diff --git a/src/liballoc/arc.rs b/src/liballoc/arc.rs
index f9f6de2df5876..32fe2bb0a3201 100644
--- a/src/liballoc/arc.rs
+++ b/src/liballoc/arc.rs
@@ -12,20 +12,22 @@
 
 //! Threadsafe reference-counted boxes (the `Arc<T>` type).
 //!
-//! The `Arc<T>` type provides shared ownership of an immutable value. Destruction is
-//! deterministic, and will occur as soon as the last owner is gone. It is marked as `Send` because
-//! it uses atomic reference counting.
+//! The `Arc<T>` type provides shared ownership of an immutable value.
+//! Destruction is deterministic, and will occur as soon as the last owner is
+//! gone. It is marked as `Send` because it uses atomic reference counting.
 //!
-//! If you do not need thread-safety, and just need shared ownership, consider the [`Rc<T>`
-//! type](../rc/struct.Rc.html). It is the same as `Arc<T>`, but does not use atomics, making it
-//! both thread-unsafe as well as significantly faster when updating the reference count.
+//! If you do not need thread-safety, and just need shared ownership, consider
+//! the [`Rc<T>` type](../rc/struct.Rc.html). It is the same as `Arc<T>`, but
+//! does not use atomics, making it both thread-unsafe as well as significantly
+//! faster when updating the reference count.
 //!
-//! The `downgrade` method can be used to create a non-owning `Weak<T>` pointer to the box. A
-//! `Weak<T>` pointer can be upgraded to an `Arc<T>` pointer, but will return `None` if the value
-//! has already been dropped.
+//! The `downgrade` method can be used to create a non-owning `Weak<T>` pointer
+//! to the box. A `Weak<T>` pointer can be upgraded to an `Arc<T>` pointer, but
+//! will return `None` if the value has already been dropped.
 //!
-//! For example, a tree with parent pointers can be represented by putting the nodes behind strong
-//! `Arc<T>` pointers, and then storing the parent pointers as `Weak<T>` pointers.
+//! For example, a tree with parent pointers can be represented by putting the
+//! nodes behind strong `Arc<T>` pointers, and then storing the parent pointers
+//! as `Weak<T>` pointers.
 //!
 //! # Examples
 //!
@@ -87,8 +89,9 @@ use heap::deallocate;
 ///
 /// # Example
 ///
-/// In this example, a large vector of floats is shared between several tasks. With simple pipes,
-/// without `Arc`, a copy would have to be made for each task.
+/// In this example, a large vector of floats is shared between several tasks.
+/// With simple pipes, without `Arc`, a copy would have to be made for each
+/// task.
 ///
 /// ```rust
 /// use std::sync::Arc;
diff --git a/src/libcollections/bit.rs b/src/libcollections/bit.rs
index c627574057969..99f650db44969 100644
--- a/src/libcollections/bit.rs
+++ b/src/libcollections/bit.rs
@@ -1730,6 +1730,7 @@ impl BitvSet {
     }
 }
 
+#[stable(feature = "rust1", since = "1.0.0")]
 impl fmt::Debug for BitvSet {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         try!(write!(fmt, "BitvSet {{"));
diff --git a/src/libcollections/enum_set.rs b/src/libcollections/enum_set.rs
index b542259eba0dd..c70794262c967 100644
--- a/src/libcollections/enum_set.rs
+++ b/src/libcollections/enum_set.rs
@@ -31,6 +31,7 @@ pub struct EnumSet<E> {
 
 impl<E> Copy for EnumSet<E> {}
 
+#[stable(feature = "rust1", since = "1.0.0")]
 impl<E:CLike + fmt::Debug> fmt::Debug for EnumSet<E> {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         try!(write!(fmt, "EnumSet {{"));
diff --git a/src/libcollections/string.rs b/src/libcollections/string.rs
index 8f7920fe1c44b..ae52eff0111b1 100644
--- a/src/libcollections/string.rs
+++ b/src/libcollections/string.rs
@@ -938,11 +938,14 @@ impl FromStr for String {
 }
 
 /// A generic trait for converting a value to a string
+#[stable(feature = "rust1", since = "1.0.0")]
 pub trait ToString {
     /// Converts the value of `self` to an owned string
+    #[stable(feature = "rust1", since = "1.0.0")]
     fn to_string(&self) -> String;
 }
 
+#[stable(feature = "rust1", since = "1.0.0")]
 impl<T: fmt::Display + ?Sized> ToString for T {
     #[inline]
     fn to_string(&self) -> String {
@@ -979,6 +982,7 @@ impl<'a> Str for CowString<'a> {
     }
 }
 
+#[stable(feature = "rust1", since = "1.0.0")]
 impl fmt::Writer for String {
     #[inline]
     fn write_str(&mut self, s: &str) -> fmt::Result {
diff --git a/src/libcollections/vec.rs b/src/libcollections/vec.rs
index 336a3d7521a19..f57bffa190078 100644
--- a/src/libcollections/vec.rs
+++ b/src/libcollections/vec.rs
@@ -1546,13 +1546,6 @@ impl<T: fmt::Debug> fmt::Debug for Vec<T> {
     }
 }
 
-impl<'a> fmt::Writer for Vec<u8> {
-    fn write_str(&mut self, s: &str) -> fmt::Result {
-        self.push_all(s.as_bytes());
-        Ok(())
-    }
-}
-
 ////////////////////////////////////////////////////////////////////////////////
 // Clone-on-write
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/src/libcore/fmt/mod.rs b/src/libcore/fmt/mod.rs
index 8b7a4c677ac75..2ff67ebd550ab 100644
--- a/src/libcore/fmt/mod.rs
+++ b/src/libcore/fmt/mod.rs
@@ -10,7 +10,6 @@
 
 //! Utilities for formatting and printing strings
 
-#![allow(unused_variables)]
 #![stable(feature = "rust1", since = "1.0.0")]
 
 use any;
@@ -27,6 +26,7 @@ use result;
 use slice::SliceExt;
 use slice;
 use str::{self, StrExt};
+use self::rt::v1::Alignment;
 
 pub use self::num::radix;
 pub use self::num::Radix;
@@ -34,10 +34,15 @@ pub use self::num::RadixFmt;
 
 mod num;
 mod float;
-pub mod rt;
 
-#[unstable(feature = "core",
-           reason = "core and I/O reconciliation may alter this definition")]
+#[stable(feature = "rust1", since = "1.0.0")]
+#[doc(hidden)]
+pub mod rt {
+    #[cfg(stage0)] pub use self::v1::*;
+    pub mod v1;
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
 /// The type returned by formatter methods.
 pub type Result = result::Result<(), Error>;
 
@@ -46,8 +51,7 @@ pub type Result = result::Result<(), Error>;
 /// This type does not support transmission of an error other than that an error
 /// occurred. Any extra information must be arranged to be transmitted through
 /// some other means.
-#[unstable(feature = "core",
-           reason = "core and I/O reconciliation may alter this definition")]
+#[stable(feature = "rust1", since = "1.0.0")]
 #[derive(Copy, Debug)]
 pub struct Error;
 
@@ -60,8 +64,7 @@ pub struct Error;
 /// This trait should generally not be implemented by consumers of the standard
 /// library. The `write!` macro accepts an instance of `io::Writer`, and the
 /// `io::Writer` trait is favored over implementing this trait.
-#[unstable(feature = "core",
-           reason = "waiting for core and I/O reconciliation")]
+#[stable(feature = "rust1", since = "1.0.0")]
 pub trait Writer {
     /// Writes a slice of bytes into this writer, returning whether the write
     /// succeeded.
@@ -73,12 +76,14 @@ pub trait Writer {
     /// # Errors
     ///
     /// This function will return an instance of `FormatError` on error.
+    #[stable(feature = "rust1", since = "1.0.0")]
     fn write_str(&mut self, s: &str) -> Result;
 
     /// Glue for usage of the `write!` macro with implementers of this trait.
     ///
     /// This method should generally not be invoked manually, but rather through
     /// the `write!` macro itself.
+    #[stable(feature = "rust1", since = "1.0.0")]
     fn write_fmt(&mut self, args: Arguments) -> Result {
         // This Adapter is needed to allow `self` (of type `&mut
         // Self`) to be cast to a FormatWriter (below) without
@@ -104,18 +109,17 @@ pub trait Writer {
 /// A struct to represent both where to emit formatting strings to and how they
 /// should be formatted. A mutable version of this is passed to all formatting
 /// traits.
-#[unstable(feature = "core",
-           reason = "name may change and implemented traits are also unstable")]
+#[stable(feature = "rust1", since = "1.0.0")]
 pub struct Formatter<'a> {
     flags: uint,
     fill: char,
-    align: rt::Alignment,
+    align: rt::v1::Alignment,
     width: Option<uint>,
     precision: Option<uint>,
 
     buf: &'a mut (Writer+'a),
-    curarg: slice::Iter<'a, Argument<'a>>,
-    args: &'a [Argument<'a>],
+    curarg: slice::Iter<'a, ArgumentV1<'a>>,
+    args: &'a [ArgumentV1<'a>],
 }
 
 // NB. Argument is essentially an optimized partially applied formatting function,
@@ -127,35 +131,40 @@ enum Void {}
 /// family of functions. It contains a function to format the given value. At
 /// compile time it is ensured that the function and the value have the correct
 /// types, and then this struct is used to canonicalize arguments to one type.
-#[unstable(feature = "core",
-           reason = "implementation detail of the `format_args!` macro")]
 #[derive(Copy)]
-pub struct Argument<'a> {
+#[stable(feature = "rust1", since = "1.0.0")]
+#[doc(hidden)]
+pub struct ArgumentV1<'a> {
     value: &'a Void,
     formatter: fn(&Void, &mut Formatter) -> Result,
 }
 
-impl<'a> Argument<'a> {
+impl<'a> ArgumentV1<'a> {
     #[inline(never)]
     fn show_uint(x: &uint, f: &mut Formatter) -> Result {
         Display::fmt(x, f)
     }
 
-    fn new<'b, T>(x: &'b T, f: fn(&T, &mut Formatter) -> Result) -> Argument<'b> {
+    #[doc(hidden)]
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub fn new<'b, T>(x: &'b T,
+                      f: fn(&T, &mut Formatter) -> Result) -> ArgumentV1<'b> {
         unsafe {
-            Argument {
+            ArgumentV1 {
                 formatter: mem::transmute(f),
                 value: mem::transmute(x)
             }
         }
     }
 
-    fn from_uint(x: &uint) -> Argument {
-        Argument::new(x, Argument::show_uint)
+    #[doc(hidden)]
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub fn from_uint(x: &uint) -> ArgumentV1 {
+        ArgumentV1::new(x, ArgumentV1::show_uint)
     }
 
     fn as_uint(&self) -> Option<uint> {
-        if self.formatter as uint == Argument::show_uint as uint {
+        if self.formatter as uint == ArgumentV1::show_uint as uint {
             Some(unsafe { *(self.value as *const _ as *const uint) })
         } else {
             None
@@ -163,14 +172,32 @@ impl<'a> Argument<'a> {
     }
 }
 
+// flags available in the v1 format of format_args
+#[derive(Copy)]
+#[allow(dead_code)] // SignMinus isn't currently used
+enum FlagV1 { SignPlus, SignMinus, Alternate, SignAwareZeroPad, }
+
 impl<'a> Arguments<'a> {
     /// When using the format_args!() macro, this function is used to generate the
     /// Arguments structure.
     #[doc(hidden)] #[inline]
-    #[unstable(feature = "core",
-               reason = "implementation detail of the `format_args!` macro")]
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub fn new_v1(pieces: &'a [&'a str],
+                  args: &'a [ArgumentV1<'a>]) -> Arguments<'a> {
+        Arguments {
+            pieces: pieces,
+            fmt: None,
+            args: args
+        }
+    }
+
+    /// When using the format_args!() macro, this function is used to generate the
+    /// Arguments structure.
+    #[doc(hidden)] #[inline]
+    #[cfg(stage0)]
+    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn new(pieces: &'a [&'a str],
-               args: &'a [Argument<'a>]) -> Arguments<'a> {
+               args: &'a [ArgumentV1<'a>]) -> Arguments<'a> {
         Arguments {
             pieces: pieces,
             fmt: None,
@@ -185,11 +212,28 @@ impl<'a> Arguments<'a> {
     /// created with `argumentuint`. However, failing to do so doesn't cause
     /// unsafety, but will ignore invalid .
     #[doc(hidden)] #[inline]
-    #[unstable(feature = "core",
-               reason = "implementation detail of the `format_args!` macro")]
+    #[cfg(stage0)]
+    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn with_placeholders(pieces: &'a [&'a str],
-                             fmt: &'a [rt::Argument],
-                             args: &'a [Argument<'a>]) -> Arguments<'a> {
+                             fmt: &'a [rt::v1::Argument],
+                             args: &'a [ArgumentV1<'a>]) -> Arguments<'a> {
+        Arguments {
+            pieces: pieces,
+            fmt: Some(fmt),
+            args: args
+        }
+    }
+    /// This function is used to specify nonstandard formatting parameters.
+    /// The `pieces` array must be at least as long as `fmt` to construct
+    /// a valid Arguments structure. Also, any `Count` within `fmt` that is
+    /// `CountIsParam` or `CountIsNextParam` has to point to an argument
+    /// created with `argumentuint`. However, failing to do so doesn't cause
+    /// unsafety, but will ignore invalid .
+    #[doc(hidden)] #[inline]
+    #[cfg(not(stage0))]
+    pub fn new_v1_formatted(pieces: &'a [&'a str],
+                            args: &'a [ArgumentV1<'a>],
+                            fmt: &'a [rt::v1::Argument]) -> Arguments<'a> {
         Arguments {
             pieces: pieces,
             fmt: Some(fmt),
@@ -214,11 +258,11 @@ pub struct Arguments<'a> {
     pieces: &'a [&'a str],
 
     // Placeholder specs, or `None` if all specs are default (as in "{}{}").
-    fmt: Option<&'a [rt::Argument]>,
+    fmt: Option<&'a [rt::v1::Argument]>,
 
     // Dynamic arguments for interpolation, to be interleaved with string
     // pieces. (Every argument is preceded by a string piece.)
-    args: &'a [Argument<'a>],
+    args: &'a [ArgumentV1<'a>],
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -237,20 +281,20 @@ impl<'a> Display for Arguments<'a> {
 
 /// Format trait for the `:?` format. Useful for debugging, all types
 /// should implement this.
-#[unstable(feature = "core",
-           reason = "I/O and core have yet to be reconciled")]
 #[deprecated(since = "1.0.0", reason = "renamed to Debug")]
+#[unstable(feature = "old_fmt")]
 pub trait Show {
     /// Formats the value using the given formatter.
+    #[stable(feature = "rust1", since = "1.0.0")]
     fn fmt(&self, &mut Formatter) -> Result;
 }
 
 /// Format trait for the `:?` format. Useful for debugging, all types
 /// should implement this.
-#[unstable(feature = "core",
-           reason = "I/O and core have yet to be reconciled")]
-#[rustc_on_unimplemented = "`{Self}` cannot be formatted using `:?`; if it is defined in your \
-                            crate, add `#[derive(Debug)]` or manually implement it"]
+#[stable(feature = "rust1", since = "1.0.0")]
+#[rustc_on_unimplemented = "`{Self}` cannot be formatted using `:?`; if it is \
+                            defined in your crate, add `#[derive(Debug)]` or \
+                            manually implement it"]
 #[lang = "debug_trait"]
 pub trait Debug {
     /// Formats the value using the given formatter.
@@ -264,19 +308,20 @@ impl<T: Show + ?Sized> Debug for T {
 
 /// When a value can be semantically expressed as a String, this trait may be
 /// used. It corresponds to the default format, `{}`.
-#[unstable(feature = "core")]
 #[deprecated(since = "1.0.0", reason = "renamed to Display")]
+#[unstable(feature = "old_fmt")]
 pub trait String {
     /// Formats the value using the given formatter.
+    #[stable(feature = "rust1", since = "1.0.0")]
     fn fmt(&self, &mut Formatter) -> Result;
 }
 
 /// When a value can be semantically expressed as a String, this trait may be
 /// used. It corresponds to the default format, `{}`.
-#[unstable(feature = "core",
-           reason = "I/O and core have yet to be reconciled")]
-#[rustc_on_unimplemented = "`{Self}` cannot be formatted with the default formatter; try using \
-                            `:?` instead if you are using a format string"]
+#[rustc_on_unimplemented = "`{Self}` cannot be formatted with the default \
+                            formatter; try using `:?` instead if you are using \
+                            a format string"]
+#[stable(feature = "rust1", since = "1.0.0")]
 pub trait Display {
     /// Formats the value using the given formatter.
     fn fmt(&self, &mut Formatter) -> Result;
@@ -288,58 +333,58 @@ impl<T: String + ?Sized> Display for T {
 }
 
 /// Format trait for the `o` character
-#[unstable(feature = "core",
-           reason = "I/O and core have yet to be reconciled")]
+#[stable(feature = "rust1", since = "1.0.0")]
 pub trait Octal {
     /// Formats the value using the given formatter.
+    #[stable(feature = "rust1", since = "1.0.0")]
     fn fmt(&self, &mut Formatter) -> Result;
 }
 
 /// Format trait for the `b` character
-#[unstable(feature = "core",
-           reason = "I/O and core have yet to be reconciled")]
+#[stable(feature = "rust1", since = "1.0.0")]
 pub trait Binary {
     /// Formats the value using the given formatter.
+    #[stable(feature = "rust1", since = "1.0.0")]
     fn fmt(&self, &mut Formatter) -> Result;
 }
 
 /// Format trait for the `x` character
-#[unstable(feature = "core",
-           reason = "I/O and core have yet to be reconciled")]
+#[stable(feature = "rust1", since = "1.0.0")]
 pub trait LowerHex {
     /// Formats the value using the given formatter.
+    #[stable(feature = "rust1", since = "1.0.0")]
     fn fmt(&self, &mut Formatter) -> Result;
 }
 
 /// Format trait for the `X` character
-#[unstable(feature = "core",
-           reason = "I/O and core have yet to be reconciled")]
+#[stable(feature = "rust1", since = "1.0.0")]
 pub trait UpperHex {
     /// Formats the value using the given formatter.
+    #[stable(feature = "rust1", since = "1.0.0")]
     fn fmt(&self, &mut Formatter) -> Result;
 }
 
 /// Format trait for the `p` character
-#[unstable(feature = "core",
-           reason = "I/O and core have yet to be reconciled")]
+#[stable(feature = "rust1", since = "1.0.0")]
 pub trait Pointer {
     /// Formats the value using the given formatter.
+    #[stable(feature = "rust1", since = "1.0.0")]
     fn fmt(&self, &mut Formatter) -> Result;
 }
 
 /// Format trait for the `e` character
-#[unstable(feature = "core",
-           reason = "I/O and core have yet to be reconciled")]
+#[stable(feature = "rust1", since = "1.0.0")]
 pub trait LowerExp {
     /// Formats the value using the given formatter.
+    #[stable(feature = "rust1", since = "1.0.0")]
     fn fmt(&self, &mut Formatter) -> Result;
 }
 
 /// Format trait for the `E` character
-#[unstable(feature = "core",
-           reason = "I/O and core have yet to be reconciled")]
+#[stable(feature = "rust1", since = "1.0.0")]
 pub trait UpperExp {
     /// Formats the value using the given formatter.
+    #[stable(feature = "rust1", since = "1.0.0")]
     fn fmt(&self, &mut Formatter) -> Result;
 }
 
@@ -351,16 +396,14 @@ pub trait UpperExp {
 ///
 ///   * output - the buffer to write output to
 ///   * args - the precompiled arguments generated by `format_args!`
-#[unstable(feature = "core",
-           reason = "libcore and I/O have yet to be reconciled, and this is an \
-                     implementation detail which should not otherwise be exported")]
+#[stable(feature = "rust1", since = "1.0.0")]
 pub fn write(output: &mut Writer, args: Arguments) -> Result {
     let mut formatter = Formatter {
         flags: 0,
         width: None,
         precision: None,
         buf: output,
-        align: rt::AlignUnknown,
+        align: Alignment::Unknown,
         fill: ' ',
         args: args.args,
         curarg: args.args.iter(),
@@ -402,7 +445,7 @@ impl<'a> Formatter<'a> {
     // First up is the collection of functions used to execute a format string
     // at runtime. This consumes all of the compile-time statics generated by
     // the format! syntax extension.
-    fn run(&mut self, arg: &rt::Argument) -> Result {
+    fn run(&mut self, arg: &rt::v1::Argument) -> Result {
         // Fill in the format parameters into the formatter
         self.fill = arg.format.fill;
         self.align = arg.format.align;
@@ -412,22 +455,22 @@ impl<'a> Formatter<'a> {
 
         // Extract the correct argument
         let value = match arg.position {
-            rt::ArgumentNext => { *self.curarg.next().unwrap() }
-            rt::ArgumentIs(i) => self.args[i],
+            rt::v1::Position::Next => { *self.curarg.next().unwrap() }
+            rt::v1::Position::At(i) => self.args[i],
         };
 
         // Then actually do some printing
         (value.formatter)(value.value, self)
     }
 
-    fn getcount(&mut self, cnt: &rt::Count) -> Option<uint> {
+    fn getcount(&mut self, cnt: &rt::v1::Count) -> Option<uint> {
         match *cnt {
-            rt::CountIs(n) => Some(n),
-            rt::CountImplied => None,
-            rt::CountIsParam(i) => {
+            rt::v1::Count::Is(n) => Some(n),
+            rt::v1::Count::Implied => None,
+            rt::v1::Count::Param(i) => {
                 self.args[i].as_uint()
             }
-            rt::CountIsNextParam => {
+            rt::v1::Count::NextParam => {
                 self.curarg.next().and_then(|arg| arg.as_uint())
             }
         }
@@ -437,8 +480,8 @@ impl<'a> Formatter<'a> {
     // all formatting traits can use.
 
     /// Performs the correct padding for an integer which has already been
-    /// emitted into a byte-array. The byte-array should *not* contain the sign
-    /// for the integer, that will be added by this method.
+    /// emitted into a str. The str should *not* contain the sign for the
+    /// integer, that will be added by this method.
     ///
     /// # Arguments
     ///
@@ -449,27 +492,25 @@ impl<'a> Formatter<'a> {
     ///
     /// This function will correctly account for the flags provided as well as
     /// the minimum width. It will not take precision into account.
-    #[unstable(feature = "core",
-               reason = "definition may change slightly over time")]
+    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn pad_integral(&mut self,
                         is_positive: bool,
                         prefix: &str,
                         buf: &str)
                         -> Result {
         use char::CharExt;
-        use fmt::rt::{FlagAlternate, FlagSignPlus, FlagSignAwareZeroPad};
 
         let mut width = buf.len();
 
         let mut sign = None;
         if !is_positive {
             sign = Some('-'); width += 1;
-        } else if self.flags & (1 << (FlagSignPlus as uint)) != 0 {
+        } else if self.flags & (1 << (FlagV1::SignPlus as uint)) != 0 {
             sign = Some('+'); width += 1;
         }
 
         let mut prefixed = false;
-        if self.flags & (1 << (FlagAlternate as uint)) != 0 {
+        if self.flags & (1 << (FlagV1::Alternate as uint)) != 0 {
             prefixed = true; width += prefix.char_len();
         }
 
@@ -499,16 +540,16 @@ impl<'a> Formatter<'a> {
             }
             // The sign and prefix goes before the padding if the fill character
             // is zero
-            Some(min) if self.flags & (1 << (FlagSignAwareZeroPad as uint)) != 0 => {
+            Some(min) if self.flags & (1 << (FlagV1::SignAwareZeroPad as uint)) != 0 => {
                 self.fill = '0';
                 try!(write_prefix(self));
-                self.with_padding(min - width, rt::AlignRight, |f| {
+                self.with_padding(min - width, Alignment::Right, |f| {
                     f.buf.write_str(buf)
                 })
             }
             // Otherwise, the sign and prefix goes after the padding
             Some(min) => {
-                self.with_padding(min - width, rt::AlignRight, |f| {
+                self.with_padding(min - width, Alignment::Right, |f| {
                     try!(write_prefix(f)); f.buf.write_str(buf)
                 })
             }
@@ -526,8 +567,7 @@ impl<'a> Formatter<'a> {
     ///               is longer than this length
     ///
     /// Notably this function ignored the `flag` parameters
-    #[unstable(feature = "core",
-               reason = "definition may change slightly over time")]
+    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn pad(&mut self, s: &str) -> Result {
         // Make sure there's a fast path up front
         if self.width.is_none() && self.precision.is_none() {
@@ -561,7 +601,7 @@ impl<'a> Formatter<'a> {
             // If we're under both the maximum and the minimum width, then fill
             // up the minimum width with the specified string + some alignment.
             Some(width) => {
-                self.with_padding(width - s.char_len(), rt::AlignLeft, |me| {
+                self.with_padding(width - s.char_len(), Alignment::Left, |me| {
                     me.buf.write_str(s)
                 })
             }
@@ -570,19 +610,20 @@ impl<'a> Formatter<'a> {
 
     /// Runs a callback, emitting the correct padding either before or
     /// afterwards depending on whether right or left alignment is requested.
-    fn with_padding<F>(&mut self, padding: uint, default: rt::Alignment, f: F) -> Result where
-        F: FnOnce(&mut Formatter) -> Result,
+    fn with_padding<F>(&mut self, padding: uint, default: Alignment,
+                       f: F) -> Result
+        where F: FnOnce(&mut Formatter) -> Result,
     {
         use char::CharExt;
         let align = match self.align {
-            rt::AlignUnknown => default,
+            Alignment::Unknown => default,
             _ => self.align
         };
 
         let (pre_pad, post_pad) = match align {
-            rt::AlignLeft => (0, padding),
-            rt::AlignRight | rt::AlignUnknown => (padding, 0),
-            rt::AlignCenter => (padding / 2, (padding + 1) / 2),
+            Alignment::Left => (0, padding),
+            Alignment::Right | Alignment::Unknown => (padding, 0),
+            Alignment::Center => (padding / 2, (padding + 1) / 2),
         };
 
         let mut fill = [0u8; 4];
@@ -604,23 +645,20 @@ impl<'a> Formatter<'a> {
 
     /// Writes some data to the underlying buffer contained within this
     /// formatter.
-    #[unstable(feature = "core",
-               reason = "reconciling core and I/O may alter this definition")]
+    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn write_str(&mut self, data: &str) -> Result {
         self.buf.write_str(data)
     }
 
     /// Writes some formatted information into this instance
-    #[unstable(feature = "core",
-               reason = "reconciling core and I/O may alter this definition")]
+    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn write_fmt(&mut self, fmt: Arguments) -> Result {
         write(self.buf, fmt)
     }
 
     /// Flags for formatting (packed version of rt::Flag)
-    #[unstable(feature = "core",
-               reason = "return type may change and method was just created")]
-    pub fn flags(&self) -> uint { self.flags }
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub fn flags(&self) -> usize { self.flags }
 
     /// Character used as 'fill' whenever there is alignment
     #[unstable(feature = "core", reason = "method was just created")]
@@ -628,7 +666,7 @@ impl<'a> Formatter<'a> {
 
     /// Flag indicating what form of alignment was requested
     #[unstable(feature = "core", reason = "method was just created")]
-    pub fn align(&self) -> rt::Alignment { self.align }
+    pub fn align(&self) -> Alignment { self.align }
 
     /// Optionally specified integer width that the output should be
     #[unstable(feature = "core", reason = "method was just created")]
@@ -649,20 +687,20 @@ impl Display for Error {
 /// This is a function which calls are emitted to by the compiler itself to
 /// create the Argument structures that are passed into the `format` function.
 #[doc(hidden)] #[inline]
-#[unstable(feature = "core",
-           reason = "implementation detail of the `format_args!` macro")]
+#[cfg(stage0)]
+#[stable(feature = "rust1", since = "1.0.0")]
 pub fn argument<'a, T>(f: fn(&T, &mut Formatter) -> Result,
-                       t: &'a T) -> Argument<'a> {
-    Argument::new(t, f)
+                       t: &'a T) -> ArgumentV1<'a> {
+    ArgumentV1::new(t, f)
 }
 
 /// When the compiler determines that the type of an argument *must* be a uint
 /// (such as for width and precision), then it invokes this method.
 #[doc(hidden)] #[inline]
-#[unstable(feature = "core",
-           reason = "implementation detail of the `format_args!` macro")]
-pub fn argumentuint<'a>(s: &'a uint) -> Argument<'a> {
-    Argument::from_uint(s)
+#[cfg(stage0)]
+#[stable(feature = "rust1", since = "1.0.0")]
+pub fn argumentuint<'a>(s: &'a uint) -> ArgumentV1<'a> {
+    ArgumentV1::from_uint(s)
 }
 
 // Implementations of the core formatting traits
@@ -741,9 +779,9 @@ impl Display for char {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> Pointer for *const T {
     fn fmt(&self, f: &mut Formatter) -> Result {
-        f.flags |= 1 << (rt::FlagAlternate as uint);
+        f.flags |= 1 << (FlagV1::Alternate as uint);
         let ret = LowerHex::fmt(&(*self as uint), f);
-        f.flags &= !(1 << (rt::FlagAlternate as uint));
+        f.flags &= !(1 << (FlagV1::Alternate as uint));
         ret
     }
 }
@@ -899,7 +937,7 @@ impl<'a> Debug for &'a (any::Any+'a) {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: Debug> Debug for [T] {
     fn fmt(&self, f: &mut Formatter) -> Result {
-        if f.flags & (1 << (rt::FlagAlternate as uint)) == 0 {
+        if f.flags & (1 << (FlagV1::Alternate as uint)) == 0 {
             try!(write!(f, "["));
         }
         let mut is_first = true;
@@ -911,7 +949,7 @@ impl<T: Debug> Debug for [T] {
             }
             try!(write!(f, "{:?}", *x))
         }
-        if f.flags & (1 << (rt::FlagAlternate as uint)) == 0 {
+        if f.flags & (1 << (FlagV1::Alternate as uint)) == 0 {
             try!(write!(f, "]"));
         }
         Ok(())
diff --git a/src/libcore/fmt/rt.rs b/src/libcore/fmt/rt.rs
deleted file mode 100644
index 0b2c1efbc5dee..0000000000000
--- a/src/libcore/fmt/rt.rs
+++ /dev/null
@@ -1,86 +0,0 @@
-// Copyright 2013 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.
-
-//! This is an internal module used by the ifmt! runtime. These structures are
-//! emitted to static arrays to precompile format strings ahead of time.
-//!
-//! These definitions are similar to their `ct` equivalents, but differ in that
-//! these can be statically allocated and are slightly optimized for the runtime
-
-#![unstable(feature = "core",
-            reason = "implementation detail of the `format_args!` macro")]
-
-pub use self::Alignment::*;
-pub use self::Count::*;
-pub use self::Position::*;
-pub use self::Flag::*;
-
-#[doc(hidden)]
-#[derive(Copy)]
-pub struct Argument {
-    pub position: Position,
-    pub format: FormatSpec,
-}
-
-#[doc(hidden)]
-#[derive(Copy)]
-pub struct FormatSpec {
-    pub fill: char,
-    pub align: Alignment,
-    pub flags: uint,
-    pub precision: Count,
-    pub width: Count,
-}
-
-/// Possible alignments that can be requested as part of a formatting directive.
-#[derive(Copy, PartialEq)]
-pub enum Alignment {
-    /// Indication that contents should be left-aligned.
-    AlignLeft,
-    /// Indication that contents should be right-aligned.
-    AlignRight,
-    /// Indication that contents should be center-aligned.
-    AlignCenter,
-    /// No alignment was requested.
-    AlignUnknown,
-}
-
-#[doc(hidden)]
-#[derive(Copy)]
-pub enum Count {
-    CountIs(uint), CountIsParam(uint), CountIsNextParam, CountImplied,
-}
-
-#[doc(hidden)]
-#[derive(Copy)]
-pub enum Position {
-    ArgumentNext, ArgumentIs(uint)
-}
-
-/// Flags which can be passed to formatting via a directive.
-///
-/// These flags are discovered through the `flags` field of the `Formatter`
-/// structure. The flag in that structure is a union of these flags into a
-/// `uint` where each flag's discriminant is the corresponding bit.
-#[derive(Copy)]
-pub enum Flag {
-    /// A flag which enables number formatting to always print the sign of a
-    /// number.
-    FlagSignPlus,
-    /// Currently not a used flag
-    FlagSignMinus,
-    /// Indicates that the "alternate formatting" for a type should be used.
-    ///
-    /// The meaning of this flag is type-specific.
-    FlagAlternate,
-    /// Indicates that padding should be done with a `0` character as well as
-    /// being aware of the sign to be printed.
-    FlagSignAwareZeroPad,
-}
diff --git a/src/libcore/fmt/rt/v1.rs b/src/libcore/fmt/rt/v1.rs
new file mode 100644
index 0000000000000..f0c82759b7056
--- /dev/null
+++ b/src/libcore/fmt/rt/v1.rs
@@ -0,0 +1,94 @@
+// Copyright 2013 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.
+
+//! This is an internal module used by the ifmt! runtime. These structures are
+//! emitted to static arrays to precompile format strings ahead of time.
+//!
+//! These definitions are similar to their `ct` equivalents, but differ in that
+//! these can be statically allocated and are slightly optimized for the runtime
+
+#![stable(feature = "rust1", since = "1.0.0")]
+
+#[cfg(stage0)] pub use self::Position::*;
+
+#[cfg(stage0)] pub use self::Alignment::Left as AlignLeft;
+#[cfg(stage0)] pub use self::Alignment::Right as AlignRight;
+#[cfg(stage0)] pub use self::Alignment::Center as AlignCenter;
+#[cfg(stage0)] pub use self::Alignment::Unknown as AlignUnknown;
+#[cfg(stage0)] pub use self::Count::Is as CountIs;
+#[cfg(stage0)] pub use self::Count::Implied as CountImplied;
+#[cfg(stage0)] pub use self::Count::Param as CountIsParam;
+#[cfg(stage0)] pub use self::Count::NextParam as CountIsNextParam;
+#[cfg(stage0)] pub use self::Position::Next as ArgumentNext;
+#[cfg(stage0)] pub use self::Position::At as ArgumentIs;
+
+#[derive(Copy)]
+#[stable(feature = "rust1", since = "1.0.0")]
+pub struct Argument {
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub position: Position,
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub format: FormatSpec,
+}
+
+#[derive(Copy)]
+#[stable(feature = "rust1", since = "1.0.0")]
+pub struct FormatSpec {
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub fill: char,
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub align: Alignment,
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub flags: uint,
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub precision: Count,
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub width: Count,
+}
+
+/// Possible alignments that can be requested as part of a formatting directive.
+#[derive(Copy, PartialEq)]
+#[stable(feature = "rust1", since = "1.0.0")]
+pub enum Alignment {
+    /// Indication that contents should be left-aligned.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    Left,
+    /// Indication that contents should be right-aligned.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    Right,
+    /// Indication that contents should be center-aligned.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    Center,
+    /// No alignment was requested.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    Unknown,
+}
+
+#[derive(Copy)]
+#[stable(feature = "rust1", since = "1.0.0")]
+pub enum Count {
+    #[stable(feature = "rust1", since = "1.0.0")]
+    Is(usize),
+    #[stable(feature = "rust1", since = "1.0.0")]
+    Param(usize),
+    #[stable(feature = "rust1", since = "1.0.0")]
+    NextParam,
+    #[stable(feature = "rust1", since = "1.0.0")]
+    Implied,
+}
+
+#[derive(Copy)]
+#[stable(feature = "rust1", since = "1.0.0")]
+pub enum Position {
+    #[stable(feature = "rust1", since = "1.0.0")]
+    Next,
+    #[stable(feature = "rust1", since = "1.0.0")]
+    At(usize)
+}
diff --git a/src/libcore/result.rs b/src/libcore/result.rs
index 92a7465038bb1..fc7d4e868f746 100644
--- a/src/libcore/result.rs
+++ b/src/libcore/result.rs
@@ -229,7 +229,7 @@
 use self::Result::{Ok, Err};
 
 use clone::Clone;
-use fmt::Debug;
+use fmt;
 use iter::{Iterator, IteratorExt, DoubleEndedIterator, FromIterator, ExactSizeIterator};
 use ops::{FnMut, FnOnce};
 use option::Option::{self, None, Some};
@@ -715,7 +715,7 @@ impl<T, E> Result<T, E> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T, E: Debug> Result<T, E> {
+impl<T, E: fmt::Debug> Result<T, E> {
     /// Unwraps a result, yielding the content of an `Ok`.
     ///
     /// # Panics
@@ -746,7 +746,7 @@ impl<T, E: Debug> Result<T, E> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T: Debug, E> Result<T, E> {
+impl<T: fmt::Debug, E> Result<T, E> {
     /// Unwraps a result, yielding the content of an `Err`.
     ///
     /// # Panics
diff --git a/src/libgraphviz/lib.rs b/src/libgraphviz/lib.rs
index 21d5cd3d516ab..6b14592c23b8c 100644
--- a/src/libgraphviz/lib.rs
+++ b/src/libgraphviz/lib.rs
@@ -362,19 +362,19 @@ impl<'a> Id<'a> {
     ///
     /// Passing an invalid string (containing spaces, brackets,
     /// quotes, ...) will return an empty `Err` value.
-    pub fn new<Name: IntoCow<'a, String, str>>(name: Name) -> Option<Id<'a>> {
+    pub fn new<Name: IntoCow<'a, String, str>>(name: Name) -> Result<Id<'a>, ()> {
         let name = name.into_cow();
         {
             let mut chars = name.chars();
             match chars.next() {
                 Some(c) if is_letter_or_underscore(c) => { ; },
-                _ => return None
+                _ => return Err(())
             }
             if !chars.all(is_constituent) {
-                return None
+                return Err(())
             }
         }
-        return Some(Id{ name: name });
+        return Ok(Id{ name: name });
 
         fn is_letter_or_underscore(c: char) -> bool {
             in_range('a', c, 'z') || in_range('A', c, 'Z') || c == '_'
@@ -878,8 +878,8 @@ r#"digraph syntax_tree {
     fn simple_id_construction() {
         let id1 = Id::new("hello");
         match id1 {
-            Some(_) => {;},
-            None => panic!("'hello' is not a valid value for id anymore")
+            Ok(_) => {;},
+            Err(..) => panic!("'hello' is not a valid value for id anymore")
         }
     }
 
@@ -887,8 +887,8 @@ r#"digraph syntax_tree {
     fn badly_formatted_id() {
         let id2 = Id::new("Weird { struct : ure } !!!");
         match id2 {
-            Some(_) => panic!("graphviz id suddenly allows spaces, brackets and stuff"),
-            None => {;}
+            Ok(_) => panic!("graphviz id suddenly allows spaces, brackets and stuff"),
+            Err(..) => {;}
         }
     }
 }
diff --git a/src/librustc/middle/cfg/graphviz.rs b/src/librustc/middle/cfg/graphviz.rs
index 3d8348e8f5a99..1f0fe4f1acaea 100644
--- a/src/librustc/middle/cfg/graphviz.rs
+++ b/src/librustc/middle/cfg/graphviz.rs
@@ -54,10 +54,10 @@ fn replace_newline_with_backslash_l(s: String) -> String {
 }
 
 impl<'a, 'ast> dot::Labeller<'a, Node<'a>, Edge<'a>> for LabelledCFG<'a, 'ast> {
-    fn graph_id(&'a self) -> dot::Id<'a> { dot::Id::new(&self.name[]).unwrap() }
+    fn graph_id(&'a self) -> dot::Id<'a> { dot::Id::new(&self.name[]).ok().unwrap() }
 
     fn node_id(&'a self, &(i,_): &Node<'a>) -> dot::Id<'a> {
-        dot::Id::new(format!("N{}", i.node_id())).unwrap()
+        dot::Id::new(format!("N{}", i.node_id())).ok().unwrap()
     }
 
     fn node_label(&'a self, &(i, n): &Node<'a>) -> dot::LabelText<'a> {
diff --git a/src/librustc/middle/infer/region_inference/graphviz.rs b/src/librustc/middle/infer/region_inference/graphviz.rs
index 215c4945ea920..b1ca4e625155d 100644
--- a/src/librustc/middle/infer/region_inference/graphviz.rs
+++ b/src/librustc/middle/infer/region_inference/graphviz.rs
@@ -157,10 +157,10 @@ impl<'a, 'tcx> ConstraintGraph<'a, 'tcx> {
 
 impl<'a, 'tcx> dot::Labeller<'a, Node, Edge> for ConstraintGraph<'a, 'tcx> {
     fn graph_id(&self) -> dot::Id {
-        dot::Id::new(self.graph_name.as_slice()).unwrap()
+        dot::Id::new(self.graph_name.as_slice()).ok().unwrap()
     }
     fn node_id(&self, n: &Node) -> dot::Id {
-        dot::Id::new(format!("node_{}", self.node_ids.get(n).unwrap())).unwrap()
+        dot::Id::new(format!("node_{}", self.node_ids.get(n).unwrap())).ok().unwrap()
     }
     fn node_label(&self, n: &Node) -> dot::LabelText {
         match *n {
diff --git a/src/libserialize/json.rs b/src/libserialize/json.rs
index 2e7a6fd492354..d6eb05a867eca 100644
--- a/src/libserialize/json.rs
+++ b/src/libserialize/json.rs
@@ -3951,8 +3951,8 @@ mod tests {
         struct ArbitraryType(uint);
         let mut hm: HashMap<ArbitraryType, bool> = HashMap::new();
         hm.insert(ArbitraryType(1), true);
-        let mut mem_buf = Vec::new();
-        let mut encoder = Encoder::new(&mut mem_buf as &mut fmt::Writer);
+        let mut mem_buf = string::String::new();
+        let mut encoder = Encoder::new(&mut mem_buf);
         let result = hm.encode(&mut encoder);
         match result.err().unwrap() {
             EncoderError::BadHashmapKey => (),
diff --git a/src/libstd/ffi/c_str.rs b/src/libstd/ffi/c_str.rs
index fdd7aa216d3c0..2e55c007b551b 100644
--- a/src/libstd/ffi/c_str.rs
+++ b/src/libstd/ffi/c_str.rs
@@ -122,7 +122,7 @@ impl Deref for CString {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl fmt::Debug for CString {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        String::from_utf8_lossy(self.as_bytes()).fmt(f)
+        fmt::Debug::fmt(&String::from_utf8_lossy(self.as_bytes()), f)
     }
 }
 
diff --git a/src/libstd/fmt.rs b/src/libstd/fmt.rs
index 4ab43e875cdff..a1d6d097607bf 100644
--- a/src/libstd/fmt.rs
+++ b/src/libstd/fmt.rs
@@ -411,9 +411,10 @@ pub use core::fmt::{Display, Debug};
 pub use core::fmt::{LowerHex, UpperHex, Pointer};
 pub use core::fmt::{LowerExp, UpperExp};
 pub use core::fmt::Error;
-pub use core::fmt::{Argument, Arguments, write, radix, Radix, RadixFmt};
+pub use core::fmt::{ArgumentV1, Arguments, write, radix, Radix, RadixFmt};
 
 #[doc(hidden)]
+#[cfg(stage0)]
 pub use core::fmt::{argument, argumentuint};
 
 /// The format function takes a precompiled format string and a list of
@@ -431,9 +432,7 @@ pub use core::fmt::{argument, argumentuint};
 /// let s = fmt::format(format_args!("Hello, {}!", "world"));
 /// assert_eq!(s, "Hello, world!".to_string());
 /// ```
-#[unstable(feature = "std_misc",
-           reason = "this is an implementation detail of format! and should not \
-                     be called directly")]
+#[stable(feature = "rust1", since = "1.0.0")]
 pub fn format(args: Arguments) -> string::String {
     let mut output = string::String::new();
     let _ = write!(&mut output, "{}", args);
diff --git a/src/libstd/old_io/process.rs b/src/libstd/old_io/process.rs
index d3e60de2780e9..b47d81ae17364 100644
--- a/src/libstd/old_io/process.rs
+++ b/src/libstd/old_io/process.rs
@@ -393,14 +393,15 @@ impl Command {
     }
 }
 
+#[stable(feature = "rust1", since = "1.0.0")]
 impl fmt::Debug for Command {
     /// Format the program and arguments of a Command for display. Any
     /// non-utf8 data is lossily converted using the utf8 replacement
     /// character.
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        try!(write!(f, "{}", String::from_utf8_lossy(self.program.as_bytes())));
+        try!(write!(f, "{:?}", self.program));
         for arg in self.args.iter() {
-            try!(write!(f, " '{}'", String::from_utf8_lossy(arg.as_bytes())));
+            try!(write!(f, " '{:?}'", arg));
         }
         Ok(())
     }
diff --git a/src/libstd/sync/mpsc/mod.rs b/src/libstd/sync/mpsc/mod.rs
index 6a43eccbaba4e..f048dc9a84dc1 100644
--- a/src/libstd/sync/mpsc/mod.rs
+++ b/src/libstd/sync/mpsc/mod.rs
@@ -382,8 +382,8 @@ impl<T> !Sync for SyncSender<T> {}
 /// A `send` operation can only fail if the receiving end of a channel is
 /// disconnected, implying that the data could never be received. The error
 /// contains the data being sent as a payload so it can be recovered.
-#[derive(PartialEq, Eq)]
 #[stable(feature = "rust1", since = "1.0.0")]
+#[derive(PartialEq, Eq, Clone, Copy)]
 pub struct SendError<T>(pub T);
 
 /// An error returned from the `recv` function on a `Receiver`.
@@ -396,7 +396,7 @@ pub struct RecvError;
 
 /// This enumeration is the list of the possible reasons that try_recv could not
 /// return data when called.
-#[derive(PartialEq, Clone, Copy, Debug)]
+#[derive(PartialEq, Eq, Clone, Copy, Debug)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub enum TryRecvError {
     /// This channel is currently empty, but the sender(s) have not yet
@@ -412,8 +412,8 @@ pub enum TryRecvError {
 
 /// This enumeration is the list of the possible error outcomes for the
 /// `SyncSender::try_send` method.
-#[derive(PartialEq, Clone)]
 #[stable(feature = "rust1", since = "1.0.0")]
+#[derive(PartialEq, Eq, Clone, Copy)]
 pub enum TrySendError<T> {
     /// The data could not be sent on the channel because it would require that
     /// the callee block to send the data.
diff --git a/src/libsyntax/ext/format.rs b/src/libsyntax/ext/format.rs
index 2a0a352f1281a..36dbf11760457 100644
--- a/src/libsyntax/ext/format.rs
+++ b/src/libsyntax/ext/format.rs
@@ -17,7 +17,7 @@ use ext::base::*;
 use ext::base;
 use ext::build::AstBuilder;
 use fmt_macros as parse;
-use parse::token::{InternedString, special_idents};
+use parse::token::special_idents;
 use parse::token;
 use ptr::P;
 
@@ -300,56 +300,35 @@ impl<'a, 'b> Context<'a, 'b> {
         }
     }
 
-    /// These attributes are applied to all statics that this syntax extension
-    /// will generate.
-    fn static_attrs(ecx: &ExtCtxt, fmtsp: Span) -> Vec<ast::Attribute> {
-        // Flag statics as `inline` so LLVM can merge duplicate globals as much
-        // as possible (which we're generating a whole lot of).
-        let unnamed = ecx.meta_word(fmtsp, InternedString::new("inline"));
-        let unnamed = ecx.attribute(fmtsp, unnamed);
-
-        // Do not warn format string as dead code
-        let dead_code = ecx.meta_word(fmtsp, InternedString::new("dead_code"));
-        let allow_dead_code = ecx.meta_list(fmtsp,
-                                            InternedString::new("allow"),
-                                            vec![dead_code]);
-        let allow_dead_code = ecx.attribute(fmtsp, allow_dead_code);
-        vec![unnamed, allow_dead_code]
-    }
-
     fn rtpath(ecx: &ExtCtxt, s: &str) -> Vec<ast::Ident> {
-        vec![ecx.ident_of("std"), ecx.ident_of("fmt"), ecx.ident_of("rt"), ecx.ident_of(s)]
+        vec![ecx.ident_of("std"), ecx.ident_of("fmt"), ecx.ident_of("rt"),
+             ecx.ident_of("v1"), ecx.ident_of(s)]
     }
 
     fn trans_count(&self, c: parse::Count) -> P<ast::Expr> {
         let sp = self.fmtsp;
-        match c {
-            parse::CountIs(i) => {
-                self.ecx.expr_call_global(sp, Context::rtpath(self.ecx, "CountIs"),
-                                          vec!(self.ecx.expr_usize(sp, i)))
+        let count = |: c, arg| {
+            let mut path = Context::rtpath(self.ecx, "Count");
+            path.push(self.ecx.ident_of(c));
+            match arg {
+                Some(arg) => self.ecx.expr_call_global(sp, path, vec![arg]),
+                None => self.ecx.expr_path(self.ecx.path_global(sp, path)),
             }
+        };
+        match c {
+            parse::CountIs(i) => count("Is", Some(self.ecx.expr_usize(sp, i))),
             parse::CountIsParam(i) => {
-                self.ecx.expr_call_global(sp, Context::rtpath(self.ecx, "CountIsParam"),
-                                          vec!(self.ecx.expr_usize(sp, i)))
-            }
-            parse::CountImplied => {
-                let path = self.ecx.path_global(sp, Context::rtpath(self.ecx,
-                                                                    "CountImplied"));
-                self.ecx.expr_path(path)
-            }
-            parse::CountIsNextParam => {
-                let path = self.ecx.path_global(sp, Context::rtpath(self.ecx,
-                                                                    "CountIsNextParam"));
-                self.ecx.expr_path(path)
+                count("Param", Some(self.ecx.expr_usize(sp, i)))
             }
+            parse::CountImplied => count("Implied", None),
+            parse::CountIsNextParam => count("NextParam", None),
             parse::CountIsName(n) => {
                 let i = match self.name_positions.get(n) {
                     Some(&i) => i,
                     None => 0, // error already emitted elsewhere
                 };
                 let i = i + self.args.len();
-                self.ecx.expr_call_global(sp, Context::rtpath(self.ecx, "CountIsParam"),
-                                          vec!(self.ecx.expr_usize(sp, i)))
+                count("Param", Some(self.ecx.expr_usize(sp, i)))
             }
         }
     }
@@ -373,27 +352,35 @@ impl<'a, 'b> Context<'a, 'b> {
             }
             parse::NextArgument(ref arg) => {
                 // Translate the position
-                let pos = match arg.position {
-                    // These two have a direct mapping
-                    parse::ArgumentNext => {
-                        let path = self.ecx.path_global(sp, Context::rtpath(self.ecx,
-                                                                            "ArgumentNext"));
-                        self.ecx.expr_path(path)
-                    }
-                    parse::ArgumentIs(i) => {
-                        self.ecx.expr_call_global(sp, Context::rtpath(self.ecx, "ArgumentIs"),
-                                                  vec!(self.ecx.expr_usize(sp, i)))
-                    }
-                    // Named arguments are converted to positional arguments at
-                    // the end of the list of arguments
-                    parse::ArgumentNamed(n) => {
-                        let i = match self.name_positions.get(n) {
-                            Some(&i) => i,
-                            None => 0, // error already emitted elsewhere
-                        };
-                        let i = i + self.args.len();
-                        self.ecx.expr_call_global(sp, Context::rtpath(self.ecx, "ArgumentIs"),
-                                                  vec!(self.ecx.expr_usize(sp, i)))
+                let pos = {
+                    let pos = |: c, arg| {
+                        let mut path = Context::rtpath(self.ecx, "Position");
+                        path.push(self.ecx.ident_of(c));
+                        match arg {
+                            Some(i) => {
+                                let arg = self.ecx.expr_usize(sp, i);
+                                self.ecx.expr_call_global(sp, path, vec![arg])
+                            }
+                            None => {
+                                self.ecx.expr_path(self.ecx.path_global(sp, path))
+                            }
+                        }
+                    };
+                    match arg.position {
+                        // These two have a direct mapping
+                        parse::ArgumentNext => pos("Next", None),
+                        parse::ArgumentIs(i) => pos("At", Some(i)),
+
+                        // Named arguments are converted to positional arguments
+                        // at the end of the list of arguments
+                        parse::ArgumentNamed(n) => {
+                            let i = match self.name_positions.get(n) {
+                                Some(&i) => i,
+                                None => 0, // error already emitted elsewhere
+                            };
+                            let i = i + self.args.len();
+                            pos("At", Some(i))
+                        }
                     }
                 };
 
@@ -417,19 +404,16 @@ impl<'a, 'b> Context<'a, 'b> {
 
                 // Translate the format
                 let fill = self.ecx.expr_lit(sp, ast::LitChar(fill));
+                let align = |:name| {
+                    let mut p = Context::rtpath(self.ecx, "Alignment");
+                    p.push(self.ecx.ident_of(name));
+                    self.ecx.path_global(sp, p)
+                };
                 let align = match arg.format.align {
-                    parse::AlignLeft => {
-                        self.ecx.path_global(sp, Context::rtpath(self.ecx, "AlignLeft"))
-                    }
-                    parse::AlignRight => {
-                        self.ecx.path_global(sp, Context::rtpath(self.ecx, "AlignRight"))
-                    }
-                    parse::AlignCenter => {
-                        self.ecx.path_global(sp, Context::rtpath(self.ecx, "AlignCenter"))
-                    }
-                    parse::AlignUnknown => {
-                        self.ecx.path_global(sp, Context::rtpath(self.ecx, "AlignUnknown"))
-                    }
+                    parse::AlignLeft => align("Left"),
+                    parse::AlignRight => align("Right"),
+                    parse::AlignCenter => align("Center"),
+                    parse::AlignUnknown => align("Unknown"),
                 };
                 let align = self.ecx.expr_path(align);
                 let flags = self.ecx.expr_usize(sp, arg.format.flags);
@@ -465,7 +449,7 @@ impl<'a, 'b> Context<'a, 'b> {
         let st = ast::ItemStatic(ty, ast::MutImmutable, slice);
 
         let name = ecx.ident_of(name);
-        let item = ecx.item(fmtsp, name, Context::static_attrs(ecx, fmtsp), st);
+        let item = ecx.item(fmtsp, name, vec![], st);
         let decl = respan(fmtsp, ast::DeclItem(item));
 
         // Wrap the declaration in a block so that it forms a single expression.
@@ -575,7 +559,7 @@ impl<'a, 'b> Context<'a, 'b> {
 
         // Now create the fmt::Arguments struct with all our locals we created.
         let (fn_name, fn_args) = if self.all_pieces_simple {
-            ("new", vec![pieces, args_slice])
+            ("new_v1", vec![pieces, args_slice])
         } else {
             // Build up the static array which will store our precompiled
             // nonstandard placeholders, if there are any.
@@ -587,7 +571,7 @@ impl<'a, 'b> Context<'a, 'b> {
                                             piece_ty,
                                             self.pieces);
 
-            ("with_placeholders", vec![pieces, fmt, args_slice])
+            ("new_v1_formatted", vec![pieces, args_slice, fmt])
         };
 
         self.ecx.expr_call_global(self.fmtsp, vec!(
@@ -624,7 +608,8 @@ impl<'a, 'b> Context<'a, 'b> {
                 return ecx.expr_call_global(sp, vec![
                         ecx.ident_of("std"),
                         ecx.ident_of("fmt"),
-                        ecx.ident_of("argumentuint")], vec![arg])
+                        ecx.ident_of("ArgumentV1"),
+                        ecx.ident_of("from_uint")], vec![arg])
             }
         };
 
@@ -636,7 +621,8 @@ impl<'a, 'b> Context<'a, 'b> {
         ecx.expr_call_global(sp, vec![
                 ecx.ident_of("std"),
                 ecx.ident_of("fmt"),
-                ecx.ident_of("argument")], vec![ecx.expr_path(format_fn), arg])
+                ecx.ident_of("ArgumentV1"),
+                ecx.ident_of("new")], vec![arg, ecx.expr_path(format_fn)])
     }
 }
 
diff --git a/src/test/compile-fail/lint-dead-code-4.rs b/src/test/compile-fail/lint-dead-code-4.rs
index 22570bad61696..449788459dcff 100644
--- a/src/test/compile-fail/lint-dead-code-4.rs
+++ b/src/test/compile-fail/lint-dead-code-4.rs
@@ -13,7 +13,6 @@
 #![deny(dead_code)]
 #![feature(libc)]
 #![feature(core)]
-#![feature(collections)]
 
 extern crate libc;
 
diff --git a/src/test/compile-fail/missing_debug_impls.rs b/src/test/compile-fail/missing_debug_impls.rs
index 5b781a40fe548..bc4bfef4d48c4 100644
--- a/src/test/compile-fail/missing_debug_impls.rs
+++ b/src/test/compile-fail/missing_debug_impls.rs
@@ -11,7 +11,6 @@
 // compile-flags: --crate-type lib
 #![deny(missing_debug_implementations)]
 #![allow(unused, missing_copy_implementations)]
-#![feature(core)]
 
 use std::fmt;
 
diff --git a/src/test/pretty/issue-4264.pp b/src/test/pretty/issue-4264.pp
index c18d076c0d318..b1d38f5dc9b16 100644
--- a/src/test/pretty/issue-4264.pp
+++ b/src/test/pretty/issue-4264.pp
@@ -41,41 +41,39 @@
 
 
     ((::std::fmt::format as
-         fn(core::fmt::Arguments<'_>) -> collections::string::String {std::fmt::format})(((::std::fmt::Arguments::new
+         fn(core::fmt::Arguments<'_>) -> collections::string::String {std::fmt::format})(((::std::fmt::Arguments::new_v1
                                                                                               as
-                                                                                              fn(&[&str], &[core::fmt::Argument<'_>]) -> core::fmt::Arguments<'_> {core::fmt::Arguments<'a>::new})(({
-                                                                                                                                                                                                        #[inline]
-                                                                                                                                                                                                        #[allow(dead_code)]
-                                                                                                                                                                                                        static __STATIC_FMTSTR:
-                                                                                                                                                                                                               &'static [&'static str]
-                                                                                                                                                                                                               =
-                                                                                                                                                                                                            (&([("test"
-                                                                                                                                                                                                                    as
-                                                                                                                                                                                                                    &'static str)]
-                                                                                                                                                                                                                  as
-                                                                                                                                                                                                                  [&'static str; 1])
-                                                                                                                                                                                                                as
-                                                                                                                                                                                                                &'static [&'static str; 1]);
-                                                                                                                                                                                                        (__STATIC_FMTSTR
+                                                                                              fn(&[&str], &[core::fmt::ArgumentV1<'_>]) -> core::fmt::Arguments<'_> {core::fmt::Arguments<'a>::new_v1})(({
+                                                                                                                                                                                                             static __STATIC_FMTSTR:
+                                                                                                                                                                                                                    &'static [&'static str]
+                                                                                                                                                                                                                    =
+                                                                                                                                                                                                                 (&([("test"
+                                                                                                                                                                                                                         as
+                                                                                                                                                                                                                         &'static str)]
+                                                                                                                                                                                                                       as
+                                                                                                                                                                                                                       [&'static str; 1])
+                                                                                                                                                                                                                     as
+                                                                                                                                                                                                                     &'static [&'static str; 1]);
+                                                                                                                                                                                                             (__STATIC_FMTSTR
+                                                                                                                                                                                                                 as
+                                                                                                                                                                                                                 &'static [&'static str])
+                                                                                                                                                                                                         }
                                                                                                                                                                                                             as
-                                                                                                                                                                                                            &'static [&'static str])
-                                                                                                                                                                                                    }
-                                                                                                                                                                                                       as
-                                                                                                                                                                                                       &[&str]),
-                                                                                                                                                                                                   (&(match (()
-                                                                                                                                                                                                                as
-                                                                                                                                                                                                                ())
-                                                                                                                                                                                                          {
-                                                                                                                                                                                                          ()
-                                                                                                                                                                                                          =>
-                                                                                                                                                                                                          ([]
+                                                                                                                                                                                                            &[&str]),
+                                                                                                                                                                                                        (&(match (()
+                                                                                                                                                                                                                     as
+                                                                                                                                                                                                                     ())
+                                                                                                                                                                                                               {
+                                                                                                                                                                                                               ()
+                                                                                                                                                                                                               =>
+                                                                                                                                                                                                               ([]
+                                                                                                                                                                                                                   as
+                                                                                                                                                                                                                   [core::fmt::ArgumentV1<'_>; 0]),
+                                                                                                                                                                                                           }
                                                                                                                                                                                                               as
-                                                                                                                                                                                                              [core::fmt::Argument<'_>; 0]),
-                                                                                                                                                                                                      }
-                                                                                                                                                                                                         as
-                                                                                                                                                                                                         [core::fmt::Argument<'_>; 0])
-                                                                                                                                                                                                       as
-                                                                                                                                                                                                       &[core::fmt::Argument<'_>; 0]))
+                                                                                                                                                                                                              [core::fmt::ArgumentV1<'_>; 0])
+                                                                                                                                                                                                            as
+                                                                                                                                                                                                            &[core::fmt::ArgumentV1<'_>; 0]))
                                                                                              as
                                                                                              core::fmt::Arguments<'_>))
         as collections::string::String);