diff --git a/src/libextra/arc.rs b/src/libextra/arc.rs
index 1de2003aa99d5..151ae678b0908 100644
--- a/src/libextra/arc.rs
+++ b/src/libextra/arc.rs
@@ -200,15 +200,13 @@ pub impl<T:Owned> MutexARC<T> {
      */
     #[inline(always)]
     unsafe fn access<U>(&self, blk: &fn(x: &mut T) -> U) -> U {
-        unsafe {
-            let state = self.x.get();
-            // Borrowck would complain about this if the function were
-            // not already unsafe. See borrow_rwlock, far below.
-            do (&(*state).lock).lock {
-                check_poison(true, (*state).failed);
-                let _z = PoisonOnFail(&mut (*state).failed);
-                blk(&mut (*state).data)
-            }
+        let state = self.x.get();
+        // Borrowck would complain about this if the function were
+        // not already unsafe. See borrow_rwlock, far below.
+        do (&(*state).lock).lock {
+            check_poison(true, (*state).failed);
+            let _z = PoisonOnFail(&mut (*state).failed);
+            blk(&mut (*state).data)
         }
     }
 
diff --git a/src/libextra/bitv.rs b/src/libextra/bitv.rs
index 672a61b1ad8dd..3df4d36345547 100644
--- a/src/libextra/bitv.rs
+++ b/src/libextra/bitv.rs
@@ -13,7 +13,6 @@ use core::prelude::*;
 use core::cmp;
 use core::ops;
 use core::uint;
-use core::vec::from_elem;
 use core::vec;
 
 struct SmallBitv {
diff --git a/src/libextra/flate.rs b/src/libextra/flate.rs
index 076126e04329c..39f8b43537de6 100644
--- a/src/libextra/flate.rs
+++ b/src/libextra/flate.rs
@@ -16,8 +16,6 @@ Simple compression
 
 #[allow(missing_doc)];
 
-use core::prelude::*;
-
 use core::libc::{c_void, size_t, c_int};
 use core::libc;
 use core::vec;
diff --git a/src/libextra/std.rc b/src/libextra/std.rc
index a81ab3005f6d1..aa31cf04846e5 100644
--- a/src/libextra/std.rc
+++ b/src/libextra/std.rc
@@ -37,6 +37,7 @@ not required in or otherwise suitable for the core library.
 
 extern mod core(name = "std", vers = "0.7-pre");
 
+#[cfg(stage0)]
 use core::{str, unstable};
 use core::str::{StrSlice, OwnedStr};
 
diff --git a/src/libextra/test.rs b/src/libextra/test.rs
index 59c6a12e03643..6f6afc6b7b509 100644
--- a/src/libextra/test.rs
+++ b/src/libextra/test.rs
@@ -24,13 +24,11 @@ use term;
 use core::comm::{stream, SharedChan};
 use core::either;
 use core::io;
-use core::num;
 use core::option;
 use core::result;
 use core::str;
 use core::task;
 use core::to_str::ToStr;
-use core::u64;
 use core::uint;
 use core::vec;
 
diff --git a/src/libextra/uv_global_loop.rs b/src/libextra/uv_global_loop.rs
index 8752f675a8d27..ae59f91cf83d2 100644
--- a/src/libextra/uv_global_loop.rs
+++ b/src/libextra/uv_global_loop.rs
@@ -16,9 +16,7 @@ use iotask = uv_iotask;
 use uv_iotask::{IoTask, spawn_iotask};
 
 use core::comm::Chan;
-use core::libc;
 use core::option::{Some, None};
-use core::str;
 use core::task::task;
 use core::unstable::global::{global_data_clone_create, global_data_clone};
 use core::unstable::weak_task::weaken_task;
diff --git a/src/librustc/back/link.rs b/src/librustc/back/link.rs
index 02c0b19e56553..f4c72cd5f565d 100644
--- a/src/librustc/back/link.rs
+++ b/src/librustc/back/link.rs
@@ -106,9 +106,7 @@ pub mod jit {
     use metadata::cstore;
 
     use core::cast;
-    use core::char;
     use core::libc::c_int;
-    use core::os;
     use core::ptr;
     use core::str;
 
diff --git a/src/librustc/back/passes.rs b/src/librustc/back/passes.rs
index cc9fe57715918..a752453804425 100644
--- a/src/librustc/back/passes.rs
+++ b/src/librustc/back/passes.rs
@@ -12,7 +12,7 @@ use core::prelude::*;
 use core::str;
 use core::io;
 
-use driver::session::{OptLevel, No, Less, Default, Aggressive};
+use driver::session::{OptLevel, No, Less, Aggressive};
 use driver::session::{Session};
 use lib::llvm::{PassRef, ModuleRef,PassManagerRef,TargetDataRef};
 use lib::llvm::llvm;
diff --git a/src/librustc/middle/trans/foreign.rs b/src/librustc/middle/trans/foreign.rs
index a7a8cd088d2b0..196b4e5338fec 100644
--- a/src/librustc/middle/trans/foreign.rs
+++ b/src/librustc/middle/trans/foreign.rs
@@ -34,7 +34,6 @@ use middle::ty;
 use middle::ty::FnSig;
 use util::ppaux::ty_to_str;
 
-use core::str;
 use core::uint;
 use core::vec;
 use syntax::codemap::span;
diff --git a/src/librustc/middle/trans/glue.rs b/src/librustc/middle/trans/glue.rs
index 013a40c95c54d..b1826b9b8e0d3 100644
--- a/src/librustc/middle/trans/glue.rs
+++ b/src/librustc/middle/trans/glue.rs
@@ -19,7 +19,6 @@ use back::link::*;
 use driver::session;
 use lib;
 use lib::llvm::{llvm, ValueRef, TypeRef, True};
-use lib::llvm::type_to_str;
 use middle::trans::adt;
 use middle::trans::base::*;
 use middle::trans::callee;
diff --git a/src/librustc/middle/ty.rs b/src/librustc/middle/ty.rs
index 8815259b3cc7b..108ea333e1a97 100644
--- a/src/librustc/middle/ty.rs
+++ b/src/librustc/middle/ty.rs
@@ -37,7 +37,6 @@ use core::to_bytes;
 use core::u32;
 use core::uint;
 use core::vec;
-use extra::smallintmap::SmallIntMap;
 use syntax::ast::*;
 use syntax::ast_util::is_local;
 use syntax::ast_util;
diff --git a/src/librustc/rustc.rc b/src/librustc/rustc.rc
index 07056a10f3a94..dfd033ea089ff 100644
--- a/src/librustc/rustc.rc
+++ b/src/librustc/rustc.rc
@@ -53,6 +53,7 @@ use middle::lint;
 use core::io;
 use core::os;
 use core::result;
+#[cfg(not(stage0))]
 use core::str;
 use core::task;
 use core::uint;
diff --git a/src/libstd/cell.rs b/src/libstd/cell.rs
index f6d4e966db9ea..f43f2a1028d74 100644
--- a/src/libstd/cell.rs
+++ b/src/libstd/cell.rs
@@ -11,7 +11,6 @@
 //! A mutable, nullable memory location
 
 use cast::transmute_mut;
-use cmp;
 use prelude::*;
 use util::replace;
 
diff --git a/src/libstd/iterator.rs b/src/libstd/iterator.rs
index b13c4ca23e6cc..7be9e8c354e91 100644
--- a/src/libstd/iterator.rs
+++ b/src/libstd/iterator.rs
@@ -20,7 +20,6 @@ implementing the `Iterator` trait.
 use cmp;
 use iter;
 use num::{Zero, One};
-use num;
 use prelude::*;
 
 /// An interface for dealing with "external iterators". These types of iterators
diff --git a/src/libstd/local_data.rs b/src/libstd/local_data.rs
index 6227f9ad3888e..af148cefc7d49 100644
--- a/src/libstd/local_data.rs
+++ b/src/libstd/local_data.rs
@@ -29,7 +29,6 @@ magic.
 use prelude::*;
 
 use task::local_data_priv::{local_get, local_pop, local_modify, local_set, Handle};
-use task;
 
 /**
  * Indexes a task-local data slot. The function's code pointer is used for
diff --git a/src/libstd/rand/distributions.rs b/src/libstd/rand/distributions.rs
index a66e35f68df7d..cf2733976c487 100644
--- a/src/libstd/rand/distributions.rs
+++ b/src/libstd/rand/distributions.rs
@@ -21,7 +21,6 @@
 // could implement VIZIGNOR the ZIGNOR paper for more speed.
 
 use f64;
-use prelude::*;
 use rand::{Rng,Rand};
 
 mod ziggurat_tables;
diff --git a/src/libstd/rt/task.rs b/src/libstd/rt/task.rs
index 12c683120c8da..eb7282bae0597 100644
--- a/src/libstd/rt/task.rs
+++ b/src/libstd/rt/task.rs
@@ -20,7 +20,6 @@ use prelude::*;
 use rt::local::Local;
 use rt::logging::StdErrLogger;
 use super::local_heap::LocalHeap;
-use super::sched::Scheduler;
 
 pub struct Task {
     heap: LocalHeap,
diff --git a/src/libstd/task/mod.rs b/src/libstd/task/mod.rs
index 28fb73e6eef52..2f866576e6394 100644
--- a/src/libstd/task/mod.rs
+++ b/src/libstd/task/mod.rs
@@ -37,17 +37,13 @@
 
 use prelude::*;
 
-use cast;
 use cell::Cell;
 use cmp::Eq;
 use comm::{stream, Chan, GenericChan, GenericPort, Port};
-use comm;
-use ptr;
 use result::Result;
 use result;
 use rt::{context, OldTaskContext};
 use task::rt::{task_id, sched_id};
-use task;
 use unstable::finally::Finally;
 use util::replace;
 use util;
diff --git a/src/libstd/task/spawn.rs b/src/libstd/task/spawn.rs
index 0b345b88d6261..f1eaf1bf2ee11 100644
--- a/src/libstd/task/spawn.rs
+++ b/src/libstd/task/spawn.rs
@@ -79,7 +79,6 @@ use cast;
 use cell::Cell;
 use container::Map;
 use comm::{Chan, GenericChan};
-use comm;
 use ptr;
 use hashmap::HashSet;
 use task::local_data_priv::{local_get, local_set, OldHandle};
@@ -89,7 +88,6 @@ use task::{Failure, ManualThreads, PlatformThread, SchedOpts, SingleThreaded};
 use task::{Success, TaskOpts, TaskResult, ThreadPerCore, ThreadPerTask};
 use task::{ExistingScheduler, SchedulerHandle};
 use task::unkillable;
-use task;
 use uint;
 use util;
 use unstable::sync::{Exclusive, exclusive};
diff --git a/src/libstd/trie.rs b/src/libstd/trie.rs
index 460f29d597ac4..e5b1385974e23 100644
--- a/src/libstd/trie.rs
+++ b/src/libstd/trie.rs
@@ -10,8 +10,6 @@
 
 //! An ordered map and set for integer keys implemented as a radix trie
 
-use local_data;
-use os;
 use prelude::*;
 use uint;
 use util::{swap, replace};
diff --git a/src/libstd/unstable/mod.rs b/src/libstd/unstable/mod.rs
index 1f73aa02b017b..12c7d45345a21 100644
--- a/src/libstd/unstable/mod.rs
+++ b/src/libstd/unstable/mod.rs
@@ -14,7 +14,6 @@ use comm::{GenericChan, GenericPort};
 use comm;
 use libc;
 use prelude::*;
-use ptr;
 use task;
 
 pub mod at_exit;
diff --git a/src/libstd/util.rs b/src/libstd/util.rs
index 18fc6af3ac66b..2b61356129e01 100644
--- a/src/libstd/util.rs
+++ b/src/libstd/util.rs
@@ -11,7 +11,6 @@
 //! Miscellaneous helpers for common patterns.
 
 use cast;
-use local_data;
 use ptr;
 use prelude::*;
 use unstable::intrinsics;
diff --git a/src/libsyntax/ext/pipes/ast_builder.rs b/src/libsyntax/ext/pipes/ast_builder.rs
index 37d5e0206cb02..337df6c0124fe 100644
--- a/src/libsyntax/ext/pipes/ast_builder.rs
+++ b/src/libsyntax/ext/pipes/ast_builder.rs
@@ -19,7 +19,6 @@ use ast::ident;
 use ast;
 use codemap::span;
 
-use core::str;
 use core::vec;
 
 // Transitional reexports so qquote can find the paths it is looking for
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 27dfc2c0a46d1..208ed1c41c865 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -92,7 +92,6 @@ use parse::{new_sub_parser_from_file, next_node_id, ParseSess};
 use opt_vec;
 use opt_vec::OptVec;
 
-use core::char;
 use core::either::Either;
 use core::either;
 use core::hashmap::HashSet;
diff --git a/src/libsyntax/parse/token.rs b/src/libsyntax/parse/token.rs
index b1a385ada0734..c4ee9f232582a 100644
--- a/src/libsyntax/parse/token.rs
+++ b/src/libsyntax/parse/token.rs
@@ -19,11 +19,9 @@ use util::interner;
 use core::cast;
 use core::char;
 use core::cmp::Equiv;
-use core::hashmap::HashSet;
 use core::local_data;
 use core::str;
 use core::to_bytes;
-use core::vec;
 
 #[deriving(Encodable, Decodable, Eq)]
 pub enum binop {