Work around ICEs during cross-compilation

src/librustc_ast/lib.rs

@@ -19,6 +19,10 @@
 #![feature(unicode_internals)]
 #![recursion_limit = "256"]
 
+// FIXME(#56935): Work around ICEs during cross-compilation.
+#[allow(unused)]
+extern crate rustc_macros;
+
 #[macro_export]
 macro_rules! unwrap_or {
     ($opt:expr, $default:expr) => {

src/librustc_attr/lib.rs

@@ -6,6 +6,10 @@
 
 #![feature(or_patterns)]
 
+// FIXME(#56935): Work around ICEs during cross-compilation.
+#[allow(unused)]
+extern crate rustc_macros;
+
 mod builtin;
 
 pub use builtin::*;

src/librustc_target/lib.rs

@@ -17,6 +17,10 @@
 #![feature(associated_type_bounds)]
 #![feature(exhaustive_patterns)]
 
+// FIXME(#56935): Work around ICEs during cross-compilation.
+#[allow(unused)]
+extern crate rustc_macros;
+
 #[macro_use]
 extern crate log;