diff --git a/core/src/lib.rs b/core/src/lib.rs
index 50e9884fea1b4..bda3825436273 100644
--- a/core/src/lib.rs
+++ b/core/src/lib.rs
@@ -121,7 +121,6 @@
 #![feature(const_cell_into_inner)]
 #![feature(const_eval_select)]
 #![feature(const_exact_div)]
-#![feature(const_float_bits_conv)]
 #![feature(const_float_classify)]
 #![feature(const_fmt_arguments_new)]
 #![feature(const_hash)]
@@ -165,6 +164,8 @@
 #![feature(coverage_attribute)]
 #![feature(do_not_recommend)]
 #![feature(duration_consts_float)]
+#![feature(f128_const)]
+#![feature(f16_const)]
 #![feature(internal_impls_macro)]
 #![feature(ip)]
 #![feature(is_ascii_octdigit)]
diff --git a/core/src/num/f128.rs b/core/src/num/f128.rs
index d4236e47bfe3b..1959628bd8f59 100644
--- a/core/src/num/f128.rs
+++ b/core/src/num/f128.rs
@@ -914,7 +914,7 @@ impl f128 {
     /// ```
     #[inline]
     #[unstable(feature = "f128", issue = "116909")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_unstable(feature = "f128_const", issue = "116909")]
     #[must_use = "this returns the result of the operation, without modifying the original"]
     pub const fn to_bits(self) -> u128 {
         // SAFETY: `u128` is a plain old datatype so we can always transmute to it.
@@ -963,7 +963,7 @@ impl f128 {
     #[inline]
     #[must_use]
     #[unstable(feature = "f128", issue = "116909")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_unstable(feature = "f128_const", issue = "116909")]
     pub const fn from_bits(v: u128) -> Self {
         // It turns out the safety issues with sNaN were overblown! Hooray!
         // SAFETY: `u128` is a plain old datatype so we can always transmute from it.
@@ -990,7 +990,7 @@ impl f128 {
     /// ```
     #[inline]
     #[unstable(feature = "f128", issue = "116909")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_unstable(feature = "f128_const", issue = "116909")]
     #[must_use = "this returns the result of the operation, without modifying the original"]
     pub const fn to_be_bytes(self) -> [u8; 16] {
         self.to_bits().to_be_bytes()
@@ -1016,7 +1016,7 @@ impl f128 {
     /// ```
     #[inline]
     #[unstable(feature = "f128", issue = "116909")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_unstable(feature = "f128_const", issue = "116909")]
     #[must_use = "this returns the result of the operation, without modifying the original"]
     pub const fn to_le_bytes(self) -> [u8; 16] {
         self.to_bits().to_le_bytes()
@@ -1053,7 +1053,7 @@ impl f128 {
     /// ```
     #[inline]
     #[unstable(feature = "f128", issue = "116909")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_unstable(feature = "f128_const", issue = "116909")]
     #[must_use = "this returns the result of the operation, without modifying the original"]
     pub const fn to_ne_bytes(self) -> [u8; 16] {
         self.to_bits().to_ne_bytes()
@@ -1081,7 +1081,7 @@ impl f128 {
     #[inline]
     #[must_use]
     #[unstable(feature = "f128", issue = "116909")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_unstable(feature = "f128_const", issue = "116909")]
     pub const fn from_be_bytes(bytes: [u8; 16]) -> Self {
         Self::from_bits(u128::from_be_bytes(bytes))
     }
@@ -1108,7 +1108,7 @@ impl f128 {
     #[inline]
     #[must_use]
     #[unstable(feature = "f128", issue = "116909")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_unstable(feature = "f128_const", issue = "116909")]
     pub const fn from_le_bytes(bytes: [u8; 16]) -> Self {
         Self::from_bits(u128::from_le_bytes(bytes))
     }
@@ -1145,7 +1145,7 @@ impl f128 {
     #[inline]
     #[must_use]
     #[unstable(feature = "f128", issue = "116909")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_unstable(feature = "f128_const", issue = "116909")]
     pub const fn from_ne_bytes(bytes: [u8; 16]) -> Self {
         Self::from_bits(u128::from_ne_bytes(bytes))
     }
diff --git a/core/src/num/f16.rs b/core/src/num/f16.rs
index 1e2f841aca733..9252e8c601558 100644
--- a/core/src/num/f16.rs
+++ b/core/src/num/f16.rs
@@ -925,7 +925,7 @@ impl f16 {
     /// ```
     #[inline]
     #[unstable(feature = "f16", issue = "116909")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_unstable(feature = "f16_const", issue = "116909")]
     #[must_use = "this returns the result of the operation, without modifying the original"]
     pub const fn to_bits(self) -> u16 {
         // SAFETY: `u16` is a plain old datatype so we can always transmute to it.
@@ -973,7 +973,7 @@ impl f16 {
     #[inline]
     #[must_use]
     #[unstable(feature = "f16", issue = "116909")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_unstable(feature = "f16_const", issue = "116909")]
     pub const fn from_bits(v: u16) -> Self {
         // It turns out the safety issues with sNaN were overblown! Hooray!
         // SAFETY: `u16` is a plain old datatype so we can always transmute from it.
@@ -999,7 +999,7 @@ impl f16 {
     /// ```
     #[inline]
     #[unstable(feature = "f16", issue = "116909")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_unstable(feature = "f16_const", issue = "116909")]
     #[must_use = "this returns the result of the operation, without modifying the original"]
     pub const fn to_be_bytes(self) -> [u8; 2] {
         self.to_bits().to_be_bytes()
@@ -1024,7 +1024,7 @@ impl f16 {
     /// ```
     #[inline]
     #[unstable(feature = "f16", issue = "116909")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_unstable(feature = "f16_const", issue = "116909")]
     #[must_use = "this returns the result of the operation, without modifying the original"]
     pub const fn to_le_bytes(self) -> [u8; 2] {
         self.to_bits().to_le_bytes()
@@ -1062,7 +1062,7 @@ impl f16 {
     /// ```
     #[inline]
     #[unstable(feature = "f16", issue = "116909")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_unstable(feature = "f16_const", issue = "116909")]
     #[must_use = "this returns the result of the operation, without modifying the original"]
     pub const fn to_ne_bytes(self) -> [u8; 2] {
         self.to_bits().to_ne_bytes()
@@ -1086,7 +1086,7 @@ impl f16 {
     #[inline]
     #[must_use]
     #[unstable(feature = "f16", issue = "116909")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_unstable(feature = "f16_const", issue = "116909")]
     pub const fn from_be_bytes(bytes: [u8; 2]) -> Self {
         Self::from_bits(u16::from_be_bytes(bytes))
     }
@@ -1109,7 +1109,7 @@ impl f16 {
     #[inline]
     #[must_use]
     #[unstable(feature = "f16", issue = "116909")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_unstable(feature = "f16_const", issue = "116909")]
     pub const fn from_le_bytes(bytes: [u8; 2]) -> Self {
         Self::from_bits(u16::from_le_bytes(bytes))
     }
@@ -1143,7 +1143,7 @@ impl f16 {
     #[inline]
     #[must_use]
     #[unstable(feature = "f16", issue = "116909")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_unstable(feature = "f16_const", issue = "116909")]
     pub const fn from_ne_bytes(bytes: [u8; 2]) -> Self {
         Self::from_bits(u16::from_ne_bytes(bytes))
     }
diff --git a/core/src/num/f32.rs b/core/src/num/f32.rs
index c1adcc753f2e5..2bc897224970d 100644
--- a/core/src/num/f32.rs
+++ b/core/src/num/f32.rs
@@ -1115,7 +1115,7 @@ impl f32 {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[stable(feature = "float_bits_conv", since = "1.20.0")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub const fn to_bits(self) -> u32 {
         // SAFETY: `u32` is a plain old datatype so we can always transmute to it.
@@ -1159,7 +1159,7 @@ impl f32 {
     /// assert_eq!(v, 12.5);
     /// ```
     #[stable(feature = "float_bits_conv", since = "1.20.0")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     #[inline]
     pub const fn from_bits(v: u32) -> Self {
@@ -1183,7 +1183,7 @@ impl f32 {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub const fn to_be_bytes(self) -> [u8; 4] {
         self.to_bits().to_be_bytes()
@@ -1204,7 +1204,7 @@ impl f32 {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub const fn to_le_bytes(self) -> [u8; 4] {
         self.to_bits().to_le_bytes()
@@ -1238,7 +1238,7 @@ impl f32 {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub const fn to_ne_bytes(self) -> [u8; 4] {
         self.to_bits().to_ne_bytes()
@@ -1256,7 +1256,7 @@ impl f32 {
     /// assert_eq!(value, 12.5);
     /// ```
     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     #[inline]
     pub const fn from_be_bytes(bytes: [u8; 4]) -> Self {
@@ -1275,7 +1275,7 @@ impl f32 {
     /// assert_eq!(value, 12.5);
     /// ```
     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     #[inline]
     pub const fn from_le_bytes(bytes: [u8; 4]) -> Self {
@@ -1305,7 +1305,7 @@ impl f32 {
     /// assert_eq!(value, 12.5);
     /// ```
     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     #[inline]
     pub const fn from_ne_bytes(bytes: [u8; 4]) -> Self {
diff --git a/core/src/num/f64.rs b/core/src/num/f64.rs
index e6406771ad333..b3f5be9fc8a46 100644
--- a/core/src/num/f64.rs
+++ b/core/src/num/f64.rs
@@ -1111,7 +1111,7 @@ impl f64 {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[stable(feature = "float_bits_conv", since = "1.20.0")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub const fn to_bits(self) -> u64 {
         // SAFETY: `u64` is a plain old datatype so we can always transmute to it.
@@ -1155,7 +1155,7 @@ impl f64 {
     /// assert_eq!(v, 12.5);
     /// ```
     #[stable(feature = "float_bits_conv", since = "1.20.0")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     #[inline]
     pub const fn from_bits(v: u64) -> Self {
@@ -1179,7 +1179,7 @@ impl f64 {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub const fn to_be_bytes(self) -> [u8; 8] {
         self.to_bits().to_be_bytes()
@@ -1200,7 +1200,7 @@ impl f64 {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub const fn to_le_bytes(self) -> [u8; 8] {
         self.to_bits().to_le_bytes()
@@ -1234,7 +1234,7 @@ impl f64 {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub const fn to_ne_bytes(self) -> [u8; 8] {
         self.to_bits().to_ne_bytes()
@@ -1252,7 +1252,7 @@ impl f64 {
     /// assert_eq!(value, 12.5);
     /// ```
     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     #[inline]
     pub const fn from_be_bytes(bytes: [u8; 8]) -> Self {
@@ -1271,7 +1271,7 @@ impl f64 {
     /// assert_eq!(value, 12.5);
     /// ```
     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     #[inline]
     pub const fn from_le_bytes(bytes: [u8; 8]) -> Self {
@@ -1301,7 +1301,7 @@ impl f64 {
     /// assert_eq!(value, 12.5);
     /// ```
     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
-    #[rustc_const_unstable(feature = "const_float_bits_conv", issue = "72447")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     #[inline]
     pub const fn from_ne_bytes(bytes: [u8; 8]) -> Self {
diff --git a/core/src/str/mod.rs b/core/src/str/mod.rs
index cf9f1bfc0eb72..e947686487e06 100644
--- a/core/src/str/mod.rs
+++ b/core/src/str/mod.rs
@@ -338,9 +338,10 @@ impl str {
     /// assert_eq!("🍔∈🌏", s);
     /// ```
     #[stable(feature = "str_mut_extras", since = "1.20.0")]
+    #[rustc_const_unstable(feature = "const_str_as_mut", issue = "130086")]
     #[must_use]
     #[inline(always)]
-    pub unsafe fn as_bytes_mut(&mut self) -> &mut [u8] {
+    pub const unsafe fn as_bytes_mut(&mut self) -> &mut [u8] {
         // SAFETY: the cast from `&str` to `&[u8]` is safe since `str`
         // has the same layout as `&[u8]` (only std can make this guarantee).
         // The pointer dereference is safe since it comes from a mutable reference which
@@ -383,10 +384,11 @@ impl str {
     /// It is your responsibility to make sure that the string slice only gets
     /// modified in a way that it remains valid UTF-8.
     #[stable(feature = "str_as_mut_ptr", since = "1.36.0")]
+    #[rustc_const_unstable(feature = "const_str_as_mut", issue = "130086")]
     #[rustc_never_returns_null_ptr]
     #[must_use]
     #[inline(always)]
-    pub fn as_mut_ptr(&mut self) -> *mut u8 {
+    pub const fn as_mut_ptr(&mut self) -> *mut u8 {
         self as *mut str as *mut u8
     }
 
diff --git a/windows_targets/src/lib.rs b/windows_targets/src/lib.rs
index 1965b6cf4ce8f..395cd6a4bab55 100644
--- a/windows_targets/src/lib.rs
+++ b/windows_targets/src/lib.rs
@@ -38,4 +38,5 @@ pub macro link {
 #[link(name = "ntdll")]
 #[link(name = "userenv")]
 #[link(name = "ws2_32")]
+#[link(name = "dbghelp")] // required for backtrace-rs symbolization
 extern "C" {}