1. move node_id to syntax

2. invert rustc_session & syntax deps
3. drop rustc_session dep in rustc_hir

4 files changed, 50 insertions, 14 deletions

diff --git a/src/libsyntax/Cargo.toml b/src/libsyntax/Cargo.toml
index 2e647d2a1e0..b3e16f740fd 100644
--- a/src/libsyntax/Cargo.toml
+++ b/src/libsyntax/Cargo.toml
@@ -16,9 +16,7 @@ scoped-tls = "1.0"
 rustc_errors = { path = "../librustc_errors" }
 rustc_span = { path = "../librustc_span" }
 rustc_data_structures = { path = "../librustc_data_structures" }
-rustc_feature = { path = "../librustc_feature" }
 rustc_index = { path = "../librustc_index" }
 rustc_lexer = { path = "../librustc_lexer" }
 rustc_macros = { path = "../librustc_macros" }
 smallvec = { version = "1.0", features = ["union", "may_dangle"] }
-rustc_session = { path = "../librustc_session" }
diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index db4fd53fe16..49f559de1b1 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -256,15 +256,7 @@ impl ParenthesizedArgs {
     }
 }
 
-pub use rustc_session::node_id::NodeId;
-
-/// `NodeId` used to represent the root of the crate.
-pub const CRATE_NODE_ID: NodeId = NodeId::from_u32_const(0);
-
-/// When parsing and doing expansions, we initially give all AST nodes this AST
-/// node value. Then later, in the renumber pass, we renumber them to have
-/// small, positive ids.
-pub const DUMMY_NODE_ID: NodeId = NodeId::MAX;
+pub use crate::node_id::{NodeId, CRATE_NODE_ID, DUMMY_NODE_ID};
 
 /// A modifier on a bound, e.g., `?Sized` or `?const Trait`.
 ///
@@ -432,8 +424,6 @@ pub struct WhereEqPredicate {
     pub rhs_ty: P<Ty>,
 }
 
-pub use rustc_session::parse::CrateConfig;
-
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct Crate {
     pub module: Mod,
diff --git a/src/libsyntax/lib.rs b/src/libsyntax/lib.rs
index 9fcc7a1dfa8..a0b2d50cef3 100644
--- a/src/libsyntax/lib.rs
+++ b/src/libsyntax/lib.rs
@@ -41,8 +41,8 @@ pub mod attr;
 pub mod entry;
 pub mod expand;
 pub mod mut_visit;
+pub mod node_id;
 pub mod ptr;
-pub use rustc_session::parse as sess;
 pub mod token;
 pub mod tokenstream;
 pub mod visit;
diff --git a/src/libsyntax/node_id.rs b/src/libsyntax/node_id.rs
new file mode 100644
index 00000000000..58d2334a7b1
--- /dev/null
+++ b/src/libsyntax/node_id.rs
@@ -0,0 +1,48 @@
+use rustc_serialize::{Decoder, Encoder};
+use rustc_span::ExpnId;
+use std::fmt;
+
+rustc_index::newtype_index! {
+    pub struct NodeId {
+        ENCODABLE = custom
+        DEBUG_FORMAT = "NodeId({})"
+    }
+}
+
+rustc_data_structures::define_id_collections!(NodeMap, NodeSet, NodeId);
+
+/// `NodeId` used to represent the root of the crate.
+pub const CRATE_NODE_ID: NodeId = NodeId::from_u32_const(0);
+
+/// When parsing and doing expansions, we initially give all AST nodes this AST
+/// node value. Then later, in the renumber pass, we renumber them to have
+/// small, positive ids.
+pub const DUMMY_NODE_ID: NodeId = NodeId::MAX;
+
+impl NodeId {
+    pub fn placeholder_from_expn_id(expn_id: ExpnId) -> Self {
+        NodeId::from_u32(expn_id.as_u32())
+    }
+
+    pub fn placeholder_to_expn_id(self) -> ExpnId {
+        ExpnId::from_u32(self.as_u32())
+    }
+}
+
+impl fmt::Display for NodeId {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(&self.as_u32(), f)
+    }
+}
+
+impl rustc_serialize::UseSpecializedEncodable for NodeId {
+    fn default_encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
+        s.emit_u32(self.as_u32())
+    }
+}
+
+impl rustc_serialize::UseSpecializedDecodable for NodeId {
+    fn default_decode<D: Decoder>(d: &mut D) -> Result<NodeId, D::Error> {
+        d.read_u32().map(NodeId::from_u32)
+    }
+}