Preserve yield position during pretty printing

Author: eholk

src/utils.rs

@@ -485,7 +485,7 @@ pub(crate) fn is_block_expr(context: &RewriteContext<'_>, expr: &ast::Expr, repr
         | ast::ExprKind::Index(_, ref expr, _)
         | ast::ExprKind::Unary(_, ref expr)
         | ast::ExprKind::Try(ref expr)
-        | ast::ExprKind::Yield(Some(ref expr)) => is_block_expr(context, expr, repr),
+        | ast::ExprKind::Yield(Some(ref expr), _) => is_block_expr(context, expr, repr),
         ast::ExprKind::Closure(ref closure) => is_block_expr(context, &closure.body, repr),
         // This can only be a string lit
         ast::ExprKind::Lit(_) => {
@@ -515,7 +515,7 @@ pub(crate) fn is_block_expr(context: &RewriteContext<'_>, expr: &ast::Expr, repr
         | ast::ExprKind::Tup(..)
         | ast::ExprKind::Use(..)
         | ast::ExprKind::Type(..)
-        | ast::ExprKind::Yield(None)
+        | ast::ExprKind::Yield(None, _)
         | ast::ExprKind::Underscore => false,
     }
 }