diff --git a/src/libcore/intrinsics.rs b/src/libcore/intrinsics.rs
index 4f5310f5285c9..db19baf7a2c64 100644
--- a/src/libcore/intrinsics.rs
+++ b/src/libcore/intrinsics.rs
@@ -1348,7 +1348,7 @@ extern "rust-intrinsic" {
     /// use std::intrinsics::ctlz;
     ///
     /// let x = 0b0001_1100_u8;
-    /// let num_leading = unsafe { ctlz(x) };
+    /// let num_leading = ctlz(x);
     /// assert_eq!(num_leading, 3);
     /// ```
     ///
@@ -1360,7 +1360,7 @@ extern "rust-intrinsic" {
     /// use std::intrinsics::ctlz;
     ///
     /// let x = 0u16;
-    /// let num_leading = unsafe { ctlz(x) };
+    /// let num_leading = ctlz(x);
     /// assert_eq!(num_leading, 16);
     /// ```
     pub fn ctlz<T>(x: T) -> T;
@@ -1391,7 +1391,7 @@ extern "rust-intrinsic" {
     /// use std::intrinsics::cttz;
     ///
     /// let x = 0b0011_1000_u8;
-    /// let num_trailing = unsafe { cttz(x) };
+    /// let num_trailing = cttz(x);
     /// assert_eq!(num_trailing, 3);
     /// ```
     ///
@@ -1403,7 +1403,7 @@ extern "rust-intrinsic" {
     /// use std::intrinsics::cttz;
     ///
     /// let x = 0u16;
-    /// let num_trailing = unsafe { cttz(x) };
+    /// let num_trailing = cttz(x);
     /// assert_eq!(num_trailing, 16);
     /// ```
     pub fn cttz<T>(x: T) -> T;
diff --git a/src/libcore/lib.rs b/src/libcore/lib.rs
index b2cafc4cede2e..a5f20d08e47be 100644
--- a/src/libcore/lib.rs
+++ b/src/libcore/lib.rs
@@ -71,7 +71,7 @@
 #![feature(cfg_target_has_atomic)]
 #![feature(concat_idents)]
 #![feature(const_fn)]
-#![feature(const_int_ops)]
+#![cfg_attr(stage0, feature(const_int_ops))]
 #![feature(const_fn_union)]
 #![feature(custom_attribute)]
 #![feature(doc_cfg)]
@@ -114,9 +114,7 @@
 #![feature(const_slice_len)]
 #![feature(const_str_as_bytes)]
 #![feature(const_str_len)]
-#![feature(const_int_rotate)]
-#![feature(const_int_wrapping)]
-#![feature(const_int_sign)]
+#![cfg_attr(stage0, feature(const_int_rotate))]
 #![feature(const_int_conversion)]
 #![feature(const_transmute)]
 #![feature(reverse_bits)]
diff --git a/src/libcore/num/mod.rs b/src/libcore/num/mod.rs
index 97bf582df5a8c..7ff04410516a3 100644
--- a/src/libcore/num/mod.rs
+++ b/src/libcore/num/mod.rs
@@ -275,7 +275,7 @@ $EndFeature, "
 ```
 "),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_ops")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_ops"))]
             #[inline]
             pub const fn count_ones(self) -> u32 { (self as $UnsignedT).count_ones() }
         }
@@ -291,7 +291,7 @@ Basic usage:
 ", $Feature, "assert_eq!(", stringify!($SelfT), "::max_value().count_zeros(), 1);", $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_ops")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_ops"))]
             #[inline]
             pub const fn count_zeros(self) -> u32 {
                 (!self).count_ones()
@@ -312,7 +312,7 @@ assert_eq!(n.leading_zeros(), 0);",
 $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_ops")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_ops"))]
             #[inline]
             pub const fn leading_zeros(self) -> u32 {
                 (self as $UnsignedT).leading_zeros()
@@ -333,7 +333,7 @@ assert_eq!(n.trailing_zeros(), 2);",
 $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_ops")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_ops"))]
             #[inline]
             pub const fn trailing_zeros(self) -> u32 {
                 (self as $UnsignedT).trailing_zeros()
@@ -357,7 +357,7 @@ let m = ", $rot_result, ";
 assert_eq!(n.rotate_left(", $rot, "), m);
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_rotate")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_rotate"))]
             #[inline]
             pub const fn rotate_left(self, n: u32) -> Self {
                 (self as $UnsignedT).rotate_left(n) as Self
@@ -382,7 +382,7 @@ let m = ", $rot_op, ";
 assert_eq!(n.rotate_right(", $rot, "), m);
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_rotate")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_rotate"))]
             #[inline]
             pub const fn rotate_right(self, n: u32) -> Self {
                 (self as $UnsignedT).rotate_right(n) as Self
@@ -404,7 +404,7 @@ let m = n.swap_bytes();
 assert_eq!(m, ", $swapped, ");
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_ops")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_ops"))]
             #[inline]
             pub const fn swap_bytes(self) -> Self {
                 (self as $UnsignedT).swap_bytes() as Self
@@ -454,7 +454,7 @@ if cfg!(target_endian = \"big\") {
 $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_ops")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_ops"))]
             #[inline]
             pub const fn from_be(x: Self) -> Self {
                 #[cfg(target_endian = "big")]
@@ -488,7 +488,7 @@ if cfg!(target_endian = \"little\") {
 $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_ops")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_ops"))]
             #[inline]
             pub const fn from_le(x: Self) -> Self {
                 #[cfg(target_endian = "little")]
@@ -522,7 +522,7 @@ if cfg!(target_endian = \"big\") {
 $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_ops")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_ops"))]
             #[inline]
             pub const fn to_be(self) -> Self { // or not to be?
                 #[cfg(target_endian = "big")]
@@ -556,7 +556,7 @@ if cfg!(target_endian = \"little\") {
 $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_ops")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_ops"))]
             #[inline]
             pub const fn to_le(self) -> Self {
                 #[cfg(target_endian = "little")]
@@ -994,12 +994,15 @@ assert_eq!(", stringify!($SelfT), "::max_value().wrapping_add(2), ", stringify!(
 $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_wrapping")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_wrapping"))]
             #[inline]
             pub const fn wrapping_add(self, rhs: Self) -> Self {
+                #[cfg(stage0)]
                 unsafe {
                     intrinsics::overflowing_add(self, rhs)
                 }
+                #[cfg(not(stage0))]
+                intrinsics::overflowing_add(self, rhs)
             }
         }
 
@@ -1018,12 +1021,15 @@ stringify!($SelfT), "::max_value());",
 $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_wrapping")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_wrapping"))]
             #[inline]
             pub const fn wrapping_sub(self, rhs: Self) -> Self {
+                #[cfg(stage0)]
                 unsafe {
                     intrinsics::overflowing_sub(self, rhs)
                 }
+                #[cfg(not(stage0))]
+                intrinsics::overflowing_sub(self, rhs)
             }
         }
 
@@ -1041,12 +1047,15 @@ assert_eq!(11i8.wrapping_mul(12), -124);",
 $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_wrapping")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_wrapping"))]
             #[inline]
             pub const fn wrapping_mul(self, rhs: Self) -> Self {
+                #[cfg(stage0)]
                 unsafe {
                     intrinsics::overflowing_mul(self, rhs)
                 }
+                #[cfg(not(stage0))]
+                intrinsics::overflowing_mul(self, rhs)
             }
         }
 
@@ -1205,7 +1214,7 @@ assert_eq!((-1", stringify!($SelfT), ").wrapping_shl(128), -1);",
 $EndFeature, "
 ```"),
             #[stable(feature = "num_wrapping", since = "1.2.0")]
-            #[rustc_const_unstable(feature = "const_int_wrapping")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_wrapping"))]
             #[inline]
             pub const fn wrapping_shl(self, rhs: u32) -> Self {
                 unsafe {
@@ -1233,7 +1242,7 @@ assert_eq!((-128i16).wrapping_shr(64), -128);",
 $EndFeature, "
 ```"),
             #[stable(feature = "num_wrapping", since = "1.2.0")]
-            #[rustc_const_unstable(feature = "const_int_wrapping")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_wrapping"))]
             #[inline]
             pub const fn wrapping_shr(self, rhs: u32) -> Self {
                 unsafe {
@@ -1886,7 +1895,6 @@ assert!(!(-10", stringify!($SelfT), ").is_positive());",
 $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_sign")]
             #[inline]
             pub const fn is_positive(self) -> bool { self > 0 }
         }
@@ -1905,7 +1913,6 @@ assert!(!10", stringify!($SelfT), ".is_negative());",
 $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_sign")]
             #[inline]
             pub const fn is_negative(self) -> bool { self < 0 }
         }
@@ -2227,10 +2234,13 @@ Basic usage:
 assert_eq!(n.count_ones(), 3);", $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_ops")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_ops"))]
             #[inline]
             pub const fn count_ones(self) -> u32 {
+                #[cfg(stage0)]
                 unsafe { intrinsics::ctpop(self as $ActualT) as u32 }
+                #[cfg(not(stage0))]
+                { intrinsics::ctpop(self as $ActualT) as u32 }
             }
         }
 
@@ -2245,7 +2255,7 @@ Basic usage:
 ", $Feature, "assert_eq!(", stringify!($SelfT), "::max_value().count_zeros(), 0);", $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_ops")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_ops"))]
             #[inline]
             pub const fn count_zeros(self) -> u32 {
                 (!self).count_ones()
@@ -2265,10 +2275,13 @@ Basic usage:
 assert_eq!(n.leading_zeros(), 2);", $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_ops")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_ops"))]
             #[inline]
             pub const fn leading_zeros(self) -> u32 {
+                #[cfg(stage0)]
                 unsafe { intrinsics::ctlz(self as $ActualT) as u32 }
+                #[cfg(not(stage0))]
+                { intrinsics::ctlz(self as $ActualT) as u32 }
             }
         }
 
@@ -2286,10 +2299,13 @@ Basic usage:
 assert_eq!(n.trailing_zeros(), 3);", $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_ops")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_ops"))]
             #[inline]
             pub const fn trailing_zeros(self) -> u32 {
+                #[cfg(stage0)]
                 unsafe { intrinsics::cttz(self) as u32 }
+                #[cfg(not(stage0))]
+                { intrinsics::cttz(self) as u32 }
             }
         }
 
@@ -2310,10 +2326,13 @@ let m = ", $rot_result, ";
 assert_eq!(n.rotate_left(", $rot, "), m);
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_rotate")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_rotate"))]
             #[inline]
             pub const fn rotate_left(self, n: u32) -> Self {
+                #[cfg(stage0)]
                 unsafe { intrinsics::rotate_left(self, n as $SelfT) }
+                #[cfg(not(stage0))]
+                intrinsics::rotate_left(self, n as $SelfT)
             }
         }
 
@@ -2335,10 +2354,13 @@ let m = ", $rot_op, ";
 assert_eq!(n.rotate_right(", $rot, "), m);
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_rotate")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_rotate"))]
             #[inline]
             pub const fn rotate_right(self, n: u32) -> Self {
+                #[cfg(stage0)]
                 unsafe { intrinsics::rotate_right(self, n as $SelfT) }
+                #[cfg(not(stage0))]
+                intrinsics::rotate_right(self, n as $SelfT)
             }
         }
 
@@ -2357,10 +2379,13 @@ let m = n.swap_bytes();
 assert_eq!(m, ", $swapped, ");
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_ops")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_ops"))]
             #[inline]
             pub const fn swap_bytes(self) -> Self {
+                #[cfg(stage0)]
                 unsafe { intrinsics::bswap(self as $ActualT) as Self }
+                #[cfg(not(stage0))]
+                { intrinsics::bswap(self as $ActualT) as Self }
             }
         }
 
@@ -2380,10 +2405,13 @@ let m = n.reverse_bits();
 assert_eq!(m, ", $reversed, ");
 ```"),
             #[unstable(feature = "reverse_bits", issue = "48763")]
-            #[rustc_const_unstable(feature = "const_int_conversion")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_conversion"))]
             #[inline]
             pub const fn reverse_bits(self) -> Self {
+                #[cfg(stage0)]
                 unsafe { intrinsics::bitreverse(self as $ActualT) as Self }
+                #[cfg(not(stage0))]
+                { intrinsics::bitreverse(self as $ActualT) as Self }
             }
         }
 
@@ -2407,7 +2435,7 @@ if cfg!(target_endian = \"big\") {
 }", $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_ops")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_ops"))]
             #[inline]
             pub const fn from_be(x: Self) -> Self {
                 #[cfg(target_endian = "big")]
@@ -2441,7 +2469,7 @@ if cfg!(target_endian = \"little\") {
 }", $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_ops")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_ops"))]
             #[inline]
             pub const fn from_le(x: Self) -> Self {
                 #[cfg(target_endian = "little")]
@@ -2475,7 +2503,7 @@ if cfg!(target_endian = \"big\") {
 }", $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_ops")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_ops"))]
             #[inline]
             pub const fn to_be(self) -> Self { // or not to be?
                 #[cfg(target_endian = "big")]
@@ -2509,7 +2537,7 @@ if cfg!(target_endian = \"little\") {
 }", $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_ops")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_ops"))]
             #[inline]
             pub const fn to_le(self) -> Self {
                 #[cfg(target_endian = "little")]
@@ -2884,12 +2912,15 @@ assert_eq!(200", stringify!($SelfT), ".wrapping_add(", stringify!($SelfT), "::ma
 $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_wrapping")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_wrapping"))]
             #[inline]
             pub const fn wrapping_add(self, rhs: Self) -> Self {
+                #[cfg(stage0)]
                 unsafe {
                     intrinsics::overflowing_add(self, rhs)
                 }
+                #[cfg(not(stage0))]
+                intrinsics::overflowing_add(self, rhs)
             }
         }
 
@@ -2907,12 +2938,15 @@ assert_eq!(100", stringify!($SelfT), ".wrapping_sub(", stringify!($SelfT), "::ma
 $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_wrapping")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_wrapping"))]
             #[inline]
             pub const fn wrapping_sub(self, rhs: Self) -> Self {
+                #[cfg(stage0)]
                 unsafe {
                     intrinsics::overflowing_sub(self, rhs)
                 }
+                #[cfg(not(stage0))]
+                intrinsics::overflowing_sub(self, rhs)
             }
         }
 
@@ -2931,12 +2965,15 @@ $EndFeature, "
         /// assert_eq!(25u8.wrapping_mul(12), 44);
         /// ```
         #[stable(feature = "rust1", since = "1.0.0")]
-        #[rustc_const_unstable(feature = "const_int_wrapping")]
+        #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_wrapping"))]
         #[inline]
         pub const fn wrapping_mul(self, rhs: Self) -> Self {
+            #[cfg(stage0)]
             unsafe {
                 intrinsics::overflowing_mul(self, rhs)
             }
+            #[cfg(not(stage0))]
+            intrinsics::overflowing_mul(self, rhs)
         }
 
         doc_comment! {
@@ -3081,7 +3118,7 @@ Basic usage:
 assert_eq!(1", stringify!($SelfT), ".wrapping_shl(128), 1);", $EndFeature, "
 ```"),
             #[stable(feature = "num_wrapping", since = "1.2.0")]
-            #[rustc_const_unstable(feature = "const_int_wrapping")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_wrapping"))]
             #[inline]
             pub const fn wrapping_shl(self, rhs: u32) -> Self {
                 unsafe {
@@ -3111,7 +3148,7 @@ Basic usage:
 assert_eq!(128", stringify!($SelfT), ".wrapping_shr(128), 128);", $EndFeature, "
 ```"),
             #[stable(feature = "num_wrapping", since = "1.2.0")]
-            #[rustc_const_unstable(feature = "const_int_wrapping")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_wrapping"))]
             #[inline]
             pub const fn wrapping_shr(self, rhs: u32) -> Self {
                 unsafe {
diff --git a/src/librustc_mir/transform/qualify_consts.rs b/src/librustc_mir/transform/qualify_consts.rs
index a04dd5bb5970f..193b0fe05f002 100644
--- a/src/librustc_mir/transform/qualify_consts.rs
+++ b/src/librustc_mir/transform/qualify_consts.rs
@@ -21,7 +21,7 @@ use rustc::mir::visit::{PlaceContext, Visitor, MutatingUseContext, NonMutatingUs
 use rustc::middle::lang_items;
 use rustc::session::config::nightly_options;
 use syntax::ast::LitKind;
-use syntax::feature_gate::{UnstableFeatures, feature_err, emit_feature_err, GateIssue};
+use syntax::feature_gate::{UnstableFeatures, emit_feature_err, GateIssue};
 use syntax_pos::{Span, DUMMY_SP};
 
 use std::fmt;
@@ -104,7 +104,6 @@ struct Qualifier<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
     param_env: ty::ParamEnv<'tcx>,
     local_qualif: IndexVec<Local, Option<Qualif>>,
     qualif: Qualif,
-    const_fn_arg_vars: BitSet<Local>,
     temp_promotion_state: IndexVec<Local, TempState>,
     promotion_candidates: Vec<Candidate>
 }
@@ -139,7 +138,6 @@ impl<'a, 'tcx> Qualifier<'a, 'tcx, 'tcx> {
             param_env,
             local_qualif,
             qualif: Qualif::empty(),
-            const_fn_arg_vars: BitSet::new_empty(mir.local_decls.len()),
             temp_promotion_state: temps,
             promotion_candidates: vec![]
         }
@@ -168,26 +166,6 @@ impl<'a, 'tcx> Qualifier<'a, 'tcx, 'tcx> {
         }
     }
 
-    /// Error about extra statements in a constant.
-    fn statement_like(&mut self) {
-        self.add(Qualif::NOT_CONST);
-        if self.mode != Mode::Fn {
-            let mut err = feature_err(
-                &self.tcx.sess.parse_sess,
-                "const_let",
-                self.span,
-                GateIssue::Language,
-                &format!("statements in {}s are unstable", self.mode),
-            );
-            if self.tcx.sess.teach(&err.get_code().unwrap()) {
-                err.note("Blocks in constants may only contain items (such as constant, function \
-                          definition, etc...) and a tail expression.");
-                err.help("To avoid it, you have to replace the non-item object.");
-            }
-            err.emit();
-        }
-    }
-
     /// Add the given qualification to self.qualif.
     fn add(&mut self, qualif: Qualif) {
         self.qualif = self.qualif | qualif;
@@ -233,80 +211,46 @@ impl<'a, 'tcx> Qualifier<'a, 'tcx, 'tcx> {
             return;
         }
 
-        if self.tcx.features().const_let {
-            let mut dest = dest;
-            let index = loop {
-                match dest {
-                    // with `const_let` active, we treat all locals equal
-                    Place::Local(index) => break *index,
-                    // projections are transparent for assignments
-                    // we qualify the entire destination at once, even if just a field would have
-                    // stricter qualification
-                    Place::Projection(proj) => {
-                        // Catch more errors in the destination. `visit_place` also checks various
-                        // projection rules like union field access and raw pointer deref
-                        self.visit_place(
-                            dest,
-                            PlaceContext::MutatingUse(MutatingUseContext::Store),
-                            location
-                        );
-                        dest = &proj.base;
-                    },
-                    Place::Promoted(..) => bug!("promoteds don't exist yet during promotion"),
-                    Place::Static(..) => {
-                        // Catch more errors in the destination. `visit_place` also checks that we
-                        // do not try to access statics from constants or try to mutate statics
-                        self.visit_place(
-                            dest,
-                            PlaceContext::MutatingUse(MutatingUseContext::Store),
-                            location
-                        );
-                        return;
-                    }
+        let mut dest = dest;
+        let index = loop {
+            match dest {
+                // We treat all locals equal in constants
+                Place::Local(index) => break *index,
+                // projections are transparent for assignments
+                // we qualify the entire destination at once, even if just a field would have
+                // stricter qualification
+                Place::Projection(proj) => {
+                    // Catch more errors in the destination. `visit_place` also checks various
+                    // projection rules like union field access and raw pointer deref
+                    self.visit_place(
+                        dest,
+                        PlaceContext::MutatingUse(MutatingUseContext::Store),
+                        location
+                    );
+                    dest = &proj.base;
+                },
+                Place::Promoted(..) => bug!("promoteds don't exist yet during promotion"),
+                Place::Static(..) => {
+                    // Catch more errors in the destination. `visit_place` also checks that we
+                    // do not try to access statics from constants or try to mutate statics
+                    self.visit_place(
+                        dest,
+                        PlaceContext::MutatingUse(MutatingUseContext::Store),
+                        location
+                    );
+                    return;
                 }
-            };
-            debug!("store to var {:?}", index);
-            match &mut self.local_qualif[index] {
-                // this is overly restrictive, because even full assignments do not clear the qualif
-                // While we could special case full assignments, this would be inconsistent with
-                // aggregates where we overwrite all fields via assignments, which would not get
-                // that feature.
-                Some(ref mut qualif) => *qualif = *qualif | self.qualif,
-                // insert new qualification
-                qualif @ None => *qualif = Some(self.qualif),
-            }
-            return;
-        }
-
-        match *dest {
-            Place::Local(index) if self.mir.local_kind(index) == LocalKind::Temp ||
-                                   self.mir.local_kind(index) == LocalKind::ReturnPointer => {
-                debug!("store to {:?} (temp or return pointer)", index);
-                store(&mut self.local_qualif[index])
-            }
-
-            Place::Projection(box Projection {
-                base: Place::Local(index),
-                elem: ProjectionElem::Deref
-            }) if self.mir.local_kind(index) == LocalKind::Temp
-               && self.mir.local_decls[index].ty.is_box()
-               && self.local_qualif[index].map_or(false, |qualif| {
-                    qualif.contains(Qualif::NOT_CONST)
-               }) => {
-                // Part of `box expr`, we should've errored
-                // already for the Box allocation Rvalue.
-            }
-
-            // This must be an explicit assignment.
-            _ => {
-                // Catch more errors in the destination.
-                self.visit_place(
-                    dest,
-                    PlaceContext::MutatingUse(MutatingUseContext::Store),
-                    location
-                );
-                self.statement_like();
             }
+        };
+        debug!("store to var {:?}", index);
+        match &mut self.local_qualif[index] {
+            // this is overly restrictive, because even full assignments do not clear the qualif
+            // While we could special case full assignments, this would be inconsistent with
+            // aggregates where we overwrite all fields via assignments, which would not get
+            // that feature.
+            Some(ref mut qualif) => *qualif = *qualif | self.qualif,
+            // insert new qualification
+            qualif @ None => *qualif = Some(self.qualif),
         }
     }
 
@@ -347,45 +291,6 @@ impl<'a, 'tcx> Qualifier<'a, 'tcx, 'tcx> {
                 TerminatorKind::FalseUnwind { .. } => None,
 
                 TerminatorKind::Return => {
-                    if !self.tcx.features().const_let {
-                        // Check for unused values. This usually means
-                        // there are extra statements in the AST.
-                        for temp in mir.temps_iter() {
-                            if self.local_qualif[temp].is_none() {
-                                continue;
-                            }
-
-                            let state = self.temp_promotion_state[temp];
-                            if let TempState::Defined { location, uses: 0 } = state {
-                                let data = &mir[location.block];
-                                let stmt_idx = location.statement_index;
-
-                                // Get the span for the initialization.
-                                let source_info = if stmt_idx < data.statements.len() {
-                                    data.statements[stmt_idx].source_info
-                                } else {
-                                    data.terminator().source_info
-                                };
-                                self.span = source_info.span;
-
-                                // Treat this as a statement in the AST.
-                                self.statement_like();
-                            }
-                        }
-
-                        // Make sure there are no extra unassigned variables.
-                        self.qualif = Qualif::NOT_CONST;
-                        for index in mir.vars_iter() {
-                            if !self.const_fn_arg_vars.contains(index) {
-                                debug!("unassigned variable {:?}", index);
-                                self.assign(&Place::Local(index), Location {
-                                    block: bb,
-                                    statement_index: usize::MAX,
-                                });
-                            }
-                        }
-                    }
-
                     break;
                 }
             };
@@ -454,12 +359,7 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> {
             LocalKind::ReturnPointer => {
                 self.not_const();
             }
-            LocalKind::Var if !self.tcx.features().const_let => {
-                if self.mode != Mode::Fn {
-                    emit_feature_err(&self.tcx.sess.parse_sess, "const_let",
-                                    self.span, GateIssue::Language,
-                                    &format!("let bindings in {}s are unstable",self.mode));
-                }
+            LocalKind::Var if self.mode == Mode::Fn => {
                 self.add(Qualif::NOT_CONST);
             }
             LocalKind::Var |
@@ -569,6 +469,8 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> {
                             }
                         }
 
+                        ProjectionElem::ConstantIndex {..} |
+                        ProjectionElem::Subslice {..} |
                         ProjectionElem::Field(..) |
                         ProjectionElem::Index(_) => {
                             let base_ty = proj.base.ty(this.mir, this.tcx).to_ty(this.tcx);
@@ -598,8 +500,6 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> {
                             this.qualif.restrict(ty, this.tcx, this.param_env);
                         }
 
-                        ProjectionElem::ConstantIndex {..} |
-                        ProjectionElem::Subslice {..} |
                         ProjectionElem::Downcast(..) => {
                             this.not_const()
                         }
@@ -1168,46 +1068,6 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> {
         debug!("visit_assign: dest={:?} rvalue={:?} location={:?}", dest, rvalue, location);
         self.visit_rvalue(rvalue, location);
 
-        // Check the allowed const fn argument forms.
-        if let (Mode::ConstFn, &Place::Local(index)) = (self.mode, dest) {
-            if self.mir.local_kind(index) == LocalKind::Var &&
-               self.const_fn_arg_vars.insert(index) &&
-               !self.tcx.features().const_let {
-                // Direct use of an argument is permitted.
-                match *rvalue {
-                    Rvalue::Use(Operand::Copy(Place::Local(local))) |
-                    Rvalue::Use(Operand::Move(Place::Local(local))) => {
-                        if self.mir.local_kind(local) == LocalKind::Arg {
-                            return;
-                        }
-                    }
-                    _ => {}
-                }
-                // Avoid a generic error for other uses of arguments.
-                if self.qualif.contains(Qualif::FN_ARGUMENT) {
-                    let decl = &self.mir.local_decls[index];
-                    let mut err = feature_err(
-                        &self.tcx.sess.parse_sess,
-                        "const_let",
-                        decl.source_info.span,
-                        GateIssue::Language,
-                        "arguments of constant functions can only be immutable by-value bindings"
-                    );
-                    if self.tcx.sess.teach(&err.get_code().unwrap()) {
-                        err.note("Constant functions are not allowed to mutate anything. Thus, \
-                                  binding to an argument with a mutable pattern is not allowed.");
-                        err.note("Remove any mutable bindings from the argument list to fix this \
-                                  error. In case you need to mutate the argument, try lazily \
-                                  initializing a global variable instead of using a const fn, or \
-                                  refactoring the code to a functional style to avoid mutation if \
-                                  possible.");
-                    }
-                    err.emit();
-                    return;
-                }
-            }
-        }
-
         self.assign(dest, location);
     }
 
diff --git a/src/librustc_mir/transform/qualify_min_const_fn.rs b/src/librustc_mir/transform/qualify_min_const_fn.rs
index c1c5b18915aed..41a042ebcb643 100644
--- a/src/librustc_mir/transform/qualify_min_const_fn.rs
+++ b/src/librustc_mir/transform/qualify_min_const_fn.rs
@@ -65,12 +65,6 @@ pub fn is_min_const_fn(
         }
     }
 
-    for local in mir.vars_iter() {
-        return Err((
-            mir.local_decls[local].source_info.span,
-            "local variables in const fn are unstable".into(),
-        ));
-    }
     for local in &mir.local_decls {
         check_ty(tcx, local.ty, local.source_info.span)?;
     }
@@ -147,7 +141,7 @@ fn check_rvalue(
             check_operand(tcx, mir, operand, span)
         }
         Rvalue::Len(place) | Rvalue::Discriminant(place) | Rvalue::Ref(_, _, place) => {
-            check_place(tcx, mir, place, span, PlaceMode::Read)
+            check_place(tcx, mir, place, span)
         }
         Rvalue::Cast(CastKind::Misc, operand, cast_ty) => {
             use rustc::ty::cast::CastTy;
@@ -213,11 +207,6 @@ fn check_rvalue(
     }
 }
 
-enum PlaceMode {
-    Assign,
-    Read,
-}
-
 fn check_statement(
     tcx: TyCtxt<'a, 'tcx, 'tcx>,
     mir: &'a Mir<'tcx>,
@@ -226,11 +215,11 @@ fn check_statement(
     let span = statement.source_info.span;
     match &statement.kind {
         StatementKind::Assign(place, rval) => {
-            check_place(tcx, mir, place, span, PlaceMode::Assign)?;
+            check_place(tcx, mir, place, span)?;
             check_rvalue(tcx, mir, rval, span)
         }
 
-        StatementKind::FakeRead(_, place) => check_place(tcx, mir, place, span, PlaceMode::Read),
+        StatementKind::FakeRead(_, place) => check_place(tcx, mir, place, span),
 
         // just an assignment
         StatementKind::SetDiscriminant { .. } => Ok(()),
@@ -256,7 +245,7 @@ fn check_operand(
 ) -> McfResult {
     match operand {
         Operand::Move(place) | Operand::Copy(place) => {
-            check_place(tcx, mir, place, span, PlaceMode::Read)
+            check_place(tcx, mir, place, span)
         }
         Operand::Constant(_) => Ok(()),
     }
@@ -267,29 +256,17 @@ fn check_place(
     mir: &'a Mir<'tcx>,
     place: &Place<'tcx>,
     span: Span,
-    mode: PlaceMode,
 ) -> McfResult {
     match place {
-        Place::Local(l) => match mode {
-            PlaceMode::Assign => match mir.local_kind(*l) {
-                LocalKind::Temp | LocalKind::ReturnPointer => Ok(()),
-                LocalKind::Arg | LocalKind::Var => {
-                    Err((span, "assignments in const fn are unstable".into()))
-                }
-            },
-            PlaceMode::Read => Ok(()),
-        },
+        Place::Local(_) => Ok(()),
         // promoteds are always fine, they are essentially constants
         Place::Promoted(_) => Ok(()),
         Place::Static(_) => Err((span, "cannot access `static` items in const fn".into())),
         Place::Projection(proj) => {
             match proj.elem {
+                | ProjectionElem::ConstantIndex { .. } | ProjectionElem::Subslice { .. }
                 | ProjectionElem::Deref | ProjectionElem::Field(..) | ProjectionElem::Index(_) => {
-                    check_place(tcx, mir, &proj.base, span, mode)
-                }
-                // slice patterns are unstable
-                | ProjectionElem::ConstantIndex { .. } | ProjectionElem::Subslice { .. } => {
-                    return Err((span, "slice patterns in const fn are unstable".into()))
+                    check_place(tcx, mir, &proj.base, span)
                 }
                 | ProjectionElem::Downcast(..) => {
                     Err((span, "`match` or `if let` in `const fn` is unstable".into()))
@@ -311,10 +288,10 @@ fn check_terminator(
         | TerminatorKind::Resume => Ok(()),
 
         TerminatorKind::Drop { location, .. } => {
-            check_place(tcx, mir, location, span, PlaceMode::Read)
+            check_place(tcx, mir, location, span)
         }
         TerminatorKind::DropAndReplace { location, value, .. } => {
-            check_place(tcx, mir, location, span, PlaceMode::Read)?;
+            check_place(tcx, mir, location, span)?;
             check_operand(tcx, mir, value, span)
         },
 
@@ -342,15 +319,11 @@ fn check_terminator(
                 // some intrinsics are waved through if called inside the
                 // standard library. Users never need to call them directly
                 match tcx.fn_sig(def_id).abi() {
-                    abi::Abi::RustIntrinsic => match &tcx.item_name(def_id).as_str()[..] {
-                        | "size_of"
-                        | "min_align_of"
-                        | "needs_drop"
-                        => {},
-                        _ => return Err((
+                    abi::Abi::RustIntrinsic => if !is_intrinsic_whitelisted(tcx, def_id) {
+                        return Err((
                             span,
                             "can only call a curated list of intrinsics in `min_const_fn`".into(),
-                        )),
+                        ))
                     },
                     abi::Abi::Rust if tcx.is_min_const_fn(def_id) => {},
                     abi::Abi::Rust => return Err((
@@ -390,3 +363,30 @@ fn check_terminator(
         },
     }
 }
+
+/// Returns true if the `def_id` refers to an intrisic which we've whitelisted
+/// for being called from stable `const fn`s (`min_const_fn`).
+///
+/// Adding more intrinsics requires sign-off from @rust-lang/lang.
+fn is_intrinsic_whitelisted(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> bool {
+    match &tcx.item_name(def_id).as_str()[..] {
+        | "size_of"
+        | "min_align_of"
+        | "needs_drop"
+        // Arithmetic:
+        | "overflowing_add" // ~> .wrapping_add
+        | "overflowing_sub" // ~> .wrapping_sub
+        | "overflowing_mul" // ~> .wrapping_mul
+        | "unchecked_shl" // ~> .wrapping_shl
+        | "unchecked_shr" // ~> .wrapping_shr
+        | "rotate_left" // ~> .rotate_left
+        | "rotate_right" // ~> .rotate_right
+        | "ctpop" // ~> .count_ones
+        | "ctlz" // ~> .leading_zeros
+        | "cttz" // ~> .trailing_zeros
+        | "bswap" // ~> .swap_bytes
+        | "bitreverse" // ~> .reverse_bits
+        => true,
+        _ => false,
+    }
+}
diff --git a/src/librustc_typeck/check/intrinsic.rs b/src/librustc_typeck/check/intrinsic.rs
index 821c30b4fa709..04d18ff7aa372 100644
--- a/src/librustc_typeck/check/intrinsic.rs
+++ b/src/librustc_typeck/check/intrinsic.rs
@@ -66,6 +66,18 @@ fn equate_intrinsic_type<'a, 'tcx>(
     require_same_types(tcx, &cause, tcx.mk_fn_ptr(tcx.fn_sig(def_id)), fty);
 }
 
+/// Returns whether the given intrinsic is unsafe to call or not.
+pub fn intrisic_operation_unsafety(intrinsic: &str) -> hir::Unsafety {
+    match intrinsic {
+        "size_of" | "min_align_of" | "needs_drop" |
+        "overflowing_add" | "overflowing_sub" | "overflowing_mul" |
+        "rotate_left" | "rotate_right" |
+        "ctpop" | "ctlz" | "cttz" | "bswap" | "bitreverse"
+        => hir::Unsafety::Normal,
+        _ => hir::Unsafety::Unsafe,
+    }
+}
+
 /// Remember to add all intrinsics here, in librustc_codegen_llvm/intrinsic.rs,
 /// and in libcore/intrinsics.rs
 pub fn check_intrinsic_type<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
@@ -117,10 +129,7 @@ pub fn check_intrinsic_type<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     } else if &name[..] == "abort" || &name[..] == "unreachable" {
         (0, Vec::new(), tcx.types.never, hir::Unsafety::Unsafe)
     } else {
-        let unsafety = match &name[..] {
-            "size_of" | "min_align_of" | "needs_drop" => hir::Unsafety::Normal,
-            _ => hir::Unsafety::Unsafe,
-        };
+        let unsafety = intrisic_operation_unsafety(&name[..]);
         let (n_tps, inputs, output) = match &name[..] {
             "breakpoint" => (0, Vec::new(), tcx.mk_unit()),
             "size_of" |
diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index 1a5d164873d32..870c6dd8bc1f6 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -80,7 +80,7 @@ mod closure;
 mod callee;
 mod compare_method;
 mod generator_interior;
-mod intrinsic;
+pub mod intrinsic;
 mod op;
 
 use astconv::{AstConv, PathSeg};
diff --git a/src/librustc_typeck/collect.rs b/src/librustc_typeck/collect.rs
index e0e173901ef38..2ac52bcda76f7 100644
--- a/src/librustc_typeck/collect.rs
+++ b/src/librustc_typeck/collect.rs
@@ -16,6 +16,7 @@
 
 use astconv::{AstConv, Bounds};
 use constrained_type_params as ctp;
+use check::intrinsic::intrisic_operation_unsafety;
 use lint;
 use middle::lang_items::SizedTraitLangItem;
 use middle::resolve_lifetime as rl;
@@ -2080,10 +2081,7 @@ fn compute_sig_of_foreign_fn_decl<'a, 'tcx>(
     abi: abi::Abi,
 ) -> ty::PolyFnSig<'tcx> {
     let unsafety = if abi == abi::Abi::RustIntrinsic {
-        match &*tcx.item_name(def_id).as_str() {
-            "size_of" | "min_align_of" | "needs_drop" => hir::Unsafety::Normal,
-            _ => hir::Unsafety::Unsafe,
-        }
+        intrisic_operation_unsafety(&*tcx.item_name(def_id).as_str())
     } else {
         hir::Unsafety::Unsafe
     };
diff --git a/src/libstd/lib.rs b/src/libstd/lib.rs
index ccfce672e5f9e..701565191b960 100644
--- a/src/libstd/lib.rs
+++ b/src/libstd/lib.rs
@@ -242,8 +242,8 @@
 #![feature(char_error_internals)]
 #![feature(compiler_builtins_lib)]
 #![feature(concat_idents)]
-#![feature(const_int_ops)]
-#![feature(const_ip)]
+#![cfg_attr(stage0, feature(const_int_ops))]
+#![cfg_attr(stage0, feature(const_ip))]
 #![feature(const_raw_ptr_deref)]
 #![feature(const_cstr_unchecked)]
 #![feature(core_intrinsics)]
diff --git a/src/libstd/net/ip.rs b/src/libstd/net/ip.rs
index 52a29f4885f56..f98113e0896f7 100644
--- a/src/libstd/net/ip.rs
+++ b/src/libstd/net/ip.rs
@@ -328,7 +328,7 @@ impl Ipv4Addr {
     /// let addr = Ipv4Addr::new(127, 0, 0, 1);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_unstable(feature = "const_ip")]
+    #[cfg_attr(stage0, rustc_const_unstable(feature = "const_ip"))]
     pub const fn new(a: u8, b: u8, c: u8, d: u8) -> Ipv4Addr {
         Ipv4Addr {
             inner: c::in_addr {
diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs
index cddec3eb23a5a..a7b391f2d1a4c 100644
--- a/src/libsyntax/feature_gate.rs
+++ b/src/libsyntax/feature_gate.rs
@@ -193,9 +193,6 @@ declare_features! (
     // Allows the definition of `const` functions with some advanced features.
     (active, const_fn, "1.2.0", Some(24111), None),
 
-    // Allows let bindings and destructuring in `const` functions and constants.
-    (active, const_let, "1.22.1", Some(48821), None),
-
     // Allows accessing fields of unions inside `const` functions.
     (active, const_fn_union, "1.27.0", Some(51909), None),
 
@@ -688,6 +685,10 @@ declare_features! (
     (accepted, min_const_unsafe_fn, "1.33.0", Some(55607), None),
     // `#[cfg_attr(predicate, multiple, attributes, here)]`
     (accepted, cfg_attr_multi, "1.33.0", Some(54881), None),
+    // Allows let bindings, assignments and destructuring in `const` functions and constants.
+    // As long as control flow is not implemented in const eval, `&&` and `||` may not be used
+    // at the same time as let bindings.
+    (accepted, const_let, "1.33.0", Some(48821), None),
 );
 
 // If you change this, please modify `src/doc/unstable-book` as well. You must
diff --git a/src/test/compile-fail/const-fn-error.rs b/src/test/compile-fail/const-fn-error.rs
index 9913138693c94..da6036a04a549 100644
--- a/src/test/compile-fail/const-fn-error.rs
+++ b/src/test/compile-fail/const-fn-error.rs
@@ -1,4 +1,4 @@
-#![feature(const_fn, const_let)]
+#![feature(const_fn)]
 
 const X : usize = 2;
 
diff --git a/src/test/run-pass/const-int-conversion.rs b/src/test/run-pass/const-int-conversion.rs
index 2b4904cc6c39a..19d65860179b2 100644
--- a/src/test/run-pass/const-int-conversion.rs
+++ b/src/test/run-pass/const-int-conversion.rs
@@ -1,4 +1,4 @@
-#![feature(const_int_conversion, const_int_ops, reverse_bits)]
+#![feature(const_int_conversion, reverse_bits)]
 
 const REVERSE: u32 = 0x12345678_u32.reverse_bits();
 const FROM_BE_BYTES: i32 = i32::from_be_bytes([0x12, 0x34, 0x56, 0x78]);
@@ -21,4 +21,3 @@ fn main() {
     assert_eq!(TO_LE_BYTES, ident([0x78, 0x56, 0x34, 0x12]));
     assert_eq!(TO_NE_BYTES, ident([0x80, 0, 0, 0]));
 }
-
diff --git a/src/test/run-pass/const-int-rotate.rs b/src/test/run-pass/const-int-rotate.rs
index 68c77f27a3193..c014e97ef19b8 100644
--- a/src/test/run-pass/const-int-rotate.rs
+++ b/src/test/run-pass/const-int-rotate.rs
@@ -1,5 +1,3 @@
-#![feature(const_int_rotate)]
-
 const LEFT: u32 = 0x10000b3u32.rotate_left(8);
 const RIGHT: u32 = 0xb301u32.rotate_right(8);
 
diff --git a/src/test/run-pass/const-int-sign.rs b/src/test/run-pass/const-int-sign.rs
index ae55c1a9b0e39..9d656a0203069 100644
--- a/src/test/run-pass/const-int-sign.rs
+++ b/src/test/run-pass/const-int-sign.rs
@@ -1,5 +1,3 @@
-#![feature(const_int_sign)]
-
 const NEGATIVE_A: bool = (-10i32).is_negative();
 const NEGATIVE_B: bool = 10i32.is_negative();
 const POSITIVE_A: bool= (-10i32).is_positive();
diff --git a/src/test/run-pass/const-int-wrapping.rs b/src/test/run-pass/const-int-wrapping.rs
index 504a654c0db65..5ab712015dfc3 100644
--- a/src/test/run-pass/const-int-wrapping.rs
+++ b/src/test/run-pass/const-int-wrapping.rs
@@ -1,5 +1,3 @@
-#![feature(const_int_wrapping)]
-
 const ADD_A: u32 = 200u32.wrapping_add(55);
 const ADD_B: u32 = 200u32.wrapping_add(u32::max_value());
 
diff --git a/src/test/run-pass/consts/const-endianess.rs b/src/test/run-pass/consts/const-endianess.rs
index dfc6678ba289d..cbe6d864c9c3a 100644
--- a/src/test/run-pass/consts/const-endianess.rs
+++ b/src/test/run-pass/consts/const-endianess.rs
@@ -1,5 +1,4 @@
 // run-pass
-#![feature(const_int_ops)]
 #![feature(test)]
 
 extern crate test;
@@ -8,7 +7,6 @@ use test::black_box as b;
 const BE_U32: u32 = 55u32.to_be();
 const LE_U32: u32 = 55u32.to_le();
 
-
 fn main() {
     assert_eq!(BE_U32, b(55u32).to_be());
     assert_eq!(LE_U32, b(55u32).to_le());
diff --git a/src/test/run-pass/ctfe/bswap-const.rs b/src/test/run-pass/ctfe/bswap-const.rs
index 90e97c8edbdd5..3145c21acc988 100644
--- a/src/test/run-pass/ctfe/bswap-const.rs
+++ b/src/test/run-pass/ctfe/bswap-const.rs
@@ -4,9 +4,9 @@
 
 use std::intrinsics;
 
-const SWAPPED_U8: u8 = unsafe { intrinsics::bswap(0x12_u8) };
-const SWAPPED_U16: u16 = unsafe { intrinsics::bswap(0x12_34_u16) };
-const SWAPPED_I32: i32 = unsafe { intrinsics::bswap(0x12_34_56_78_i32) };
+const SWAPPED_U8: u8 = intrinsics::bswap(0x12_u8);
+const SWAPPED_U16: u16 = intrinsics::bswap(0x12_34_u16);
+const SWAPPED_I32: i32 = intrinsics::bswap(0x12_34_56_78_i32);
 
 fn main() {
     assert_eq!(SWAPPED_U8, 0x12);
diff --git a/src/test/run-pass/ctfe/const-block-non-item-statement-3.rs b/src/test/run-pass/ctfe/const-block-non-item-statement-3.rs
index 90295414d3efc..10a4c31f24ed4 100644
--- a/src/test/run-pass/ctfe/const-block-non-item-statement-3.rs
+++ b/src/test/run-pass/ctfe/const-block-non-item-statement-3.rs
@@ -1,8 +1,8 @@
 // run-pass
 #![allow(dead_code)]
 
-#![feature(const_let)]
-
 type Array = [u32; {  let x = 2; 5 }];
 
-pub fn main() {}
+pub fn main() {
+    let _: Array = [0; 5];
+}
diff --git a/src/test/run-pass/ctfe/const-block-non-item-statement.rs b/src/test/run-pass/ctfe/const-block-non-item-statement.rs
index 21ce08ab69c73..a1b9b586ad038 100644
--- a/src/test/run-pass/ctfe/const-block-non-item-statement.rs
+++ b/src/test/run-pass/ctfe/const-block-non-item-statement.rs
@@ -1,10 +1,11 @@
 // run-pass
 #![allow(dead_code)]
 
-#![feature(const_let)]
-
+#[repr(u8)]
 enum Foo {
     Bar = { let x = 1; 3 }
 }
 
-pub fn main() {}
+pub fn main() {
+    assert_eq!(3, Foo::Bar as u8);
+}
diff --git a/src/test/run-pass/ctfe/issue-37550.rs b/src/test/run-pass/ctfe/issue-37550.rs
index 732c34dff5a80..04865830df2eb 100644
--- a/src/test/run-pass/ctfe/issue-37550.rs
+++ b/src/test/run-pass/ctfe/issue-37550.rs
@@ -2,7 +2,7 @@
 #![allow(dead_code)]
 #![allow(unused_variables)]
 
-#![feature(const_fn, const_let)]
+#![feature(const_fn)]
 
 const fn x() {
     let t = true;
diff --git a/src/test/run-pass/ctfe/locals-in-const-fn.rs b/src/test/run-pass/ctfe/locals-in-const-fn.rs
index e527e1e88c8da..95d50171a847b 100644
--- a/src/test/run-pass/ctfe/locals-in-const-fn.rs
+++ b/src/test/run-pass/ctfe/locals-in-const-fn.rs
@@ -2,8 +2,6 @@
 
 // https://github.com/rust-lang/rust/issues/48821
 
-#![feature(const_fn, const_let)]
-
 const fn foo(i: usize) -> usize {
     let x = i;
     x
diff --git a/src/test/run-pass/intrinsics/intrinsics-integer.rs b/src/test/run-pass/intrinsics/intrinsics-integer.rs
index 66e07f8683a87..0154f04995029 100644
--- a/src/test/run-pass/intrinsics/intrinsics-integer.rs
+++ b/src/test/run-pass/intrinsics/intrinsics-integer.rs
@@ -16,63 +16,63 @@ mod rusti {
 }
 
 pub fn main() {
-    unsafe {
-        use rusti::*;
-
-        assert_eq!(ctpop(0u8), 0); assert_eq!(ctpop(0i8), 0);
-        assert_eq!(ctpop(0u16), 0); assert_eq!(ctpop(0i16), 0);
-        assert_eq!(ctpop(0u32), 0); assert_eq!(ctpop(0i32), 0);
-        assert_eq!(ctpop(0u64), 0); assert_eq!(ctpop(0i64), 0);
-        assert_eq!(ctpop(0u128), 0); assert_eq!(ctpop(0i128), 0);
-
-        assert_eq!(ctpop(1u8), 1); assert_eq!(ctpop(1i8), 1);
-        assert_eq!(ctpop(1u16), 1); assert_eq!(ctpop(1i16), 1);
-        assert_eq!(ctpop(1u32), 1); assert_eq!(ctpop(1i32), 1);
-        assert_eq!(ctpop(1u64), 1); assert_eq!(ctpop(1i64), 1);
-        assert_eq!(ctpop(1u128), 1); assert_eq!(ctpop(1i128), 1);
-
-        assert_eq!(ctpop(10u8), 2); assert_eq!(ctpop(10i8), 2);
-        assert_eq!(ctpop(10u16), 2); assert_eq!(ctpop(10i16), 2);
-        assert_eq!(ctpop(10u32), 2); assert_eq!(ctpop(10i32), 2);
-        assert_eq!(ctpop(10u64), 2); assert_eq!(ctpop(10i64), 2);
-        assert_eq!(ctpop(10u128), 2); assert_eq!(ctpop(10i128), 2);
-
-        assert_eq!(ctpop(100u8), 3); assert_eq!(ctpop(100i8), 3);
-        assert_eq!(ctpop(100u16), 3); assert_eq!(ctpop(100i16), 3);
-        assert_eq!(ctpop(100u32), 3); assert_eq!(ctpop(100i32), 3);
-        assert_eq!(ctpop(100u64), 3); assert_eq!(ctpop(100i64), 3);
-        assert_eq!(ctpop(100u128), 3); assert_eq!(ctpop(100i128), 3);
-
-        assert_eq!(ctpop(-1i8 as u8), 8); assert_eq!(ctpop(-1i8), 8);
-        assert_eq!(ctpop(-1i16 as u16), 16); assert_eq!(ctpop(-1i16), 16);
-        assert_eq!(ctpop(-1i32 as u32), 32); assert_eq!(ctpop(-1i32), 32);
-        assert_eq!(ctpop(-1i64 as u64), 64); assert_eq!(ctpop(-1i64), 64);
-        assert_eq!(ctpop(-1i128 as u128), 128); assert_eq!(ctpop(-1i128), 128);
-
-        assert_eq!(ctlz(0u8), 8); assert_eq!(ctlz(0i8), 8);
-        assert_eq!(ctlz(0u16), 16); assert_eq!(ctlz(0i16), 16);
-        assert_eq!(ctlz(0u32), 32); assert_eq!(ctlz(0i32), 32);
-        assert_eq!(ctlz(0u64), 64); assert_eq!(ctlz(0i64), 64);
-        assert_eq!(ctlz(0u128), 128); assert_eq!(ctlz(0i128), 128);
-
-        assert_eq!(ctlz(1u8), 7); assert_eq!(ctlz(1i8), 7);
-        assert_eq!(ctlz(1u16), 15); assert_eq!(ctlz(1i16), 15);
-        assert_eq!(ctlz(1u32), 31); assert_eq!(ctlz(1i32), 31);
-        assert_eq!(ctlz(1u64), 63); assert_eq!(ctlz(1i64), 63);
-        assert_eq!(ctlz(1u128), 127); assert_eq!(ctlz(1i128), 127);
-
-        assert_eq!(ctlz(10u8), 4); assert_eq!(ctlz(10i8), 4);
-        assert_eq!(ctlz(10u16), 12); assert_eq!(ctlz(10i16), 12);
-        assert_eq!(ctlz(10u32), 28); assert_eq!(ctlz(10i32), 28);
-        assert_eq!(ctlz(10u64), 60); assert_eq!(ctlz(10i64), 60);
-        assert_eq!(ctlz(10u128), 124); assert_eq!(ctlz(10i128), 124);
-
-        assert_eq!(ctlz(100u8), 1); assert_eq!(ctlz(100i8), 1);
-        assert_eq!(ctlz(100u16), 9); assert_eq!(ctlz(100i16), 9);
-        assert_eq!(ctlz(100u32), 25); assert_eq!(ctlz(100i32), 25);
-        assert_eq!(ctlz(100u64), 57); assert_eq!(ctlz(100i64), 57);
-        assert_eq!(ctlz(100u128), 121); assert_eq!(ctlz(100i128), 121);
+    use rusti::*;
+
+    assert_eq!(ctpop(0u8), 0); assert_eq!(ctpop(0i8), 0);
+    assert_eq!(ctpop(0u16), 0); assert_eq!(ctpop(0i16), 0);
+    assert_eq!(ctpop(0u32), 0); assert_eq!(ctpop(0i32), 0);
+    assert_eq!(ctpop(0u64), 0); assert_eq!(ctpop(0i64), 0);
+    assert_eq!(ctpop(0u128), 0); assert_eq!(ctpop(0i128), 0);
+
+    assert_eq!(ctpop(1u8), 1); assert_eq!(ctpop(1i8), 1);
+    assert_eq!(ctpop(1u16), 1); assert_eq!(ctpop(1i16), 1);
+    assert_eq!(ctpop(1u32), 1); assert_eq!(ctpop(1i32), 1);
+    assert_eq!(ctpop(1u64), 1); assert_eq!(ctpop(1i64), 1);
+    assert_eq!(ctpop(1u128), 1); assert_eq!(ctpop(1i128), 1);
+
+    assert_eq!(ctpop(10u8), 2); assert_eq!(ctpop(10i8), 2);
+    assert_eq!(ctpop(10u16), 2); assert_eq!(ctpop(10i16), 2);
+    assert_eq!(ctpop(10u32), 2); assert_eq!(ctpop(10i32), 2);
+    assert_eq!(ctpop(10u64), 2); assert_eq!(ctpop(10i64), 2);
+    assert_eq!(ctpop(10u128), 2); assert_eq!(ctpop(10i128), 2);
+
+    assert_eq!(ctpop(100u8), 3); assert_eq!(ctpop(100i8), 3);
+    assert_eq!(ctpop(100u16), 3); assert_eq!(ctpop(100i16), 3);
+    assert_eq!(ctpop(100u32), 3); assert_eq!(ctpop(100i32), 3);
+    assert_eq!(ctpop(100u64), 3); assert_eq!(ctpop(100i64), 3);
+    assert_eq!(ctpop(100u128), 3); assert_eq!(ctpop(100i128), 3);
+
+    assert_eq!(ctpop(-1i8 as u8), 8); assert_eq!(ctpop(-1i8), 8);
+    assert_eq!(ctpop(-1i16 as u16), 16); assert_eq!(ctpop(-1i16), 16);
+    assert_eq!(ctpop(-1i32 as u32), 32); assert_eq!(ctpop(-1i32), 32);
+    assert_eq!(ctpop(-1i64 as u64), 64); assert_eq!(ctpop(-1i64), 64);
+    assert_eq!(ctpop(-1i128 as u128), 128); assert_eq!(ctpop(-1i128), 128);
+
+    assert_eq!(ctlz(0u8), 8); assert_eq!(ctlz(0i8), 8);
+    assert_eq!(ctlz(0u16), 16); assert_eq!(ctlz(0i16), 16);
+    assert_eq!(ctlz(0u32), 32); assert_eq!(ctlz(0i32), 32);
+    assert_eq!(ctlz(0u64), 64); assert_eq!(ctlz(0i64), 64);
+    assert_eq!(ctlz(0u128), 128); assert_eq!(ctlz(0i128), 128);
+
+    assert_eq!(ctlz(1u8), 7); assert_eq!(ctlz(1i8), 7);
+    assert_eq!(ctlz(1u16), 15); assert_eq!(ctlz(1i16), 15);
+    assert_eq!(ctlz(1u32), 31); assert_eq!(ctlz(1i32), 31);
+    assert_eq!(ctlz(1u64), 63); assert_eq!(ctlz(1i64), 63);
+    assert_eq!(ctlz(1u128), 127); assert_eq!(ctlz(1i128), 127);
+
+    assert_eq!(ctlz(10u8), 4); assert_eq!(ctlz(10i8), 4);
+    assert_eq!(ctlz(10u16), 12); assert_eq!(ctlz(10i16), 12);
+    assert_eq!(ctlz(10u32), 28); assert_eq!(ctlz(10i32), 28);
+    assert_eq!(ctlz(10u64), 60); assert_eq!(ctlz(10i64), 60);
+    assert_eq!(ctlz(10u128), 124); assert_eq!(ctlz(10i128), 124);
+
+    assert_eq!(ctlz(100u8), 1); assert_eq!(ctlz(100i8), 1);
+    assert_eq!(ctlz(100u16), 9); assert_eq!(ctlz(100i16), 9);
+    assert_eq!(ctlz(100u32), 25); assert_eq!(ctlz(100i32), 25);
+    assert_eq!(ctlz(100u64), 57); assert_eq!(ctlz(100i64), 57);
+    assert_eq!(ctlz(100u128), 121); assert_eq!(ctlz(100i128), 121);
 
+    unsafe {
         assert_eq!(ctlz_nonzero(1u8), 7); assert_eq!(ctlz_nonzero(1i8), 7);
         assert_eq!(ctlz_nonzero(1u16), 15); assert_eq!(ctlz_nonzero(1i16), 15);
         assert_eq!(ctlz_nonzero(1u32), 31); assert_eq!(ctlz_nonzero(1i32), 31);
@@ -90,37 +90,39 @@ pub fn main() {
         assert_eq!(ctlz_nonzero(100u32), 25); assert_eq!(ctlz_nonzero(100i32), 25);
         assert_eq!(ctlz_nonzero(100u64), 57); assert_eq!(ctlz_nonzero(100i64), 57);
         assert_eq!(ctlz_nonzero(100u128), 121); assert_eq!(ctlz_nonzero(100i128), 121);
+    }
 
-        assert_eq!(cttz(-1i8 as u8), 0); assert_eq!(cttz(-1i8), 0);
-        assert_eq!(cttz(-1i16 as u16), 0); assert_eq!(cttz(-1i16), 0);
-        assert_eq!(cttz(-1i32 as u32), 0); assert_eq!(cttz(-1i32), 0);
-        assert_eq!(cttz(-1i64 as u64), 0); assert_eq!(cttz(-1i64), 0);
-        assert_eq!(cttz(-1i128 as u128), 0); assert_eq!(cttz(-1i128), 0);
-
-        assert_eq!(cttz(0u8), 8); assert_eq!(cttz(0i8), 8);
-        assert_eq!(cttz(0u16), 16); assert_eq!(cttz(0i16), 16);
-        assert_eq!(cttz(0u32), 32); assert_eq!(cttz(0i32), 32);
-        assert_eq!(cttz(0u64), 64); assert_eq!(cttz(0i64), 64);
-        assert_eq!(cttz(0u128), 128); assert_eq!(cttz(0i128), 128);
-
-        assert_eq!(cttz(1u8), 0); assert_eq!(cttz(1i8), 0);
-        assert_eq!(cttz(1u16), 0); assert_eq!(cttz(1i16), 0);
-        assert_eq!(cttz(1u32), 0); assert_eq!(cttz(1i32), 0);
-        assert_eq!(cttz(1u64), 0); assert_eq!(cttz(1i64), 0);
-        assert_eq!(cttz(1u128), 0); assert_eq!(cttz(1i128), 0);
-
-        assert_eq!(cttz(10u8), 1); assert_eq!(cttz(10i8), 1);
-        assert_eq!(cttz(10u16), 1); assert_eq!(cttz(10i16), 1);
-        assert_eq!(cttz(10u32), 1); assert_eq!(cttz(10i32), 1);
-        assert_eq!(cttz(10u64), 1); assert_eq!(cttz(10i64), 1);
-        assert_eq!(cttz(10u128), 1); assert_eq!(cttz(10i128), 1);
-
-        assert_eq!(cttz(100u8), 2); assert_eq!(cttz(100i8), 2);
-        assert_eq!(cttz(100u16), 2); assert_eq!(cttz(100i16), 2);
-        assert_eq!(cttz(100u32), 2); assert_eq!(cttz(100i32), 2);
-        assert_eq!(cttz(100u64), 2); assert_eq!(cttz(100i64), 2);
-        assert_eq!(cttz(100u128), 2); assert_eq!(cttz(100i128), 2);
+    assert_eq!(cttz(-1i8 as u8), 0); assert_eq!(cttz(-1i8), 0);
+    assert_eq!(cttz(-1i16 as u16), 0); assert_eq!(cttz(-1i16), 0);
+    assert_eq!(cttz(-1i32 as u32), 0); assert_eq!(cttz(-1i32), 0);
+    assert_eq!(cttz(-1i64 as u64), 0); assert_eq!(cttz(-1i64), 0);
+    assert_eq!(cttz(-1i128 as u128), 0); assert_eq!(cttz(-1i128), 0);
+
+    assert_eq!(cttz(0u8), 8); assert_eq!(cttz(0i8), 8);
+    assert_eq!(cttz(0u16), 16); assert_eq!(cttz(0i16), 16);
+    assert_eq!(cttz(0u32), 32); assert_eq!(cttz(0i32), 32);
+    assert_eq!(cttz(0u64), 64); assert_eq!(cttz(0i64), 64);
+    assert_eq!(cttz(0u128), 128); assert_eq!(cttz(0i128), 128);
+
+    assert_eq!(cttz(1u8), 0); assert_eq!(cttz(1i8), 0);
+    assert_eq!(cttz(1u16), 0); assert_eq!(cttz(1i16), 0);
+    assert_eq!(cttz(1u32), 0); assert_eq!(cttz(1i32), 0);
+    assert_eq!(cttz(1u64), 0); assert_eq!(cttz(1i64), 0);
+    assert_eq!(cttz(1u128), 0); assert_eq!(cttz(1i128), 0);
+
+    assert_eq!(cttz(10u8), 1); assert_eq!(cttz(10i8), 1);
+    assert_eq!(cttz(10u16), 1); assert_eq!(cttz(10i16), 1);
+    assert_eq!(cttz(10u32), 1); assert_eq!(cttz(10i32), 1);
+    assert_eq!(cttz(10u64), 1); assert_eq!(cttz(10i64), 1);
+    assert_eq!(cttz(10u128), 1); assert_eq!(cttz(10i128), 1);
+
+    assert_eq!(cttz(100u8), 2); assert_eq!(cttz(100i8), 2);
+    assert_eq!(cttz(100u16), 2); assert_eq!(cttz(100i16), 2);
+    assert_eq!(cttz(100u32), 2); assert_eq!(cttz(100i32), 2);
+    assert_eq!(cttz(100u64), 2); assert_eq!(cttz(100i64), 2);
+    assert_eq!(cttz(100u128), 2); assert_eq!(cttz(100i128), 2);
 
+    unsafe {
         assert_eq!(cttz_nonzero(-1i8 as u8), 0); assert_eq!(cttz_nonzero(-1i8), 0);
         assert_eq!(cttz_nonzero(-1i16 as u16), 0); assert_eq!(cttz_nonzero(-1i16), 0);
         assert_eq!(cttz_nonzero(-1i32 as u32), 0); assert_eq!(cttz_nonzero(-1i32), 0);
@@ -144,27 +146,27 @@ pub fn main() {
         assert_eq!(cttz_nonzero(100u32), 2); assert_eq!(cttz_nonzero(100i32), 2);
         assert_eq!(cttz_nonzero(100u64), 2); assert_eq!(cttz_nonzero(100i64), 2);
         assert_eq!(cttz_nonzero(100u128), 2); assert_eq!(cttz_nonzero(100i128), 2);
-
-        assert_eq!(bswap(0x0Au8), 0x0A); // no-op
-        assert_eq!(bswap(0x0Ai8), 0x0A); // no-op
-        assert_eq!(bswap(0x0A0Bu16), 0x0B0A);
-        assert_eq!(bswap(0x0A0Bi16), 0x0B0A);
-        assert_eq!(bswap(0x0ABBCC0Du32), 0x0DCCBB0A);
-        assert_eq!(bswap(0x0ABBCC0Di32), 0x0DCCBB0A);
-        assert_eq!(bswap(0x0122334455667708u64), 0x0877665544332201);
-        assert_eq!(bswap(0x0122334455667708i64), 0x0877665544332201);
-        assert_eq!(bswap(0x0122334455667708u128), 0x08776655443322010000000000000000);
-        assert_eq!(bswap(0x0122334455667708i128), 0x08776655443322010000000000000000);
-
-        assert_eq!(bitreverse(0x0Au8), 0x50);
-        assert_eq!(bitreverse(0x0Ai8), 0x50);
-        assert_eq!(bitreverse(0x0A0Cu16), 0x3050);
-        assert_eq!(bitreverse(0x0A0Ci16), 0x3050);
-        assert_eq!(bitreverse(0x0ABBCC0Eu32), 0x7033DD50);
-        assert_eq!(bitreverse(0x0ABBCC0Ei32), 0x7033DD50);
-        assert_eq!(bitreverse(0x0122334455667708u64), 0x10EE66AA22CC4480);
-        assert_eq!(bitreverse(0x0122334455667708i64), 0x10EE66AA22CC4480);
-        assert_eq!(bitreverse(0x0122334455667708u128), 0x10EE66AA22CC44800000000000000000);
-        assert_eq!(bitreverse(0x0122334455667708i128), 0x10EE66AA22CC44800000000000000000);
     }
+
+    assert_eq!(bswap(0x0Au8), 0x0A); // no-op
+    assert_eq!(bswap(0x0Ai8), 0x0A); // no-op
+    assert_eq!(bswap(0x0A0Bu16), 0x0B0A);
+    assert_eq!(bswap(0x0A0Bi16), 0x0B0A);
+    assert_eq!(bswap(0x0ABBCC0Du32), 0x0DCCBB0A);
+    assert_eq!(bswap(0x0ABBCC0Di32), 0x0DCCBB0A);
+    assert_eq!(bswap(0x0122334455667708u64), 0x0877665544332201);
+    assert_eq!(bswap(0x0122334455667708i64), 0x0877665544332201);
+    assert_eq!(bswap(0x0122334455667708u128), 0x08776655443322010000000000000000);
+    assert_eq!(bswap(0x0122334455667708i128), 0x08776655443322010000000000000000);
+
+    assert_eq!(bitreverse(0x0Au8), 0x50);
+    assert_eq!(bitreverse(0x0Ai8), 0x50);
+    assert_eq!(bitreverse(0x0A0Cu16), 0x3050);
+    assert_eq!(bitreverse(0x0A0Ci16), 0x3050);
+    assert_eq!(bitreverse(0x0ABBCC0Eu32), 0x7033DD50);
+    assert_eq!(bitreverse(0x0ABBCC0Ei32), 0x7033DD50);
+    assert_eq!(bitreverse(0x0122334455667708u64), 0x10EE66AA22CC4480);
+    assert_eq!(bitreverse(0x0122334455667708i64), 0x10EE66AA22CC4480);
+    assert_eq!(bitreverse(0x0122334455667708u128), 0x10EE66AA22CC44800000000000000000);
+    assert_eq!(bitreverse(0x0122334455667708i128), 0x10EE66AA22CC44800000000000000000);
 }
diff --git a/src/test/ui/bad/bad-intrinsic-monomorphization.rs b/src/test/ui/bad/bad-intrinsic-monomorphization.rs
index b56e1ea039cf1..a29723f34b432 100644
--- a/src/test/ui/bad/bad-intrinsic-monomorphization.rs
+++ b/src/test/ui/bad/bad-intrinsic-monomorphization.rs
@@ -14,7 +14,7 @@ use std::intrinsics;
 #[derive(Copy, Clone)]
 pub struct Foo(i64);
 
-pub unsafe fn test_cttz(v: Foo) -> Foo {
+pub fn test_cttz(v: Foo) -> Foo {
     intrinsics::cttz(v)
     //~^ ERROR `cttz` intrinsic: expected basic integer type, found `Foo`
 }
diff --git a/src/test/ui/check-static-values-constraints.rs b/src/test/ui/check-static-values-constraints.rs
index eb0fc39e1bf15..acfb3b5e44bab 100644
--- a/src/test/ui/check-static-values-constraints.rs
+++ b/src/test/ui/check-static-values-constraints.rs
@@ -78,6 +78,7 @@ struct MyOwned;
 
 static STATIC11: Box<MyOwned> = box MyOwned;
 //~^ ERROR allocations are not allowed in statics
+//~| ERROR static contains unimplemented expression type
 
 static mut STATIC12: UnsafeStruct = UnsafeStruct;
 
@@ -92,12 +93,16 @@ static mut STATIC14: SafeStruct = SafeStruct {
 
 static STATIC15: &'static [Box<MyOwned>] = &[
     box MyOwned, //~ ERROR allocations are not allowed in statics
+    //~| ERROR contains unimplemented expression
     box MyOwned, //~ ERROR allocations are not allowed in statics
+    //~| ERROR contains unimplemented expression
 ];
 
 static STATIC16: (&'static Box<MyOwned>, &'static Box<MyOwned>) = (
     &box MyOwned, //~ ERROR allocations are not allowed in statics
+    //~| ERROR contains unimplemented expression
     &box MyOwned, //~ ERROR allocations are not allowed in statics
+    //~| ERROR contains unimplemented expression
 );
 
 static mut STATIC17: SafeEnum = SafeEnum::Variant1;
@@ -105,9 +110,11 @@ static mut STATIC17: SafeEnum = SafeEnum::Variant1;
 static STATIC19: Box<isize> =
     box 3;
 //~^ ERROR allocations are not allowed in statics
+    //~| ERROR contains unimplemented expression
 
 pub fn main() {
     let y = { static x: Box<isize> = box 3; x };
     //~^ ERROR allocations are not allowed in statics
-    //~^^ ERROR cannot move out of static item
+    //~| ERROR cannot move out of static item
+    //~| ERROR contains unimplemented expression
 }
diff --git a/src/test/ui/check-static-values-constraints.stderr b/src/test/ui/check-static-values-constraints.stderr
index 450a9ba0c0d11..5b1f265c34aef 100644
--- a/src/test/ui/check-static-values-constraints.stderr
+++ b/src/test/ui/check-static-values-constraints.stderr
@@ -13,55 +13,97 @@ error[E0010]: allocations are not allowed in statics
 LL | static STATIC11: Box<MyOwned> = box MyOwned;
    |                                 ^^^^^^^^^^^ allocation not allowed in statics
 
+error[E0019]: static contains unimplemented expression type
+  --> $DIR/check-static-values-constraints.rs:79:37
+   |
+LL | static STATIC11: Box<MyOwned> = box MyOwned;
+   |                                     ^^^^^^^
+
 error[E0015]: calls in statics are limited to constant functions, tuple structs and tuple variants
-  --> $DIR/check-static-values-constraints.rs:89:32
+  --> $DIR/check-static-values-constraints.rs:90:32
    |
 LL |     field2: SafeEnum::Variant4("str".to_string())
    |                                ^^^^^^^^^^^^^^^^^
 
 error[E0010]: allocations are not allowed in statics
-  --> $DIR/check-static-values-constraints.rs:94:5
+  --> $DIR/check-static-values-constraints.rs:95:5
    |
 LL |     box MyOwned, //~ ERROR allocations are not allowed in statics
    |     ^^^^^^^^^^^ allocation not allowed in statics
 
+error[E0019]: static contains unimplemented expression type
+  --> $DIR/check-static-values-constraints.rs:95:9
+   |
+LL |     box MyOwned, //~ ERROR allocations are not allowed in statics
+   |         ^^^^^^^
+
 error[E0010]: allocations are not allowed in statics
-  --> $DIR/check-static-values-constraints.rs:95:5
+  --> $DIR/check-static-values-constraints.rs:97:5
    |
 LL |     box MyOwned, //~ ERROR allocations are not allowed in statics
    |     ^^^^^^^^^^^ allocation not allowed in statics
 
+error[E0019]: static contains unimplemented expression type
+  --> $DIR/check-static-values-constraints.rs:97:9
+   |
+LL |     box MyOwned, //~ ERROR allocations are not allowed in statics
+   |         ^^^^^^^
+
 error[E0010]: allocations are not allowed in statics
-  --> $DIR/check-static-values-constraints.rs:99:6
+  --> $DIR/check-static-values-constraints.rs:102:6
    |
 LL |     &box MyOwned, //~ ERROR allocations are not allowed in statics
    |      ^^^^^^^^^^^ allocation not allowed in statics
 
+error[E0019]: static contains unimplemented expression type
+  --> $DIR/check-static-values-constraints.rs:102:10
+   |
+LL |     &box MyOwned, //~ ERROR allocations are not allowed in statics
+   |          ^^^^^^^
+
 error[E0010]: allocations are not allowed in statics
-  --> $DIR/check-static-values-constraints.rs:100:6
+  --> $DIR/check-static-values-constraints.rs:104:6
    |
 LL |     &box MyOwned, //~ ERROR allocations are not allowed in statics
    |      ^^^^^^^^^^^ allocation not allowed in statics
 
+error[E0019]: static contains unimplemented expression type
+  --> $DIR/check-static-values-constraints.rs:104:10
+   |
+LL |     &box MyOwned, //~ ERROR allocations are not allowed in statics
+   |          ^^^^^^^
+
 error[E0010]: allocations are not allowed in statics
-  --> $DIR/check-static-values-constraints.rs:106:5
+  --> $DIR/check-static-values-constraints.rs:111:5
    |
 LL |     box 3;
    |     ^^^^^ allocation not allowed in statics
 
+error[E0019]: static contains unimplemented expression type
+  --> $DIR/check-static-values-constraints.rs:111:9
+   |
+LL |     box 3;
+   |         ^
+
 error[E0507]: cannot move out of static item
-  --> $DIR/check-static-values-constraints.rs:110:45
+  --> $DIR/check-static-values-constraints.rs:116:45
    |
 LL |     let y = { static x: Box<isize> = box 3; x };
    |                                             ^ cannot move out of static item
 
 error[E0010]: allocations are not allowed in statics
-  --> $DIR/check-static-values-constraints.rs:110:38
+  --> $DIR/check-static-values-constraints.rs:116:38
    |
 LL |     let y = { static x: Box<isize> = box 3; x };
    |                                      ^^^^^ allocation not allowed in statics
 
-error: aborting due to 10 previous errors
+error[E0019]: static contains unimplemented expression type
+  --> $DIR/check-static-values-constraints.rs:116:42
+   |
+LL |     let y = { static x: Box<isize> = box 3; x };
+   |                                          ^
+
+error: aborting due to 17 previous errors
 
-Some errors occurred: E0010, E0015, E0493, E0507.
+Some errors occurred: E0010, E0015, E0019, E0493, E0507.
 For more information about an error, try `rustc --explain E0010`.
diff --git a/src/test/ui/consts/const-block-non-item-statement-2.rs b/src/test/ui/consts/const-block-non-item-statement-2.rs
deleted file mode 100644
index 58a6cf6dcfdeb..0000000000000
--- a/src/test/ui/consts/const-block-non-item-statement-2.rs
+++ /dev/null
@@ -1,18 +0,0 @@
-const A: usize = { 1; 2 };
-//~^ ERROR statements in constants are unstable
-
-const B: usize = { { } 2 };
-//~^ ERROR statements in constants are unstable
-
-macro_rules! foo {
-    () => (()) //~ ERROR statements in constants are unstable
-}
-const C: usize = { foo!(); 2 };
-
-const D: usize = { let x = 4; 2 };
-//~^ ERROR let bindings in constants are unstable
-//~| ERROR statements in constants are unstable
-//~| ERROR let bindings in constants are unstable
-//~| ERROR statements in constants are unstable
-
-pub fn main() {}
diff --git a/src/test/ui/consts/const-block-non-item-statement-2.stderr b/src/test/ui/consts/const-block-non-item-statement-2.stderr
deleted file mode 100644
index e0c61a953f50b..0000000000000
--- a/src/test/ui/consts/const-block-non-item-statement-2.stderr
+++ /dev/null
@@ -1,62 +0,0 @@
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement-2.rs:1:20
-   |
-LL | const A: usize = { 1; 2 };
-   |                    ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement-2.rs:4:20
-   |
-LL | const B: usize = { { } 2 };
-   |                    ^^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement-2.rs:8:12
-   |
-LL |     () => (()) //~ ERROR statements in constants are unstable
-   |            ^^
-LL | }
-LL | const C: usize = { foo!(); 2 };
-   |                    ------- in this macro invocation
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: let bindings in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement-2.rs:12:28
-   |
-LL | const D: usize = { let x = 4; 2 };
-   |                            ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement-2.rs:12:28
-   |
-LL | const D: usize = { let x = 4; 2 };
-   |                            ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: let bindings in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement-2.rs:12:1
-   |
-LL | const D: usize = { let x = 4; 2 };
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement-2.rs:12:1
-   |
-LL | const D: usize = { let x = 4; 2 };
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error: aborting due to 7 previous errors
-
-For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/consts/const-block-non-item-statement-3.rs b/src/test/ui/consts/const-block-non-item-statement-3.rs
deleted file mode 100644
index 867840925b2d5..0000000000000
--- a/src/test/ui/consts/const-block-non-item-statement-3.rs
+++ /dev/null
@@ -1,7 +0,0 @@
-type Array = [u32; {  let x = 2; 5 }];
-//~^ ERROR let bindings in constants are unstable
-//~| ERROR statements in constants are unstable
-//~| ERROR let bindings in constants are unstable
-//~| ERROR statements in constants are unstable
-
-pub fn main() {}
diff --git a/src/test/ui/consts/const-block-non-item-statement-3.stderr b/src/test/ui/consts/const-block-non-item-statement-3.stderr
deleted file mode 100644
index 0a549bc0c8ded..0000000000000
--- a/src/test/ui/consts/const-block-non-item-statement-3.stderr
+++ /dev/null
@@ -1,35 +0,0 @@
-error[E0658]: let bindings in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement-3.rs:1:31
-   |
-LL | type Array = [u32; {  let x = 2; 5 }];
-   |                               ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement-3.rs:1:31
-   |
-LL | type Array = [u32; {  let x = 2; 5 }];
-   |                               ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: let bindings in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement-3.rs:1:20
-   |
-LL | type Array = [u32; {  let x = 2; 5 }];
-   |                    ^^^^^^^^^^^^^^^^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement-3.rs:1:20
-   |
-LL | type Array = [u32; {  let x = 2; 5 }];
-   |                    ^^^^^^^^^^^^^^^^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error: aborting due to 4 previous errors
-
-For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/consts/const-block-non-item-statement.rs b/src/test/ui/consts/const-block-non-item-statement.rs
index 2db9e2413e5b5..5ecf9a049842d 100644
--- a/src/test/ui/consts/const-block-non-item-statement.rs
+++ b/src/test/ui/consts/const-block-non-item-statement.rs
@@ -1,9 +1,23 @@
+// compile-pass
+
 enum Foo {
     Bar = { let x = 1; 3 }
-    //~^ ERROR let bindings in constants are unstable
-    //~| ERROR statements in constants are unstable
-    //~| ERROR let bindings in constants are unstable
-    //~| ERROR statements in constants are unstable
 }
 
+
+const A: usize = { 1; 2 };
+
+const B: usize = { { } 2 };
+
+macro_rules! foo {
+    () => (())
+}
+
+const C: usize = { foo!(); 2 };
+
+const D: usize = { let x = 4; 2 };
+
+type Array = [u32; {  let x = 2; 5 }];
+type Array2 = [u32; { let mut x = 2; x = 3; x}];
+
 pub fn main() {}
diff --git a/src/test/ui/consts/const-block-non-item-statement.stderr b/src/test/ui/consts/const-block-non-item-statement.stderr
deleted file mode 100644
index f0d751e07561c..0000000000000
--- a/src/test/ui/consts/const-block-non-item-statement.stderr
+++ /dev/null
@@ -1,35 +0,0 @@
-error[E0658]: let bindings in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement.rs:2:21
-   |
-LL |     Bar = { let x = 1; 3 }
-   |                     ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement.rs:2:21
-   |
-LL |     Bar = { let x = 1; 3 }
-   |                     ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: let bindings in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement.rs:2:11
-   |
-LL |     Bar = { let x = 1; 3 }
-   |           ^^^^^^^^^^^^^^^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement.rs:2:11
-   |
-LL |     Bar = { let x = 1; 3 }
-   |           ^^^^^^^^^^^^^^^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error: aborting due to 4 previous errors
-
-For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/consts/const-eval/assign-to-static-within-other-static-2.rs b/src/test/ui/consts/const-eval/assign-to-static-within-other-static-2.rs
index ba8d032367ef8..4d3c714481a29 100644
--- a/src/test/ui/consts/const-eval/assign-to-static-within-other-static-2.rs
+++ b/src/test/ui/consts/const-eval/assign-to-static-within-other-static-2.rs
@@ -2,7 +2,6 @@
 // The test should never compile successfully
 
 #![feature(const_raw_ptr_deref)]
-#![feature(const_let)]
 
 use std::cell::UnsafeCell;
 
diff --git a/src/test/ui/consts/const-eval/assign-to-static-within-other-static-2.stderr b/src/test/ui/consts/const-eval/assign-to-static-within-other-static-2.stderr
index 6ca9d688bd062..be1be6c060071 100644
--- a/src/test/ui/consts/const-eval/assign-to-static-within-other-static-2.stderr
+++ b/src/test/ui/consts/const-eval/assign-to-static-within-other-static-2.stderr
@@ -1,5 +1,5 @@
 error[E0019]: static contains unimplemented expression type
-  --> $DIR/assign-to-static-within-other-static-2.rs:17:5
+  --> $DIR/assign-to-static-within-other-static-2.rs:16:5
    |
 LL |     *FOO.0.get() = 5; //~ ERROR contains unimplemented expression type
    |     ^^^^^^^^^^^^^^^^
diff --git a/src/test/ui/consts/const-eval/assign-to-static-within-other-static.rs b/src/test/ui/consts/const-eval/assign-to-static-within-other-static.rs
index 9fe17bfc6a06e..b4c416b1c55f0 100644
--- a/src/test/ui/consts/const-eval/assign-to-static-within-other-static.rs
+++ b/src/test/ui/consts/const-eval/assign-to-static-within-other-static.rs
@@ -2,7 +2,6 @@
 // The test should never compile successfully
 
 #![feature(const_raw_ptr_deref)]
-#![feature(const_let)]
 
 use std::cell::UnsafeCell;
 
diff --git a/src/test/ui/consts/const-eval/assign-to-static-within-other-static.stderr b/src/test/ui/consts/const-eval/assign-to-static-within-other-static.stderr
index 2ab9765305f47..31e49dc10ca60 100644
--- a/src/test/ui/consts/const-eval/assign-to-static-within-other-static.stderr
+++ b/src/test/ui/consts/const-eval/assign-to-static-within-other-static.stderr
@@ -1,5 +1,5 @@
 error: cannot mutate statics in the initializer of another static
-  --> $DIR/assign-to-static-within-other-static.rs:11:5
+  --> $DIR/assign-to-static-within-other-static.rs:10:5
    |
 LL |     FOO = 5; //~ ERROR cannot mutate statics in the initializer of another static
    |     ^^^^^^^
diff --git a/src/test/ui/consts/const-eval/const_let.rs b/src/test/ui/consts/const-eval/const_let.rs
index 9e6952733bb0b..63321b9120076 100644
--- a/src/test/ui/consts/const-eval/const_let.rs
+++ b/src/test/ui/consts/const-eval/const_let.rs
@@ -1,5 +1,3 @@
-#![feature(const_let)]
-
 fn main() {}
 
 struct FakeNeedsDrop;
diff --git a/src/test/ui/consts/const-eval/const_let.stderr b/src/test/ui/consts/const-eval/const_let.stderr
index e128ca07d8659..00de97e6fb3a0 100644
--- a/src/test/ui/consts/const-eval/const_let.stderr
+++ b/src/test/ui/consts/const-eval/const_let.stderr
@@ -1,11 +1,11 @@
 error[E0019]: constant contains unimplemented expression type
-  --> $DIR/const_let.rs:15:55
+  --> $DIR/const_let.rs:13:55
    |
 LL | const Y: FakeNeedsDrop = { let mut x = FakeNeedsDrop; x = FakeNeedsDrop; x };
    |                                                       ^
 
 error[E0019]: constant contains unimplemented expression type
-  --> $DIR/const_let.rs:19:35
+  --> $DIR/const_let.rs:17:35
    |
 LL | const Z: () = { let mut x = None; x = Some(FakeNeedsDrop); };
    |                                   ^
diff --git a/src/test/ui/consts/const-eval/infinite_loop.rs b/src/test/ui/consts/const-eval/infinite_loop.rs
index 0d5530acc9582..a2a45af7cb086 100644
--- a/src/test/ui/consts/const-eval/infinite_loop.rs
+++ b/src/test/ui/consts/const-eval/infinite_loop.rs
@@ -1,5 +1,3 @@
-#![feature(const_let)]
-
 fn main() {
     // Tests the Collatz conjecture with an incorrect base case (0 instead of 1).
     // The value of `n` will loop indefinitely (4 - 2 - 1 - 4).
diff --git a/src/test/ui/consts/const-eval/infinite_loop.stderr b/src/test/ui/consts/const-eval/infinite_loop.stderr
index 90d2159d7b551..422c2bab6ea90 100644
--- a/src/test/ui/consts/const-eval/infinite_loop.stderr
+++ b/src/test/ui/consts/const-eval/infinite_loop.stderr
@@ -1,5 +1,5 @@
 error[E0019]: constant contains unimplemented expression type
-  --> $DIR/infinite_loop.rs:9:9
+  --> $DIR/infinite_loop.rs:7:9
    |
 LL | /         while n != 0 { //~ ERROR constant contains unimplemented expression type
 LL | |             n = if n % 2 == 0 { n/2 } else { 3*n + 1 };
@@ -8,7 +8,7 @@ LL | |         }
    | |_________^
 
 warning: Constant evaluating a complex constant, this might take some time
-  --> $DIR/infinite_loop.rs:6:18
+  --> $DIR/infinite_loop.rs:4:18
    |
 LL |       let _ = [(); {
    |  __________________^
@@ -21,7 +21,7 @@ LL | |     }];
    | |_____^
 
 error[E0080]: evaluation of constant value failed
-  --> $DIR/infinite_loop.rs:10:20
+  --> $DIR/infinite_loop.rs:8:20
    |
 LL |             n = if n % 2 == 0 { n/2 } else { 3*n + 1 };
    |                    ^^^^^^^^^^ duplicate interpreter state observed here, const evaluation will never terminate
diff --git a/src/test/ui/consts/const-eval/issue-52475.rs b/src/test/ui/consts/const-eval/issue-52475.rs
index 2e3d6fb9e84be..aafdd5fe61782 100644
--- a/src/test/ui/consts/const-eval/issue-52475.rs
+++ b/src/test/ui/consts/const-eval/issue-52475.rs
@@ -1,5 +1,3 @@
-#![feature(const_let)]
-
 fn main() {
     let _ = [(); {
         //~^ WARNING Constant evaluating a complex constant, this might take some time
diff --git a/src/test/ui/consts/const-eval/issue-52475.stderr b/src/test/ui/consts/const-eval/issue-52475.stderr
index 329ea8a21f989..4f1b2ab4c8f46 100644
--- a/src/test/ui/consts/const-eval/issue-52475.stderr
+++ b/src/test/ui/consts/const-eval/issue-52475.stderr
@@ -1,5 +1,5 @@
 error[E0019]: constant contains unimplemented expression type
-  --> $DIR/issue-52475.rs:8:9
+  --> $DIR/issue-52475.rs:6:9
    |
 LL | /         while n < 5 { //~ ERROR constant contains unimplemented expression type
 LL | |             n = (n + 1) % 5; //~ ERROR evaluation of constant value failed
@@ -8,7 +8,7 @@ LL | |         }
    | |_________^
 
 warning: Constant evaluating a complex constant, this might take some time
-  --> $DIR/issue-52475.rs:4:18
+  --> $DIR/issue-52475.rs:2:18
    |
 LL |       let _ = [(); {
    |  __________________^
@@ -21,7 +21,7 @@ LL | |     }];
    | |_____^
 
 error[E0080]: evaluation of constant value failed
-  --> $DIR/issue-52475.rs:9:17
+  --> $DIR/issue-52475.rs:7:17
    |
 LL |             n = (n + 1) % 5; //~ ERROR evaluation of constant value failed
    |                 ^^^^^^^^^^^ duplicate interpreter state observed here, const evaluation will never terminate
diff --git a/src/test/ui/consts/const-eval/mod-static-with-const-fn.rs b/src/test/ui/consts/const-eval/mod-static-with-const-fn.rs
index 62090f4180d36..32f0062168b3d 100644
--- a/src/test/ui/consts/const-eval/mod-static-with-const-fn.rs
+++ b/src/test/ui/consts/const-eval/mod-static-with-const-fn.rs
@@ -2,7 +2,6 @@
 // The test should never compile successfully
 
 #![feature(const_raw_ptr_deref)]
-#![feature(const_let)]
 
 use std::cell::UnsafeCell;
 
diff --git a/src/test/ui/consts/const-eval/mod-static-with-const-fn.stderr b/src/test/ui/consts/const-eval/mod-static-with-const-fn.stderr
index 12d6e3be40a99..9fad6868d2038 100644
--- a/src/test/ui/consts/const-eval/mod-static-with-const-fn.stderr
+++ b/src/test/ui/consts/const-eval/mod-static-with-const-fn.stderr
@@ -1,11 +1,11 @@
 error[E0019]: static contains unimplemented expression type
-  --> $DIR/mod-static-with-const-fn.rs:19:5
+  --> $DIR/mod-static-with-const-fn.rs:18:5
    |
 LL |     *FOO.0.get() = 5;
    |     ^^^^^^^^^^^^^^^^
 
 error[E0015]: calls in statics are limited to constant functions, tuple structs and tuple variants
-  --> $DIR/mod-static-with-const-fn.rs:22:5
+  --> $DIR/mod-static-with-const-fn.rs:21:5
    |
 LL |     foo();
    |     ^^^^^
diff --git a/src/test/ui/consts/const-eval/ub-upvars.rs b/src/test/ui/consts/const-eval/ub-upvars.rs
index 16df0c1b0cc0e..9b7bca6b72d61 100644
--- a/src/test/ui/consts/const-eval/ub-upvars.rs
+++ b/src/test/ui/consts/const-eval/ub-upvars.rs
@@ -1,4 +1,4 @@
-#![feature(const_transmute,const_let)]
+#![feature(const_transmute)]
 #![allow(const_err)] // make sure we cannot allow away the errors tested here
 
 use std::mem;
diff --git a/src/test/ui/consts/const-fn-destructuring-arg.rs b/src/test/ui/consts/const-fn-destructuring-arg.rs
index 7f818079a19d1..dcf89f90e31da 100644
--- a/src/test/ui/consts/const-fn-destructuring-arg.rs
+++ b/src/test/ui/consts/const-fn-destructuring-arg.rs
@@ -1,17 +1,7 @@
-// test that certain things are disallowed in constant functions
+// compile-pass
 
-#![feature(const_fn)]
-
-// no destructuring
-const fn i((
-            a,
-            //~^ ERROR arguments of constant functions can only be immutable by-value bindings
-            b
-            //~^ ERROR arguments of constant functions can only be immutable by-value bindings
-           ): (u32, u32)) -> u32 {
+const fn i((a, b): (u32, u32)) -> u32 {
     a + b
-    //~^ ERROR let bindings in constant functions are unstable
-    //~| ERROR let bindings in constant functions are unstable
 }
 
 fn main() {}
diff --git a/src/test/ui/consts/const-fn-destructuring-arg.stderr b/src/test/ui/consts/const-fn-destructuring-arg.stderr
deleted file mode 100644
index db63e8308045a..0000000000000
--- a/src/test/ui/consts/const-fn-destructuring-arg.stderr
+++ /dev/null
@@ -1,35 +0,0 @@
-error[E0658]: arguments of constant functions can only be immutable by-value bindings (see issue #48821)
-  --> $DIR/const-fn-destructuring-arg.rs:7:13
-   |
-LL |             a,
-   |             ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: arguments of constant functions can only be immutable by-value bindings (see issue #48821)
-  --> $DIR/const-fn-destructuring-arg.rs:9:13
-   |
-LL |             b
-   |             ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: let bindings in constant functions are unstable (see issue #48821)
-  --> $DIR/const-fn-destructuring-arg.rs:12:5
-   |
-LL |     a + b
-   |     ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: let bindings in constant functions are unstable (see issue #48821)
-  --> $DIR/const-fn-destructuring-arg.rs:12:9
-   |
-LL |     a + b
-   |         ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error: aborting due to 4 previous errors
-
-For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/consts/const-fn-not-safe-for-const.rs b/src/test/ui/consts/const-fn-not-safe-for-const.rs
index fe672e7b3e6da..085ff5c58e60c 100644
--- a/src/test/ui/consts/const-fn-not-safe-for-const.rs
+++ b/src/test/ui/consts/const-fn-not-safe-for-const.rs
@@ -27,13 +27,9 @@ const fn get_Y_addr() -> &'static u32 {
 }
 
 const fn get() -> u32 {
-    let x = 22; //~ ERROR let bindings in constant functions are unstable
-//~^ ERROR statements in constant functions
-    let y = 44; //~ ERROR let bindings in constant functions are unstable
-//~^ ERROR statements in constant functions
+    let x = 22;
+    let y = 44;
     x + y
-//~^ ERROR let bindings in constant functions are unstable
-//~| ERROR let bindings in constant functions are unstable
 }
 
 fn main() {}
diff --git a/src/test/ui/consts/const-fn-not-safe-for-const.stderr b/src/test/ui/consts/const-fn-not-safe-for-const.stderr
index 8cc4c38526238..2003b137c272b 100644
--- a/src/test/ui/consts/const-fn-not-safe-for-const.stderr
+++ b/src/test/ui/consts/const-fn-not-safe-for-const.stderr
@@ -16,55 +16,7 @@ error[E0013]: constant functions cannot refer to statics, use a constant instead
 LL |     &Y
    |     ^^
 
-error[E0658]: let bindings in constant functions are unstable (see issue #48821)
-  --> $DIR/const-fn-not-safe-for-const.rs:30:13
-   |
-LL |     let x = 22; //~ ERROR let bindings in constant functions are unstable
-   |             ^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constant functions are unstable (see issue #48821)
-  --> $DIR/const-fn-not-safe-for-const.rs:30:13
-   |
-LL |     let x = 22; //~ ERROR let bindings in constant functions are unstable
-   |             ^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: let bindings in constant functions are unstable (see issue #48821)
-  --> $DIR/const-fn-not-safe-for-const.rs:32:13
-   |
-LL |     let y = 44; //~ ERROR let bindings in constant functions are unstable
-   |             ^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constant functions are unstable (see issue #48821)
-  --> $DIR/const-fn-not-safe-for-const.rs:32:13
-   |
-LL |     let y = 44; //~ ERROR let bindings in constant functions are unstable
-   |             ^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: let bindings in constant functions are unstable (see issue #48821)
-  --> $DIR/const-fn-not-safe-for-const.rs:34:5
-   |
-LL |     x + y
-   |     ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: let bindings in constant functions are unstable (see issue #48821)
-  --> $DIR/const-fn-not-safe-for-const.rs:34:9
-   |
-LL |     x + y
-   |         ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error: aborting due to 9 previous errors
+error: aborting due to 3 previous errors
 
-Some errors occurred: E0013, E0015, E0658.
+Some errors occurred: E0013, E0015.
 For more information about an error, try `rustc --explain E0013`.
diff --git a/src/test/ui/consts/const-int-unchecked.rs b/src/test/ui/consts/const-int-unchecked.rs
index aeac6c37dcbab..8ee029b6cc390 100644
--- a/src/test/ui/consts/const-int-unchecked.rs
+++ b/src/test/ui/consts/const-int-unchecked.rs
@@ -2,10 +2,119 @@
 
 use std::intrinsics;
 
-const SHR: u8 = unsafe { intrinsics::unchecked_shr(5_u8, 8) };
+// The documentation of `unchecked_shl` states that it:
+//
+// Performs an unchecked left shift, resulting in undefined behavior when
+// y < 0 or y >= N, where N is the width of T in bits.
+//
+// So we check this for a few `y`.
+
+// unsigned types:
+
+const SHL_U8: u8 = unsafe { intrinsics::unchecked_shl(5_u8, 8) };
+//~^ ERROR any use of this value will cause an error
+const SHL_U16: u16 = unsafe { intrinsics::unchecked_shl(5_u16, 16) };
+//~^ ERROR any use of this value will cause an error
+const SHL_U32: u32 = unsafe { intrinsics::unchecked_shl(5_u32, 32) };
+//~^ ERROR any use of this value will cause an error
+const SHL_U64: u64 = unsafe { intrinsics::unchecked_shl(5_u64, 64) };
+//~^ ERROR any use of this value will cause an error
+const SHL_U128: u128 = unsafe { intrinsics::unchecked_shl(5_u128, 128) };
+//~^ ERROR any use of this value will cause an error
+
+// signed types:
+
+const SHL_I8: i8 = unsafe { intrinsics::unchecked_shl(5_i8, 8) };
+//~^ ERROR any use of this value will cause an error
+const SHL_I16: i16 = unsafe { intrinsics::unchecked_shl(5_16, 16) };
+//~^ ERROR any use of this value will cause an error
+const SHL_I32: i32 = unsafe { intrinsics::unchecked_shl(5_i32, 32) };
+//~^ ERROR any use of this value will cause an error
+const SHL_I64: i64 = unsafe { intrinsics::unchecked_shl(5_i64, 64) };
+//~^ ERROR any use of this value will cause an error
+const SHL_I128: i128 = unsafe { intrinsics::unchecked_shl(5_i128, 128) };
+//~^ ERROR any use of this value will cause an error
+
+// and make sure we capture y < 0:
+
+const SHL_I8_NEG: i8 = unsafe { intrinsics::unchecked_shl(5_i8, -1) };
+//~^ ERROR any use of this value will cause an error
+const SHL_I16_NEG: i16 = unsafe { intrinsics::unchecked_shl(5_16, -1) };
+//~^ ERROR any use of this value will cause an error
+const SHL_I32_NEG: i32 = unsafe { intrinsics::unchecked_shl(5_i32, -1) };
+//~^ ERROR any use of this value will cause an error
+const SHL_I64_NEG: i64 = unsafe { intrinsics::unchecked_shl(5_i64, -1) };
+//~^ ERROR any use of this value will cause an error
+const SHL_I128_NEG: i128 = unsafe { intrinsics::unchecked_shl(5_i128, -1) };
+//~^ ERROR any use of this value will cause an error
+
+// and that there's no special relation to the value -1 by picking some
+// negative values at random:
+
+const SHL_I8_NEG_RANDOM: i8 = unsafe { intrinsics::unchecked_shl(5_i8, -6) };
+//~^ ERROR any use of this value will cause an error
+const SHL_I16_NEG_RANDOM: i16 = unsafe { intrinsics::unchecked_shl(5_16, -13) };
+//~^ ERROR any use of this value will cause an error
+const SHL_I32_NEG_RANDOM: i32 = unsafe { intrinsics::unchecked_shl(5_i32, -25) };
+//~^ ERROR any use of this value will cause an error
+const SHL_I64_NEG_RANDOM: i64 = unsafe { intrinsics::unchecked_shl(5_i64, -30) };
+//~^ ERROR any use of this value will cause an error
+const SHL_I128_NEG_RANDOM: i128 = unsafe { intrinsics::unchecked_shl(5_i128, -93) };
+//~^ ERROR any use of this value will cause an error
+
+// Repeat it all over for `unchecked_shr`
+
+// unsigned types:
+
+const SHR_U8: u8 = unsafe { intrinsics::unchecked_shr(5_u8, 8) };
+//~^ ERROR any use of this value will cause an error
+const SHR_U16: u16 = unsafe { intrinsics::unchecked_shr(5_u16, 16) };
+//~^ ERROR any use of this value will cause an error
+const SHR_U32: u32 = unsafe { intrinsics::unchecked_shr(5_u32, 32) };
+//~^ ERROR any use of this value will cause an error
+const SHR_U64: u64 = unsafe { intrinsics::unchecked_shr(5_u64, 64) };
+//~^ ERROR any use of this value will cause an error
+const SHR_U128: u128 = unsafe { intrinsics::unchecked_shr(5_u128, 128) };
+//~^ ERROR any use of this value will cause an error
+
+// signed types:
+
+const SHR_I8: i8 = unsafe { intrinsics::unchecked_shr(5_i8, 8) };
+//~^ ERROR any use of this value will cause an error
+const SHR_I16: i16 = unsafe { intrinsics::unchecked_shr(5_16, 16) };
+//~^ ERROR any use of this value will cause an error
+const SHR_I32: i32 = unsafe { intrinsics::unchecked_shr(5_i32, 32) };
+//~^ ERROR any use of this value will cause an error
+const SHR_I64: i64 = unsafe { intrinsics::unchecked_shr(5_i64, 64) };
+//~^ ERROR any use of this value will cause an error
+const SHR_I128: i128 = unsafe { intrinsics::unchecked_shr(5_i128, 128) };
+//~^ ERROR any use of this value will cause an error
+
+// and make sure we capture y < 0:
+
+const SHR_I8_NEG: i8 = unsafe { intrinsics::unchecked_shr(5_i8, -1) };
+//~^ ERROR any use of this value will cause an error
+const SHR_I16_NEG: i16 = unsafe { intrinsics::unchecked_shr(5_16, -1) };
+//~^ ERROR any use of this value will cause an error
+const SHR_I32_NEG: i32 = unsafe { intrinsics::unchecked_shr(5_i32, -1) };
+//~^ ERROR any use of this value will cause an error
+const SHR_I64_NEG: i64 = unsafe { intrinsics::unchecked_shr(5_i64, -1) };
+//~^ ERROR any use of this value will cause an error
+const SHR_I128_NEG: i128 = unsafe { intrinsics::unchecked_shr(5_i128, -1) };
+//~^ ERROR any use of this value will cause an error
+
+// and that there's no special relation to the value -1 by picking some
+// negative values at random:
+
+const SHR_I8_NEG_RANDOM: i8 = unsafe { intrinsics::unchecked_shr(5_i8, -6) };
+//~^ ERROR any use of this value will cause an error
+const SHR_I16_NEG_RANDOM: i16 = unsafe { intrinsics::unchecked_shr(5_16, -13) };
+//~^ ERROR any use of this value will cause an error
+const SHR_I32_NEG_RANDOM: i32 = unsafe { intrinsics::unchecked_shr(5_i32, -25) };
+//~^ ERROR any use of this value will cause an error
+const SHR_I64_NEG_RANDOM: i64 = unsafe { intrinsics::unchecked_shr(5_i64, -30) };
 //~^ ERROR any use of this value will cause an error
-const SHL: u8 = unsafe { intrinsics::unchecked_shl(5_u8, 8) };
+const SHR_I128_NEG_RANDOM: i128 = unsafe { intrinsics::unchecked_shr(5_i128, -93) };
 //~^ ERROR any use of this value will cause an error
 
-fn main() {
-}
+fn main() {}
diff --git a/src/test/ui/consts/const-int-unchecked.stderr b/src/test/ui/consts/const-int-unchecked.stderr
index dd28cc4d533e9..4382d9174b757 100644
--- a/src/test/ui/consts/const-int-unchecked.stderr
+++ b/src/test/ui/consts/const-int-unchecked.stderr
@@ -1,20 +1,324 @@
 error: any use of this value will cause an error
-  --> $DIR/const-int-unchecked.rs:5:1
+  --> $DIR/const-int-unchecked.rs:14:1
    |
-LL | const SHR: u8 = unsafe { intrinsics::unchecked_shr(5_u8, 8) };
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^----------------------------------^^^
-   |                          |
-   |                          Overflowing shift by 8 in unchecked_shr
+LL | const SHL_U8: u8 = unsafe { intrinsics::unchecked_shl(5_u8, 8) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^----------------------------------^^^
+   |                             |
+   |                             Overflowing shift by 8 in unchecked_shl
    |
    = note: #[deny(const_err)] on by default
 
 error: any use of this value will cause an error
-  --> $DIR/const-int-unchecked.rs:7:1
+  --> $DIR/const-int-unchecked.rs:16:1
    |
-LL | const SHL: u8 = unsafe { intrinsics::unchecked_shl(5_u8, 8) };
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^----------------------------------^^^
-   |                          |
-   |                          Overflowing shift by 8 in unchecked_shl
+LL | const SHL_U16: u16 = unsafe { intrinsics::unchecked_shl(5_u16, 16) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^------------------------------------^^^
+   |                               |
+   |                               Overflowing shift by 16 in unchecked_shl
 
-error: aborting due to 2 previous errors
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:18:1
+   |
+LL | const SHL_U32: u32 = unsafe { intrinsics::unchecked_shl(5_u32, 32) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^------------------------------------^^^
+   |                               |
+   |                               Overflowing shift by 32 in unchecked_shl
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:20:1
+   |
+LL | const SHL_U64: u64 = unsafe { intrinsics::unchecked_shl(5_u64, 64) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^------------------------------------^^^
+   |                               |
+   |                               Overflowing shift by 64 in unchecked_shl
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:22:1
+   |
+LL | const SHL_U128: u128 = unsafe { intrinsics::unchecked_shl(5_u128, 128) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^--------------------------------------^^^
+   |                                 |
+   |                                 Overflowing shift by 128 in unchecked_shl
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:27:1
+   |
+LL | const SHL_I8: i8 = unsafe { intrinsics::unchecked_shl(5_i8, 8) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^----------------------------------^^^
+   |                             |
+   |                             Overflowing shift by 8 in unchecked_shl
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:29:1
+   |
+LL | const SHL_I16: i16 = unsafe { intrinsics::unchecked_shl(5_16, 16) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-----------------------------------^^^
+   |                               |
+   |                               Overflowing shift by 16 in unchecked_shl
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:31:1
+   |
+LL | const SHL_I32: i32 = unsafe { intrinsics::unchecked_shl(5_i32, 32) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^------------------------------------^^^
+   |                               |
+   |                               Overflowing shift by 32 in unchecked_shl
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:33:1
+   |
+LL | const SHL_I64: i64 = unsafe { intrinsics::unchecked_shl(5_i64, 64) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^------------------------------------^^^
+   |                               |
+   |                               Overflowing shift by 64 in unchecked_shl
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:35:1
+   |
+LL | const SHL_I128: i128 = unsafe { intrinsics::unchecked_shl(5_i128, 128) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^--------------------------------------^^^
+   |                                 |
+   |                                 Overflowing shift by 128 in unchecked_shl
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:40:1
+   |
+LL | const SHL_I8_NEG: i8 = unsafe { intrinsics::unchecked_shl(5_i8, -1) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-----------------------------------^^^
+   |                                 |
+   |                                 Overflowing shift by 255 in unchecked_shl
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:42:1
+   |
+LL | const SHL_I16_NEG: i16 = unsafe { intrinsics::unchecked_shl(5_16, -1) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-----------------------------------^^^
+   |                                   |
+   |                                   Overflowing shift by 65535 in unchecked_shl
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:44:1
+   |
+LL | const SHL_I32_NEG: i32 = unsafe { intrinsics::unchecked_shl(5_i32, -1) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^------------------------------------^^^
+   |                                   |
+   |                                   Overflowing shift by 4294967295 in unchecked_shl
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:46:1
+   |
+LL | const SHL_I64_NEG: i64 = unsafe { intrinsics::unchecked_shl(5_i64, -1) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^------------------------------------^^^
+   |                                   |
+   |                                   Overflowing shift by 18446744073709551615 in unchecked_shl
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:48:1
+   |
+LL | const SHL_I128_NEG: i128 = unsafe { intrinsics::unchecked_shl(5_i128, -1) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-------------------------------------^^^
+   |                                     |
+   |                                     Overflowing shift by 340282366920938463463374607431768211455 in unchecked_shl
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:54:1
+   |
+LL | const SHL_I8_NEG_RANDOM: i8 = unsafe { intrinsics::unchecked_shl(5_i8, -6) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-----------------------------------^^^
+   |                                        |
+   |                                        Overflowing shift by 250 in unchecked_shl
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:56:1
+   |
+LL | const SHL_I16_NEG_RANDOM: i16 = unsafe { intrinsics::unchecked_shl(5_16, -13) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^------------------------------------^^^
+   |                                          |
+   |                                          Overflowing shift by 65523 in unchecked_shl
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:58:1
+   |
+LL | const SHL_I32_NEG_RANDOM: i32 = unsafe { intrinsics::unchecked_shl(5_i32, -25) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-------------------------------------^^^
+   |                                          |
+   |                                          Overflowing shift by 4294967271 in unchecked_shl
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:60:1
+   |
+LL | const SHL_I64_NEG_RANDOM: i64 = unsafe { intrinsics::unchecked_shl(5_i64, -30) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-------------------------------------^^^
+   |                                          |
+   |                                          Overflowing shift by 18446744073709551586 in unchecked_shl
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:62:1
+   |
+LL | const SHL_I128_NEG_RANDOM: i128 = unsafe { intrinsics::unchecked_shl(5_i128, -93) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^--------------------------------------^^^
+   |                                            |
+   |                                            Overflowing shift by 340282366920938463463374607431768211363 in unchecked_shl
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:69:1
+   |
+LL | const SHR_U8: u8 = unsafe { intrinsics::unchecked_shr(5_u8, 8) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^----------------------------------^^^
+   |                             |
+   |                             Overflowing shift by 8 in unchecked_shr
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:71:1
+   |
+LL | const SHR_U16: u16 = unsafe { intrinsics::unchecked_shr(5_u16, 16) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^------------------------------------^^^
+   |                               |
+   |                               Overflowing shift by 16 in unchecked_shr
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:73:1
+   |
+LL | const SHR_U32: u32 = unsafe { intrinsics::unchecked_shr(5_u32, 32) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^------------------------------------^^^
+   |                               |
+   |                               Overflowing shift by 32 in unchecked_shr
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:75:1
+   |
+LL | const SHR_U64: u64 = unsafe { intrinsics::unchecked_shr(5_u64, 64) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^------------------------------------^^^
+   |                               |
+   |                               Overflowing shift by 64 in unchecked_shr
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:77:1
+   |
+LL | const SHR_U128: u128 = unsafe { intrinsics::unchecked_shr(5_u128, 128) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^--------------------------------------^^^
+   |                                 |
+   |                                 Overflowing shift by 128 in unchecked_shr
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:82:1
+   |
+LL | const SHR_I8: i8 = unsafe { intrinsics::unchecked_shr(5_i8, 8) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^----------------------------------^^^
+   |                             |
+   |                             Overflowing shift by 8 in unchecked_shr
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:84:1
+   |
+LL | const SHR_I16: i16 = unsafe { intrinsics::unchecked_shr(5_16, 16) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-----------------------------------^^^
+   |                               |
+   |                               Overflowing shift by 16 in unchecked_shr
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:86:1
+   |
+LL | const SHR_I32: i32 = unsafe { intrinsics::unchecked_shr(5_i32, 32) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^------------------------------------^^^
+   |                               |
+   |                               Overflowing shift by 32 in unchecked_shr
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:88:1
+   |
+LL | const SHR_I64: i64 = unsafe { intrinsics::unchecked_shr(5_i64, 64) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^------------------------------------^^^
+   |                               |
+   |                               Overflowing shift by 64 in unchecked_shr
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:90:1
+   |
+LL | const SHR_I128: i128 = unsafe { intrinsics::unchecked_shr(5_i128, 128) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^--------------------------------------^^^
+   |                                 |
+   |                                 Overflowing shift by 128 in unchecked_shr
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:95:1
+   |
+LL | const SHR_I8_NEG: i8 = unsafe { intrinsics::unchecked_shr(5_i8, -1) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-----------------------------------^^^
+   |                                 |
+   |                                 Overflowing shift by 255 in unchecked_shr
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:97:1
+   |
+LL | const SHR_I16_NEG: i16 = unsafe { intrinsics::unchecked_shr(5_16, -1) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-----------------------------------^^^
+   |                                   |
+   |                                   Overflowing shift by 65535 in unchecked_shr
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:99:1
+   |
+LL | const SHR_I32_NEG: i32 = unsafe { intrinsics::unchecked_shr(5_i32, -1) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^------------------------------------^^^
+   |                                   |
+   |                                   Overflowing shift by 4294967295 in unchecked_shr
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:101:1
+   |
+LL | const SHR_I64_NEG: i64 = unsafe { intrinsics::unchecked_shr(5_i64, -1) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^------------------------------------^^^
+   |                                   |
+   |                                   Overflowing shift by 18446744073709551615 in unchecked_shr
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:103:1
+   |
+LL | const SHR_I128_NEG: i128 = unsafe { intrinsics::unchecked_shr(5_i128, -1) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-------------------------------------^^^
+   |                                     |
+   |                                     Overflowing shift by 340282366920938463463374607431768211455 in unchecked_shr
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:109:1
+   |
+LL | const SHR_I8_NEG_RANDOM: i8 = unsafe { intrinsics::unchecked_shr(5_i8, -6) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-----------------------------------^^^
+   |                                        |
+   |                                        Overflowing shift by 250 in unchecked_shr
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:111:1
+   |
+LL | const SHR_I16_NEG_RANDOM: i16 = unsafe { intrinsics::unchecked_shr(5_16, -13) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^------------------------------------^^^
+   |                                          |
+   |                                          Overflowing shift by 65523 in unchecked_shr
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:113:1
+   |
+LL | const SHR_I32_NEG_RANDOM: i32 = unsafe { intrinsics::unchecked_shr(5_i32, -25) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-------------------------------------^^^
+   |                                          |
+   |                                          Overflowing shift by 4294967271 in unchecked_shr
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:115:1
+   |
+LL | const SHR_I64_NEG_RANDOM: i64 = unsafe { intrinsics::unchecked_shr(5_i64, -30) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-------------------------------------^^^
+   |                                          |
+   |                                          Overflowing shift by 18446744073709551586 in unchecked_shr
+
+error: any use of this value will cause an error
+  --> $DIR/const-int-unchecked.rs:117:1
+   |
+LL | const SHR_I128_NEG_RANDOM: i128 = unsafe { intrinsics::unchecked_shr(5_i128, -93) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^--------------------------------------^^^
+   |                                            |
+   |                                            Overflowing shift by 340282366920938463463374607431768211363 in unchecked_shr
+
+error: aborting due to 40 previous errors
 
diff --git a/src/test/ui/consts/const_let_assign.rs b/src/test/ui/consts/const_let_assign.rs
index a3c53a451e106..0b09b8469fd75 100644
--- a/src/test/ui/consts/const_let_assign.rs
+++ b/src/test/ui/consts/const_let_assign.rs
@@ -1,7 +1,5 @@
 // compile-pass
 
-#![feature(const_let)]
-
 struct S(i32);
 
 const A: () = {
diff --git a/src/test/ui/consts/const_let_assign2.rs b/src/test/ui/consts/const_let_assign2.rs
index 0de7396501adc..1c44237e49b7a 100644
--- a/src/test/ui/consts/const_let_assign2.rs
+++ b/src/test/ui/consts/const_let_assign2.rs
@@ -1,8 +1,5 @@
 // compile-pass
 
-#![feature(const_let)]
-#![feature(const_fn)]
-
 pub struct AA {
     pub data: [u8; 10],
 }
diff --git a/src/test/ui/consts/const_let_assign3.rs b/src/test/ui/consts/const_let_assign3.rs
index c2ed6cd85ab5c..cbe73923e9c42 100644
--- a/src/test/ui/consts/const_let_assign3.rs
+++ b/src/test/ui/consts/const_let_assign3.rs
@@ -1,4 +1,3 @@
-#![feature(const_let)]
 #![feature(const_fn)]
 
 struct S {
@@ -18,6 +17,15 @@ const FOO: S = {
     s
 };
 
+type Array = [u32; {
+    let mut x = 2;
+    let y = &mut x;
+//~^ ERROR references in constants may only refer to immutable values
+    *y = 42;
+//~^ ERROR constant contains unimplemented expression type
+    *y
+}];
+
 fn main() {
     assert_eq!(FOO.state, 3);
 }
diff --git a/src/test/ui/consts/const_let_assign3.stderr b/src/test/ui/consts/const_let_assign3.stderr
index 0f294616d255c..6649fb997cce4 100644
--- a/src/test/ui/consts/const_let_assign3.stderr
+++ b/src/test/ui/consts/const_let_assign3.stderr
@@ -1,16 +1,28 @@
 error[E0019]: constant function contains unimplemented expression type
-  --> $DIR/const_let_assign3.rs:10:9
+  --> $DIR/const_let_assign3.rs:9:9
    |
 LL |         self.state = x;
    |         ^^^^^^^^^^^^^^
 
 error[E0017]: references in constants may only refer to immutable values
-  --> $DIR/const_let_assign3.rs:17:5
+  --> $DIR/const_let_assign3.rs:16:5
    |
 LL |     s.foo(3); //~ ERROR references in constants may only refer to immutable values
    |     ^ constants require immutable values
 
-error: aborting due to 2 previous errors
+error[E0017]: references in constants may only refer to immutable values
+  --> $DIR/const_let_assign3.rs:22:13
+   |
+LL |     let y = &mut x;
+   |             ^^^^^^ constants require immutable values
+
+error[E0019]: constant contains unimplemented expression type
+  --> $DIR/const_let_assign3.rs:24:5
+   |
+LL |     *y = 42;
+   |     ^^^^^^^
+
+error: aborting due to 4 previous errors
 
 Some errors occurred: E0017, E0019.
 For more information about an error, try `rustc --explain E0017`.
diff --git a/src/test/ui/consts/const_let_eq.rs b/src/test/ui/consts/const_let_eq.rs
index 8739cb80e9403..a2364c392f26b 100644
--- a/src/test/ui/consts/const_let_eq.rs
+++ b/src/test/ui/consts/const_let_eq.rs
@@ -1,5 +1,3 @@
-#![feature(const_let, const_fn)]
-
 // run-pass
 
 struct Foo<T>(T);
diff --git a/src/test/ui/consts/const_let_eq_float.rs b/src/test/ui/consts/const_let_eq_float.rs
index 2c7262df367a3..c48f54e567b2c 100644
--- a/src/test/ui/consts/const_let_eq_float.rs
+++ b/src/test/ui/consts/const_let_eq_float.rs
@@ -1,6 +1,6 @@
 // compile-pass
 
-#![feature(const_let, const_fn)]
+#![feature(const_fn)]
 
 struct Foo<T>(T);
 struct Bar<T> { x: T }
diff --git a/src/test/ui/consts/const_let_irrefutable.rs b/src/test/ui/consts/const_let_irrefutable.rs
new file mode 100644
index 0000000000000..424a16f7ed39b
--- /dev/null
+++ b/src/test/ui/consts/const_let_irrefutable.rs
@@ -0,0 +1,11 @@
+// compile-pass
+
+fn main() {}
+
+const fn tup((a, b): (i32, i32)) -> i32 {
+    a + b
+}
+
+const fn array([a, b]: [i32; 2]) -> i32 {
+    a + b
+}
diff --git a/src/test/ui/consts/const_let_refutable.rs b/src/test/ui/consts/const_let_refutable.rs
new file mode 100644
index 0000000000000..345f682868fbc
--- /dev/null
+++ b/src/test/ui/consts/const_let_refutable.rs
@@ -0,0 +1,5 @@
+fn main() {}
+
+const fn slice([a, b]: &[i32]) -> i32 { //~ ERROR refutable pattern in function argument
+    a + b
+}
diff --git a/src/test/ui/consts/const_let_refutable.stderr b/src/test/ui/consts/const_let_refutable.stderr
new file mode 100644
index 0000000000000..c5d2ba02a70c6
--- /dev/null
+++ b/src/test/ui/consts/const_let_refutable.stderr
@@ -0,0 +1,9 @@
+error[E0005]: refutable pattern in function argument: `&[]` not covered
+  --> $DIR/const_let_refutable.rs:3:16
+   |
+LL | const fn slice([a, b]: &[i32]) -> i32 { //~ ERROR refutable pattern in function argument
+   |                ^^^^^^ pattern `&[]` not covered
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0005`.
diff --git a/src/test/ui/consts/const_short_circuit.rs b/src/test/ui/consts/const_short_circuit.rs
index cc49e4696e58f..1e7b7ed319355 100644
--- a/src/test/ui/consts/const_short_circuit.rs
+++ b/src/test/ui/consts/const_short_circuit.rs
@@ -1,4 +1,4 @@
-#![feature(underscore_const_names, const_let)]
+#![feature(underscore_const_names)]
 
 const _: bool = false && false;
 const _: bool = true && false;
diff --git a/src/test/ui/consts/dangling-alloc-id-ice.rs b/src/test/ui/consts/dangling-alloc-id-ice.rs
index 695d33b690898..dbc50f1fbd4b4 100644
--- a/src/test/ui/consts/dangling-alloc-id-ice.rs
+++ b/src/test/ui/consts/dangling-alloc-id-ice.rs
@@ -1,7 +1,5 @@
 // https://github.com/rust-lang/rust/issues/55223
 
-#![feature(const_let)]
-
 union Foo<'a> {
     y: &'a (),
     long_live_the_unit: &'static (),
diff --git a/src/test/ui/consts/dangling-alloc-id-ice.stderr b/src/test/ui/consts/dangling-alloc-id-ice.stderr
index a5fa88e5e6832..2cd8711f03d31 100644
--- a/src/test/ui/consts/dangling-alloc-id-ice.stderr
+++ b/src/test/ui/consts/dangling-alloc-id-ice.stderr
@@ -1,5 +1,5 @@
 error: any use of this value will cause an error
-  --> $DIR/dangling-alloc-id-ice.rs:10:1
+  --> $DIR/dangling-alloc-id-ice.rs:8:1
    |
 LL | / const FOO: &() = { //~ ERROR any use of this value will cause an error
 LL | |     let y = ();
diff --git a/src/test/ui/consts/dangling_raw_ptr.rs b/src/test/ui/consts/dangling_raw_ptr.rs
index 7fc773412f2f8..c2d8e6d421a28 100644
--- a/src/test/ui/consts/dangling_raw_ptr.rs
+++ b/src/test/ui/consts/dangling_raw_ptr.rs
@@ -1,5 +1,3 @@
-#![feature(const_let)]
-
 const FOO: *const u32 = { //~ ERROR any use of this value will cause an error
     let x = 42;
     &x
diff --git a/src/test/ui/consts/dangling_raw_ptr.stderr b/src/test/ui/consts/dangling_raw_ptr.stderr
index 3b20936f8ae97..091f1f785cb02 100644
--- a/src/test/ui/consts/dangling_raw_ptr.stderr
+++ b/src/test/ui/consts/dangling_raw_ptr.stderr
@@ -1,5 +1,5 @@
 error: any use of this value will cause an error
-  --> $DIR/dangling_raw_ptr.rs:3:1
+  --> $DIR/dangling_raw_ptr.rs:1:1
    |
 LL | / const FOO: *const u32 = { //~ ERROR any use of this value will cause an error
 LL | |     let x = 42;
diff --git a/src/test/ui/consts/min_const_fn/min_const_fn.rs b/src/test/ui/consts/min_const_fn/min_const_fn.rs
index 238b5f7e31003..05cf3d5f1f173 100644
--- a/src/test/ui/consts/min_const_fn/min_const_fn.rs
+++ b/src/test/ui/consts/min_const_fn/min_const_fn.rs
@@ -96,7 +96,7 @@ const fn foo30_2(x: *mut u32) -> usize { x as usize }
 const fn foo30_4(b: bool) -> usize { if b { 1 } else { 42 } }
 //~^ ERROR `if`, `match`, `&&` and `||` are not stable in const fn
 const fn foo30_5(b: bool) { while b { } } //~ ERROR not stable in const fn
-const fn foo30_6() -> bool { let x = true; x } //~ ERROR local variables in const fn
+const fn foo30_6() -> bool { let x = true; x }
 const fn foo36(a: bool, b: bool) -> bool { a && b }
 //~^ ERROR `if`, `match`, `&&` and `||` are not stable in const fn
 const fn foo37(a: bool, b: bool) -> bool { a || b }
diff --git a/src/test/ui/consts/min_const_fn/min_const_fn.stderr b/src/test/ui/consts/min_const_fn/min_const_fn.stderr
index 1c68df513b697..2cae714fbf727 100644
--- a/src/test/ui/consts/min_const_fn/min_const_fn.stderr
+++ b/src/test/ui/consts/min_const_fn/min_const_fn.stderr
@@ -112,12 +112,6 @@ error: `if`, `match`, `&&` and `||` are not stable in const fn
 LL | const fn foo30_5(b: bool) { while b { } } //~ ERROR not stable in const fn
    |                             ^^^^^^^^^^^
 
-error: local variables in const fn are unstable
-  --> $DIR/min_const_fn.rs:99:34
-   |
-LL | const fn foo30_6() -> bool { let x = true; x } //~ ERROR local variables in const fn
-   |                                  ^
-
 error: `if`, `match`, `&&` and `||` are not stable in const fn
   --> $DIR/min_const_fn.rs:100:44
    |
@@ -208,6 +202,6 @@ error: function pointers in const fn are unstable
 LL | const fn no_fn_ptrs2() -> fn() { fn foo() {} foo }
    |                           ^^^^
 
-error: aborting due to 35 previous errors
+error: aborting due to 34 previous errors
 
 For more information about this error, try `rustc --explain E0493`.
diff --git a/src/test/ui/consts/min_const_fn/mutable_borrow.rs b/src/test/ui/consts/min_const_fn/mutable_borrow.rs
index 3dd76b630a883..89acfea6ed8ff 100644
--- a/src/test/ui/consts/min_const_fn/mutable_borrow.rs
+++ b/src/test/ui/consts/min_const_fn/mutable_borrow.rs
@@ -1,6 +1,6 @@
 const fn mutable_ref_in_const() -> u8 {
-    let mut a = 0; //~ ERROR local variables in const fn
-    let b = &mut a;
+    let mut a = 0;
+    let b = &mut a; //~ ERROR mutable references in const fn
     *b
 }
 
@@ -8,8 +8,8 @@ struct X;
 
 impl X {
     const fn inherent_mutable_ref_in_const() -> u8 {
-        let mut a = 0; //~ ERROR local variables in const fn
-        let b = &mut a;
+        let mut a = 0;
+        let b = &mut a; //~ ERROR mutable references in const fn
         *b
     }
 }
diff --git a/src/test/ui/consts/min_const_fn/mutable_borrow.stderr b/src/test/ui/consts/min_const_fn/mutable_borrow.stderr
index fa46f5c804fe0..5ce0f30dc6e1f 100644
--- a/src/test/ui/consts/min_const_fn/mutable_borrow.stderr
+++ b/src/test/ui/consts/min_const_fn/mutable_borrow.stderr
@@ -1,14 +1,14 @@
-error: local variables in const fn are unstable
-  --> $DIR/mutable_borrow.rs:2:9
+error: mutable references in const fn are unstable
+  --> $DIR/mutable_borrow.rs:3:9
    |
-LL |     let mut a = 0; //~ ERROR local variables in const fn
-   |         ^^^^^
+LL |     let b = &mut a; //~ ERROR mutable references in const fn
+   |         ^
 
-error: local variables in const fn are unstable
-  --> $DIR/mutable_borrow.rs:11:13
+error: mutable references in const fn are unstable
+  --> $DIR/mutable_borrow.rs:12:13
    |
-LL |         let mut a = 0; //~ ERROR local variables in const fn
-   |             ^^^^^
+LL |         let b = &mut a; //~ ERROR mutable references in const fn
+   |             ^
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/consts/partial_qualif.rs b/src/test/ui/consts/partial_qualif.rs
index 4ce41f80f82c8..32c68e69f4bed 100644
--- a/src/test/ui/consts/partial_qualif.rs
+++ b/src/test/ui/consts/partial_qualif.rs
@@ -1,5 +1,3 @@
-#![feature(const_let)]
-
 use std::cell::Cell;
 
 const FOO: &(Cell<usize>, bool) = {
diff --git a/src/test/ui/consts/partial_qualif.stderr b/src/test/ui/consts/partial_qualif.stderr
index d695f64e2c3b5..967fb83b78b08 100644
--- a/src/test/ui/consts/partial_qualif.stderr
+++ b/src/test/ui/consts/partial_qualif.stderr
@@ -1,5 +1,5 @@
 error[E0492]: cannot borrow a constant which may contain interior mutability, create a static instead
-  --> $DIR/partial_qualif.rs:8:5
+  --> $DIR/partial_qualif.rs:6:5
    |
 LL |     &{a} //~ ERROR cannot borrow a constant which may contain interior mutability
    |     ^^^^
diff --git a/src/test/ui/consts/projection_qualif.rs b/src/test/ui/consts/projection_qualif.rs
index 5863429a2f2c5..dedb7db592089 100644
--- a/src/test/ui/consts/projection_qualif.rs
+++ b/src/test/ui/consts/projection_qualif.rs
@@ -1,5 +1,3 @@
-#![feature(const_let)]
-
 use std::cell::Cell;
 
 const FOO: &u32 = {
diff --git a/src/test/ui/consts/projection_qualif.stderr b/src/test/ui/consts/projection_qualif.stderr
index cc3635a979b37..410c51c4b54e1 100644
--- a/src/test/ui/consts/projection_qualif.stderr
+++ b/src/test/ui/consts/projection_qualif.stderr
@@ -1,17 +1,17 @@
 error[E0017]: references in constants may only refer to immutable values
-  --> $DIR/projection_qualif.rs:8:27
+  --> $DIR/projection_qualif.rs:6:27
    |
 LL |         let b: *mut u32 = &mut a; //~ ERROR may only refer to immutable values
    |                           ^^^^^^ constants require immutable values
 
 error[E0019]: constant contains unimplemented expression type
-  --> $DIR/projection_qualif.rs:9:18
+  --> $DIR/projection_qualif.rs:7:18
    |
 LL |         unsafe { *b = 5; } //~ ERROR dereferencing raw pointers in constants
    |                  ^^^^^^
 
 error[E0658]: dereferencing raw pointers in constants is unstable (see issue #51911)
-  --> $DIR/projection_qualif.rs:9:18
+  --> $DIR/projection_qualif.rs:7:18
    |
 LL |         unsafe { *b = 5; } //~ ERROR dereferencing raw pointers in constants
    |                  ^^^^^^
diff --git a/src/test/ui/consts/promote_const_let.rs b/src/test/ui/consts/promote_const_let.rs
index 8de9b00eb111d..a8a6d4d99c6ff 100644
--- a/src/test/ui/consts/promote_const_let.rs
+++ b/src/test/ui/consts/promote_const_let.rs
@@ -1,8 +1,10 @@
-#![feature(const_let)]
-
 fn main() {
     let x: &'static u32 = {
         let y = 42;
         &y //~ ERROR does not live long enough
     };
+    let x: &'static u32 = &{ //~ ERROR does not live long enough
+        let y = 42;
+        y
+    };
 }
diff --git a/src/test/ui/consts/promote_const_let.stderr b/src/test/ui/consts/promote_const_let.stderr
index 6bbb7495fb0dc..d37bd49186032 100644
--- a/src/test/ui/consts/promote_const_let.stderr
+++ b/src/test/ui/consts/promote_const_let.stderr
@@ -1,5 +1,5 @@
 error[E0597]: `y` does not live long enough
-  --> $DIR/promote_const_let.rs:6:10
+  --> $DIR/promote_const_let.rs:4:10
    |
 LL |         &y //~ ERROR does not live long enough
    |          ^ borrowed value does not live long enough
@@ -8,6 +8,20 @@ LL |     };
    |
    = note: borrowed value must be valid for the static lifetime...
 
-error: aborting due to previous error
+error[E0597]: borrowed value does not live long enough
+  --> $DIR/promote_const_let.rs:6:28
+   |
+LL |       let x: &'static u32 = &{ //~ ERROR does not live long enough
+   |  ____________________________^
+LL | |         let y = 42;
+LL | |         y
+LL | |     };
+   | |_____^ temporary value does not live long enough
+LL |   }
+   |   - temporary value only lives until here
+   |
+   = note: borrowed value must be valid for the static lifetime...
+
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0597`.
diff --git a/src/test/ui/consts/qualif_overwrite.rs b/src/test/ui/consts/qualif_overwrite.rs
index 806a74ee4530b..430eea37de73c 100644
--- a/src/test/ui/consts/qualif_overwrite.rs
+++ b/src/test/ui/consts/qualif_overwrite.rs
@@ -1,5 +1,3 @@
-#![feature(const_let)]
-
 use std::cell::Cell;
 
 // this is overly conservative. The reset to `None` should clear `a` of all qualifications
diff --git a/src/test/ui/consts/qualif_overwrite.stderr b/src/test/ui/consts/qualif_overwrite.stderr
index 4fac64bf8063f..30479139e314c 100644
--- a/src/test/ui/consts/qualif_overwrite.stderr
+++ b/src/test/ui/consts/qualif_overwrite.stderr
@@ -1,5 +1,5 @@
 error[E0492]: cannot borrow a constant which may contain interior mutability, create a static instead
-  --> $DIR/qualif_overwrite.rs:12:5
+  --> $DIR/qualif_overwrite.rs:10:5
    |
 LL |     &{a} //~ ERROR cannot borrow a constant which may contain interior mutability
    |     ^^^^
diff --git a/src/test/ui/consts/qualif_overwrite_2.rs b/src/test/ui/consts/qualif_overwrite_2.rs
index 29557a3da4781..fa79b5c14a736 100644
--- a/src/test/ui/consts/qualif_overwrite_2.rs
+++ b/src/test/ui/consts/qualif_overwrite_2.rs
@@ -1,5 +1,3 @@
-#![feature(const_let)]
-
 use std::cell::Cell;
 
 // const qualification is not smart enough to know about fields and always assumes that there might
diff --git a/src/test/ui/consts/qualif_overwrite_2.stderr b/src/test/ui/consts/qualif_overwrite_2.stderr
index 181b728c7b76f..8276db99a12c0 100644
--- a/src/test/ui/consts/qualif_overwrite_2.stderr
+++ b/src/test/ui/consts/qualif_overwrite_2.stderr
@@ -1,5 +1,5 @@
 error[E0492]: cannot borrow a constant which may contain interior mutability, create a static instead
-  --> $DIR/qualif_overwrite_2.rs:10:5
+  --> $DIR/qualif_overwrite_2.rs:8:5
    |
 LL |     &{a.0} //~ ERROR cannot borrow a constant which may contain interior mutability
    |     ^^^^^^
diff --git a/src/test/ui/consts/static_mut_containing_mut_ref2.rs b/src/test/ui/consts/static_mut_containing_mut_ref2.rs
index 4180b1e295ab0..ef378fa84518e 100644
--- a/src/test/ui/consts/static_mut_containing_mut_ref2.rs
+++ b/src/test/ui/consts/static_mut_containing_mut_ref2.rs
@@ -1,5 +1,3 @@
-#![feature(const_let)]
-
 static mut STDERR_BUFFER_SPACE: u8 = 0;
 
 pub static mut STDERR_BUFFER: () = unsafe { *(&mut STDERR_BUFFER_SPACE) = 42; };
diff --git a/src/test/ui/consts/static_mut_containing_mut_ref2.stderr b/src/test/ui/consts/static_mut_containing_mut_ref2.stderr
index f0ae1545056b7..72186571d697e 100644
--- a/src/test/ui/consts/static_mut_containing_mut_ref2.stderr
+++ b/src/test/ui/consts/static_mut_containing_mut_ref2.stderr
@@ -1,11 +1,11 @@
 error[E0017]: references in statics may only refer to immutable values
-  --> $DIR/static_mut_containing_mut_ref2.rs:5:46
+  --> $DIR/static_mut_containing_mut_ref2.rs:3:46
    |
 LL | pub static mut STDERR_BUFFER: () = unsafe { *(&mut STDERR_BUFFER_SPACE) = 42; };
    |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^ statics require immutable values
 
 error[E0019]: static contains unimplemented expression type
-  --> $DIR/static_mut_containing_mut_ref2.rs:5:45
+  --> $DIR/static_mut_containing_mut_ref2.rs:3:45
    |
 LL | pub static mut STDERR_BUFFER: () = unsafe { *(&mut STDERR_BUFFER_SPACE) = 42; };
    |                                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/src/test/ui/consts/static_mut_containing_mut_ref3.rs b/src/test/ui/consts/static_mut_containing_mut_ref3.rs
index 0bc7faa9afdec..c24c7e2792079 100644
--- a/src/test/ui/consts/static_mut_containing_mut_ref3.rs
+++ b/src/test/ui/consts/static_mut_containing_mut_ref3.rs
@@ -1,5 +1,3 @@
-#![feature(const_let)]
-
 static mut FOO: (u8, u8) = (42, 43);
 
 static mut BAR: () = unsafe { FOO.0 = 99; };
diff --git a/src/test/ui/consts/static_mut_containing_mut_ref3.stderr b/src/test/ui/consts/static_mut_containing_mut_ref3.stderr
index cae53c6fee9dd..e88e49b097af2 100644
--- a/src/test/ui/consts/static_mut_containing_mut_ref3.stderr
+++ b/src/test/ui/consts/static_mut_containing_mut_ref3.stderr
@@ -1,5 +1,5 @@
 error[E0080]: could not evaluate static initializer
-  --> $DIR/static_mut_containing_mut_ref3.rs:5:31
+  --> $DIR/static_mut_containing_mut_ref3.rs:3:31
    |
 LL | static mut BAR: () = unsafe { FOO.0 = 99; };
    |                               ^^^^^^^^^^ tried to modify a static's initial value from another static's initializer
diff --git a/src/test/ui/error-codes/E0010-teach.rs b/src/test/ui/error-codes/E0010-teach.rs
index fc5dffb37cfe7..da51035ab5550 100644
--- a/src/test/ui/error-codes/E0010-teach.rs
+++ b/src/test/ui/error-codes/E0010-teach.rs
@@ -4,5 +4,6 @@
 #![allow(warnings)]
 
 const CON : Box<i32> = box 0; //~ ERROR E0010
+//~^ ERROR constant contains unimplemented expression type
 
 fn main() {}
diff --git a/src/test/ui/error-codes/E0010-teach.stderr b/src/test/ui/error-codes/E0010-teach.stderr
index da0aadfded5f8..77e7b5ec0e860 100644
--- a/src/test/ui/error-codes/E0010-teach.stderr
+++ b/src/test/ui/error-codes/E0010-teach.stderr
@@ -6,6 +6,16 @@ LL | const CON : Box<i32> = box 0; //~ ERROR E0010
    |
    = note: The value of statics and constants must be known at compile time, and they live for the entire lifetime of a program. Creating a boxed value allocates memory on the heap at runtime, and therefore cannot be done at compile time.
 
-error: aborting due to previous error
+error[E0019]: constant contains unimplemented expression type
+  --> $DIR/E0010-teach.rs:6:28
+   |
+LL | const CON : Box<i32> = box 0; //~ ERROR E0010
+   |                            ^
+   |
+   = note: A function call isn't allowed in the const's initialization expression because the expression's value must be known at compile-time.
+   = note: Remember: you can't use a function call inside a const's initialization expression! However, you can use it anywhere else.
+
+error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0010`.
+Some errors occurred: E0010, E0019.
+For more information about an error, try `rustc --explain E0010`.
diff --git a/src/test/ui/error-codes/E0010.rs b/src/test/ui/error-codes/E0010.rs
index e62997640f473..3398e2c28ba6b 100644
--- a/src/test/ui/error-codes/E0010.rs
+++ b/src/test/ui/error-codes/E0010.rs
@@ -2,5 +2,6 @@
 #![allow(warnings)]
 
 const CON : Box<i32> = box 0; //~ ERROR E0010
+//~^ ERROR constant contains unimplemented expression type
 
 fn main() {}
diff --git a/src/test/ui/error-codes/E0010.stderr b/src/test/ui/error-codes/E0010.stderr
index b4b490922c45f..1364693109e08 100644
--- a/src/test/ui/error-codes/E0010.stderr
+++ b/src/test/ui/error-codes/E0010.stderr
@@ -4,6 +4,13 @@ error[E0010]: allocations are not allowed in constants
 LL | const CON : Box<i32> = box 0; //~ ERROR E0010
    |                        ^^^^^ allocation not allowed in constants
 
-error: aborting due to previous error
+error[E0019]: constant contains unimplemented expression type
+  --> $DIR/E0010.rs:4:28
+   |
+LL | const CON : Box<i32> = box 0; //~ ERROR E0010
+   |                            ^
+
+error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0010`.
+Some errors occurred: E0010, E0019.
+For more information about an error, try `rustc --explain E0010`.
diff --git a/src/test/ui/feature-gates/feature-gate-const_let.rs b/src/test/ui/feature-gates/feature-gate-const_let.rs
deleted file mode 100644
index 74cefd7c0670d..0000000000000
--- a/src/test/ui/feature-gates/feature-gate-const_let.rs
+++ /dev/null
@@ -1,21 +0,0 @@
-// Test use of const let without feature gate.
-
-const FOO: usize = {
-    //~^ ERROR statements in constants are unstable
-    //~| ERROR: let bindings in constants are unstable
-    let x = 42;
-    //~^ ERROR statements in constants are unstable
-    //~| ERROR: let bindings in constants are unstable
-    42
-};
-
-static BAR: usize = {
-    //~^ ERROR statements in statics are unstable
-    //~| ERROR: let bindings in statics are unstable
-    let x = 42;
-    //~^ ERROR statements in statics are unstable
-    //~| ERROR: let bindings in statics are unstable
-    42
-};
-
-fn main() {}
diff --git a/src/test/ui/feature-gates/feature-gate-const_let.stderr b/src/test/ui/feature-gates/feature-gate-const_let.stderr
deleted file mode 100644
index 56312999a5fd8..0000000000000
--- a/src/test/ui/feature-gates/feature-gate-const_let.stderr
+++ /dev/null
@@ -1,91 +0,0 @@
-error[E0658]: let bindings in constants are unstable (see issue #48821)
-  --> $DIR/feature-gate-const_let.rs:6:13
-   |
-LL |     let x = 42;
-   |             ^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/feature-gate-const_let.rs:6:13
-   |
-LL |     let x = 42;
-   |             ^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: let bindings in constants are unstable (see issue #48821)
-  --> $DIR/feature-gate-const_let.rs:3:1
-   |
-LL | / const FOO: usize = {
-LL | |     //~^ ERROR statements in constants are unstable
-LL | |     //~| ERROR: let bindings in constants are unstable
-LL | |     let x = 42;
-...  |
-LL | |     42
-LL | | };
-   | |__^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/feature-gate-const_let.rs:3:1
-   |
-LL | / const FOO: usize = {
-LL | |     //~^ ERROR statements in constants are unstable
-LL | |     //~| ERROR: let bindings in constants are unstable
-LL | |     let x = 42;
-...  |
-LL | |     42
-LL | | };
-   | |__^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: let bindings in statics are unstable (see issue #48821)
-  --> $DIR/feature-gate-const_let.rs:15:13
-   |
-LL |     let x = 42;
-   |             ^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in statics are unstable (see issue #48821)
-  --> $DIR/feature-gate-const_let.rs:15:13
-   |
-LL |     let x = 42;
-   |             ^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: let bindings in statics are unstable (see issue #48821)
-  --> $DIR/feature-gate-const_let.rs:12:1
-   |
-LL | / static BAR: usize = {
-LL | |     //~^ ERROR statements in statics are unstable
-LL | |     //~| ERROR: let bindings in statics are unstable
-LL | |     let x = 42;
-...  |
-LL | |     42
-LL | | };
-   | |__^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in statics are unstable (see issue #48821)
-  --> $DIR/feature-gate-const_let.rs:12:1
-   |
-LL | / static BAR: usize = {
-LL | |     //~^ ERROR statements in statics are unstable
-LL | |     //~| ERROR: let bindings in statics are unstable
-LL | |     let x = 42;
-...  |
-LL | |     42
-LL | | };
-   | |__^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error: aborting due to 8 previous errors
-
-For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/feature-gates/feature-gate-underscore_const_names.rs b/src/test/ui/feature-gates/feature-gate-underscore_const_names.rs
index a82b356c75216..6b97c24a47ed2 100644
--- a/src/test/ui/feature-gates/feature-gate-underscore_const_names.rs
+++ b/src/test/ui/feature-gates/feature-gate-underscore_const_names.rs
@@ -1,5 +1,3 @@
-#![feature(const_let)]
-
 trait Trt {}
 struct Str {}
 
diff --git a/src/test/ui/feature-gates/feature-gate-underscore_const_names.stderr b/src/test/ui/feature-gates/feature-gate-underscore_const_names.stderr
index b3658208828e9..d608f3d37cf2a 100644
--- a/src/test/ui/feature-gates/feature-gate-underscore_const_names.stderr
+++ b/src/test/ui/feature-gates/feature-gate-underscore_const_names.stderr
@@ -1,5 +1,5 @@
 error[E0658]: naming constants with `_` is unstable (see issue #54912)
-  --> $DIR/feature-gate-underscore_const_names.rs:8:1
+  --> $DIR/feature-gate-underscore_const_names.rs:6:1
    |
 LL | / const _ : () = {
 LL | | //~^ ERROR is unstable
diff --git a/src/test/ui/issues/issue-18118.rs b/src/test/ui/issues/issue-18118.rs
index 7bbea191cd167..f58a3de281f1a 100644
--- a/src/test/ui/issues/issue-18118.rs
+++ b/src/test/ui/issues/issue-18118.rs
@@ -1,11 +1,6 @@
 pub fn main() {
     const z: &'static isize = {
-        //~^ ERROR let bindings in constants are unstable
-        //~| ERROR statements in constants are unstable
         let p = 3;
-        //~^ ERROR let bindings in constants are unstable
-        //~| ERROR statements in constants are unstable
         &p //~ ERROR `p` does not live long enough
-        //~^ ERROR let bindings in constants are unstable
     };
 }
diff --git a/src/test/ui/issues/issue-18118.stderr b/src/test/ui/issues/issue-18118.stderr
index 1383cdb4438c9..9b21ece341a9f 100644
--- a/src/test/ui/issues/issue-18118.stderr
+++ b/src/test/ui/issues/issue-18118.stderr
@@ -1,67 +1,13 @@
-error[E0658]: let bindings in constants are unstable (see issue #48821)
-  --> $DIR/issue-18118.rs:5:17
-   |
-LL |         let p = 3;
-   |                 ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/issue-18118.rs:5:17
-   |
-LL |         let p = 3;
-   |                 ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: let bindings in constants are unstable (see issue #48821)
-  --> $DIR/issue-18118.rs:8:9
-   |
-LL |         &p //~ ERROR `p` does not live long enough
-   |         ^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: let bindings in constants are unstable (see issue #48821)
-  --> $DIR/issue-18118.rs:2:5
-   |
-LL | /     const z: &'static isize = {
-LL | |         //~^ ERROR let bindings in constants are unstable
-LL | |         //~| ERROR statements in constants are unstable
-LL | |         let p = 3;
-...  |
-LL | |         //~^ ERROR let bindings in constants are unstable
-LL | |     };
-   | |______^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/issue-18118.rs:2:5
-   |
-LL | /     const z: &'static isize = {
-LL | |         //~^ ERROR let bindings in constants are unstable
-LL | |         //~| ERROR statements in constants are unstable
-LL | |         let p = 3;
-...  |
-LL | |         //~^ ERROR let bindings in constants are unstable
-LL | |     };
-   | |______^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
 error[E0597]: `p` does not live long enough
-  --> $DIR/issue-18118.rs:8:10
+  --> $DIR/issue-18118.rs:4:10
    |
 LL |         &p //~ ERROR `p` does not live long enough
    |          ^ borrowed value does not live long enough
-LL |         //~^ ERROR let bindings in constants are unstable
 LL |     };
    |     - borrowed value only lives until here
    |
    = note: borrowed value must be valid for the static lifetime...
 
-error: aborting due to 6 previous errors
+error: aborting due to previous error
 
-Some errors occurred: E0597, E0658.
-For more information about an error, try `rustc --explain E0597`.
+For more information about this error, try `rustc --explain E0597`.
diff --git a/src/test/ui/issues/issue-32829-2.rs b/src/test/ui/issues/issue-32829-2.rs
index 9db9d30411d6f..c93c84b5fb773 100644
--- a/src/test/ui/issues/issue-32829-2.rs
+++ b/src/test/ui/issues/issue-32829-2.rs
@@ -1,11 +1,8 @@
 // ignore-tidy-linelength
 
-#![feature(const_fn)]
-
 const bad : u32 = {
     {
         5;
-        //~^ ERROR statements in constants are unstable
         0
     }
 };
@@ -13,8 +10,7 @@ const bad : u32 = {
 const bad_two : u32 = {
     {
         invalid();
-        //~^ ERROR statements in constants are unstable
-        //~^^ ERROR: calls in constants are limited to constant functions, tuple structs and tuple variants
+        //~^ ERROR: calls in constants are limited to constant functions, tuple structs and tuple variants
         0
     }
 };
@@ -22,7 +18,6 @@ const bad_two : u32 = {
 const bad_three : u32 = {
     {
         valid();
-        //~^ ERROR statements in constants are unstable
         0
     }
 };
@@ -30,7 +25,6 @@ const bad_three : u32 = {
 static bad_four : u32 = {
     {
         5;
-        //~^ ERROR statements in statics are unstable
         0
     }
 };
@@ -39,7 +33,6 @@ static bad_five : u32 = {
     {
         invalid();
         //~^ ERROR: calls in statics are limited to constant functions, tuple structs and tuple variants
-        //~| ERROR statements in statics are unstable
         0
     }
 };
@@ -47,7 +40,6 @@ static bad_five : u32 = {
 static bad_six : u32 = {
     {
         valid();
-        //~^ ERROR statements in statics are unstable
         0
     }
 };
@@ -55,7 +47,6 @@ static bad_six : u32 = {
 static mut bad_seven : u32 = {
     {
         5;
-        //~^ ERROR statements in statics are unstable
         0
     }
 };
@@ -63,8 +54,7 @@ static mut bad_seven : u32 = {
 static mut bad_eight : u32 = {
     {
         invalid();
-        //~^ ERROR statements in statics are unstable
-        //~| ERROR: calls in statics are limited to constant functions, tuple structs and tuple variants
+        //~^ ERROR: calls in statics are limited to constant functions, tuple structs and tuple variants
         0
     }
 };
@@ -72,7 +62,6 @@ static mut bad_eight : u32 = {
 static mut bad_nine : u32 = {
     {
         valid();
-        //~^ ERROR statements in statics are unstable
         0
     }
 };
diff --git a/src/test/ui/issues/issue-32829-2.stderr b/src/test/ui/issues/issue-32829-2.stderr
index 7fe0261281830..8d7423f29ae97 100644
--- a/src/test/ui/issues/issue-32829-2.stderr
+++ b/src/test/ui/issues/issue-32829-2.stderr
@@ -1,94 +1,21 @@
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/issue-32829-2.rs:7:9
-   |
-LL |         5;
-   |         ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
 error[E0015]: calls in constants are limited to constant functions, tuple structs and tuple variants
-  --> $DIR/issue-32829-2.rs:15:9
+  --> $DIR/issue-32829-2.rs:12:9
    |
 LL |         invalid();
    |         ^^^^^^^^^
 
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/issue-32829-2.rs:15:9
-   |
-LL |         invalid();
-   |         ^^^^^^^^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/issue-32829-2.rs:24:9
-   |
-LL |         valid();
-   |         ^^^^^^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in statics are unstable (see issue #48821)
-  --> $DIR/issue-32829-2.rs:32:9
-   |
-LL |         5;
-   |         ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
 error[E0015]: calls in statics are limited to constant functions, tuple structs and tuple variants
-  --> $DIR/issue-32829-2.rs:40:9
+  --> $DIR/issue-32829-2.rs:34:9
    |
 LL |         invalid();
    |         ^^^^^^^^^
 
-error[E0658]: statements in statics are unstable (see issue #48821)
-  --> $DIR/issue-32829-2.rs:40:9
-   |
-LL |         invalid();
-   |         ^^^^^^^^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in statics are unstable (see issue #48821)
-  --> $DIR/issue-32829-2.rs:49:9
-   |
-LL |         valid();
-   |         ^^^^^^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in statics are unstable (see issue #48821)
-  --> $DIR/issue-32829-2.rs:57:9
-   |
-LL |         5;
-   |         ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
 error[E0015]: calls in statics are limited to constant functions, tuple structs and tuple variants
-  --> $DIR/issue-32829-2.rs:65:9
+  --> $DIR/issue-32829-2.rs:56:9
    |
 LL |         invalid();
    |         ^^^^^^^^^
 
-error[E0658]: statements in statics are unstable (see issue #48821)
-  --> $DIR/issue-32829-2.rs:65:9
-   |
-LL |         invalid();
-   |         ^^^^^^^^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in statics are unstable (see issue #48821)
-  --> $DIR/issue-32829-2.rs:74:9
-   |
-LL |         valid();
-   |         ^^^^^^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error: aborting due to 12 previous errors
+error: aborting due to 3 previous errors
 
-Some errors occurred: E0015, E0658.
-For more information about an error, try `rustc --explain E0015`.
+For more information about this error, try `rustc --explain E0015`.
diff --git a/src/test/ui/issues/issue-37550.rs b/src/test/ui/issues/issue-37550.rs
index 12282f3e54887..505c030b96712 100644
--- a/src/test/ui/issues/issue-37550.rs
+++ b/src/test/ui/issues/issue-37550.rs
@@ -1,6 +1,6 @@
 const fn x() {
-    let t = true; //~ ERROR local variables in const fn
-    let x = || t;
+    let t = true;
+    let x = || t; //~ ERROR function pointers in const fn are unstable
 }
 
 fn main() {}
diff --git a/src/test/ui/issues/issue-37550.stderr b/src/test/ui/issues/issue-37550.stderr
index d42f72ad3fac8..d2b03416cb73c 100644
--- a/src/test/ui/issues/issue-37550.stderr
+++ b/src/test/ui/issues/issue-37550.stderr
@@ -1,7 +1,7 @@
-error: local variables in const fn are unstable
-  --> $DIR/issue-37550.rs:2:9
+error: function pointers in const fn are unstable
+  --> $DIR/issue-37550.rs:3:9
    |
-LL |     let t = true; //~ ERROR local variables in const fn
+LL |     let x = || t; //~ ERROR function pointers in const fn are unstable
    |         ^
 
 error: aborting due to previous error
diff --git a/src/test/ui/issues/issue-7364.rs b/src/test/ui/issues/issue-7364.rs
index 3f9c2ef48a7af..52ec9e42be782 100644
--- a/src/test/ui/issues/issue-7364.rs
+++ b/src/test/ui/issues/issue-7364.rs
@@ -6,5 +6,6 @@ use std::cell::RefCell;
 static boxed: Box<RefCell<isize>> = box RefCell::new(0);
 //~^ ERROR allocations are not allowed in statics
 //~| ERROR `std::cell::RefCell<isize>` cannot be shared between threads safely [E0277]
+//~| ERROR static contains unimplemented expression type
 
 fn main() { }
diff --git a/src/test/ui/issues/issue-7364.stderr b/src/test/ui/issues/issue-7364.stderr
index 0e4d6ff1d71fa..52a99ce36b870 100644
--- a/src/test/ui/issues/issue-7364.stderr
+++ b/src/test/ui/issues/issue-7364.stderr
@@ -4,6 +4,12 @@ error[E0010]: allocations are not allowed in statics
 LL | static boxed: Box<RefCell<isize>> = box RefCell::new(0);
    |                                     ^^^^^^^^^^^^^^^^^^^ allocation not allowed in statics
 
+error[E0019]: static contains unimplemented expression type
+  --> $DIR/issue-7364.rs:6:41
+   |
+LL | static boxed: Box<RefCell<isize>> = box RefCell::new(0);
+   |                                         ^^^^^^^^^^^^^^^
+
 error[E0277]: `std::cell::RefCell<isize>` cannot be shared between threads safely
   --> $DIR/issue-7364.rs:6:1
    |
@@ -15,7 +21,7 @@ LL | static boxed: Box<RefCell<isize>> = box RefCell::new(0);
    = note: required because it appears within the type `std::boxed::Box<std::cell::RefCell<isize>>`
    = note: shared static variables must have a type that implements `Sync`
 
-error: aborting due to 2 previous errors
+error: aborting due to 3 previous errors
 
-Some errors occurred: E0010, E0277.
+Some errors occurred: E0010, E0019, E0277.
 For more information about an error, try `rustc --explain E0010`.
diff --git a/src/test/ui/static/static-mut-not-constant.rs b/src/test/ui/static/static-mut-not-constant.rs
index 2091fffd418ee..84d401c9fa61d 100644
--- a/src/test/ui/static/static-mut-not-constant.rs
+++ b/src/test/ui/static/static-mut-not-constant.rs
@@ -2,5 +2,6 @@
 
 static mut a: Box<isize> = box 3;
 //~^ ERROR allocations are not allowed in statics
+//~| ERROR static contains unimplemented expression type
 
 fn main() {}
diff --git a/src/test/ui/static/static-mut-not-constant.stderr b/src/test/ui/static/static-mut-not-constant.stderr
index a0fa245156f87..d2c6ba6a2f85a 100644
--- a/src/test/ui/static/static-mut-not-constant.stderr
+++ b/src/test/ui/static/static-mut-not-constant.stderr
@@ -4,6 +4,13 @@ error[E0010]: allocations are not allowed in statics
 LL | static mut a: Box<isize> = box 3;
    |                            ^^^^^ allocation not allowed in statics
 
-error: aborting due to previous error
+error[E0019]: static contains unimplemented expression type
+  --> $DIR/static-mut-not-constant.rs:3:32
+   |
+LL | static mut a: Box<isize> = box 3;
+   |                                ^
+
+error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0010`.
+Some errors occurred: E0010, E0019.
+For more information about an error, try `rustc --explain E0010`.
diff --git a/src/test/ui/underscore_const_names.rs b/src/test/ui/underscore_const_names.rs
index 811d166ed65a7..1db022e886208 100644
--- a/src/test/ui/underscore_const_names.rs
+++ b/src/test/ui/underscore_const_names.rs
@@ -1,6 +1,5 @@
 // compile-pass
 
-#![feature(const_let)]
 #![feature(underscore_const_names)]
 
 trait Trt {}
diff --git a/src/test/ui/unsafe/ranged_ints2_const.rs b/src/test/ui/unsafe/ranged_ints2_const.rs
index a61e3329bdce8..788f49f743cda 100644
--- a/src/test/ui/unsafe/ranged_ints2_const.rs
+++ b/src/test/ui/unsafe/ranged_ints2_const.rs
@@ -1,4 +1,4 @@
-#![feature(rustc_attrs, const_let, const_fn)]
+#![feature(rustc_attrs)]
 
 #[rustc_layout_scalar_valid_range_start(1)]
 #[repr(transparent)]
@@ -8,13 +8,13 @@ fn main() {
 
 const fn foo() -> NonZero<u32> {
     let mut x = unsafe { NonZero(1) };
-    let y = &mut x.0; //~ ERROR references in constant functions may only refer to immutable
+    let y = &mut x.0; //~ ERROR references in const fn are unstable
     //~^ ERROR mutation of layout constrained field is unsafe
     unsafe { NonZero(1) }
 }
 
 const fn bar() -> NonZero<u32> {
     let mut x = unsafe { NonZero(1) };
-    let y = unsafe { &mut x.0 }; //~ ERROR references in constant functions may only refer to immut
+    let y = unsafe { &mut x.0 }; //~ ERROR mutable references in const fn are unstable
     unsafe { NonZero(1) }
 }
diff --git a/src/test/ui/unsafe/ranged_ints2_const.stderr b/src/test/ui/unsafe/ranged_ints2_const.stderr
index f79792ffba9be..39a55190b17de 100644
--- a/src/test/ui/unsafe/ranged_ints2_const.stderr
+++ b/src/test/ui/unsafe/ranged_ints2_const.stderr
@@ -1,24 +1,23 @@
-error[E0017]: references in constant functions may only refer to immutable values
-  --> $DIR/ranged_ints2_const.rs:11:13
+error: mutable references in const fn are unstable
+  --> $DIR/ranged_ints2_const.rs:11:9
    |
-LL |     let y = &mut x.0; //~ ERROR references in constant functions may only refer to immutable
-   |             ^^^^^^^^ constant functions require immutable values
+LL |     let y = &mut x.0; //~ ERROR references in const fn are unstable
+   |         ^
 
-error[E0017]: references in constant functions may only refer to immutable values
-  --> $DIR/ranged_ints2_const.rs:18:22
+error: mutable references in const fn are unstable
+  --> $DIR/ranged_ints2_const.rs:18:9
    |
-LL |     let y = unsafe { &mut x.0 }; //~ ERROR references in constant functions may only refer to immut
-   |                      ^^^^^^^^ constant functions require immutable values
+LL |     let y = unsafe { &mut x.0 }; //~ ERROR mutable references in const fn are unstable
+   |         ^
 
 error[E0133]: mutation of layout constrained field is unsafe and requires unsafe function or block
   --> $DIR/ranged_ints2_const.rs:11:13
    |
-LL |     let y = &mut x.0; //~ ERROR references in constant functions may only refer to immutable
+LL |     let y = &mut x.0; //~ ERROR references in const fn are unstable
    |             ^^^^^^^^ mutation of layout constrained field
    |
    = note: mutating layout constrained fields cannot statically be checked for valid values
 
 error: aborting due to 3 previous errors
 
-Some errors occurred: E0017, E0133.
-For more information about an error, try `rustc --explain E0017`.
+For more information about this error, try `rustc --explain E0133`.
diff --git a/src/test/ui/unsafe/ranged_ints3_const.rs b/src/test/ui/unsafe/ranged_ints3_const.rs
index 6497b611224b6..7b03d8eda9380 100644
--- a/src/test/ui/unsafe/ranged_ints3_const.rs
+++ b/src/test/ui/unsafe/ranged_ints3_const.rs
@@ -1,4 +1,4 @@
-#![feature(rustc_attrs, const_let, const_fn)]
+#![feature(rustc_attrs)]
 
 use std::cell::Cell;
 
diff --git a/src/test/ui/unsafe/ranged_ints4_const.rs b/src/test/ui/unsafe/ranged_ints4_const.rs
index f589e4739baf1..f09168c3d3f9c 100644
--- a/src/test/ui/unsafe/ranged_ints4_const.rs
+++ b/src/test/ui/unsafe/ranged_ints4_const.rs
@@ -1,4 +1,4 @@
-#![feature(rustc_attrs, const_let, const_fn)]
+#![feature(rustc_attrs)]
 
 #[rustc_layout_scalar_valid_range_start(1)]
 #[repr(transparent)]
diff --git a/src/test/ui/write-to-static-mut-in-static.rs b/src/test/ui/write-to-static-mut-in-static.rs
index 3c34a7704e0df..43c63fed8cef1 100644
--- a/src/test/ui/write-to-static-mut-in-static.rs
+++ b/src/test/ui/write-to-static-mut-in-static.rs
@@ -1,5 +1,3 @@
-#![feature(const_let)]
-
 pub static mut A: u32 = 0;
 pub static mut B: () = unsafe { A = 1; };
 //~^ ERROR could not evaluate static initializer
diff --git a/src/test/ui/write-to-static-mut-in-static.stderr b/src/test/ui/write-to-static-mut-in-static.stderr
index 7be83b8dafcfd..eba1c609d2f83 100644
--- a/src/test/ui/write-to-static-mut-in-static.stderr
+++ b/src/test/ui/write-to-static-mut-in-static.stderr
@@ -1,23 +1,23 @@
 error[E0080]: could not evaluate static initializer
-  --> $DIR/write-to-static-mut-in-static.rs:4:33
+  --> $DIR/write-to-static-mut-in-static.rs:2:33
    |
 LL | pub static mut B: () = unsafe { A = 1; };
    |                                 ^^^^^ tried to modify a static's initial value from another static's initializer
 
 error[E0391]: cycle detected when const-evaluating `C`
-  --> $DIR/write-to-static-mut-in-static.rs:7:34
+  --> $DIR/write-to-static-mut-in-static.rs:5:34
    |
 LL | pub static mut C: u32 = unsafe { C = 1; 0 };
    |                                  ^^^^^
    |
 note: ...which requires const-evaluating `C`...
-  --> $DIR/write-to-static-mut-in-static.rs:7:1
+  --> $DIR/write-to-static-mut-in-static.rs:5:1
    |
 LL | pub static mut C: u32 = unsafe { C = 1; 0 };
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    = note: ...which again requires const-evaluating `C`, completing the cycle
 note: cycle used when const-evaluating + checking `C`
-  --> $DIR/write-to-static-mut-in-static.rs:7:1
+  --> $DIR/write-to-static-mut-in-static.rs:5:1
    |
 LL | pub static mut C: u32 = unsafe { C = 1; 0 };
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^