rustc: Obsolete the `@` syntax entirely

This removes all remnants of `@` pointers from rustc. Additionally, this removes
the `GC` structure from the prelude as it seems odd exporting an experimental
type in the prelude by default.

Closes #14193
[breaking-change]

1 files changed, 1 insertions, 1 deletions

diff --git a/src/libsyntax/ast_map.rs b/src/libsyntax/ast_map.rs
index d78c9c2edc3..828e9ab12c2 100644
--- a/src/libsyntax/ast_map.rs
+++ b/src/libsyntax/ast_map.rs
@@ -20,7 +20,7 @@ use util::small_vector::SmallVector;
 
 use std::cell::RefCell;
 use std::fmt;
-use std::gc::Gc;
+use std::gc::{Gc, GC};
 use std::iter;
 use std::slice;