Switch to in-tree rustc dependencies with a cfg flag

crates/rustc-dependencies/src/lib.rs

@@ -0,0 +1,39 @@
+//! A wrapper around rustc internal crates, which enables switching between compiler provided
+//! ones and stable ones published in crates.io
+
+#![cfg_attr(feature = "in-rust-tree", feature(rustc_private))]
+
+#[cfg(feature = "in-rust-tree")]
+extern crate rustc_lexer;
+
+#[cfg(feature = "in-rust-tree")]
+pub mod lexer {
+    pub use ::rustc_lexer::*;
+}
+
+#[cfg(not(feature = "in-rust-tree"))]
+pub mod lexer {
+    pub use ::ra_ap_rustc_lexer::*;
+}
+
+#[cfg(feature = "in-rust-tree")]
+extern crate rustc_parse_format;
+
+#[cfg(feature = "in-rust-tree")]
+pub mod parse_format {
+    pub use ::rustc_parse_format::*;
+}
+
+#[cfg(not(feature = "in-rust-tree"))]
+pub mod parse_format {
+    pub use ::ra_ap_rustc_parse_format::*;
+}
+
+// Upstream broke this for us so we can't update it
+pub mod abi {
+    pub use ::hkalbasi_rustc_ap_rustc_abi::*;
+}
+
+pub mod index {
+    pub use ::hkalbasi_rustc_ap_rustc_index::*;
+}