Fix unstable Rust code block issue

1 files changed, 1 insertions, 1 deletions

diff --git a/src/doc/rustc-dev-guide/src/traits-lowering-module.md b/src/doc/rustc-dev-guide/src/traits-lowering-module.md
index cb3b4a5f7e7..fbf1d6425d8 100644
--- a/src/doc/rustc-dev-guide/src/traits-lowering-module.md
+++ b/src/doc/rustc-dev-guide/src/traits-lowering-module.md
@@ -26,7 +26,7 @@ Unit tests are located in [`src/test/ui/chalkify`][chalkify]. A good
 example test is [the `lower_impl` test][lower_impl]. At the time of
 this writing, it looked like this:
 
-```rust
+```rust,ignore
 #![feature(rustc_attrs)]
 
 trait Foo { }