Rollup merge of rust-lang#48086 - Zoxc:gen-fix, r=nikomatsakis

Fix visitation order of calls so that it matches execution order. Fixes rust-lang#48048

r? @nikomatsakis

Author: kennytm

src/librustc/hir/intravisit.rs

@@ -965,8 +965,8 @@ pub fn walk_expr<'v, V: Visitor<'v>>(visitor: &mut V, expression: &'v Expr) {
             walk_list!(visitor, visit_expr, subexpressions);
         }
         ExprCall(ref callee_expression, ref arguments) => {
+            visitor.visit_expr(callee_expression);
             walk_list!(visitor, visit_expr, arguments);
-            visitor.visit_expr(callee_expression)
         }
         ExprMethodCall(ref segment, _, ref arguments) => {
             visitor.visit_path_segment(expression.span, segment);

src/test/ui/generator/issue-48048.rs

@@ -0,0 +1,23 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(generators)]
+
+fn main() {
+    let x = (|_| {},);
+
+    || {
+        let x = x;
+
+        x.0({ //~ ERROR borrow may still be in use when generator yields
+            yield;
+        });
+    };
+}

src/test/ui/generator/issue-48048.stderr

@@ -0,0 +1,10 @@
+error[E0626]: borrow may still be in use when generator yields
+  --> $DIR/issue-48048.rs:19:9
+   |
+19 |         x.0({ //~ ERROR borrow may still be in use when generator yields
+   |         ^^^
+20 |             yield;
+   |             ----- possible yield occurs here
+
+error: aborting due to previous error
+