
         }
     }
 
@@ -927,8 +927,7 @@ impl<'a> Parser<'a> {
     }
 
     /// Parses `a.b` or `a(13)` or `a[4]` or just `a`.
-    fn parse_expr_dot_or_call(&mut self, attrs: Option<AttrWrapper>) -> PResult<'a, P<Expr>> {
-        let attrs = self.parse_or_use_outer_attributes(attrs)?;
+    fn parse_expr_dot_or_call(&mut self, attrs: AttrWrapper) -> PResult<'a, P<Expr>> {
         self.collect_tokens_for_expr(attrs, |this, attrs| {
             let base = this.parse_expr_bottom()?;
             let span = this.interpolated_or_expr_span(&base);