diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index 2eeb2691eaee4..6c46f3e58cffb 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -114,8 +114,7 @@
 //! also check out the `src/bootstrap/README.md` file for more information.
 
 #![deny(warnings)]
-#![feature(conservative_impl_trait, fs_read_write, core_intrinsics)]
-#![feature(slice_concat_ext)]
+#![feature(core_intrinsics)]
 
 #[macro_use]
 extern crate build_helper;
@@ -1149,7 +1148,7 @@ impl Build {
 
     fn read(&self, path: &Path) -> String {
         if self.config.dry_run { return String::new(); }
-        t!(fs::read_string(path))
+        t!(fs::read_to_string(path))
     }
 
     fn create_dir(&self, dir: &Path) {
diff --git a/src/bootstrap/tool.rs b/src/bootstrap/tool.rs
index 93b6153fcb2f8..5fc92611e6529 100644
--- a/src/bootstrap/tool.rs
+++ b/src/bootstrap/tool.rs
@@ -12,7 +12,6 @@ use std::fs;
 use std::env;
 use std::path::PathBuf;
 use std::process::{Command, exit};
-use std::slice::SliceConcatExt;
 
 use Mode;
 use Compiler;
diff --git a/src/liballoc/benches/lib.rs b/src/liballoc/benches/lib.rs
index a43aadfe9a23a..4d92fc67b2a50 100644
--- a/src/liballoc/benches/lib.rs
+++ b/src/liballoc/benches/lib.rs
@@ -10,7 +10,6 @@
 
 #![deny(warnings)]
 
-#![cfg_attr(stage0, feature(i128_type))]
 #![feature(rand)]
 #![feature(repr_simd)]
 #![feature(slice_sort_by_cached_key)]
diff --git a/src/liballoc/lib.rs b/src/liballoc/lib.rs
index 6ce2547ef6e6d..da26e7c852c46 100644
--- a/src/liballoc/lib.rs
+++ b/src/liballoc/lib.rs
@@ -97,8 +97,6 @@
 #![feature(fmt_internals)]
 #![feature(from_ref)]
 #![feature(fundamental)]
-#![cfg_attr(stage0, feature(generic_param_attrs))]
-#![cfg_attr(stage0, feature(i128_type))]
 #![feature(lang_items)]
 #![feature(needs_allocator)]
 #![feature(nonzero)]
@@ -123,6 +121,7 @@
 #![feature(exact_chunks)]
 #![feature(pointer_methods)]
 #![feature(inclusive_range_fields)]
+#![cfg_attr(stage0, feature(generic_param_attrs))]
 
 #![cfg_attr(not(test), feature(fn_traits, swap_with_slice, i128))]
 #![cfg_attr(test, feature(test))]
diff --git a/src/liballoc/tests/lib.rs b/src/liballoc/tests/lib.rs
index 1a49fb9964ad7..a173ef10a818e 100644
--- a/src/liballoc/tests/lib.rs
+++ b/src/liballoc/tests/lib.rs
@@ -14,7 +14,6 @@
 #![feature(alloc_system)]
 #![feature(attr_literals)]
 #![feature(box_syntax)]
-#![cfg_attr(stage0, feature(inclusive_range_syntax))]
 #![feature(const_fn)]
 #![feature(drain_filter)]
 #![feature(exact_size_is_empty)]
diff --git a/src/libcore/cmp.rs b/src/libcore/cmp.rs
index 67445daa43602..3ae9b05b86538 100644
--- a/src/libcore/cmp.rs
+++ b/src/libcore/cmp.rs
@@ -427,7 +427,7 @@ impl<T: Ord> Ord for Reverse<T> {
 ///     }
 /// }
 /// ```
-#[cfg_attr(not(stage0), lang = "ord")]
+#[lang = "ord"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub trait Ord: Eq + PartialOrd<Self> {
     /// This method returns an `Ordering` between `self` and `other`.
@@ -597,8 +597,7 @@ impl PartialOrd for Ordering {
 /// assert_eq!(x < y, true);
 /// assert_eq!(x.lt(&y), true);
 /// ```
-#[cfg_attr(stage0, lang = "ord")]
-#[cfg_attr(not(stage0), lang = "partial_ord")]
+#[lang = "partial_ord"]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_on_unimplemented = "can't compare `{Self}` with `{Rhs}`"]
 pub trait PartialOrd<Rhs: ?Sized = Self>: PartialEq<Rhs> {
diff --git a/src/libcore/intrinsics.rs b/src/libcore/intrinsics.rs
index 3b740adc46832..83274682250b0 100644
--- a/src/libcore/intrinsics.rs
+++ b/src/libcore/intrinsics.rs
@@ -1293,7 +1293,6 @@ extern "rust-intrinsic" {
     pub fn bswap<T>(x: T) -> T;
 
     /// Reverses the bits in an integer type `T`.
-    #[cfg(not(stage0))]
     pub fn bitreverse<T>(x: T) -> T;
 
     /// Performs checked integer addition.
@@ -1316,7 +1315,6 @@ extern "rust-intrinsic" {
 
     /// Performs an exact division, resulting in undefined behavior where
     /// `x % y != 0` or `y == 0` or `x == T::min_value() && y == -1`
-    #[cfg(not(stage0))]
     pub fn exact_div<T>(x: T, y: T) -> T;
 
     /// Performs an unchecked division, resulting in undefined behavior
@@ -1401,8 +1399,3 @@ extern "rust-intrinsic" {
     /// Probably will never become stable.
     pub fn nontemporal_store<T>(ptr: *mut T, val: T);
 }
-
-#[cfg(stage0)]
-pub unsafe fn exact_div<T>(a: T, b: T) -> T {
-    unchecked_div(a, b)
-}
diff --git a/src/libcore/lib.rs b/src/libcore/lib.rs
index 5a62b8438f93d..cf9abb26d3e1a 100644
--- a/src/libcore/lib.rs
+++ b/src/libcore/lib.rs
@@ -78,8 +78,6 @@
 #![feature(doc_spotlight)]
 #![feature(fn_must_use)]
 #![feature(fundamental)]
-#![cfg_attr(stage0, feature(i128_type))]
-#![cfg_attr(stage0, feature(inclusive_range_syntax))]
 #![feature(intrinsics)]
 #![feature(iterator_flatten)]
 #![feature(iterator_repeat_with)]
@@ -103,9 +101,6 @@
 #![feature(untagged_unions)]
 #![feature(unwind_attributes)]
 
-#![cfg_attr(stage0, allow(unused_attributes))]
-#![cfg_attr(stage0, feature(never_type))]
-
 #[prelude_import]
 #[allow(unused)]
 use prelude::v1::*;
diff --git a/src/libcore/macros.rs b/src/libcore/macros.rs
index 8a87bea71e253..90a9cb3379b82 100644
--- a/src/libcore/macros.rs
+++ b/src/libcore/macros.rs
@@ -28,71 +28,6 @@ macro_rules! panic {
     });
 }
 
-/// Ensure that a boolean expression is `true` at runtime.
-///
-/// This will invoke the [`panic!`] macro if the provided expression cannot be
-/// evaluated to `true` at runtime.
-///
-/// # Uses
-///
-/// Assertions are always checked in both debug and release builds, and cannot
-/// be disabled. See [`debug_assert!`] for assertions that are not enabled in
-/// release builds by default.
-///
-/// Unsafe code relies on `assert!` to enforce run-time invariants that, if
-/// violated could lead to unsafety.
-///
-/// Other use-cases of `assert!` include [testing] and enforcing run-time
-/// invariants in safe code (whose violation cannot result in unsafety).
-///
-/// # Custom Messages
-///
-/// This macro has a second form, where a custom panic message can
-/// be provided with or without arguments for formatting.  See [`std::fmt`]
-/// for syntax for this form.
-///
-/// [`panic!`]: macro.panic.html
-/// [`debug_assert!`]: macro.debug_assert.html
-/// [testing]: ../book/second-edition/ch11-01-writing-tests.html#checking-results-with-the-assert-macro
-/// [`std::fmt`]: ../std/fmt/index.html
-///
-/// # Examples
-///
-/// ```
-/// // the panic message for these assertions is the stringified value of the
-/// // expression given.
-/// assert!(true);
-///
-/// fn some_computation() -> bool { true } // a very simple function
-///
-/// assert!(some_computation());
-///
-/// // assert with a custom message
-/// let x = true;
-/// assert!(x, "x wasn't true!");
-///
-/// let a = 3; let b = 27;
-/// assert!(a + b == 30, "a = {}, b = {}", a, b);
-/// ```
-#[macro_export]
-#[stable(feature = "rust1", since = "1.0.0")]
-#[cfg(stage0)]
-macro_rules! assert {
-    ($cond:expr) => (
-        if !$cond {
-            panic!(concat!("assertion failed: ", stringify!($cond)))
-        }
-    );
-    ($cond:expr,) => (
-        assert!($cond)
-    );
-    ($cond:expr, $($arg:tt)+) => (
-        if !$cond {
-            panic!($($arg)+)
-        }
-    );
-}
-
 /// Asserts that two expressions are equal to each other (using [`PartialEq`]).
 ///
 /// On panic, this macro will print the values of the expressions with their
diff --git a/src/libcore/panicking.rs b/src/libcore/panicking.rs
index 94db0baa3f95f..6b3dc75af4633 100644
--- a/src/libcore/panicking.rs
+++ b/src/libcore/panicking.rs
@@ -64,8 +64,7 @@ pub fn panic_fmt(fmt: fmt::Arguments, file_line_col: &(&'static str, u32, u32))
     #[allow(improper_ctypes)]
     extern {
         #[lang = "panic_fmt"]
-        #[cfg_attr(stage0, unwind)]
-        #[cfg_attr(not(stage0), unwind(allowed))]
+        #[unwind(allowed)]
         fn panic_impl(fmt: fmt::Arguments, file: &'static str, line: u32, col: u32) -> !;
     }
     let (file, line, col) = *file_line_col;
diff --git a/src/libcore/tests/lib.rs b/src/libcore/tests/lib.rs
index de7211e718c9f..971759dcdd08d 100644
--- a/src/libcore/tests/lib.rs
+++ b/src/libcore/tests/lib.rs
@@ -23,10 +23,7 @@
 #![feature(fmt_internals)]
 #![feature(hashmap_internals)]
 #![feature(iterator_step_by)]
-#![cfg_attr(stage0, feature(i128_type))]
-#![cfg_attr(stage0, feature(inclusive_range_syntax))]
 #![feature(iterator_flatten)]
-#![cfg_attr(stage0, feature(conservative_impl_trait))]
 #![feature(iterator_repeat_with)]
 #![feature(nonzero)]
 #![feature(pattern)]
diff --git a/src/libpanic_unwind/gcc.rs b/src/libpanic_unwind/gcc.rs
index ca2fd561cadcf..eb6dc5b548869 100644
--- a/src/libpanic_unwind/gcc.rs
+++ b/src/libpanic_unwind/gcc.rs
@@ -286,8 +286,7 @@ unsafe fn find_eh_action(context: *mut uw::_Unwind_Context)
 // See docs in the `unwind` module.
 #[cfg(all(target_os="windows", target_arch = "x86", target_env="gnu"))]
 #[lang = "eh_unwind_resume"]
-#[cfg_attr(stage0, unwind)]
-#[cfg_attr(not(stage0), unwind(allowed))]
+#[unwind(allowed)]
 unsafe extern "C" fn rust_eh_unwind_resume(panic_ctx: *mut u8) -> ! {
     uw::_Unwind_Resume(panic_ctx as *mut uw::_Unwind_Exception);
 }
diff --git a/src/libpanic_unwind/lib.rs b/src/libpanic_unwind/lib.rs
index a5cebc3e4d04b..a5c227cb4015c 100644
--- a/src/libpanic_unwind/lib.rs
+++ b/src/libpanic_unwind/lib.rs
@@ -112,8 +112,7 @@ pub unsafe extern "C" fn __rust_maybe_catch_panic(f: fn(*mut u8),
 // Entry point for raising an exception, just delegates to the platform-specific
 // implementation.
 #[no_mangle]
-#[cfg_attr(stage0, unwind)]
-#[cfg_attr(not(stage0), unwind(allowed))]
+#[unwind(allowed)]
 pub unsafe extern "C" fn __rust_start_panic(data: usize, vtable: usize) -> u32 {
     imp::panic(mem::transmute(raw::TraitObject {
         data: data as *mut (),
diff --git a/src/libpanic_unwind/seh64_gnu.rs b/src/libpanic_unwind/seh64_gnu.rs
index 090cd095380ee..c3715f96c6482 100644
--- a/src/libpanic_unwind/seh64_gnu.rs
+++ b/src/libpanic_unwind/seh64_gnu.rs
@@ -108,8 +108,7 @@ unsafe extern "C" fn rust_eh_personality(exceptionRecord: *mut c::EXCEPTION_RECO
 }
 
 #[lang = "eh_unwind_resume"]
-#[cfg_attr(stage0, unwind)]
-#[cfg_attr(not(stage0), unwind(allowed))]
+#[unwind(allowed)]
 unsafe extern "C" fn rust_eh_unwind_resume(panic_ctx: c::LPVOID) -> ! {
     let params = [panic_ctx as c::ULONG_PTR];
     c::RaiseException(RUST_PANIC,
diff --git a/src/libpanic_unwind/windows.rs b/src/libpanic_unwind/windows.rs
index 50fba5faee747..5f1dda36a889e 100644
--- a/src/libpanic_unwind/windows.rs
+++ b/src/libpanic_unwind/windows.rs
@@ -79,21 +79,18 @@ pub enum EXCEPTION_DISPOSITION {
 pub use self::EXCEPTION_DISPOSITION::*;
 
 extern "system" {
-    #[cfg_attr(stage0, unwind)]
-    #[cfg_attr(not(stage0), unwind(allowed))]
+    #[unwind(allowed)]
     pub fn RaiseException(dwExceptionCode: DWORD,
                           dwExceptionFlags: DWORD,
                           nNumberOfArguments: DWORD,
                           lpArguments: *const ULONG_PTR);
-    #[cfg_attr(stage0, unwind)]
-    #[cfg_attr(not(stage0), unwind(allowed))]
+    #[unwind(allowed)]
     pub fn RtlUnwindEx(TargetFrame: LPVOID,
                        TargetIp: LPVOID,
                        ExceptionRecord: *const EXCEPTION_RECORD,
                        ReturnValue: LPVOID,
                        OriginalContext: *const CONTEXT,
                        HistoryTable: *const UNWIND_HISTORY_TABLE);
-    #[cfg_attr(stage0, unwind)]
-    #[cfg_attr(not(stage0), unwind(allowed))]
+    #[unwind(allowed)]
     pub fn _CxxThrowException(pExceptionObject: *mut c_void, pThrowInfo: *mut u8);
 }
diff --git a/src/libproc_macro/lib.rs b/src/libproc_macro/lib.rs
index 007093981d3e1..6b2b68b1faacc 100644
--- a/src/libproc_macro/lib.rs
+++ b/src/libproc_macro/lib.rs
@@ -34,7 +34,6 @@
        test(no_crate_inject, attr(deny(warnings))),
        test(attr(allow(dead_code, deprecated, unused_variables, unused_mut))))]
 
-#![cfg_attr(stage0, feature(i128_type))]
 #![feature(rustc_private)]
 #![feature(staged_api)]
 #![feature(lang_items)]
diff --git a/src/librustc/lib.rs b/src/librustc/lib.rs
index dcad8132c2b24..7da664e6d0255 100644
--- a/src/librustc/lib.rs
+++ b/src/librustc/lib.rs
@@ -43,19 +43,14 @@
 
 #![feature(box_patterns)]
 #![feature(box_syntax)]
-#![cfg_attr(stage0, feature(conservative_impl_trait))]
 #![feature(const_fn)]
-#![cfg_attr(stage0, feature(copy_closures, clone_closures))]
 #![feature(core_intrinsics)]
 #![feature(drain_filter)]
 #![feature(dyn_trait)]
 #![feature(entry_or_default)]
 #![feature(from_ref)]
 #![feature(fs_read_write)]
-#![cfg_attr(stage0, feature(i128_type, i128))]
-#![cfg_attr(stage0, feature(inclusive_range_syntax))]
 #![cfg_attr(windows, feature(libc))]
-#![cfg_attr(stage0, feature(match_default_bindings))]
 #![feature(macro_lifetime_matcher)]
 #![feature(macro_vis_matcher)]
 #![feature(exhaustive_patterns)]
@@ -68,8 +63,6 @@
 #![feature(slice_patterns)]
 #![feature(specialization)]
 #![feature(unboxed_closures)]
-#![cfg_attr(stage0, feature(underscore_lifetimes))]
-#![cfg_attr(stage0, feature(universal_impl_trait))]
 #![feature(trace_macros)]
 #![feature(trusted_len)]
 #![feature(catch_expr)]
diff --git a/src/librustc_apfloat/lib.rs b/src/librustc_apfloat/lib.rs
index 6f08fcf702595..276f6cd09bf7a 100644
--- a/src/librustc_apfloat/lib.rs
+++ b/src/librustc_apfloat/lib.rs
@@ -46,10 +46,6 @@
 #![deny(warnings)]
 #![forbid(unsafe_code)]
 
-#![cfg_attr(stage0, feature(slice_patterns))]
-#![cfg_attr(stage0, feature(i128_type))]
-#![cfg_attr(stage0, feature(try_from))]
-
 // See librustc_cratesio_shim/Cargo.toml for a comment explaining this.
 #[allow(unused_extern_crates)]
 extern crate rustc_cratesio_shim;
diff --git a/src/librustc_apfloat/tests/ieee.rs b/src/librustc_apfloat/tests/ieee.rs
index 627d79724b28a..6e06ea858efad 100644
--- a/src/librustc_apfloat/tests/ieee.rs
+++ b/src/librustc_apfloat/tests/ieee.rs
@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![cfg_attr(stage0, feature(i128_type))]
-
 #[macro_use]
 extern crate rustc_apfloat;
 
diff --git a/src/librustc_borrowck/lib.rs b/src/librustc_borrowck/lib.rs
index d54654c60868c..6fe2ac2b0ca25 100644
--- a/src/librustc_borrowck/lib.rs
+++ b/src/librustc_borrowck/lib.rs
@@ -16,7 +16,6 @@
 #![allow(non_camel_case_types)]
 
 #![feature(from_ref)]
-#![cfg_attr(stage0, feature(match_default_bindings))]
 #![feature(quote)]
 
 #[macro_use] extern crate log;
diff --git a/src/librustc_const_math/lib.rs b/src/librustc_const_math/lib.rs
index 7177e2818fbcc..c4c5886d465d8 100644
--- a/src/librustc_const_math/lib.rs
+++ b/src/librustc_const_math/lib.rs
@@ -19,8 +19,6 @@
       html_root_url = "https://doc.rust-lang.org/nightly/")]
 #![deny(warnings)]
 
-#![cfg_attr(stage0, feature(i128_type, i128))]
-
 extern crate rustc_apfloat;
 
 extern crate syntax;
diff --git a/src/librustc_data_structures/lib.rs b/src/librustc_data_structures/lib.rs
index 622fb423b51e4..1e1628936d5ca 100644
--- a/src/librustc_data_structures/lib.rs
+++ b/src/librustc_data_structures/lib.rs
@@ -26,14 +26,10 @@
 #![feature(unboxed_closures)]
 #![feature(fn_traits)]
 #![feature(unsize)]
-#![cfg_attr(stage0, feature(conservative_impl_trait))]
-#![cfg_attr(stage0, feature(i128_type, i128))]
 #![feature(specialization)]
 #![feature(optin_builtin_traits)]
-#![cfg_attr(stage0, feature(underscore_lifetimes))]
 #![feature(macro_vis_matcher)]
 #![feature(allow_internal_unstable)]
-#![cfg_attr(stage0, feature(universal_impl_trait))]
 
 #![cfg_attr(unix, feature(libc))]
 #![cfg_attr(test, feature(test))]
diff --git a/src/librustc_errors/lib.rs b/src/librustc_errors/lib.rs
index 37ae64cef5725..c283df6ec0fb1 100644
--- a/src/librustc_errors/lib.rs
+++ b/src/librustc_errors/lib.rs
@@ -17,8 +17,6 @@
 #![allow(unused_attributes)]
 #![feature(range_contains)]
 #![cfg_attr(unix, feature(libc))]
-#![cfg_attr(stage0, feature(conservative_impl_trait))]
-#![cfg_attr(stage0, feature(i128_type))]
 #![feature(optin_builtin_traits)]
 
 extern crate atty;
diff --git a/src/librustc_incremental/lib.rs b/src/librustc_incremental/lib.rs
index cad72ff778b55..9e72ede309d44 100644
--- a/src/librustc_incremental/lib.rs
+++ b/src/librustc_incremental/lib.rs
@@ -15,10 +15,7 @@
       html_root_url = "https://doc.rust-lang.org/nightly/")]
 #![deny(warnings)]
 
-#![cfg_attr(stage0, feature(conservative_impl_trait))]
 #![feature(fs_read_write)]
-#![cfg_attr(stage0, feature(i128_type))]
-#![cfg_attr(stage0, feature(inclusive_range_syntax))]
 #![feature(specialization)]
 
 extern crate graphviz;
diff --git a/src/librustc_lint/lib.rs b/src/librustc_lint/lib.rs
index d024adad9d030..c915181213d38 100644
--- a/src/librustc_lint/lib.rs
+++ b/src/librustc_lint/lib.rs
@@ -27,11 +27,9 @@
 #![cfg_attr(test, feature(test))]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
-#![cfg_attr(stage0, feature(i128_type))]
 #![feature(macro_vis_matcher)]
 #![feature(quote)]
 #![feature(rustc_diagnostic_macros)]
-#![cfg_attr(stage0, feature(never_type))]
 
 #[macro_use]
 extern crate syntax;
diff --git a/src/librustc_metadata/lib.rs b/src/librustc_metadata/lib.rs
index 4af5ec9ae08ea..e89b5a7fc1b4e 100644
--- a/src/librustc_metadata/lib.rs
+++ b/src/librustc_metadata/lib.rs
@@ -14,9 +14,7 @@
 #![deny(warnings)]
 
 #![feature(box_patterns)]
-#![cfg_attr(stage0, feature(conservative_impl_trait))]
 #![feature(fs_read_write)]
-#![cfg_attr(stage0, feature(i128_type))]
 #![feature(libc)]
 #![feature(macro_lifetime_matcher)]
 #![feature(proc_macro_internals)]
diff --git a/src/librustc_mir/lib.rs b/src/librustc_mir/lib.rs
index 84baa8c541781..8762e7550cded 100644
--- a/src/librustc_mir/lib.rs
+++ b/src/librustc_mir/lib.rs
@@ -21,22 +21,16 @@ Rust MIR: a lowered representation of Rust. Also: an experiment!
 #![feature(box_patterns)]
 #![feature(box_syntax)]
 #![feature(catch_expr)]
-#![cfg_attr(stage0, feature(conservative_impl_trait))]
 #![feature(const_fn)]
 #![feature(core_intrinsics)]
 #![feature(decl_macro)]
 #![feature(dyn_trait)]
 #![feature(fs_read_write)]
-#![cfg_attr(stage0, feature(i128_type))]
-#![cfg_attr(stage0, feature(inclusive_range_syntax))]
 #![feature(macro_vis_matcher)]
-#![cfg_attr(stage0, feature(match_default_bindings))]
 #![feature(exhaustive_patterns)]
 #![feature(range_contains)]
 #![feature(rustc_diagnostic_macros)]
 #![feature(nonzero)]
-#![cfg_attr(stage0, feature(underscore_lifetimes))]
-#![cfg_attr(stage0, feature(never_type))]
 #![feature(inclusive_range_fields)]
 
 extern crate arena;
diff --git a/src/librustc_traits/lib.rs b/src/librustc_traits/lib.rs
index 90f368edeeca6..cfa3b6912f2e4 100644
--- a/src/librustc_traits/lib.rs
+++ b/src/librustc_traits/lib.rs
@@ -14,8 +14,6 @@
 #![deny(warnings)]
 
 #![feature(crate_visibility_modifier)]
-#![cfg_attr(stage0, feature(match_default_bindings))]
-#![cfg_attr(stage0, feature(underscore_lifetimes))]
 
 #[macro_use]
 extern crate log;
diff --git a/src/librustc_trans/lib.rs b/src/librustc_trans/lib.rs
index e8a1eb3071a29..2ce13a2627ff4 100644
--- a/src/librustc_trans/lib.rs
+++ b/src/librustc_trans/lib.rs
@@ -24,13 +24,9 @@
 #![feature(custom_attribute)]
 #![feature(fs_read_write)]
 #![allow(unused_attributes)]
-#![cfg_attr(stage0, feature(i128_type, i128))]
-#![cfg_attr(stage0, feature(inclusive_range_syntax))]
 #![feature(libc)]
 #![feature(quote)]
 #![feature(rustc_diagnostic_macros)]
-#![cfg_attr(stage0, feature(slice_patterns))]
-#![cfg_attr(stage0, feature(conservative_impl_trait))]
 #![feature(optin_builtin_traits)]
 #![feature(inclusive_range_fields)]
 
diff --git a/src/librustc_trans_utils/lib.rs b/src/librustc_trans_utils/lib.rs
index 99de124c6e1ad..cf47d9b62a94e 100644
--- a/src/librustc_trans_utils/lib.rs
+++ b/src/librustc_trans_utils/lib.rs
@@ -21,10 +21,8 @@
 #![feature(box_syntax)]
 #![feature(custom_attribute)]
 #![allow(unused_attributes)]
-#![cfg_attr(stage0, feature(i128_type))]
 #![feature(quote)]
 #![feature(rustc_diagnostic_macros)]
-#![cfg_attr(stage0, feature(conservative_impl_trait))]
 
 extern crate ar;
 extern crate flate2;
diff --git a/src/librustc_typeck/lib.rs b/src/librustc_typeck/lib.rs
index 44ecb32a0bf9b..6f71db998bd41 100644
--- a/src/librustc_typeck/lib.rs
+++ b/src/librustc_typeck/lib.rs
@@ -72,22 +72,16 @@ This API is completely unstable and subject to change.
 
 #![allow(non_camel_case_types)]
 
-#![cfg_attr(stage0, feature(advanced_slice_patterns))]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
-#![cfg_attr(stage0, feature(conservative_impl_trait))]
-#![cfg_attr(stage0, feature(copy_closures, clone_closures))]
 #![feature(crate_visibility_modifier)]
 #![feature(from_ref)]
-#![cfg_attr(stage0, feature(match_default_bindings))]
 #![feature(exhaustive_patterns)]
 #![feature(option_filter)]
 #![feature(quote)]
 #![feature(refcell_replace_swap)]
 #![feature(rustc_diagnostic_macros)]
 #![feature(slice_patterns)]
-#![cfg_attr(stage0, feature(i128_type))]
-#![cfg_attr(stage0, feature(never_type))]
 #![feature(dyn_trait)]
 
 #[macro_use] extern crate log;
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index e31390f59e292..42e87f88fd40d 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -20,7 +20,6 @@
 #![feature(box_syntax)]
 #![feature(fs_read_write)]
 #![feature(set_stdio)]
-#![cfg_attr(stage0, feature(slice_patterns))]
 #![feature(test)]
 #![feature(unicode)]
 #![feature(vec_remove_item)]
diff --git a/src/libserialize/lib.rs b/src/libserialize/lib.rs
index ee95252346223..f78eed3069478 100644
--- a/src/libserialize/lib.rs
+++ b/src/libserialize/lib.rs
@@ -23,7 +23,6 @@ Core encoding and decoding interfaces.
 
 #![feature(box_syntax)]
 #![feature(core_intrinsics)]
-#![cfg_attr(stage0, feature(i128_type))]
 #![feature(specialization)]
 #![cfg_attr(test, feature(test))]
 
diff --git a/src/libstd/lib.rs b/src/libstd/lib.rs
index 3f1fec4c3177d..7da2eeefaaa4e 100644
--- a/src/libstd/lib.rs
+++ b/src/libstd/lib.rs
@@ -269,7 +269,6 @@
 #![cfg_attr(stage0, feature(generic_param_attrs))]
 #![feature(hashmap_internals)]
 #![feature(heap_api)]
-#![cfg_attr(stage0, feature(i128_type, i128))]
 #![feature(int_error_internals)]
 #![feature(integer_atomics)]
 #![feature(into_cow)]
@@ -321,8 +320,6 @@
 #![feature(doc_spotlight)]
 #![cfg_attr(test, feature(update_panic_count))]
 #![cfg_attr(windows, feature(used))]
-#![cfg_attr(stage0, feature(never_type))]
-#![cfg_attr(stage0, feature(termination_trait))]
 
 #![default_lib_allocator]
 
@@ -355,7 +352,6 @@ use prelude::v1::*;
 // add a new crate name so we can attach the re-exports to it.
 #[macro_reexport(assert_eq, assert_ne, debug_assert, debug_assert_eq,
                  debug_assert_ne, unreachable, unimplemented, write, writeln, try)]
-#[cfg_attr(stage0, macro_reexport(assert))]
 extern crate core as __core;
 
 #[macro_use]
diff --git a/src/libstd/panicking.rs b/src/libstd/panicking.rs
index 454ac64735c67..fba3269204e90 100644
--- a/src/libstd/panicking.rs
+++ b/src/libstd/panicking.rs
@@ -55,8 +55,7 @@ extern {
                                 data: *mut u8,
                                 data_ptr: *mut usize,
                                 vtable_ptr: *mut usize) -> u32;
-    #[cfg_attr(stage0, unwind)]
-    #[cfg_attr(not(stage0), unwind(allowed))]
+    #[unwind(allowed)]
     fn __rust_start_panic(data: usize, vtable: usize) -> u32;
 }
 
@@ -316,8 +315,7 @@ pub fn panicking() -> bool {
 /// Entry point of panic from the libcore crate.
 #[cfg(not(test))]
 #[lang = "panic_fmt"]
-#[cfg_attr(stage0, unwind)]
-#[cfg_attr(not(stage0), unwind(allowed))]
+#[unwind(allowed)]
 pub extern fn rust_begin_panic(msg: fmt::Arguments,
                                file: &'static str,
                                line: u32,
diff --git a/src/libsyntax/lib.rs b/src/libsyntax/lib.rs
index dc349c1a3e6a1..c456dc45d2182 100644
--- a/src/libsyntax/lib.rs
+++ b/src/libsyntax/lib.rs
@@ -22,9 +22,7 @@
 
 #![feature(unicode)]
 #![feature(rustc_diagnostic_macros)]
-#![cfg_attr(stage0, feature(match_default_bindings))]
 #![feature(non_exhaustive)]
-#![cfg_attr(stage0, feature(i128_type))]
 #![feature(const_atomic_usize_new)]
 #![feature(rustc_attrs)]
 
diff --git a/src/libsyntax_pos/lib.rs b/src/libsyntax_pos/lib.rs
index eb345200f413d..b63159004854a 100644
--- a/src/libsyntax_pos/lib.rs
+++ b/src/libsyntax_pos/lib.rs
@@ -21,7 +21,6 @@
 
 #![feature(const_fn)]
 #![feature(custom_attribute)]
-#![cfg_attr(stage0, feature(i128_type))]
 #![feature(optin_builtin_traits)]
 #![allow(unused_attributes)]
 #![feature(specialization)]
diff --git a/src/libunwind/libunwind.rs b/src/libunwind/libunwind.rs
index aa73b11fb3813..a640a2b777537 100644
--- a/src/libunwind/libunwind.rs
+++ b/src/libunwind/libunwind.rs
@@ -83,8 +83,7 @@ pub enum _Unwind_Context {}
 pub type _Unwind_Exception_Cleanup_Fn = extern "C" fn(unwind_code: _Unwind_Reason_Code,
                                                       exception: *mut _Unwind_Exception);
 extern "C" {
-    #[cfg_attr(stage0, unwind)]
-    #[cfg_attr(not(stage0), unwind(allowed))]
+    #[unwind(allowed)]
     pub fn _Unwind_Resume(exception: *mut _Unwind_Exception) -> !;
     pub fn _Unwind_DeleteException(exception: *mut _Unwind_Exception);
     pub fn _Unwind_GetLanguageSpecificData(ctx: *mut _Unwind_Context) -> *mut c_void;
@@ -221,8 +220,7 @@ if #[cfg(all(any(target_os = "ios", not(target_arch = "arm"))))] {
 if #[cfg(not(all(target_os = "ios", target_arch = "arm")))] {
     // Not 32-bit iOS
     extern "C" {
-        #[cfg_attr(stage0, unwind)]
-        #[cfg_attr(not(stage0), unwind(allowed))]
+        #[unwind(allowed)]
         pub fn _Unwind_RaiseException(exception: *mut _Unwind_Exception) -> _Unwind_Reason_Code;
         pub fn _Unwind_Backtrace(trace: _Unwind_Trace_Fn,
                                  trace_argument: *mut c_void)
@@ -231,8 +229,7 @@ if #[cfg(not(all(target_os = "ios", target_arch = "arm")))] {
 } else {
     // 32-bit iOS uses SjLj and does not provide _Unwind_Backtrace()
     extern "C" {
-        #[cfg_attr(stage0, unwind)]
-        #[cfg_attr(not(stage0), unwind(allowed))]
+        #[unwind(allowed)]
         pub fn _Unwind_SjLj_RaiseException(e: *mut _Unwind_Exception) -> _Unwind_Reason_Code;
     }
 
diff --git a/src/stage0.txt b/src/stage0.txt
index 96ec1e6834dff..e8db3358cf076 100644
--- a/src/stage0.txt
+++ b/src/stage0.txt
@@ -12,7 +12,7 @@
 # source tarball for a stable release you'll likely see `1.x.0` for rustc and
 # `0.x.0` for Cargo where they were released on `date`.
 
-date: 2018-03-18
+date: 2018-04-04
 rustc: beta
 cargo: beta