After expansion, fold and renumber AST nodes to ensure that each AST node has a

unique id. Fixes numerous bugs in macro expansion and deriving. Add two
representative tests.

Fixes rust-lang#7971
Fixes rust-lang#6304
Fixes rust-lang#8367
Fixes rust-lang#8754
Fixes rust-lang#8852

Author: nikomatsakis

src/librustc/driver/driver.rs

@@ -190,6 +190,9 @@ pub fn phase_2_configure_and_expand(sess: Session,
     crate = time(time_passes, ~"std injection", ||
                  front::std_inject::maybe_inject_libstd_ref(sess, crate));
 
+    crate = time(time_passes, ~"renumbering AST", ||
+                 front::renumber::renumber_crate(sess, crate));
+
     return crate;
 }
 
@@ -207,6 +210,7 @@ pub fn phase_3_run_analysis_passes(sess: Session,
                                    crate: @ast::Crate) -> CrateAnalysis {
 
     let time_passes = sess.time_passes();
+
     let ast_map = time(time_passes, ~"ast indexing", ||
                        syntax::ast_map::map_crate(sess.diagnostic(), crate));
 

src/librustc/front/renumber.rs

@@ -0,0 +1,33 @@
+// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use driver::session::Session;
+
+use syntax::ast;
+use syntax::fold;
+
+static STD_VERSION: &'static str = "0.8-pre";
+
+pub fn renumber_crate(_sess: Session, crate: @ast::Crate) -> @ast::Crate {
+    let counter = @mut 0;
+
+    let precursor = @fold::AstFoldFns {
+        new_id: |_old_id| {
+            let new_id = *counter;
+            *counter += 1;
+            new_id
+        },
+        ..*fold::default_ast_fold()
+    };
+
+    let fold = fold::make_fold(precursor);
+
+    @fold.fold_crate(crate)
+}

src/librustc/middle/resolve.rs

@@ -5401,7 +5401,15 @@ impl Resolver {
 
     pub fn record_def(@mut self, node_id: NodeId, def: Def) {
         debug!("(recording def) recording %? for %?", def, node_id);
-        self.def_map.insert(node_id, def);
+        do self.def_map.insert_or_update_with(node_id, def) |_, old_value| {
+            // Resolve appears to "resolve" the same ID multiple
+            // times, so here is a sanity check it at least comes to
+            // the same conclusion! - nmatsakis
+            if def != *old_value {
+                self.session.bug(fmt!("node_id %? resolved first to %? \
+                                      and then %?", node_id, *old_value, def));
+            }
+        };
     }
 
     pub fn enforce_default_binding_mode(@mut self,

src/librustc/rustc.rs

@@ -80,6 +80,7 @@ pub mod front {
     pub mod config;
     pub mod test;
     pub mod std_inject;
+    pub mod renumber;
 }
 
 pub mod back {