Move syntax::ext::hygiene to syntax_pos::hygiene.

src/librustc/hir/map/def_collector.rs

@@ -92,7 +92,7 @@ impl<'a> DefCollector<'a> {
     fn visit_macro_invoc(&mut self, id: NodeId, const_expr: bool) {
         if let Some(ref mut visit) = self.visit_macro_invoc {
             visit(MacroInvocationData {
-                mark: Mark::from_placeholder_id(id),
+                mark: id.placeholder_to_mark(),
                 const_expr: const_expr,
                 def_index: self.parent_def.unwrap(),
             })

src/librustc_resolve/build_reduced_graph.rs

@@ -680,7 +680,7 @@ pub struct BuildReducedGraphVisitor<'a, 'b: 'a> {
 
 impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
     fn visit_invoc(&mut self, id: ast::NodeId) -> &'b InvocationData<'b> {
-        let mark = Mark::from_placeholder_id(id);
+        let mark = id.placeholder_to_mark();
         self.resolver.current_module.unresolved_invocations.borrow_mut().insert(mark);
         let invocation = self.resolver.invocations[&mark];
         invocation.module.set(self.resolver.current_module);

src/libsyntax/ast.rs

@@ -20,7 +20,7 @@ pub use util::ThinVec;
 use syntax_pos::{mk_sp, BytePos, Span, DUMMY_SP, ExpnId};
 use codemap::{respan, Spanned};
 use abi::Abi;
-use ext::hygiene::SyntaxContext;
+use ext::hygiene::{Mark, SyntaxContext};
 use print::pprust;
 use ptr::P;
 use rustc_data_structures::indexed_vec;
@@ -256,6 +256,14 @@ impl NodeId {
     pub fn as_u32(&self) -> u32 {
         self.0
     }
+
+    pub fn placeholder_from_mark(mark: Mark) -> Self {
+        NodeId(mark.as_u32())
+    }
+
+    pub fn placeholder_to_mark(self) -> Mark {
+        Mark::from_u32(self.0)
+    }
 }
 
 impl fmt::Display for NodeId {

src/libsyntax/ext/expand.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use ast::{self, Block, Ident, PatKind, Path};
+use ast::{self, Block, Ident, NodeId, PatKind, Path};
 use ast::{MacStmtStyle, StmtKind, ItemKind};
 use attr::{self, HasAttrs};
 use codemap::{ExpnInfo, NameAndSpan, MacroBang, MacroAttribute};
@@ -321,7 +321,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
         while let Some(expansions) = expansions.pop() {
             for (mark, expansion) in expansions.into_iter().rev() {
                 let derives = derives.remove(&mark).unwrap_or_else(Vec::new);
-                placeholder_expander.add(mark.as_placeholder_id(), expansion, derives);
+                placeholder_expander.add(NodeId::placeholder_from_mark(mark), expansion, derives);
             }
         }
 
@@ -703,7 +703,7 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
                 ..self.cx.current_expansion.clone()
             },
         });
-        placeholder(expansion_kind, mark.as_placeholder_id())
+        placeholder(expansion_kind, NodeId::placeholder_from_mark(mark))
     }
 
     fn collect_bang(&mut self, mac: ast::Mac, span: Span, kind: ExpansionKind) -> Expansion {

src/libsyntax/ext/placeholders.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use ast;
+use ast::{self, NodeId};
 use codemap::{DUMMY_SP, dummy_spanned};
 use ext::base::ExtCtxt;
 use ext::expand::{Expansion, ExpansionKind};
@@ -88,7 +88,7 @@ impl<'a, 'b> PlaceholderExpander<'a, 'b> {
         let mut expansion = expansion.fold_with(self);
         if let Expansion::Items(mut items) = expansion {
             for derive in derives {
-                match self.remove(derive.as_placeholder_id()) {
+                match self.remove(NodeId::placeholder_from_mark(derive)) {
                     Expansion::Items(derived_items) => items.extend(derived_items),
                     _ => unreachable!(),
                 }

src/libsyntax/lib.rs

@@ -136,12 +136,12 @@ pub mod print {
 }
 
 pub mod ext {
+    pub use syntax_pos::hygiene;
     pub mod base;
     pub mod build;
     pub mod derive;
     pub mod expand;
     pub mod placeholders;
-    pub mod hygiene;
     pub mod quote;
     pub mod source_util;
 

src/libsyntax/ext/hygiene.rs → src/libsyntax_pos/hygiene.rs

@@ -15,7 +15,6 @@
 //! and definition contexts*. J. Funct. Program. 22, 2 (March 2012), 181-216.
 //! DOI=10.1017/S0956796812000093 http://dx.doi.org/10.1017/S0956796812000093
 
-use ast::NodeId;
 use std::cell::RefCell;
 use std::collections::HashMap;
 use std::fmt;
@@ -47,17 +46,13 @@ impl Mark {
         Mark(0)
     }
 
-    pub fn from_placeholder_id(id: NodeId) -> Self {
-        Mark(id.as_u32())
-    }
-
-    pub fn as_placeholder_id(self) -> NodeId {
-        NodeId::from_u32(self.0)
-    }
-
     pub fn as_u32(self) -> u32 {
         self.0
     }
+
+    pub fn from_u32(raw: u32) -> Mark {
+        Mark(raw)
+    }
 }
 
 struct HygieneData {

src/libsyntax_pos/lib.rs

@@ -23,6 +23,7 @@
       html_root_url = "https://doc.rust-lang.org/nightly/")]
 #![deny(warnings)]
 
+#![feature(const_fn)]
 #![feature(custom_attribute)]
 #![allow(unused_attributes)]
 #![feature(rustc_private)]
@@ -41,6 +42,8 @@ use serialize::{Encodable, Decodable, Encoder, Decoder};
 extern crate serialize;
 extern crate serialize as rustc_serialize; // used by deriving
 
+pub mod hygiene;
+
 pub type FileName = String;
 
 /// Spans represent a region of code, used for error reporting. Positions in spans