Begin nightly-ifying rustc_type_ir

compiler/rustc_index/Cargo.toml

@@ -6,6 +6,7 @@ edition = "2021"
 [dependencies]
 # tidy-alphabetical-start
 arrayvec = { version = "0.7", default-features = false }
+rustc_index_macros = { path = "../rustc_index_macros", default-features = false }
 rustc_macros = { path = "../rustc_macros", optional = true }
 rustc_serialize = { path = "../rustc_serialize", optional = true }
 smallvec = "1.8.1"
@@ -14,5 +15,5 @@ smallvec = "1.8.1"
 [features]
 # tidy-alphabetical-start
 default = ["nightly"]
-nightly = ["rustc_serialize", "rustc_macros"]
+nightly = ["rustc_serialize", "rustc_macros", "rustc_index_macros/nightly"]
 # tidy-alphabetical-end

compiler/rustc_index/src/lib.rs

@@ -25,8 +25,7 @@ mod vec;
 
 pub use {idx::Idx, slice::IndexSlice, vec::IndexVec};
 
-#[cfg(feature = "rustc_macros")]
-pub use rustc_macros::newtype_index;
+pub use rustc_index_macros::newtype_index;
 
 /// Type size assertion. The first argument is a type and the second argument is its expected size.
 ///

compiler/rustc_index/src/vec/tests.rs

@@ -1,7 +1,7 @@
 // Allows the macro invocation below to work
 use crate as rustc_index;
 
-rustc_macros::newtype_index! {
+crate::newtype_index! {
     #[max = 0xFFFF_FFFA]
     struct MyIdx {}
 }