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-rw-r--r--library/Cargo.lock2
-rw-r--r--library/core/src/fmt/num.rs331
-rw-r--r--library/core/src/lib.rs7
-rw-r--r--library/core/src/net/ip_addr.rs12
-rw-r--r--library/core/src/num/dec2flt/mod.rs2
-rw-r--r--library/core/src/option.rs12
-rw-r--r--library/core/src/prelude/v1.rs7
-rw-r--r--library/core/src/unicode/mod.rs4
-rw-r--r--library/coretests/benches/fmt.rs180
-rw-r--r--library/coretests/tests/lib.rs1
-rw-r--r--library/std/Cargo.toml1
-rw-r--r--library/std/src/ffi/os_str.rs2
-rw-r--r--library/std/src/fs.rs21
-rw-r--r--library/std/src/io/buffered/bufreader/buffer.rs2
-rw-r--r--library/std/src/io/copy.rs7
-rw-r--r--library/std/src/lib.rs9
-rw-r--r--library/std/src/os/unix/net/stream.rs10
-rw-r--r--library/std/src/os/unix/process.rs12
-rw-r--r--library/std/src/path.rs67
-rw-r--r--library/std/src/sync/nonpoison/mutex.rs2
-rw-r--r--library/std/src/sync/poison/mutex.rs2
-rw-r--r--library/std/src/sync/reentrant_lock.rs9
-rw-r--r--library/std/src/sys/alloc/mod.rs30
-rw-r--r--library/std/src/sys/alloc/unix.rs10
-rw-r--r--library/std/src/sys/anonymous_pipe/mod.rs10
-rw-r--r--library/std/src/sys/args/mod.rs27
-rw-r--r--library/std/src/sys/cmath.rs111
-rw-r--r--library/std/src/sys/env/mod.rs31
-rw-r--r--library/std/src/sys/env/wasi.rs7
-rw-r--r--library/std/src/sys/exit_guard.rs7
-rw-r--r--library/std/src/sys/fd/mod.rs14
-rw-r--r--library/std/src/sys/fs/mod.rs37
-rw-r--r--library/std/src/sys/fs/unix.rs44
-rw-r--r--library/std/src/sys/io/mod.rs29
-rw-r--r--library/std/src/sys/mod.rs2
-rw-r--r--library/std/src/sys/net/connection/socket.rs56
-rw-r--r--library/std/src/sys/net/connection/socket/unix.rs34
-rw-r--r--library/std/src/sys/net/mod.rs21
-rw-r--r--library/std/src/sys/os_str/mod.rs10
-rw-r--r--library/std/src/sys/pal/mod.rs54
-rw-r--r--library/std/src/sys/pal/uefi/time.rs13
-rw-r--r--library/std/src/sys/pal/unix/futex.rs10
-rw-r--r--library/std/src/sys/pal/unix/mod.rs32
-rw-r--r--library/std/src/sys/pal/unix/os.rs23
-rw-r--r--library/std/src/sys/pal/unix/pipe.rs9
-rw-r--r--library/std/src/sys/pal/unix/thread.rs68
-rw-r--r--library/std/src/sys/pal/wasi/thread.rs28
-rw-r--r--library/std/src/sys/pal/wasm/mod.rs7
-rw-r--r--library/std/src/sys/pal/windows/c.rs12
-rw-r--r--library/std/src/sys/pal/windows/mod.rs20
-rw-r--r--library/std/src/sys/path/mod.rs19
-rw-r--r--library/std/src/sys/personality/gcc.rs22
-rw-r--r--library/std/src/sys/personality/mod.rs15
-rw-r--r--library/std/src/sys/process/mod.rs13
-rw-r--r--library/std/src/sys/process/unix/common.rs17
-rw-r--r--library/std/src/sys/process/unix/mod.rs13
-rw-r--r--library/std/src/sys/process/unix/unix.rs19
-rw-r--r--library/std/src/sys/random/mod.rs68
-rw-r--r--library/std/src/sys/random/uefi.rs7
-rw-r--r--library/std/src/sys/stdio/mod.rs37
-rw-r--r--library/std/src/sys/sync/condvar/mod.rs26
-rw-r--r--library/std/src/sys/sync/mutex/mod.rs29
-rw-r--r--library/std/src/sys/sync/once/mod.rs14
-rw-r--r--library/std/src/sys/sync/rwlock/mod.rs20
-rw-r--r--library/std/src/sys/sync/thread_parking/mod.rs26
-rw-r--r--library/std/src/sys/thread_local/mod.rs60
-rw-r--r--library/std/src/thread/current.rs13
-rw-r--r--library/std/src/thread/mod.rs14
-rw-r--r--library/std/tests/env_modify.rs9
-rw-r--r--library/std_detect/Cargo.toml1
-rw-r--r--library/std_detect/src/detect/arch/loongarch.rs3
-rw-r--r--library/std_detect/src/detect/arch/mod.rs36
-rw-r--r--library/std_detect/src/detect/cache.rs14
-rw-r--r--library/std_detect/src/detect/mod.rs36
-rw-r--r--library/std_detect/src/detect/os/freebsd/mod.rs13
-rw-r--r--library/std_detect/src/detect/os/linux/auxvec.rs9
-rw-r--r--library/std_detect/src/detect/os/linux/auxvec/tests.rs8
-rw-r--r--library/std_detect/src/detect/os/linux/loongarch.rs13
-rw-r--r--library/std_detect/src/detect/os/linux/mod.rs25
-rw-r--r--library/std_detect/src/lib.rs2
-rw-r--r--library/std_detect/tests/macro_trailing_commas.rs2
-rw-r--r--library/unwind/Cargo.toml1
-rw-r--r--library/unwind/src/lib.rs61
-rw-r--r--library/unwind/src/libunwind.rs353
-rw-r--r--library/unwind/src/wasm.rs7
85 files changed, 1473 insertions, 1010 deletions
diff --git a/library/Cargo.lock b/library/Cargo.lock
index 4b06f14c7ee..656576d2d8e 100644
--- a/library/Cargo.lock
+++ b/library/Cargo.lock
@@ -337,7 +337,6 @@ name = "std_detect"
 version = "0.1.5"
 dependencies = [
  "alloc",
- "cfg-if",
  "core",
  "libc",
 ]
@@ -376,7 +375,6 @@ dependencies = [
 name = "unwind"
 version = "0.0.0"
 dependencies = [
- "cfg-if",
  "libc",
  "rustc-std-workspace-core",
  "unwinding",
diff --git a/library/core/src/fmt/num.rs b/library/core/src/fmt/num.rs
index 7d41ae45093..605ba42c541 100644
--- a/library/core/src/fmt/num.rs
+++ b/library/core/src/fmt/num.rs
@@ -3,164 +3,78 @@
 use crate::fmt::NumBuffer;
 use crate::mem::MaybeUninit;
 use crate::num::fmt as numfmt;
-use crate::ops::{Div, Rem, Sub};
 use crate::{fmt, ptr, slice, str};
 
-#[doc(hidden)]
-trait DisplayInt:
-    PartialEq + PartialOrd + Div<Output = Self> + Rem<Output = Self> + Sub<Output = Self> + Copy
-{
-    fn zero() -> Self;
-    fn from_u8(u: u8) -> Self;
-    fn to_u8(&self) -> u8;
-    #[cfg(not(any(target_pointer_width = "64", target_arch = "wasm32")))]
-    fn to_u32(&self) -> u32;
-    fn to_u64(&self) -> u64;
-    fn to_u128(&self) -> u128;
-}
+/// Formatting of integers with a non-decimal radix.
+macro_rules! radix_integer {
+    (fmt::$Trait:ident for $Signed:ident and $Unsigned:ident, $prefix:literal, $dig_tab:literal) => {
+        #[stable(feature = "rust1", since = "1.0.0")]
+        impl fmt::$Trait for $Unsigned {
+            /// Format unsigned integers in the radix.
+            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+                // Check macro arguments at compile time.
+                const {
+                    assert!($Unsigned::MIN == 0, "need unsigned");
+                    assert!($dig_tab.is_ascii(), "need single-byte entries");
+                }
 
-macro_rules! impl_int {
-    ($($t:ident)*) => (
-        $(impl DisplayInt for $t {
-            fn zero() -> Self { 0 }
-            fn from_u8(u: u8) -> Self { u as Self }
-            fn to_u8(&self) -> u8 { *self as u8 }
-            #[cfg(not(any(target_pointer_width = "64", target_arch = "wasm32")))]
-            fn to_u32(&self) -> u32 { *self as u32 }
-            fn to_u64(&self) -> u64 { *self as u64 }
-            fn to_u128(&self) -> u128 { *self as u128 }
-        })*
-    )
-}
+                // ASCII digits in ascending order are used as a lookup table.
+                const DIG_TAB: &[u8] = $dig_tab;
+                const BASE: $Unsigned = DIG_TAB.len() as $Unsigned;
+                const MAX_DIG_N: usize = $Unsigned::MAX.ilog(BASE) as usize + 1;
 
-impl_int! {
-    i8 i16 i32 i64 i128 isize
-    u8 u16 u32 u64 u128 usize
-}
+                // Buffer digits of self with right alignment.
+                let mut buf = [MaybeUninit::<u8>::uninit(); MAX_DIG_N];
+                // Count the number of bytes in buf that are not initialized.
+                let mut offset = buf.len();
 
-/// A type that represents a specific radix
-///
-/// # Safety
-///
-/// `digit` must return an ASCII character.
-#[doc(hidden)]
-unsafe trait GenericRadix: Sized {
-    /// The number of digits.
-    const BASE: u8;
-
-    /// A radix-specific prefix string.
-    const PREFIX: &'static str;
-
-    /// Converts an integer to corresponding radix digit.
-    fn digit(x: u8) -> u8;
-
-    /// Format an integer using the radix using a formatter.
-    fn fmt_int<T: DisplayInt>(&self, mut x: T, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        // The radix can be as low as 2, so we need a buffer of at least 128
-        // characters for a base 2 number.
-        let zero = T::zero();
-        let is_nonnegative = x >= zero;
-        let mut buf = [MaybeUninit::<u8>::uninit(); 128];
-        let mut offset = buf.len();
-        let base = T::from_u8(Self::BASE);
-        if is_nonnegative {
-            // Accumulate each digit of the number from the least significant
-            // to the most significant figure.
-            loop {
-                let n = x % base; // Get the current place value.
-                x = x / base; // Deaccumulate the number.
-                offset -= 1;
-                buf[offset].write(Self::digit(n.to_u8())); // Store the digit in the buffer.
-                if x == zero {
-                    // No more digits left to accumulate.
-                    break;
-                };
-            }
-        } else {
-            // Do the same as above, but accounting for two's complement.
-            loop {
-                let n = zero - (x % base); // Get the current place value.
-                x = x / base; // Deaccumulate the number.
-                offset -= 1;
-                buf[offset].write(Self::digit(n.to_u8())); // Store the digit in the buffer.
-                if x == zero {
-                    // No more digits left to accumulate.
-                    break;
-                };
-            }
-        }
-        // SAFETY: Starting from `offset`, all elements of the slice have been set.
-        let buf_slice = unsafe { slice_buffer_to_str(&buf, offset) };
-        f.pad_integral(is_nonnegative, Self::PREFIX, buf_slice)
-    }
-}
+                // Accumulate each digit of the number from the least
+                // significant to the most significant figure.
+                let mut remain = *self;
+                loop {
+                    let digit = remain % BASE;
+                    remain /= BASE;
 
-/// A binary (base 2) radix
-#[derive(Clone, PartialEq)]
-struct Binary;
-
-/// An octal (base 8) radix
-#[derive(Clone, PartialEq)]
-struct Octal;
-
-/// A hexadecimal (base 16) radix, formatted with lower-case characters
-#[derive(Clone, PartialEq)]
-struct LowerHex;
-
-/// A hexadecimal (base 16) radix, formatted with upper-case characters
-#[derive(Clone, PartialEq)]
-struct UpperHex;
-
-macro_rules! radix {
-    ($T:ident, $base:expr, $prefix:expr, $($x:pat => $conv:expr),+) => {
-        unsafe impl GenericRadix for $T {
-            const BASE: u8 = $base;
-            const PREFIX: &'static str = $prefix;
-            fn digit(x: u8) -> u8 {
-                match x {
-                    $($x => $conv,)+
-                    x => panic!("number not in the range 0..={}: {}", Self::BASE - 1, x),
+                    offset -= 1;
+                    // SAFETY: `remain` will reach 0 and we will break before `offset` wraps
+                    unsafe { core::hint::assert_unchecked(offset < buf.len()) }
+                    buf[offset].write(DIG_TAB[digit as usize]);
+                    if remain == 0 {
+                        break;
+                    }
                 }
+
+                // SAFETY: Starting from `offset`, all elements of the slice have been set.
+                let digits = unsafe { slice_buffer_to_str(&buf, offset) };
+                f.pad_integral(true, $prefix, digits)
             }
         }
-    }
-}
 
-radix! { Binary,    2, "0b", x @  0 ..=  1 => b'0' + x }
-radix! { Octal,     8, "0o", x @  0 ..=  7 => b'0' + x }
-radix! { LowerHex, 16, "0x", x @  0 ..=  9 => b'0' + x, x @ 10 ..= 15 => b'a' + (x - 10) }
-radix! { UpperHex, 16, "0x", x @  0 ..=  9 => b'0' + x, x @ 10 ..= 15 => b'A' + (x - 10) }
-
-macro_rules! int_base {
-    (fmt::$Trait:ident for $T:ident as $U:ident -> $Radix:ident) => {
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl fmt::$Trait for $T {
+        impl fmt::$Trait for $Signed {
+            /// Format signed integers in the two’s-complement form.
             fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-                $Radix.fmt_int(*self as $U, f)
+                fmt::$Trait::fmt(&self.cast_unsigned(), f)
             }
         }
     };
 }
 
-macro_rules! integer {
-    ($Int:ident, $Uint:ident) => {
-        int_base! { fmt::Binary   for $Int as $Uint  -> Binary }
-        int_base! { fmt::Octal    for $Int as $Uint  -> Octal }
-        int_base! { fmt::LowerHex for $Int as $Uint  -> LowerHex }
-        int_base! { fmt::UpperHex for $Int as $Uint  -> UpperHex }
-
-        int_base! { fmt::Binary   for $Uint as $Uint -> Binary }
-        int_base! { fmt::Octal    for $Uint as $Uint -> Octal }
-        int_base! { fmt::LowerHex for $Uint as $Uint -> LowerHex }
-        int_base! { fmt::UpperHex for $Uint as $Uint -> UpperHex }
+/// Formatting of integers with a non-decimal radix.
+macro_rules! radix_integers {
+    ($Signed:ident, $Unsigned:ident) => {
+        radix_integer! { fmt::Binary   for $Signed and $Unsigned, "0b", b"01" }
+        radix_integer! { fmt::Octal    for $Signed and $Unsigned, "0o", b"01234567" }
+        radix_integer! { fmt::LowerHex for $Signed and $Unsigned, "0x", b"0123456789abcdef" }
+        radix_integer! { fmt::UpperHex for $Signed and $Unsigned, "0x", b"0123456789ABCDEF" }
     };
 }
-integer! { isize, usize }
-integer! { i8, u8 }
-integer! { i16, u16 }
-integer! { i32, u32 }
-integer! { i64, u64 }
-integer! { i128, u128 }
+radix_integers! { isize, usize }
+radix_integers! { i8, u8 }
+radix_integers! { i16, u16 }
+radix_integers! { i32, u32 }
+radix_integers! { i64, u64 }
+radix_integers! { i128, u128 }
 
 macro_rules! impl_Debug {
     ($($T:ident)*) => {
@@ -205,16 +119,21 @@ unsafe fn slice_buffer_to_str(buf: &[MaybeUninit<u8>], offset: usize) -> &str {
 }
 
 macro_rules! impl_Display {
-    ($($signed:ident, $unsigned:ident,)* ; as $u:ident via $conv_fn:ident named $gen_name:ident) => {
+    ($($Signed:ident, $Unsigned:ident),* ; as $T:ident into $fmt_fn:ident) => {
 
         $(
+        const _: () = {
+            assert!($Signed::BITS <= $T::BITS, "need lossless conversion");
+            assert!($Unsigned::BITS <= $T::BITS, "need lossless conversion");
+        };
+
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl fmt::Display for $unsigned {
+        impl fmt::Display for $Unsigned {
             fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
                 #[cfg(not(feature = "optimize_for_size"))]
                 {
-                    const MAX_DEC_N: usize = $unsigned::MAX.ilog10() as usize + 1;
-                    // Buffer decimals for $unsigned with right alignment.
+                    const MAX_DEC_N: usize = $Unsigned::MAX.ilog10() as usize + 1;
+                    // Buffer decimals for self with right alignment.
                     let mut buf = [MaybeUninit::<u8>::uninit(); MAX_DEC_N];
 
                     // SAFETY: `buf` is always big enough to contain all the digits.
@@ -222,18 +141,20 @@ macro_rules! impl_Display {
                 }
                 #[cfg(feature = "optimize_for_size")]
                 {
-                    $gen_name(self.$conv_fn(), true, f)
+                    // Lossless conversion (with as) is asserted at the top of
+                    // this macro.
+                    ${concat($fmt_fn, _small)}(*self as $T, true, f)
                 }
             }
         }
 
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl fmt::Display for $signed {
+        impl fmt::Display for $Signed {
             fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
                 #[cfg(not(feature = "optimize_for_size"))]
                 {
-                    const MAX_DEC_N: usize = $unsigned::MAX.ilog10() as usize + 1;
-                    // Buffer decimals for $unsigned with right alignment.
+                    const MAX_DEC_N: usize = $Unsigned::MAX.ilog10() as usize + 1;
+                    // Buffer decimals for self with right alignment.
                     let mut buf = [MaybeUninit::<u8>::uninit(); MAX_DEC_N];
 
                     // SAFETY: `buf` is always big enough to contain all the digits.
@@ -241,13 +162,15 @@ macro_rules! impl_Display {
                 }
                 #[cfg(feature = "optimize_for_size")]
                 {
-                    return $gen_name(self.unsigned_abs().$conv_fn(), *self >= 0, f);
+                    // Lossless conversion (with as) is asserted at the top of
+                    // this macro.
+                    return ${concat($fmt_fn, _small)}(self.unsigned_abs() as $T, *self >= 0, f);
                 }
             }
         }
 
         #[cfg(not(feature = "optimize_for_size"))]
-        impl $unsigned {
+        impl $Unsigned {
             #[doc(hidden)]
             #[unstable(
                 feature = "fmt_internals",
@@ -268,7 +191,7 @@ macro_rules! impl_Display {
                 let mut remain = self;
 
                 // Format per four digits from the lookup table.
-                // Four digits need a 16-bit $unsigned or wider.
+                // Four digits need a 16-bit $Unsigned or wider.
                 while size_of::<Self>() > 1 && remain > 999.try_into().expect("branch is not hit for types that cannot fit 999 (u8)") {
                     // SAFETY: All of the decimals fit in buf due to MAX_DEC_N
                     // and the while condition ensures at least 4 more decimals.
@@ -327,7 +250,7 @@ macro_rules! impl_Display {
             }
         }
 
-        impl $signed {
+        impl $Signed {
             /// Allows users to write an integer (in signed decimal format) into a variable `buf` of
             /// type [`NumBuffer`] that is passed by the caller by mutable reference.
             ///
@@ -337,15 +260,15 @@ macro_rules! impl_Display {
             /// #![feature(int_format_into)]
             /// use core::fmt::NumBuffer;
             ///
-            #[doc = concat!("let n = 0", stringify!($signed), ";")]
+            #[doc = concat!("let n = 0", stringify!($Signed), ";")]
             /// let mut buf = NumBuffer::new();
             /// assert_eq!(n.format_into(&mut buf), "0");
             ///
-            #[doc = concat!("let n1 = 32", stringify!($signed), ";")]
+            #[doc = concat!("let n1 = 32", stringify!($Signed), ";")]
             /// assert_eq!(n1.format_into(&mut buf), "32");
             ///
-            #[doc = concat!("let n2 = ", stringify!($signed::MAX), ";")]
-            #[doc = concat!("assert_eq!(n2.format_into(&mut buf), ", stringify!($signed::MAX), ".to_string());")]
+            #[doc = concat!("let n2 = ", stringify!($Signed::MAX), ";")]
+            #[doc = concat!("assert_eq!(n2.format_into(&mut buf), ", stringify!($Signed::MAX), ".to_string());")]
             /// ```
             #[unstable(feature = "int_format_into", issue = "138215")]
             pub fn format_into(self, buf: &mut NumBuffer<Self>) -> &str {
@@ -358,7 +281,9 @@ macro_rules! impl_Display {
                 }
                 #[cfg(feature = "optimize_for_size")]
                 {
-                    offset = ${concat(_inner_slow_integer_to_str, $gen_name)}(self.unsigned_abs().$conv_fn(), &mut buf.buf);
+                    // Lossless conversion (with as) is asserted at the top of
+                    // this macro.
+                    offset = ${concat($fmt_fn, _in_buf_small)}(self.unsigned_abs() as $T, &mut buf.buf);
                 }
                 // Only difference between signed and unsigned are these 4 lines.
                 if self < 0 {
@@ -370,7 +295,7 @@ macro_rules! impl_Display {
             }
         }
 
-        impl $unsigned {
+        impl $Unsigned {
             /// Allows users to write an integer (in signed decimal format) into a variable `buf` of
             /// type [`NumBuffer`] that is passed by the caller by mutable reference.
             ///
@@ -380,15 +305,15 @@ macro_rules! impl_Display {
             /// #![feature(int_format_into)]
             /// use core::fmt::NumBuffer;
             ///
-            #[doc = concat!("let n = 0", stringify!($unsigned), ";")]
+            #[doc = concat!("let n = 0", stringify!($Unsigned), ";")]
             /// let mut buf = NumBuffer::new();
             /// assert_eq!(n.format_into(&mut buf), "0");
             ///
-            #[doc = concat!("let n1 = 32", stringify!($unsigned), ";")]
+            #[doc = concat!("let n1 = 32", stringify!($Unsigned), ";")]
             /// assert_eq!(n1.format_into(&mut buf), "32");
             ///
-            #[doc = concat!("let n2 = ", stringify!($unsigned::MAX), ";")]
-            #[doc = concat!("assert_eq!(n2.format_into(&mut buf), ", stringify!($unsigned::MAX), ".to_string());")]
+            #[doc = concat!("let n2 = ", stringify!($Unsigned::MAX), ";")]
+            #[doc = concat!("assert_eq!(n2.format_into(&mut buf), ", stringify!($Unsigned::MAX), ".to_string());")]
             /// ```
             #[unstable(feature = "int_format_into", issue = "138215")]
             pub fn format_into(self, buf: &mut NumBuffer<Self>) -> &str {
@@ -401,7 +326,9 @@ macro_rules! impl_Display {
                 }
                 #[cfg(feature = "optimize_for_size")]
                 {
-                    offset = ${concat(_inner_slow_integer_to_str, $gen_name)}(self.$conv_fn(), &mut buf.buf);
+                    // Lossless conversion (with as) is asserted at the top of
+                    // this macro.
+                    offset = ${concat($fmt_fn, _in_buf_small)}(self as $T, &mut buf.buf);
                 }
                 // SAFETY: Starting from `offset`, all elements of the slice have been set.
                 unsafe { slice_buffer_to_str(&buf.buf, offset) }
@@ -412,7 +339,7 @@ macro_rules! impl_Display {
         )*
 
         #[cfg(feature = "optimize_for_size")]
-        fn ${concat(_inner_slow_integer_to_str, $gen_name)}(mut n: $u, buf: &mut [MaybeUninit::<u8>]) -> usize {
+        fn ${concat($fmt_fn, _in_buf_small)}(mut n: $T, buf: &mut [MaybeUninit::<u8>]) -> usize {
             let mut curr = buf.len();
 
             // SAFETY: To show that it's OK to copy into `buf_ptr`, notice that at the beginning
@@ -433,11 +360,11 @@ macro_rules! impl_Display {
         }
 
         #[cfg(feature = "optimize_for_size")]
-        fn $gen_name(n: $u, is_nonnegative: bool, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-            const MAX_DEC_N: usize = $u::MAX.ilog(10) as usize + 1;
+        fn ${concat($fmt_fn, _small)}(n: $T, is_nonnegative: bool, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+            const MAX_DEC_N: usize = $T::MAX.ilog(10) as usize + 1;
             let mut buf = [MaybeUninit::<u8>::uninit(); MAX_DEC_N];
 
-            let offset = ${concat(_inner_slow_integer_to_str, $gen_name)}(n, &mut buf);
+            let offset = ${concat($fmt_fn, _in_buf_small)}(n, &mut buf);
             // SAFETY: Starting from `offset`, all elements of the slice have been set.
             let buf_slice = unsafe { slice_buffer_to_str(&buf, offset) };
             f.pad_integral(is_nonnegative, "", buf_slice)
@@ -446,9 +373,9 @@ macro_rules! impl_Display {
 }
 
 macro_rules! impl_Exp {
-    ($($t:ident),* as $u:ident via $conv_fn:ident named $name:ident) => {
-        fn $name(
-            mut n: $u,
+    ($($Signed:ident, $Unsigned:ident),* ; as $T:ident into $fmt_fn:ident) => {
+        fn $fmt_fn(
+            mut n: $T,
             is_nonnegative: bool,
             upper: bool,
             f: &mut fmt::Formatter<'_>
@@ -582,32 +509,41 @@ macro_rules! impl_Exp {
 
         $(
             #[stable(feature = "integer_exp_format", since = "1.42.0")]
-            impl fmt::LowerExp for $t {
-                #[allow(unused_comparisons)]
+            impl fmt::LowerExp for $Signed {
                 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
                     let is_nonnegative = *self >= 0;
                     let n = if is_nonnegative {
-                        self.$conv_fn()
+                        *self as $T
                     } else {
-                        // convert the negative num to positive by summing 1 to its 2s complement
-                        (!self.$conv_fn()).wrapping_add(1)
+                        self.unsigned_abs() as $T
                     };
-                    $name(n, is_nonnegative, false, f)
+                    $fmt_fn(n, is_nonnegative, false, f)
+                }
+            }
+            #[stable(feature = "integer_exp_format", since = "1.42.0")]
+            impl fmt::LowerExp for $Unsigned {
+                fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+                    $fmt_fn(*self as $T, true, false, f)
                 }
             })*
+
         $(
             #[stable(feature = "integer_exp_format", since = "1.42.0")]
-            impl fmt::UpperExp for $t {
-                #[allow(unused_comparisons)]
+            impl fmt::UpperExp for $Signed {
                 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
                     let is_nonnegative = *self >= 0;
                     let n = if is_nonnegative {
-                        self.$conv_fn()
+                        *self as $T
                     } else {
-                        // convert the negative num to positive by summing 1 to its 2s complement
-                        (!self.$conv_fn()).wrapping_add(1)
+                        self.unsigned_abs() as $T
                     };
-                    $name(n, is_nonnegative, true, f)
+                    $fmt_fn(n, is_nonnegative, true, f)
+                }
+            }
+            #[stable(feature = "integer_exp_format", since = "1.42.0")]
+            impl fmt::UpperExp for $Unsigned {
+                fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+                    $fmt_fn(*self as $T, true, true, f)
                 }
             })*
     };
@@ -623,37 +559,20 @@ impl_Debug! {
 #[cfg(any(target_pointer_width = "64", target_arch = "wasm32"))]
 mod imp {
     use super::*;
-    impl_Display!(
-        i8, u8,
-        i16, u16,
-        i32, u32,
-        i64, u64,
-        isize, usize,
-        ; as u64 via to_u64 named fmt_u64
-    );
-    impl_Exp!(
-        i8, u8, i16, u16, i32, u32, i64, u64, usize, isize
-            as u64 via to_u64 named exp_u64
-    );
+    impl_Display!(i8, u8, i16, u16, i32, u32, i64, u64, isize, usize; as u64 into display_u64);
+    impl_Exp!(i8, u8, i16, u16, i32, u32, i64, u64, isize, usize; as u64 into exp_u64);
 }
 
 #[cfg(not(any(target_pointer_width = "64", target_arch = "wasm32")))]
 mod imp {
     use super::*;
-    impl_Display!(
-        i8, u8,
-        i16, u16,
-        i32, u32,
-        isize, usize,
-        ; as u32 via to_u32 named fmt_u32);
-    impl_Display!(
-        i64, u64,
-        ; as u64 via to_u64 named fmt_u64);
-
-    impl_Exp!(i8, u8, i16, u16, i32, u32, isize, usize as u32 via to_u32 named exp_u32);
-    impl_Exp!(i64, u64 as u64 via to_u64 named exp_u64);
+    impl_Display!(i8, u8, i16, u16, i32, u32, isize, usize; as u32 into display_u32);
+    impl_Display!(i64, u64; as u64 into display_u64);
+
+    impl_Exp!(i8, u8, i16, u16, i32, u32, isize, usize; as u32 into exp_u32);
+    impl_Exp!(i64, u64; as u64 into exp_u64);
 }
-impl_Exp!(i128, u128 as u128 via to_u128 named exp_u128);
+impl_Exp!(i128, u128; as u128 into exp_u128);
 
 const U128_MAX_DEC_N: usize = u128::MAX.ilog10() as usize + 1;
 
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index 6396b8524f2..71abd707374 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -226,6 +226,13 @@ pub mod assert_matches {
     pub use crate::macros::{assert_matches, debug_assert_matches};
 }
 
+#[unstable(feature = "derive_from", issue = "144889")]
+/// Unstable module containing the unstable `From` derive macro.
+pub mod from {
+    #[unstable(feature = "derive_from", issue = "144889")]
+    pub use crate::macros::builtin::From;
+}
+
 // We don't export this through #[macro_export] for now, to avoid breakage.
 #[unstable(feature = "autodiff", issue = "124509")]
 /// Unstable module containing the unstable `autodiff` macro.
diff --git a/library/core/src/net/ip_addr.rs b/library/core/src/net/ip_addr.rs
index 87f2110034c..3bf113d017c 100644
--- a/library/core/src/net/ip_addr.rs
+++ b/library/core/src/net/ip_addr.rs
@@ -626,13 +626,13 @@ impl Ipv4Addr {
     /// # Examples
     ///
     /// ```
-    /// #![feature(ip_from)]
     /// use std::net::Ipv4Addr;
     ///
     /// let addr = Ipv4Addr::from_octets([13u8, 12u8, 11u8, 10u8]);
     /// assert_eq!(Ipv4Addr::new(13, 12, 11, 10), addr);
     /// ```
-    #[unstable(feature = "ip_from", issue = "131360")]
+    #[stable(feature = "ip_from", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "ip_from", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     #[inline]
     pub const fn from_octets(octets: [u8; 4]) -> Ipv4Addr {
@@ -1464,7 +1464,6 @@ impl Ipv6Addr {
     /// # Examples
     ///
     /// ```
-    /// #![feature(ip_from)]
     /// use std::net::Ipv6Addr;
     ///
     /// let addr = Ipv6Addr::from_segments([
@@ -1479,7 +1478,8 @@ impl Ipv6Addr {
     ///     addr
     /// );
     /// ```
-    #[unstable(feature = "ip_from", issue = "131360")]
+    #[stable(feature = "ip_from", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "ip_from", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     #[inline]
     pub const fn from_segments(segments: [u16; 8]) -> Ipv6Addr {
@@ -2029,7 +2029,6 @@ impl Ipv6Addr {
     /// # Examples
     ///
     /// ```
-    /// #![feature(ip_from)]
     /// use std::net::Ipv6Addr;
     ///
     /// let addr = Ipv6Addr::from_octets([
@@ -2044,7 +2043,8 @@ impl Ipv6Addr {
     ///     addr
     /// );
     /// ```
-    #[unstable(feature = "ip_from", issue = "131360")]
+    #[stable(feature = "ip_from", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "ip_from", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     #[inline]
     pub const fn from_octets(octets: [u8; 16]) -> Ipv6Addr {
diff --git a/library/core/src/num/dec2flt/mod.rs b/library/core/src/num/dec2flt/mod.rs
index 1844cd98082..3118a6e5ca6 100644
--- a/library/core/src/num/dec2flt/mod.rs
+++ b/library/core/src/num/dec2flt/mod.rs
@@ -124,6 +124,8 @@ macro_rules! from_str_float_impl {
             /// * '2.5E-10'
             /// * '5.'
             /// * '.5', or, equivalently, '0.5'
+            /// * '7'
+            /// * '007'
             /// * 'inf', '-inf', '+infinity', 'NaN'
             ///
             /// Note that alphabetical characters are not case-sensitive.
diff --git a/library/core/src/option.rs b/library/core/src/option.rs
index 560d20ce617..e83e77344cf 100644
--- a/library/core/src/option.rs
+++ b/library/core/src/option.rs
@@ -2095,9 +2095,9 @@ impl<T> Option<&mut T> {
 impl<T, E> Option<Result<T, E>> {
     /// Transposes an `Option` of a [`Result`] into a [`Result`] of an `Option`.
     ///
-    /// [`None`] will be mapped to <code>[Ok]\([None])</code>.
-    /// <code>[Some]\([Ok]\(\_))</code> and <code>[Some]\([Err]\(\_))</code> will be mapped to
-    /// <code>[Ok]\([Some]\(\_))</code> and <code>[Err]\(\_)</code>.
+    /// <code>[Some]\([Ok]\(\_))</code> is mapped to <code>[Ok]\([Some]\(\_))</code>,
+    /// <code>[Some]\([Err]\(\_))</code> is mapped to <code>[Err]\(\_)</code>,
+    /// and [`None`] will be mapped to <code>[Ok]\([None])</code>.
     ///
     /// # Examples
     ///
@@ -2105,9 +2105,9 @@ impl<T, E> Option<Result<T, E>> {
     /// #[derive(Debug, Eq, PartialEq)]
     /// struct SomeErr;
     ///
-    /// let x: Result<Option<i32>, SomeErr> = Ok(Some(5));
-    /// let y: Option<Result<i32, SomeErr>> = Some(Ok(5));
-    /// assert_eq!(x, y.transpose());
+    /// let x: Option<Result<i32, SomeErr>> = Some(Ok(5));
+    /// let y: Result<Option<i32>, SomeErr> = Ok(Some(5));
+    /// assert_eq!(x.transpose(), y);
     /// ```
     #[inline]
     #[stable(feature = "transpose_result", since = "1.33.0")]
diff --git a/library/core/src/prelude/v1.rs b/library/core/src/prelude/v1.rs
index d8d82afb0e6..a4be66b90ca 100644
--- a/library/core/src/prelude/v1.rs
+++ b/library/core/src/prelude/v1.rs
@@ -117,10 +117,3 @@ pub use crate::macros::builtin::deref;
     reason = "`type_alias_impl_trait` has open design concerns"
 )]
 pub use crate::macros::builtin::define_opaque;
-
-#[unstable(
-    feature = "derive_from",
-    issue = "144889",
-    reason = "`derive(From)` is unstable"
-)]
-pub use crate::macros::builtin::From;
diff --git a/library/core/src/unicode/mod.rs b/library/core/src/unicode/mod.rs
index 49dbdeb1a6d..191fe7711f9 100644
--- a/library/core/src/unicode/mod.rs
+++ b/library/core/src/unicode/mod.rs
@@ -1,5 +1,6 @@
+//! Unicode internals used in liballoc and libstd. Not public API.
 #![unstable(feature = "unicode_internals", issue = "none")]
-#![allow(missing_docs)]
+#![doc(hidden)]
 
 // for use in alloc, not re-exported in std.
 #[rustfmt::skip]
@@ -31,5 +32,4 @@ mod unicode_data;
 ///
 /// The version numbering scheme is explained in
 /// [Unicode 11.0 or later, Section 3.1 Versions of the Unicode Standard](https://www.unicode.org/versions/Unicode11.0.0/ch03.pdf#page=4).
-#[stable(feature = "unicode_version", since = "1.45.0")]
 pub const UNICODE_VERSION: (u8, u8, u8) = unicode_data::UNICODE_VERSION;
diff --git a/library/coretests/benches/fmt.rs b/library/coretests/benches/fmt.rs
index ee8e981b46b..f45b921b939 100644
--- a/library/coretests/benches/fmt.rs
+++ b/library/coretests/benches/fmt.rs
@@ -162,3 +162,183 @@ fn write_u8_min(bh: &mut Bencher) {
         black_box(format!("{}", black_box(u8::MIN)));
     });
 }
+
+#[bench]
+fn write_i8_bin(bh: &mut Bencher) {
+    let mut buf = String::with_capacity(256);
+    bh.iter(|| {
+        write!(black_box(&mut buf), "{:b}", black_box(0_i8)).unwrap();
+        write!(black_box(&mut buf), "{:b}", black_box(100_i8)).unwrap();
+        write!(black_box(&mut buf), "{:b}", black_box(-100_i8)).unwrap();
+        write!(black_box(&mut buf), "{:b}", black_box(1_i8 << 4)).unwrap();
+        black_box(&mut buf).clear();
+    });
+}
+
+#[bench]
+fn write_i16_bin(bh: &mut Bencher) {
+    let mut buf = String::with_capacity(256);
+    bh.iter(|| {
+        write!(black_box(&mut buf), "{:b}", black_box(0_i16)).unwrap();
+        write!(black_box(&mut buf), "{:b}", black_box(100_i16)).unwrap();
+        write!(black_box(&mut buf), "{:b}", black_box(-100_i16)).unwrap();
+        write!(black_box(&mut buf), "{:b}", black_box(1_i16 << 8)).unwrap();
+        black_box(&mut buf).clear();
+    });
+}
+
+#[bench]
+fn write_i32_bin(bh: &mut Bencher) {
+    let mut buf = String::with_capacity(256);
+    bh.iter(|| {
+        write!(black_box(&mut buf), "{:b}", black_box(0_i32)).unwrap();
+        write!(black_box(&mut buf), "{:b}", black_box(100_i32)).unwrap();
+        write!(black_box(&mut buf), "{:b}", black_box(-100_i32)).unwrap();
+        write!(black_box(&mut buf), "{:b}", black_box(1_i32 << 16)).unwrap();
+        black_box(&mut buf).clear();
+    });
+}
+
+#[bench]
+fn write_i64_bin(bh: &mut Bencher) {
+    let mut buf = String::with_capacity(256);
+    bh.iter(|| {
+        write!(black_box(&mut buf), "{:b}", black_box(0_i64)).unwrap();
+        write!(black_box(&mut buf), "{:b}", black_box(100_i64)).unwrap();
+        write!(black_box(&mut buf), "{:b}", black_box(-100_i64)).unwrap();
+        write!(black_box(&mut buf), "{:b}", black_box(1_i64 << 32)).unwrap();
+        black_box(&mut buf).clear();
+    });
+}
+
+#[bench]
+fn write_i128_bin(bh: &mut Bencher) {
+    let mut buf = String::with_capacity(256);
+    bh.iter(|| {
+        write!(black_box(&mut buf), "{:b}", black_box(0_i128)).unwrap();
+        write!(black_box(&mut buf), "{:b}", black_box(100_i128)).unwrap();
+        write!(black_box(&mut buf), "{:b}", black_box(-100_i128)).unwrap();
+        write!(black_box(&mut buf), "{:b}", black_box(1_i128 << 64)).unwrap();
+        black_box(&mut buf).clear();
+    });
+}
+
+#[bench]
+fn write_i8_oct(bh: &mut Bencher) {
+    let mut buf = String::with_capacity(256);
+    bh.iter(|| {
+        write!(black_box(&mut buf), "{:o}", black_box(0_i8)).unwrap();
+        write!(black_box(&mut buf), "{:o}", black_box(100_i8)).unwrap();
+        write!(black_box(&mut buf), "{:o}", black_box(-100_i8)).unwrap();
+        write!(black_box(&mut buf), "{:o}", black_box(1_i8 << 4)).unwrap();
+        black_box(&mut buf).clear();
+    });
+}
+
+#[bench]
+fn write_i16_oct(bh: &mut Bencher) {
+    let mut buf = String::with_capacity(256);
+    bh.iter(|| {
+        write!(black_box(&mut buf), "{:o}", black_box(0_i16)).unwrap();
+        write!(black_box(&mut buf), "{:o}", black_box(100_i16)).unwrap();
+        write!(black_box(&mut buf), "{:o}", black_box(-100_i16)).unwrap();
+        write!(black_box(&mut buf), "{:o}", black_box(1_i16 << 8)).unwrap();
+        black_box(&mut buf).clear();
+    });
+}
+
+#[bench]
+fn write_i32_oct(bh: &mut Bencher) {
+    let mut buf = String::with_capacity(256);
+    bh.iter(|| {
+        write!(black_box(&mut buf), "{:o}", black_box(0_i32)).unwrap();
+        write!(black_box(&mut buf), "{:o}", black_box(100_i32)).unwrap();
+        write!(black_box(&mut buf), "{:o}", black_box(-100_i32)).unwrap();
+        write!(black_box(&mut buf), "{:o}", black_box(1_i32 << 16)).unwrap();
+        black_box(&mut buf).clear();
+    });
+}
+
+#[bench]
+fn write_i64_oct(bh: &mut Bencher) {
+    let mut buf = String::with_capacity(256);
+    bh.iter(|| {
+        write!(black_box(&mut buf), "{:o}", black_box(0_i64)).unwrap();
+        write!(black_box(&mut buf), "{:o}", black_box(100_i64)).unwrap();
+        write!(black_box(&mut buf), "{:o}", black_box(-100_i64)).unwrap();
+        write!(black_box(&mut buf), "{:o}", black_box(1_i64 << 32)).unwrap();
+        black_box(&mut buf).clear();
+    });
+}
+
+#[bench]
+fn write_i128_oct(bh: &mut Bencher) {
+    let mut buf = String::with_capacity(256);
+    bh.iter(|| {
+        write!(black_box(&mut buf), "{:o}", black_box(0_i128)).unwrap();
+        write!(black_box(&mut buf), "{:o}", black_box(100_i128)).unwrap();
+        write!(black_box(&mut buf), "{:o}", black_box(-100_i128)).unwrap();
+        write!(black_box(&mut buf), "{:o}", black_box(1_i128 << 64)).unwrap();
+        black_box(&mut buf).clear();
+    });
+}
+
+#[bench]
+fn write_i8_hex(bh: &mut Bencher) {
+    let mut buf = String::with_capacity(256);
+    bh.iter(|| {
+        write!(black_box(&mut buf), "{:x}", black_box(0_i8)).unwrap();
+        write!(black_box(&mut buf), "{:x}", black_box(100_i8)).unwrap();
+        write!(black_box(&mut buf), "{:x}", black_box(-100_i8)).unwrap();
+        write!(black_box(&mut buf), "{:x}", black_box(1_i8 << 4)).unwrap();
+        black_box(&mut buf).clear();
+    });
+}
+
+#[bench]
+fn write_i16_hex(bh: &mut Bencher) {
+    let mut buf = String::with_capacity(256);
+    bh.iter(|| {
+        write!(black_box(&mut buf), "{:x}", black_box(0_i16)).unwrap();
+        write!(black_box(&mut buf), "{:x}", black_box(100_i16)).unwrap();
+        write!(black_box(&mut buf), "{:x}", black_box(-100_i16)).unwrap();
+        write!(black_box(&mut buf), "{:x}", black_box(1_i16 << 8)).unwrap();
+        black_box(&mut buf).clear();
+    });
+}
+
+#[bench]
+fn write_i32_hex(bh: &mut Bencher) {
+    let mut buf = String::with_capacity(256);
+    bh.iter(|| {
+        write!(black_box(&mut buf), "{:x}", black_box(0_i32)).unwrap();
+        write!(black_box(&mut buf), "{:x}", black_box(100_i32)).unwrap();
+        write!(black_box(&mut buf), "{:x}", black_box(-100_i32)).unwrap();
+        write!(black_box(&mut buf), "{:x}", black_box(1_i32 << 16)).unwrap();
+        black_box(&mut buf).clear();
+    });
+}
+
+#[bench]
+fn write_i64_hex(bh: &mut Bencher) {
+    let mut buf = String::with_capacity(256);
+    bh.iter(|| {
+        write!(black_box(&mut buf), "{:x}", black_box(0_i64)).unwrap();
+        write!(black_box(&mut buf), "{:x}", black_box(100_i64)).unwrap();
+        write!(black_box(&mut buf), "{:x}", black_box(-100_i64)).unwrap();
+        write!(black_box(&mut buf), "{:x}", black_box(1_i64 << 32)).unwrap();
+        black_box(&mut buf).clear();
+    });
+}
+
+#[bench]
+fn write_i128_hex(bh: &mut Bencher) {
+    let mut buf = String::with_capacity(256);
+    bh.iter(|| {
+        write!(black_box(&mut buf), "{:x}", black_box(0_i128)).unwrap();
+        write!(black_box(&mut buf), "{:x}", black_box(100_i128)).unwrap();
+        write!(black_box(&mut buf), "{:x}", black_box(-100_i128)).unwrap();
+        write!(black_box(&mut buf), "{:x}", black_box(1_i128 << 64)).unwrap();
+        black_box(&mut buf).clear();
+    });
+}
diff --git a/library/coretests/tests/lib.rs b/library/coretests/tests/lib.rs
index ecda8a7fec6..b128acfc000 100644
--- a/library/coretests/tests/lib.rs
+++ b/library/coretests/tests/lib.rs
@@ -56,7 +56,6 @@
 #![feature(hashmap_internals)]
 #![feature(int_roundings)]
 #![feature(ip)]
-#![feature(ip_from)]
 #![feature(is_ascii_octdigit)]
 #![feature(isolate_most_least_significant_one)]
 #![feature(iter_advance_by)]
diff --git a/library/std/Cargo.toml b/library/std/Cargo.toml
index 7bc52976500..eff2562f031 100644
--- a/library/std/Cargo.toml
+++ b/library/std/Cargo.toml
@@ -14,6 +14,7 @@ crate-type = ["dylib", "rlib"]
 
 [dependencies]
 alloc = { path = "../alloc", public = true }
+# std no longer uses cfg-if directly, but the included copy of backtrace does.
 cfg-if = { version = "1.0", features = ['rustc-dep-of-std'] }
 panic_unwind = { path = "../panic_unwind", optional = true }
 panic_abort = { path = "../panic_abort" }
diff --git a/library/std/src/ffi/os_str.rs b/library/std/src/ffi/os_str.rs
index 8d7edc732af..1214490caad 100644
--- a/library/std/src/ffi/os_str.rs
+++ b/library/std/src/ffi/os_str.rs
@@ -137,7 +137,7 @@ impl OsString {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use]
     #[inline]
-    #[rustc_const_unstable(feature = "const_pathbuf_osstring_new", issue = "141520")]
+    #[rustc_const_stable(feature = "const_pathbuf_osstring_new", since = "CURRENT_RUSTC_VERSION")]
     pub const fn new() -> OsString {
         OsString { inner: Buf::from_string(String::new()) }
     }
diff --git a/library/std/src/fs.rs b/library/std/src/fs.rs
index a220a3f56e9..1ed4f2f9f0c 100644
--- a/library/std/src/fs.rs
+++ b/library/std/src/fs.rs
@@ -3119,7 +3119,7 @@ pub fn read_dir<P: AsRef<Path>>(path: P) -> io::Result<ReadDir> {
 /// On UNIX-like systems, this function will update the permission bits
 /// of the file pointed to by the symlink.
 ///
-/// Note that this behavior can lead to privalage escalation vulnerabilities,
+/// Note that this behavior can lead to privilege escalation vulnerabilities,
 /// where the ability to create a symlink in one directory allows you to
 /// cause the permissions of another file or directory to be modified.
 ///
@@ -3156,6 +3156,25 @@ pub fn set_permissions<P: AsRef<Path>>(path: P, perm: Permissions) -> io::Result
     fs_imp::set_permissions(path.as_ref(), perm.0)
 }
 
+/// Set the permissions of a file, unless it is a symlink.
+///
+/// Note that the non-final path elements are allowed to be symlinks.
+///
+/// # Platform-specific behavior
+///
+/// Currently unimplemented on Windows.
+///
+/// On Unix platforms, this results in a [`FilesystemLoop`] error if the last element is a symlink.
+///
+/// This behavior may change in the future.
+///
+/// [`FilesystemLoop`]: crate::io::ErrorKind::FilesystemLoop
+#[doc(alias = "chmod", alias = "SetFileAttributes")]
+#[unstable(feature = "set_permissions_nofollow", issue = "141607")]
+pub fn set_permissions_nofollow<P: AsRef<Path>>(path: P, perm: Permissions) -> io::Result<()> {
+    fs_imp::set_permissions_nofollow(path.as_ref(), perm)
+}
+
 impl DirBuilder {
     /// Creates a new set of options with default mode/security settings for all
     /// platforms and also non-recursive.
diff --git a/library/std/src/io/buffered/bufreader/buffer.rs b/library/std/src/io/buffered/bufreader/buffer.rs
index 574288e579e..9b600cd5575 100644
--- a/library/std/src/io/buffered/bufreader/buffer.rs
+++ b/library/std/src/io/buffered/bufreader/buffer.rs
@@ -122,7 +122,7 @@ impl Buffer {
 
     /// Remove bytes that have already been read from the buffer.
     pub fn backshift(&mut self) {
-        self.buf.copy_within(self.pos.., 0);
+        self.buf.copy_within(self.pos..self.filled, 0);
         self.filled -= self.pos;
         self.pos = 0;
     }
diff --git a/library/std/src/io/copy.rs b/library/std/src/io/copy.rs
index 15e962924ac..d060ad52897 100644
--- a/library/std/src/io/copy.rs
+++ b/library/std/src/io/copy.rs
@@ -63,10 +63,11 @@ where
     R: Read,
     W: Write,
 {
-    cfg_if::cfg_if! {
-        if #[cfg(any(target_os = "linux", target_os = "android"))] {
+    cfg_select! {
+        any(target_os = "linux", target_os = "android") => {
             crate::sys::kernel_copy::copy_spec(reader, writer)
-        } else {
+        }
+        _ => {
             generic_copy(reader, writer)
         }
     }
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index f111fcb4a47..ab417b6c72f 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -330,6 +330,7 @@
 #![feature(bstr)]
 #![feature(bstr_internals)]
 #![feature(cast_maybe_uninit)]
+#![feature(cfg_select)]
 #![feature(char_internals)]
 #![feature(clone_to_uninit)]
 #![feature(const_cmp)]
@@ -737,6 +738,14 @@ pub use core::{
     unreachable, write, writeln,
 };
 
+// Re-export unstable derive macro defined through core.
+#[unstable(feature = "derive_from", issue = "144889")]
+/// Unstable module containing the unstable `From` derive macro.
+pub mod from {
+    #[unstable(feature = "derive_from", issue = "144889")]
+    pub use core::from::From;
+}
+
 // Include a number of private modules that exist solely to provide
 // the rustdoc documentation for primitive types. Using `include!`
 // because rustdoc only looks for these modules at the crate level.
diff --git a/library/std/src/os/unix/net/stream.rs b/library/std/src/os/unix/net/stream.rs
index 035768a6fab..768fa77a5f8 100644
--- a/library/std/src/os/unix/net/stream.rs
+++ b/library/std/src/os/unix/net/stream.rs
@@ -1,14 +1,16 @@
-cfg_if::cfg_if! {
-    if #[cfg(any(
+cfg_select! {
+    any(
         target_os = "linux", target_os = "android",
         target_os = "hurd",
         target_os = "dragonfly", target_os = "freebsd",
         target_os = "openbsd", target_os = "netbsd",
         target_os = "solaris", target_os = "illumos",
         target_os = "haiku", target_os = "nto",
-        target_os = "cygwin"))] {
+        target_os = "cygwin",
+    ) => {
         use libc::MSG_NOSIGNAL;
-    } else {
+    }
+    _ => {
         const MSG_NOSIGNAL: core::ffi::c_int = 0x0;
     }
 }
diff --git a/library/std/src/os/unix/process.rs b/library/std/src/os/unix/process.rs
index 76e63a69e45..09429af06e3 100644
--- a/library/std/src/os/unix/process.rs
+++ b/library/std/src/os/unix/process.rs
@@ -4,8 +4,6 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
-use cfg_if::cfg_if;
-
 use crate::ffi::OsStr;
 use crate::os::unix::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, OwnedFd, RawFd};
 use crate::path::Path;
@@ -13,17 +11,19 @@ use crate::sealed::Sealed;
 use crate::sys_common::{AsInner, AsInnerMut, FromInner, IntoInner};
 use crate::{io, process, sys};
 
-cfg_if! {
-    if #[cfg(any(target_os = "vxworks", target_os = "espidf", target_os = "horizon", target_os = "vita"))] {
+cfg_select! {
+    any(target_os = "vxworks", target_os = "espidf", target_os = "horizon", target_os = "vita") => {
         type UserId = u16;
         type GroupId = u16;
-    } else if #[cfg(target_os = "nto")] {
+    }
+    target_os = "nto" => {
         // Both IDs are signed, see `sys/target_nto.h` of the QNX Neutrino SDP.
         // Only positive values should be used, see e.g.
         // https://www.qnx.com/developers/docs/7.1/#com.qnx.doc.neutrino.lib_ref/topic/s/setuid.html
         type UserId = i32;
         type GroupId = i32;
-    } else {
+    }
+    _ => {
         type UserId = u32;
         type GroupId = u32;
     }
diff --git a/library/std/src/path.rs b/library/std/src/path.rs
index 3b52804d6be..3899fbf86db 100644
--- a/library/std/src/path.rs
+++ b/library/std/src/path.rs
@@ -1191,7 +1191,7 @@ impl PathBuf {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use]
     #[inline]
-    #[rustc_const_unstable(feature = "const_pathbuf_osstring_new", issue = "141520")]
+    #[rustc_const_stable(feature = "const_pathbuf_osstring_new", since = "CURRENT_RUSTC_VERSION")]
     pub const fn new() -> PathBuf {
         PathBuf { inner: OsString::new() }
     }
@@ -2105,6 +2105,38 @@ impl PartialEq for PathBuf {
     }
 }
 
+#[stable(feature = "eq_str_for_path", since = "CURRENT_RUSTC_VERSION")]
+impl cmp::PartialEq<str> for PathBuf {
+    #[inline]
+    fn eq(&self, other: &str) -> bool {
+        &*self == other
+    }
+}
+
+#[stable(feature = "eq_str_for_path", since = "CURRENT_RUSTC_VERSION")]
+impl cmp::PartialEq<PathBuf> for str {
+    #[inline]
+    fn eq(&self, other: &PathBuf) -> bool {
+        other == self
+    }
+}
+
+#[stable(feature = "eq_str_for_path", since = "CURRENT_RUSTC_VERSION")]
+impl cmp::PartialEq<String> for PathBuf {
+    #[inline]
+    fn eq(&self, other: &String) -> bool {
+        **self == **other
+    }
+}
+
+#[stable(feature = "eq_str_for_path", since = "CURRENT_RUSTC_VERSION")]
+impl cmp::PartialEq<PathBuf> for String {
+    #[inline]
+    fn eq(&self, other: &PathBuf) -> bool {
+        other == self
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Hash for PathBuf {
     fn hash<H: Hasher>(&self, h: &mut H) {
@@ -3366,6 +3398,39 @@ impl PartialEq for Path {
     }
 }
 
+#[stable(feature = "eq_str_for_path", since = "CURRENT_RUSTC_VERSION")]
+impl cmp::PartialEq<str> for Path {
+    #[inline]
+    fn eq(&self, other: &str) -> bool {
+        let other: &OsStr = other.as_ref();
+        self == other
+    }
+}
+
+#[stable(feature = "eq_str_for_path", since = "CURRENT_RUSTC_VERSION")]
+impl cmp::PartialEq<Path> for str {
+    #[inline]
+    fn eq(&self, other: &Path) -> bool {
+        other == self
+    }
+}
+
+#[stable(feature = "eq_str_for_path", since = "CURRENT_RUSTC_VERSION")]
+impl cmp::PartialEq<String> for Path {
+    #[inline]
+    fn eq(&self, other: &String) -> bool {
+        self == &*other
+    }
+}
+
+#[stable(feature = "eq_str_for_path", since = "CURRENT_RUSTC_VERSION")]
+impl cmp::PartialEq<Path> for String {
+    #[inline]
+    fn eq(&self, other: &Path) -> bool {
+        other == self
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Hash for Path {
     fn hash<H: Hasher>(&self, h: &mut H) {
diff --git a/library/std/src/sync/nonpoison/mutex.rs b/library/std/src/sync/nonpoison/mutex.rs
index b6861c78f00..fd1e671d7a3 100644
--- a/library/std/src/sync/nonpoison/mutex.rs
+++ b/library/std/src/sync/nonpoison/mutex.rs
@@ -100,7 +100,7 @@ pub struct MutexGuard<'a, T: ?Sized + 'a> {
     lock: &'a Mutex<T>,
 }
 
-/// A [`MutexGuard`] is not `Send` to maximize platform portablity.
+/// A [`MutexGuard`] is not `Send` to maximize platform portability.
 ///
 /// On platforms that use POSIX threads (commonly referred to as pthreads) there is a requirement to
 /// release mutex locks on the same thread they were acquired.
diff --git a/library/std/src/sync/poison/mutex.rs b/library/std/src/sync/poison/mutex.rs
index 6205c4fa4ca..720c212c65c 100644
--- a/library/std/src/sync/poison/mutex.rs
+++ b/library/std/src/sync/poison/mutex.rs
@@ -279,7 +279,7 @@ pub struct MutexGuard<'a, T: ?Sized + 'a> {
     poison: poison::Guard,
 }
 
-/// A [`MutexGuard`] is not `Send` to maximize platform portablity.
+/// A [`MutexGuard`] is not `Send` to maximize platform portability.
 ///
 /// On platforms that use POSIX threads (commonly referred to as pthreads) there is a requirement to
 /// release mutex locks on the same thread they were acquired.
diff --git a/library/std/src/sync/reentrant_lock.rs b/library/std/src/sync/reentrant_lock.rs
index 727252f03a2..4140718560c 100644
--- a/library/std/src/sync/reentrant_lock.rs
+++ b/library/std/src/sync/reentrant_lock.rs
@@ -1,5 +1,3 @@
-use cfg_if::cfg_if;
-
 use crate::cell::UnsafeCell;
 use crate::fmt;
 use crate::ops::Deref;
@@ -87,8 +85,8 @@ pub struct ReentrantLock<T: ?Sized> {
     data: T,
 }
 
-cfg_if!(
-    if #[cfg(target_has_atomic = "64")] {
+cfg_select!(
+    target_has_atomic = "64" => {
         use crate::sync::atomic::{Atomic, AtomicU64, Ordering::Relaxed};
 
         struct Tid(Atomic<u64>);
@@ -110,7 +108,8 @@ cfg_if!(
                 self.0.store(value, Relaxed);
             }
         }
-    } else {
+    }
+    _ => {
         /// Returns the address of a TLS variable. This is guaranteed to
         /// be unique across all currently alive threads.
         fn tls_addr() -> usize {
diff --git a/library/std/src/sys/alloc/mod.rs b/library/std/src/sys/alloc/mod.rs
index f3af1f7f599..6d4b09494a3 100644
--- a/library/std/src/sys/alloc/mod.rs
+++ b/library/std/src/sys/alloc/mod.rs
@@ -68,29 +68,37 @@ unsafe fn realloc_fallback(
     }
 }
 
-cfg_if::cfg_if! {
-    if #[cfg(any(
+cfg_select! {
+    any(
         target_family = "unix",
         target_os = "wasi",
         target_os = "teeos",
         target_os = "trusty",
-    ))] {
+    ) => {
         mod unix;
-    } else if #[cfg(target_os = "windows")] {
+    }
+    target_os = "windows" => {
         mod windows;
-    } else if #[cfg(target_os = "hermit")] {
+    }
+    target_os = "hermit" => {
         mod hermit;
-    } else if #[cfg(all(target_vendor = "fortanix", target_env = "sgx"))] {
+    }
+    all(target_vendor = "fortanix", target_env = "sgx") => {
         mod sgx;
-    } else if #[cfg(target_os = "solid_asp3")] {
+    }
+    target_os = "solid_asp3" => {
         mod solid;
-    } else if #[cfg(target_os = "uefi")] {
+    }
+    target_os = "uefi" => {
         mod uefi;
-    } else if #[cfg(target_family = "wasm")] {
+    }
+    target_family = "wasm" => {
         mod wasm;
-    } else if #[cfg(target_os = "xous")] {
+    }
+    target_os = "xous" => {
         mod xous;
-    } else if #[cfg(target_os = "zkvm")] {
+    }
+    target_os = "zkvm" => {
         mod zkvm;
     }
 }
diff --git a/library/std/src/sys/alloc/unix.rs b/library/std/src/sys/alloc/unix.rs
index a7ac4117ec9..3d369b08abc 100644
--- a/library/std/src/sys/alloc/unix.rs
+++ b/library/std/src/sys/alloc/unix.rs
@@ -58,18 +58,16 @@ unsafe impl GlobalAlloc for System {
     }
 }
 
-cfg_if::cfg_if! {
+cfg_select! {
     // We use posix_memalign wherever possible, but some targets have very incomplete POSIX coverage
     // so we need a fallback for those.
-    if #[cfg(any(
-        target_os = "horizon",
-        target_os = "vita",
-    ))] {
+    any(target_os = "horizon", target_os = "vita") => {
         #[inline]
         unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 {
             unsafe { libc::memalign(layout.align(), layout.size()) as *mut u8 }
         }
-    } else {
+    }
+    _ => {
         #[inline]
         #[cfg_attr(target_os = "vxworks", allow(unused_unsafe))]
         unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 {
diff --git a/library/std/src/sys/anonymous_pipe/mod.rs b/library/std/src/sys/anonymous_pipe/mod.rs
index aa14c8b650d..b6f464161ee 100644
--- a/library/std/src/sys/anonymous_pipe/mod.rs
+++ b/library/std/src/sys/anonymous_pipe/mod.rs
@@ -1,13 +1,15 @@
 #![forbid(unsafe_op_in_unsafe_fn)]
 
-cfg_if::cfg_if! {
-    if #[cfg(unix)] {
+cfg_select! {
+    unix => {
         mod unix;
         pub use unix::{AnonPipe, pipe};
-    } else if #[cfg(windows)] {
+    }
+    windows => {
         mod windows;
         pub use windows::{AnonPipe, pipe};
-    } else {
+    }
+    _ => {
         mod unsupported;
         pub use unsupported::{AnonPipe, pipe};
     }
diff --git a/library/std/src/sys/args/mod.rs b/library/std/src/sys/args/mod.rs
index 0011f55dc14..c9627322276 100644
--- a/library/std/src/sys/args/mod.rs
+++ b/library/std/src/sys/args/mod.rs
@@ -12,32 +12,39 @@
 ))]
 mod common;
 
-cfg_if::cfg_if! {
-    if #[cfg(any(
+cfg_select! {
+    any(
         all(target_family = "unix", not(any(target_os = "espidf", target_os = "vita"))),
         target_os = "hermit",
-    ))] {
+    ) => {
         mod unix;
         pub use unix::*;
-    } else if #[cfg(target_family = "windows")] {
+    }
+    target_family = "windows" => {
         mod windows;
         pub use windows::*;
-    } else if #[cfg(all(target_vendor = "fortanix", target_env = "sgx"))] {
+    }
+    all(target_vendor = "fortanix", target_env = "sgx") => {
         mod sgx;
         pub use sgx::*;
-    } else if #[cfg(target_os = "uefi")] {
+    }
+    target_os = "uefi" => {
         mod uefi;
         pub use uefi::*;
-    } else if #[cfg(target_os = "wasi")] {
+    }
+    target_os = "wasi" => {
         mod wasi;
         pub use wasi::*;
-    } else if #[cfg(target_os = "xous")] {
+    }
+    target_os = "xous" => {
         mod xous;
         pub use xous::*;
-    } else if #[cfg(target_os = "zkvm")] {
+    }
+    target_os = "zkvm" => {
         mod zkvm;
         pub use zkvm::*;
-    } else {
+    }
+    _ => {
         mod unsupported;
         pub use unsupported::*;
     }
diff --git a/library/std/src/sys/cmath.rs b/library/std/src/sys/cmath.rs
index 299ce1a6ff0..1592218ead8 100644
--- a/library/std/src/sys/cmath.rs
+++ b/library/std/src/sys/cmath.rs
@@ -45,69 +45,70 @@ unsafe extern "C" {
     pub safe fn lgammaf128_r(n: f128, s: &mut i32) -> f128;
     pub safe fn erff128(n: f128) -> f128;
     pub safe fn erfcf128(n: f128) -> f128;
-
-    cfg_if::cfg_if! {
-    if #[cfg(not(all(target_os = "windows", target_env = "msvc", target_arch = "x86")))] {
-        pub safe fn acosf(n: f32) -> f32;
-        pub safe fn asinf(n: f32) -> f32;
-        pub safe fn atan2f(a: f32, b: f32) -> f32;
-        pub safe fn atanf(n: f32) -> f32;
-        pub safe fn coshf(n: f32) -> f32;
-        pub safe fn sinhf(n: f32) -> f32;
-        pub safe fn tanf(n: f32) -> f32;
-        pub safe fn tanhf(n: f32) -> f32;
-    }}
 }
 
-// On AIX, we don't have lgammaf_r only the f64 version, so we can
-// use the f64 version lgamma_r
-#[cfg(target_os = "aix")]
-pub fn lgammaf_r(n: f32, s: &mut i32) -> f32 {
-    lgamma_r(n.into(), s) as f32
-}
+cfg_select! {
+    all(target_os = "windows", target_env = "msvc", target_arch = "x86") => {
+        // On 32-bit x86 MSVC these functions aren't defined, so we just define shims
+        // which promote everything to f64, perform the calculation, and then demote
+        // back to f32. While not precisely correct should be "correct enough" for now.
+        #[inline]
+        pub fn acosf(n: f32) -> f32 {
+            f64::acos(n as f64) as f32
+        }
 
-// On 32-bit x86 MSVC these functions aren't defined, so we just define shims
-// which promote everything to f64, perform the calculation, and then demote
-// back to f32. While not precisely correct should be "correct enough" for now.
-cfg_if::cfg_if! {
-if #[cfg(all(target_os = "windows", target_env = "msvc", target_arch = "x86"))] {
-    #[inline]
-    pub fn acosf(n: f32) -> f32 {
-        f64::acos(n as f64) as f32
-    }
+        #[inline]
+        pub fn asinf(n: f32) -> f32 {
+            f64::asin(n as f64) as f32
+        }
 
-    #[inline]
-    pub fn asinf(n: f32) -> f32 {
-        f64::asin(n as f64) as f32
-    }
+        #[inline]
+        pub fn atan2f(n: f32, b: f32) -> f32 {
+            f64::atan2(n as f64, b as f64) as f32
+        }
 
-    #[inline]
-    pub fn atan2f(n: f32, b: f32) -> f32 {
-        f64::atan2(n as f64, b as f64) as f32
-    }
+        #[inline]
+        pub fn atanf(n: f32) -> f32 {
+            f64::atan(n as f64) as f32
+        }
 
-    #[inline]
-    pub fn atanf(n: f32) -> f32 {
-        f64::atan(n as f64) as f32
-    }
+        #[inline]
+        pub fn coshf(n: f32) -> f32 {
+            f64::cosh(n as f64) as f32
+        }
 
-    #[inline]
-    pub fn coshf(n: f32) -> f32 {
-        f64::cosh(n as f64) as f32
-    }
+        #[inline]
+        pub fn sinhf(n: f32) -> f32 {
+            f64::sinh(n as f64) as f32
+        }
 
-    #[inline]
-    pub fn sinhf(n: f32) -> f32 {
-        f64::sinh(n as f64) as f32
-    }
+        #[inline]
+        pub fn tanf(n: f32) -> f32 {
+            f64::tan(n as f64) as f32
+        }
 
-    #[inline]
-    pub fn tanf(n: f32) -> f32 {
-        f64::tan(n as f64) as f32
+        #[inline]
+        pub fn tanhf(n: f32) -> f32 {
+            f64::tanh(n as f64) as f32
+        }
     }
-
-    #[inline]
-    pub fn tanhf(n: f32) -> f32 {
-        f64::tanh(n as f64) as f32
+    _ => {
+        unsafe extern "C" {
+            pub safe fn acosf(n: f32) -> f32;
+            pub safe fn asinf(n: f32) -> f32;
+            pub safe fn atan2f(a: f32, b: f32) -> f32;
+            pub safe fn atanf(n: f32) -> f32;
+            pub safe fn coshf(n: f32) -> f32;
+            pub safe fn sinhf(n: f32) -> f32;
+            pub safe fn tanf(n: f32) -> f32;
+            pub safe fn tanhf(n: f32) -> f32;
+        }
     }
-}}
+}
+
+// On AIX, we don't have lgammaf_r only the f64 version, so we can
+// use the f64 version lgamma_r
+#[cfg(target_os = "aix")]
+pub fn lgammaf_r(n: f32, s: &mut i32) -> f32 {
+    lgamma_r(n.into(), s) as f32
+}
diff --git a/library/std/src/sys/env/mod.rs b/library/std/src/sys/env/mod.rs
index d81ff875c83..f211a9fc86b 100644
--- a/library/std/src/sys/env/mod.rs
+++ b/library/std/src/sys/env/mod.rs
@@ -13,35 +13,44 @@
 ))]
 mod common;
 
-cfg_if::cfg_if! {
-    if #[cfg(target_family = "unix")] {
+cfg_select! {
+    target_family = "unix" => {
         mod unix;
         pub use unix::*;
-    } else if #[cfg(target_family = "windows")] {
+    }
+    target_family = "windows" => {
         mod windows;
         pub use windows::*;
-    } else if #[cfg(target_os = "hermit")] {
+    }
+    target_os = "hermit" => {
         mod hermit;
         pub use hermit::*;
-    } else if #[cfg(all(target_vendor = "fortanix", target_env = "sgx"))] {
+    }
+    all(target_vendor = "fortanix", target_env = "sgx") => {
         mod sgx;
         pub use sgx::*;
-    } else if #[cfg(target_os = "solid_asp3")] {
+    }
+    target_os = "solid_asp3" => {
         mod solid;
         pub use solid::*;
-    } else if #[cfg(target_os = "uefi")] {
+    }
+    target_os = "uefi" => {
         mod uefi;
         pub use uefi::*;
-    } else if #[cfg(target_os = "wasi")] {
+    }
+    target_os = "wasi" => {
         mod wasi;
         pub use wasi::*;
-    } else if #[cfg(target_os = "xous")] {
+    }
+    target_os = "xous" => {
         mod xous;
         pub use xous::*;
-    } else if #[cfg(target_os = "zkvm")] {
+    }
+    target_os = "zkvm" => {
         mod zkvm;
         pub use zkvm::*;
-    } else {
+    }
+    _ => {
         mod unsupported;
         pub use unsupported::*;
     }
diff --git a/library/std/src/sys/env/wasi.rs b/library/std/src/sys/env/wasi.rs
index 3719f9db51e..1327cbc3263 100644
--- a/library/std/src/sys/env/wasi.rs
+++ b/library/std/src/sys/env/wasi.rs
@@ -7,8 +7,8 @@ use crate::os::wasi::prelude::*;
 use crate::sys::common::small_c_string::run_with_cstr;
 use crate::sys::pal::os::{cvt, libc};
 
-cfg_if::cfg_if! {
-    if #[cfg(target_feature = "atomics")] {
+cfg_select! {
+    target_feature = "atomics" => {
         // Access to the environment must be protected by a lock in multi-threaded scenarios.
         use crate::sync::{PoisonError, RwLock};
         static ENV_LOCK: RwLock<()> = RwLock::new(());
@@ -18,7 +18,8 @@ cfg_if::cfg_if! {
         pub fn env_write_lock() -> impl Drop {
             ENV_LOCK.write().unwrap_or_else(PoisonError::into_inner)
         }
-    } else {
+    }
+    _ => {
         // No need for a lock if we are single-threaded.
         pub fn env_read_lock() -> impl Drop {
             Box::new(())
diff --git a/library/std/src/sys/exit_guard.rs b/library/std/src/sys/exit_guard.rs
index bd70d178244..00b91842e9d 100644
--- a/library/std/src/sys/exit_guard.rs
+++ b/library/std/src/sys/exit_guard.rs
@@ -1,5 +1,5 @@
-cfg_if::cfg_if! {
-    if #[cfg(target_os = "linux")] {
+cfg_select! {
+    target_os = "linux" => {
         /// Mitigation for <https://github.com/rust-lang/rust/issues/126600>
         ///
         /// On glibc, `libc::exit` has been observed to not always be thread-safe.
@@ -56,7 +56,8 @@ cfg_if::cfg_if! {
                 }
             }
         }
-    } else {
+    }
+    _ => {
         /// Mitigation for <https://github.com/rust-lang/rust/issues/126600>
         ///
         /// Mitigation is ***NOT*** implemented on this platform, either because this platform
diff --git a/library/std/src/sys/fd/mod.rs b/library/std/src/sys/fd/mod.rs
index e0f5eab6951..7cb9dd1cba9 100644
--- a/library/std/src/sys/fd/mod.rs
+++ b/library/std/src/sys/fd/mod.rs
@@ -2,18 +2,22 @@
 
 #![forbid(unsafe_op_in_unsafe_fn)]
 
-cfg_if::cfg_if! {
-    if #[cfg(target_family = "unix")] {
+cfg_select! {
+    target_family = "unix" => {
         mod unix;
         pub use unix::*;
-    } else if #[cfg(target_os = "hermit")] {
+    }
+    target_os = "hermit" => {
         mod hermit;
         pub use hermit::*;
-    } else if #[cfg(all(target_vendor = "fortanix", target_env = "sgx"))] {
+    }
+    all(target_vendor = "fortanix", target_env = "sgx") => {
         mod sgx;
         pub use sgx::*;
-    } else if #[cfg(target_os = "wasi")] {
+    }
+    target_os = "wasi" => {
         mod wasi;
         pub use wasi::*;
     }
+    _ => {}
 }
diff --git a/library/std/src/sys/fs/mod.rs b/library/std/src/sys/fs/mod.rs
index d55e28074fe..dbd782f5018 100644
--- a/library/std/src/sys/fs/mod.rs
+++ b/library/std/src/sys/fs/mod.rs
@@ -5,8 +5,8 @@ use crate::path::{Path, PathBuf};
 
 pub mod common;
 
-cfg_if::cfg_if! {
-    if #[cfg(target_family = "unix")] {
+cfg_select! {
+    target_family = "unix" => {
         mod unix;
         use unix as imp;
         pub use unix::{chown, fchown, lchown, mkfifo};
@@ -16,24 +16,30 @@ cfg_if::cfg_if! {
         #[cfg(any(target_os = "linux", target_os = "android"))]
         pub(crate) use unix::CachedFileMetadata;
         use crate::sys::common::small_c_string::run_path_with_cstr as with_native_path;
-    } else if #[cfg(target_os = "windows")] {
+    }
+    target_os = "windows" => {
         mod windows;
         use windows as imp;
         pub use windows::{symlink_inner, junction_point};
         use crate::sys::path::with_native_path;
-    } else if #[cfg(target_os = "hermit")] {
+    }
+    target_os = "hermit" => {
         mod hermit;
         use hermit as imp;
-    } else if #[cfg(target_os = "solid_asp3")] {
+    }
+    target_os = "solid_asp3" => {
         mod solid;
         use solid as imp;
-    } else if #[cfg(target_os = "uefi")] {
+    }
+    target_os = "uefi" => {
         mod uefi;
         use uefi as imp;
-    } else if #[cfg(target_os = "wasi")] {
+    }
+    target_os = "wasi" => {
         mod wasi;
         use wasi as imp;
-    } else {
+    }
+    _ => {
         mod unsupported;
         use unsupported as imp;
     }
@@ -108,6 +114,21 @@ pub fn set_permissions(path: &Path, perm: FilePermissions) -> io::Result<()> {
     with_native_path(path, &|path| imp::set_perm(path, perm.clone()))
 }
 
+#[cfg(unix)]
+pub fn set_permissions_nofollow(path: &Path, perm: crate::fs::Permissions) -> io::Result<()> {
+    use crate::fs::OpenOptions;
+    use crate::os::unix::fs::OpenOptionsExt;
+
+    OpenOptions::new().custom_flags(libc::O_NOFOLLOW).open(path)?.set_permissions(perm)
+}
+
+#[cfg(not(unix))]
+pub fn set_permissions_nofollow(_path: &Path, _perm: crate::fs::Permissions) -> io::Result<()> {
+    crate::unimplemented!(
+        "`set_permissions_nofollow` is currently only implemented on Unix platforms"
+    )
+}
+
 pub fn canonicalize(path: &Path) -> io::Result<PathBuf> {
     with_native_path(path, &imp::canonicalize)
 }
diff --git a/library/std/src/sys/fs/unix.rs b/library/std/src/sys/fs/unix.rs
index b310db2dac4..7ee9f3c445a 100644
--- a/library/std/src/sys/fs/unix.rs
+++ b/library/std/src/sys/fs/unix.rs
@@ -101,10 +101,11 @@ pub struct File(FileDesc);
 // https://github.com/rust-lang/rust/pull/67774
 macro_rules! cfg_has_statx {
     ({ $($then_tt:tt)* } else { $($else_tt:tt)* }) => {
-        cfg_if::cfg_if! {
-            if #[cfg(all(target_os = "linux", target_env = "gnu"))] {
+        cfg_select! {
+            all(target_os = "linux", target_env = "gnu") => {
                 $($then_tt)*
-            } else {
+            }
+            _ => {
                 $($else_tt)*
             }
         }
@@ -1263,6 +1264,7 @@ impl File {
         target_os = "fuchsia",
         target_os = "linux",
         target_os = "netbsd",
+        target_os = "openbsd",
         target_vendor = "apple",
     ))]
     pub fn lock(&self) -> io::Result<()> {
@@ -1275,6 +1277,7 @@ impl File {
         target_os = "fuchsia",
         target_os = "linux",
         target_os = "netbsd",
+        target_os = "openbsd",
         target_vendor = "apple",
     )))]
     pub fn lock(&self) -> io::Result<()> {
@@ -1286,6 +1289,7 @@ impl File {
         target_os = "fuchsia",
         target_os = "linux",
         target_os = "netbsd",
+        target_os = "openbsd",
         target_vendor = "apple",
     ))]
     pub fn lock_shared(&self) -> io::Result<()> {
@@ -1298,6 +1302,7 @@ impl File {
         target_os = "fuchsia",
         target_os = "linux",
         target_os = "netbsd",
+        target_os = "openbsd",
         target_vendor = "apple",
     )))]
     pub fn lock_shared(&self) -> io::Result<()> {
@@ -1309,6 +1314,7 @@ impl File {
         target_os = "fuchsia",
         target_os = "linux",
         target_os = "netbsd",
+        target_os = "openbsd",
         target_vendor = "apple",
     ))]
     pub fn try_lock(&self) -> Result<(), TryLockError> {
@@ -1329,6 +1335,7 @@ impl File {
         target_os = "fuchsia",
         target_os = "linux",
         target_os = "netbsd",
+        target_os = "openbsd",
         target_vendor = "apple",
     )))]
     pub fn try_lock(&self) -> Result<(), TryLockError> {
@@ -1343,6 +1350,7 @@ impl File {
         target_os = "fuchsia",
         target_os = "linux",
         target_os = "netbsd",
+        target_os = "openbsd",
         target_vendor = "apple",
     ))]
     pub fn try_lock_shared(&self) -> Result<(), TryLockError> {
@@ -1363,6 +1371,7 @@ impl File {
         target_os = "fuchsia",
         target_os = "linux",
         target_os = "netbsd",
+        target_os = "openbsd",
         target_vendor = "apple",
     )))]
     pub fn try_lock_shared(&self) -> Result<(), TryLockError> {
@@ -1377,6 +1386,7 @@ impl File {
         target_os = "fuchsia",
         target_os = "linux",
         target_os = "netbsd",
+        target_os = "openbsd",
         target_vendor = "apple",
     ))]
     pub fn unlock(&self) -> io::Result<()> {
@@ -1389,6 +1399,7 @@ impl File {
         target_os = "fuchsia",
         target_os = "linux",
         target_os = "netbsd",
+        target_os = "openbsd",
         target_vendor = "apple",
     )))]
     pub fn unlock(&self) -> io::Result<()> {
@@ -1505,8 +1516,8 @@ impl File {
             )),
             None => Ok(libc::timespec { tv_sec: 0, tv_nsec: libc::UTIME_OMIT as _ }),
         };
-        cfg_if::cfg_if! {
-            if #[cfg(any(target_os = "redox", target_os = "espidf", target_os = "horizon", target_os = "nuttx"))] {
+        cfg_select! {
+            any(target_os = "redox", target_os = "espidf", target_os = "horizon", target_os = "nuttx") => {
                 // Redox doesn't appear to support `UTIME_OMIT`.
                 // ESP-IDF and HorizonOS do not support `futimens` at all and the behavior for those OS is therefore
                 // the same as for Redox.
@@ -1515,7 +1526,8 @@ impl File {
                     io::ErrorKind::Unsupported,
                     "setting file times not supported",
                 ))
-            } else if #[cfg(target_vendor = "apple")] {
+            }
+            target_vendor = "apple" => {
                 let mut buf = [mem::MaybeUninit::<libc::timespec>::uninit(); 3];
                 let mut num_times = 0;
                 let mut attrlist: libc::attrlist = unsafe { mem::zeroed() };
@@ -1543,7 +1555,8 @@ impl File {
                     0
                 ) })?;
                 Ok(())
-            } else if #[cfg(target_os = "android")] {
+            }
+            target_os = "android" => {
                 let times = [to_timespec(times.accessed)?, to_timespec(times.modified)?];
                 // futimens requires Android API level 19
                 cvt(unsafe {
@@ -1559,7 +1572,8 @@ impl File {
                     }
                 })?;
                 Ok(())
-            } else {
+            }
+            _ => {
                 #[cfg(all(target_os = "linux", target_env = "gnu", target_pointer_width = "32", not(target_arch = "riscv32")))]
                 {
                     use crate::sys::{time::__timespec64, weak::weak};
@@ -1677,13 +1691,14 @@ impl fmt::Debug for File {
             let mut buf = vec![0; libc::PATH_MAX as usize];
             let n = unsafe { libc::fcntl(fd, libc::F_GETPATH, buf.as_ptr()) };
             if n == -1 {
-                cfg_if::cfg_if! {
-                    if #[cfg(target_os = "netbsd")] {
+                cfg_select! {
+                    target_os = "netbsd" => {
                         // fallback to procfs as last resort
                         let mut p = PathBuf::from("/proc/self/fd");
                         p.push(&fd.to_string());
                         return run_path_with_cstr(&p, &readlink).ok()
-                    } else {
+                    }
+                    _ => {
                         return None;
                     }
                 }
@@ -1884,15 +1899,16 @@ pub fn symlink(original: &CStr, link: &CStr) -> io::Result<()> {
 }
 
 pub fn link(original: &CStr, link: &CStr) -> io::Result<()> {
-    cfg_if::cfg_if! {
-        if #[cfg(any(target_os = "vxworks", target_os = "redox", target_os = "android", target_os = "espidf", target_os = "horizon", target_os = "vita", target_env = "nto70"))] {
+    cfg_select! {
+        any(target_os = "vxworks", target_os = "redox", target_os = "android", target_os = "espidf", target_os = "horizon", target_os = "vita", target_env = "nto70") => {
             // VxWorks, Redox and ESP-IDF lack `linkat`, so use `link` instead. POSIX leaves
             // it implementation-defined whether `link` follows symlinks, so rely on the
             // `symlink_hard_link` test in library/std/src/fs/tests.rs to check the behavior.
             // Android has `linkat` on newer versions, but we happen to know `link`
             // always has the correct behavior, so it's here as well.
             cvt(unsafe { libc::link(original.as_ptr(), link.as_ptr()) })?;
-        } else {
+        }
+        _ => {
             // Where we can, use `linkat` instead of `link`; see the comment above
             // this one for details on why.
             cvt(unsafe { libc::linkat(libc::AT_FDCWD, original.as_ptr(), libc::AT_FDCWD, link.as_ptr(), 0) })?;
diff --git a/library/std/src/sys/io/mod.rs b/library/std/src/sys/io/mod.rs
index ae75f4d97b4..fe8ec1dbb73 100644
--- a/library/std/src/sys/io/mod.rs
+++ b/library/std/src/sys/io/mod.rs
@@ -1,20 +1,24 @@
 #![forbid(unsafe_op_in_unsafe_fn)]
 
 mod io_slice {
-    cfg_if::cfg_if! {
-        if #[cfg(any(target_family = "unix", target_os = "hermit", target_os = "solid_asp3", target_os = "trusty"))] {
+    cfg_select! {
+        any(target_family = "unix", target_os = "hermit", target_os = "solid_asp3", target_os = "trusty") => {
             mod iovec;
             pub use iovec::*;
-        } else if #[cfg(target_os = "windows")] {
+        }
+        target_os = "windows" => {
             mod windows;
             pub use windows::*;
-        } else if #[cfg(target_os = "wasi")] {
+        }
+        target_os = "wasi" => {
             mod wasi;
             pub use wasi::*;
-        } else if #[cfg(target_os = "uefi")] {
+        }
+        target_os = "uefi" => {
             mod uefi;
             pub use uefi::*;
-        } else {
+        }
+        _ => {
             mod unsupported;
             pub use unsupported::*;
         }
@@ -22,17 +26,20 @@ mod io_slice {
 }
 
 mod is_terminal {
-    cfg_if::cfg_if! {
-        if #[cfg(any(target_family = "unix", target_os = "wasi"))] {
+    cfg_select! {
+        any(target_family = "unix", target_os = "wasi") => {
             mod isatty;
             pub use isatty::*;
-        } else if #[cfg(target_os = "windows")] {
+        }
+        target_os = "windows" => {
             mod windows;
             pub use windows::*;
-        } else if #[cfg(target_os = "hermit")] {
+        }
+        target_os = "hermit" => {
             mod hermit;
             pub use hermit::*;
-        } else {
+        }
+        _ => {
             mod unsupported;
             pub use unsupported::*;
         }
diff --git a/library/std/src/sys/mod.rs b/library/std/src/sys/mod.rs
index 8ec0a0e3302..6324c1a232a 100644
--- a/library/std/src/sys/mod.rs
+++ b/library/std/src/sys/mod.rs
@@ -1,7 +1,7 @@
 #![allow(unsafe_op_in_unsafe_fn)]
 
 /// The configure builtins provides runtime support compiler-builtin features
-/// which require dynamic intialization to work as expected, e.g. aarch64
+/// which require dynamic initialization to work as expected, e.g. aarch64
 /// outline-atomics.
 mod configure_builtins;
 
diff --git a/library/std/src/sys/net/connection/socket.rs b/library/std/src/sys/net/connection/socket.rs
index 7301bde6881..aa83ed65d4c 100644
--- a/library/std/src/sys/net/connection/socket.rs
+++ b/library/std/src/sys/net/connection/socket.rs
@@ -9,29 +9,34 @@ use crate::sys_common::{AsInner, FromInner};
 use crate::time::Duration;
 use crate::{cmp, fmt, mem, ptr};
 
-cfg_if::cfg_if! {
-    if #[cfg(target_os = "hermit")] {
+cfg_select! {
+    target_os = "hermit" => {
         mod hermit;
         pub use hermit::*;
-    } else if #[cfg(target_os = "solid_asp3")] {
+    }
+    target_os = "solid_asp3" => {
         mod solid;
         pub use solid::*;
-    } else if #[cfg(target_family = "unix")] {
+    }
+    target_family = "unix" => {
         mod unix;
         pub use unix::*;
-    } else if #[cfg(all(target_os = "wasi", target_env = "p2"))] {
+    }
+    all(target_os = "wasi", target_env = "p2") => {
         mod wasip2;
         pub use wasip2::*;
-    } else if #[cfg(target_os = "windows")] {
+    }
+    target_os = "windows" => {
         mod windows;
         pub use windows::*;
     }
+    _ => {}
 }
 
 use netc as c;
 
-cfg_if::cfg_if! {
-    if #[cfg(any(
+cfg_select! {
+    any(
         target_os = "dragonfly",
         target_os = "freebsd",
         target_os = "openbsd",
@@ -43,39 +48,44 @@ cfg_if::cfg_if! {
         target_os = "nto",
         target_os = "nuttx",
         target_vendor = "apple",
-    ))] {
+    ) => {
         use c::IPV6_JOIN_GROUP as IPV6_ADD_MEMBERSHIP;
         use c::IPV6_LEAVE_GROUP as IPV6_DROP_MEMBERSHIP;
-    } else {
+    }
+    _ => {
         use c::IPV6_ADD_MEMBERSHIP;
         use c::IPV6_DROP_MEMBERSHIP;
     }
 }
 
-cfg_if::cfg_if! {
-    if #[cfg(any(
+cfg_select! {
+    any(
         target_os = "linux", target_os = "android",
         target_os = "hurd",
         target_os = "dragonfly", target_os = "freebsd",
         target_os = "openbsd", target_os = "netbsd",
         target_os = "solaris", target_os = "illumos",
         target_os = "haiku", target_os = "nto",
-        target_os = "cygwin"))] {
+        target_os = "cygwin",
+    ) => {
         use libc::MSG_NOSIGNAL;
-    } else {
+    }
+    _ => {
         const MSG_NOSIGNAL: c_int = 0x0;
     }
 }
 
-cfg_if::cfg_if! {
-    if #[cfg(any(
+cfg_select! {
+    any(
         target_os = "dragonfly", target_os = "freebsd",
         target_os = "openbsd", target_os = "netbsd",
         target_os = "solaris", target_os = "illumos",
-        target_os = "nto"))] {
+        target_os = "nto",
+    ) => {
         use crate::ffi::c_uchar;
         type IpV4MultiCastType = c_uchar;
-    } else {
+    }
+    _ => {
         type IpV4MultiCastType = c_int;
     }
 }
@@ -523,17 +533,19 @@ impl TcpListener {
         let (addr, len) = socket_addr_to_c(addr);
         cvt(unsafe { c::bind(sock.as_raw(), addr.as_ptr(), len as _) })?;
 
-        cfg_if::cfg_if! {
-            if #[cfg(target_os = "horizon")] {
+        cfg_select! {
+            target_os = "horizon" => {
                 // The 3DS doesn't support a big connection backlog. Sometimes
                 // it allows up to about 37, but other times it doesn't even
                 // accept 32. There may be a global limitation causing this.
                 let backlog = 20;
-            } else if #[cfg(target_os = "haiku")] {
+            }
+            target_os = "haiku" => {
                 // Haiku does not support a queue length > 32
                 // https://github.com/haiku/haiku/blob/979a0bc487864675517fb2fab28f87dc8bf43041/headers/posix/sys/socket.h#L81
                 let backlog = 32;
-            } else {
+            }
+            _ => {
                 // The default for all other platforms
                 let backlog = 128;
             }
diff --git a/library/std/src/sys/net/connection/socket/unix.rs b/library/std/src/sys/net/connection/socket/unix.rs
index cc111f3521b..8b5970d1494 100644
--- a/library/std/src/sys/net/connection/socket/unix.rs
+++ b/library/std/src/sys/net/connection/socket/unix.rs
@@ -12,10 +12,11 @@ use crate::sys_common::{AsInner, FromInner, IntoInner};
 use crate::time::{Duration, Instant};
 use crate::{cmp, mem};
 
-cfg_if::cfg_if! {
-    if #[cfg(target_vendor = "apple")] {
+cfg_select! {
+    target_vendor = "apple" => {
         use libc::SO_LINGER_SEC as SO_LINGER;
-    } else {
+    }
+    _ => {
         use libc::SO_LINGER;
     }
 }
@@ -72,8 +73,8 @@ impl Socket {
 
     pub fn new_raw(fam: c_int, ty: c_int) -> io::Result<Socket> {
         unsafe {
-            cfg_if::cfg_if! {
-                if #[cfg(any(
+            cfg_select! {
+                any(
                     target_os = "android",
                     target_os = "dragonfly",
                     target_os = "freebsd",
@@ -85,7 +86,7 @@ impl Socket {
                     target_os = "cygwin",
                     target_os = "nto",
                     target_os = "solaris",
-                ))] {
+                ) => {
                     // On platforms that support it we pass the SOCK_CLOEXEC
                     // flag to atomically create the socket and set it as
                     // CLOEXEC. On Linux this was added in 2.6.27.
@@ -98,7 +99,8 @@ impl Socket {
                     setsockopt(&socket, libc::SOL_SOCKET, libc::SO_NOSIGPIPE, 1)?;
 
                     Ok(socket)
-                } else {
+                }
+                _ => {
                     let fd = cvt(libc::socket(fam, ty, 0))?;
                     let fd = FileDesc::from_raw_fd(fd);
                     fd.set_cloexec()?;
@@ -120,8 +122,8 @@ impl Socket {
         unsafe {
             let mut fds = [0, 0];
 
-            cfg_if::cfg_if! {
-                if #[cfg(any(
+            cfg_select! {
+                any(
                     target_os = "android",
                     target_os = "dragonfly",
                     target_os = "freebsd",
@@ -132,11 +134,12 @@ impl Socket {
                     target_os = "openbsd",
                     target_os = "cygwin",
                     target_os = "nto",
-                ))] {
+                ) => {
                     // Like above, set cloexec atomically
                     cvt(libc::socketpair(fam, ty | libc::SOCK_CLOEXEC, 0, fds.as_mut_ptr()))?;
                     Ok((Socket(FileDesc::from_raw_fd(fds[0])), Socket(FileDesc::from_raw_fd(fds[1]))))
-                } else {
+                }
+                _ => {
                     cvt(libc::socketpair(fam, ty, 0, fds.as_mut_ptr()))?;
                     let a = FileDesc::from_raw_fd(fds[0]);
                     let b = FileDesc::from_raw_fd(fds[1]);
@@ -250,8 +253,8 @@ impl Socket {
         // atomically set the CLOEXEC flag is to use the `accept4` syscall on
         // platforms that support it. On Linux, this was added in 2.6.28,
         // glibc 2.10 and musl 0.9.5.
-        cfg_if::cfg_if! {
-            if #[cfg(any(
+        cfg_select! {
+            any(
                 target_os = "android",
                 target_os = "dragonfly",
                 target_os = "freebsd",
@@ -261,12 +264,13 @@ impl Socket {
                 target_os = "netbsd",
                 target_os = "openbsd",
                 target_os = "cygwin",
-            ))] {
+            ) => {
                 unsafe {
                     let fd = cvt_r(|| libc::accept4(self.as_raw_fd(), storage, len, libc::SOCK_CLOEXEC))?;
                     Ok(Socket(FileDesc::from_raw_fd(fd)))
                 }
-            } else {
+            }
+            _ => {
                 unsafe {
                     let fd = cvt_r(|| libc::accept(self.as_raw_fd(), storage, len))?;
                     let fd = FileDesc::from_raw_fd(fd);
diff --git a/library/std/src/sys/net/mod.rs b/library/std/src/sys/net/mod.rs
index 646679a1cc8..5df1fe138ab 100644
--- a/library/std/src/sys/net/mod.rs
+++ b/library/std/src/sys/net/mod.rs
@@ -1,36 +1,41 @@
-cfg_if::cfg_if! {
-    if #[cfg(any(
+cfg_select! {
+    any(
         all(target_family = "unix", not(target_os = "l4re")),
         target_os = "windows",
         target_os = "hermit",
         all(target_os = "wasi", target_env = "p2"),
         target_os = "solid_asp3",
-    ))] {
+    ) => {
         mod connection {
             mod socket;
             pub use socket::*;
         }
-    } else if #[cfg(all(target_vendor = "fortanix", target_env = "sgx"))] {
+    }
+    all(target_vendor = "fortanix", target_env = "sgx") => {
         mod connection {
             mod sgx;
             pub use sgx::*;
         }
-    } else if #[cfg(all(target_os = "wasi", target_env = "p1"))] {
+    }
+    all(target_os = "wasi", target_env = "p1") => {
         mod connection {
             mod wasip1;
             pub use wasip1::*;
         }
-    } else if #[cfg(target_os = "xous")] {
+    }
+    target_os = "xous" => {
         mod connection {
             mod xous;
             pub use xous::*;
         }
-    } else if #[cfg(target_os = "uefi")] {
+    }
+    target_os = "uefi" => {
         mod connection {
             mod uefi;
             pub use uefi::*;
         }
-    } else {
+    }
+    _ => {
         mod connection {
             mod unsupported;
             pub use unsupported::*;
diff --git a/library/std/src/sys/os_str/mod.rs b/library/std/src/sys/os_str/mod.rs
index 345e661586d..65c90d88049 100644
--- a/library/std/src/sys/os_str/mod.rs
+++ b/library/std/src/sys/os_str/mod.rs
@@ -1,13 +1,11 @@
 #![forbid(unsafe_op_in_unsafe_fn)]
 
-cfg_if::cfg_if! {
-    if #[cfg(any(
-        target_os = "windows",
-        target_os = "uefi",
-    ))] {
+cfg_select! {
+    any(target_os = "windows", target_os = "uefi") => {
         mod wtf8;
         pub use wtf8::{Buf, Slice};
-    } else {
+    }
+    _ => {
         mod bytes;
         pub use bytes::{Buf, Slice};
     }
diff --git a/library/std/src/sys/pal/mod.rs b/library/std/src/sys/pal/mod.rs
index fbefc62ac88..9376f5249f1 100644
--- a/library/std/src/sys/pal/mod.rs
+++ b/library/std/src/sys/pal/mod.rs
@@ -24,60 +24,70 @@
 
 pub mod common;
 
-cfg_if::cfg_if! {
-    if #[cfg(unix)] {
+cfg_select! {
+    unix => {
         mod unix;
         pub use self::unix::*;
-    } else if #[cfg(windows)] {
+    }
+    windows => {
         mod windows;
         pub use self::windows::*;
-    } else if #[cfg(target_os = "solid_asp3")] {
+    }
+    target_os = "solid_asp3" => {
         mod solid;
         pub use self::solid::*;
-    } else if #[cfg(target_os = "hermit")] {
+    }
+    target_os = "hermit" => {
         mod hermit;
         pub use self::hermit::*;
-    } else if #[cfg(target_os = "trusty")] {
+    }
+    target_os = "trusty" => {
         mod trusty;
         pub use self::trusty::*;
-    } else if #[cfg(all(target_os = "wasi", target_env = "p2"))] {
+    }
+    all(target_os = "wasi", target_env = "p2") => {
         mod wasip2;
         pub use self::wasip2::*;
-    } else if #[cfg(target_os = "wasi")] {
+    }
+    target_os = "wasi" => {
         mod wasi;
         pub use self::wasi::*;
-    } else if #[cfg(target_family = "wasm")] {
+    }
+    target_family = "wasm" => {
         mod wasm;
         pub use self::wasm::*;
-    } else if #[cfg(target_os = "xous")] {
+    }
+    target_os = "xous" => {
         mod xous;
         pub use self::xous::*;
-    } else if #[cfg(target_os = "uefi")] {
+    }
+    target_os = "uefi" => {
         mod uefi;
         pub use self::uefi::*;
-    } else if #[cfg(all(target_vendor = "fortanix", target_env = "sgx"))] {
+    }
+    all(target_vendor = "fortanix", target_env = "sgx") => {
         mod sgx;
         pub use self::sgx::*;
-    } else if #[cfg(target_os = "teeos")] {
+    }
+    target_os = "teeos" => {
         mod teeos;
         pub use self::teeos::*;
-    } else if #[cfg(target_os = "zkvm")] {
+    }
+    target_os = "zkvm" => {
         mod zkvm;
         pub use self::zkvm::*;
-    } else {
+    }
+    _ => {
         mod unsupported;
         pub use self::unsupported::*;
     }
 }
 
-cfg_if::cfg_if! {
+pub const FULL_BACKTRACE_DEFAULT: bool = cfg_select! {
     // Fuchsia components default to full backtrace.
-    if #[cfg(target_os = "fuchsia")] {
-        pub const FULL_BACKTRACE_DEFAULT: bool = true;
-    } else {
-        pub const FULL_BACKTRACE_DEFAULT: bool = false;
-    }
-}
+    target_os = "fuchsia" => true,
+    _ => false,
+};
 
 #[cfg(not(target_os = "uefi"))]
 pub type RawOsError = i32;
diff --git a/library/std/src/sys/pal/uefi/time.rs b/library/std/src/sys/pal/uefi/time.rs
index df5611b2ddd..36ce3f7ef96 100644
--- a/library/std/src/sys/pal/uefi/time.rs
+++ b/library/std/src/sys/pal/uefi/time.rs
@@ -188,7 +188,7 @@ pub(crate) mod system_time_internal {
         Duration::new(epoch, t.nanosecond)
     }
 
-    /// This algorithm is a modifed version of the one described in the post:
+    /// This algorithm is a modified version of the one described in the post:
     /// https://howardhinnant.github.io/date_algorithms.html#clive_from_days
     ///
     /// The changes are to use 1900-01-01-00:00:00 with timezone -1440 as anchor instead of UNIX
@@ -197,7 +197,7 @@ pub(crate) mod system_time_internal {
         // Check timzone validity
         assert!(timezone <= 1440 && timezone >= -1440);
 
-        // FIXME(#126043): use checked_sub_signed once stablized
+        // FIXME(#126043): use checked_sub_signed once stabilized
         let secs =
             dur.as_secs().checked_add_signed((-timezone as i64) * SECS_IN_MINUTE as i64).unwrap();
 
@@ -296,12 +296,9 @@ pub(crate) mod instant_internal {
     }
 
     pub fn platform_specific() -> Option<Instant> {
-        cfg_if::cfg_if! {
-            if #[cfg(any(target_arch = "x86_64", target_arch = "x86"))] {
-                timestamp_rdtsc().map(Instant)
-            } else {
-                None
-            }
+        cfg_select! {
+            any(target_arch = "x86_64", target_arch = "x86") => timestamp_rdtsc().map(Instant),
+            _ => None,
         }
     }
 
diff --git a/library/std/src/sys/pal/unix/futex.rs b/library/std/src/sys/pal/unix/futex.rs
index c23278bdf5e..265067d84d5 100644
--- a/library/std/src/sys/pal/unix/futex.rs
+++ b/library/std/src/sys/pal/unix/futex.rs
@@ -46,8 +46,8 @@ pub fn futex_wait(futex: &Atomic<u32>, expected: u32, timeout: Option<Duration>)
         }
 
         let r = unsafe {
-            cfg_if::cfg_if! {
-                if #[cfg(target_os = "freebsd")] {
+            cfg_select! {
+                target_os = "freebsd" => {
                     // FreeBSD doesn't have futex(), but it has
                     // _umtx_op(UMTX_OP_WAIT_UINT_PRIVATE), which is nearly
                     // identical. It supports absolute timeouts through a flag
@@ -66,7 +66,8 @@ pub fn futex_wait(futex: &Atomic<u32>, expected: u32, timeout: Option<Duration>)
                         crate::ptr::without_provenance_mut(umtx_timeout_size),
                         umtx_timeout_ptr as *mut _,
                     )
-                } else if #[cfg(any(target_os = "linux", target_os = "android"))] {
+                }
+                any(target_os = "linux", target_os = "android") => {
                     // Use FUTEX_WAIT_BITSET rather than FUTEX_WAIT to be able to give an
                     // absolute time rather than a relative time.
                     libc::syscall(
@@ -78,7 +79,8 @@ pub fn futex_wait(futex: &Atomic<u32>, expected: u32, timeout: Option<Duration>)
                         null::<u32>(), // This argument is unused for FUTEX_WAIT_BITSET.
                         !0u32,         // A full bitmask, to make it behave like a regular FUTEX_WAIT.
                     )
-                } else {
+                }
+                _ => {
                     compile_error!("unknown target_os");
                 }
             }
diff --git a/library/std/src/sys/pal/unix/mod.rs b/library/std/src/sys/pal/unix/mod.rs
index ba9e14b8009..fede3673eb6 100644
--- a/library/std/src/sys/pal/unix/mod.rs
+++ b/library/std/src/sys/pal/unix/mod.rs
@@ -366,31 +366,36 @@ pub fn abort_internal() -> ! {
     unsafe { libc::abort() }
 }
 
-cfg_if::cfg_if! {
-    if #[cfg(target_os = "android")] {
+cfg_select! {
+    target_os = "android" => {
         #[link(name = "dl", kind = "static", modifiers = "-bundle",
             cfg(target_feature = "crt-static"))]
         #[link(name = "dl", cfg(not(target_feature = "crt-static")))]
         #[link(name = "log", cfg(not(target_feature = "crt-static")))]
         unsafe extern "C" {}
-    } else if #[cfg(target_os = "freebsd")] {
+    }
+    target_os = "freebsd" => {
         #[link(name = "execinfo")]
         #[link(name = "pthread")]
         unsafe extern "C" {}
-    } else if #[cfg(target_os = "netbsd")] {
+    }
+    target_os = "netbsd" => {
         #[link(name = "pthread")]
         #[link(name = "rt")]
         unsafe extern "C" {}
-    } else if #[cfg(any(target_os = "dragonfly", target_os = "openbsd", target_os = "cygwin"))] {
+    }
+    any(target_os = "dragonfly", target_os = "openbsd", target_os = "cygwin") => {
         #[link(name = "pthread")]
         unsafe extern "C" {}
-    } else if #[cfg(target_os = "solaris")] {
+    }
+    target_os = "solaris" => {
         #[link(name = "socket")]
         #[link(name = "posix4")]
         #[link(name = "pthread")]
         #[link(name = "resolv")]
         unsafe extern "C" {}
-    } else if #[cfg(target_os = "illumos")] {
+    }
+    target_os = "illumos" => {
         #[link(name = "socket")]
         #[link(name = "posix4")]
         #[link(name = "pthread")]
@@ -399,24 +404,29 @@ cfg_if::cfg_if! {
         // Use libumem for the (malloc-compatible) allocator
         #[link(name = "umem")]
         unsafe extern "C" {}
-    } else if #[cfg(target_vendor = "apple")] {
+    }
+    target_vendor = "apple" => {
         // Link to `libSystem.dylib`.
         //
         // Don't get confused by the presence of `System.framework`,
         // it is a deprecated wrapper over the dynamic library.
         #[link(name = "System")]
         unsafe extern "C" {}
-    } else if #[cfg(target_os = "fuchsia")] {
+    }
+    target_os = "fuchsia" => {
         #[link(name = "zircon")]
         #[link(name = "fdio")]
         unsafe extern "C" {}
-    } else if #[cfg(all(target_os = "linux", target_env = "uclibc"))] {
+    }
+    all(target_os = "linux", target_env = "uclibc") => {
         #[link(name = "dl")]
         unsafe extern "C" {}
-    } else if #[cfg(target_os = "vita")] {
+    }
+    target_os = "vita" => {
         #[link(name = "pthread", kind = "static", modifiers = "-bundle")]
         unsafe extern "C" {}
     }
+    _ => {}
 }
 
 #[cfg(any(target_os = "espidf", target_os = "horizon", target_os = "vita", target_os = "nuttx"))]
diff --git a/library/std/src/sys/pal/unix/os.rs b/library/std/src/sys/pal/unix/os.rs
index 0e68313cc3e..1110b775c09 100644
--- a/library/std/src/sys/pal/unix/os.rs
+++ b/library/std/src/sys/pal/unix/os.rs
@@ -17,13 +17,10 @@ use crate::{fmt, io, iter, mem, ptr, slice, str};
 
 const TMPBUF_SZ: usize = 128;
 
-cfg_if::cfg_if! {
-    if #[cfg(target_os = "redox")] {
-        const PATH_SEPARATOR: u8 = b';';
-    } else {
-        const PATH_SEPARATOR: u8 = b':';
-    }
-}
+const PATH_SEPARATOR: u8 = cfg_select! {
+    target_os = "redox" => b';',
+    _ => b':',
+};
 
 unsafe extern "C" {
     #[cfg(not(any(target_os = "dragonfly", target_os = "vxworks", target_os = "rtems")))]
@@ -620,14 +617,10 @@ fn darwin_temp_dir() -> PathBuf {
 
 pub fn temp_dir() -> PathBuf {
     crate::env::var_os("TMPDIR").map(PathBuf::from).unwrap_or_else(|| {
-        cfg_if::cfg_if! {
-            if #[cfg(all(target_vendor = "apple", not(miri)))] {
-                darwin_temp_dir()
-            } else if #[cfg(target_os = "android")] {
-                PathBuf::from("/data/local/tmp")
-            } else {
-                PathBuf::from("/tmp")
-            }
+        cfg_select! {
+            all(target_vendor = "apple", not(miri)) => darwin_temp_dir(),
+            target_os = "android" => PathBuf::from("/data/local/tmp"),
+            _ => PathBuf::from("/tmp"),
         }
     })
 }
diff --git a/library/std/src/sys/pal/unix/pipe.rs b/library/std/src/sys/pal/unix/pipe.rs
index 55510153dc8..6b0cd14da4f 100644
--- a/library/std/src/sys/pal/unix/pipe.rs
+++ b/library/std/src/sys/pal/unix/pipe.rs
@@ -18,8 +18,8 @@ pub fn anon_pipe() -> io::Result<(AnonPipe, AnonPipe)> {
     // The only known way right now to create atomically set the CLOEXEC flag is
     // to use the `pipe2` syscall. This was added to Linux in 2.6.27, glibc 2.9
     // and musl 0.9.3, and some other targets also have it.
-    cfg_if::cfg_if! {
-        if #[cfg(any(
+    cfg_select! {
+        any(
             target_os = "dragonfly",
             target_os = "freebsd",
             target_os = "hurd",
@@ -29,12 +29,13 @@ pub fn anon_pipe() -> io::Result<(AnonPipe, AnonPipe)> {
             target_os = "openbsd",
             target_os = "cygwin",
             target_os = "redox"
-        ))] {
+        ) => {
             unsafe {
                 cvt(libc::pipe2(fds.as_mut_ptr(), libc::O_CLOEXEC))?;
                 Ok((AnonPipe(FileDesc::from_raw_fd(fds[0])), AnonPipe(FileDesc::from_raw_fd(fds[1]))))
             }
-        } else {
+        }
+        _ => {
             unsafe {
                 cvt(libc::pipe(fds.as_mut_ptr()))?;
 
diff --git a/library/std/src/sys/pal/unix/thread.rs b/library/std/src/sys/pal/unix/thread.rs
index 24b65c11fd2..3389b8c0c8a 100644
--- a/library/std/src/sys/pal/unix/thread.rs
+++ b/library/std/src/sys/pal/unix/thread.rs
@@ -151,12 +151,13 @@ impl Thread {
     ))]
     pub fn set_name(name: &CStr) {
         unsafe {
-            cfg_if::cfg_if! {
-                if #[cfg(any(target_os = "linux", target_os = "cygwin"))] {
+            cfg_select! {
+                any(target_os = "linux", target_os = "cygwin") => {
                     // Linux and Cygwin limits the allowed length of the name.
                     const TASK_COMM_LEN: usize = 16;
                     let name = truncate_cstr::<{ TASK_COMM_LEN }>(name);
-                } else {
+                }
+                _ => {
                     // FreeBSD, DragonFly BSD and NuttX do not enforce length limits.
                 }
             };
@@ -415,9 +416,9 @@ pub(crate) fn current_os_id() -> Option<u64> {
     //
     // The OS thread ID is used rather than `pthread_self` so as to match what will be displayed
     // for process inspection (debuggers, trace, `top`, etc.).
-    cfg_if::cfg_if! {
+    cfg_select! {
         // Most platforms have a function returning a `pid_t` or int, which is an `i32`.
-        if #[cfg(any(target_os = "android", target_os = "linux"))] {
+        any(target_os = "android", target_os = "linux") => {
             use crate::sys::weak::syscall;
 
             // `libc::gettid` is only available on glibc 2.30+, but the syscall is available
@@ -427,28 +428,34 @@ pub(crate) fn current_os_id() -> Option<u64> {
             // SAFETY: FFI call with no preconditions.
             let id: libc::pid_t = unsafe { gettid() };
             Some(id as u64)
-        } else if #[cfg(target_os = "nto")] {
+        }
+        target_os = "nto" => {
             // SAFETY: FFI call with no preconditions.
             let id: libc::pid_t = unsafe { libc::gettid() };
             Some(id as u64)
-        } else if #[cfg(target_os = "openbsd")] {
+        }
+        target_os = "openbsd" => {
             // SAFETY: FFI call with no preconditions.
             let id: libc::pid_t = unsafe { libc::getthrid() };
             Some(id as u64)
-        } else if #[cfg(target_os = "freebsd")] {
+        }
+        target_os = "freebsd" => {
             // SAFETY: FFI call with no preconditions.
             let id: libc::c_int = unsafe { libc::pthread_getthreadid_np() };
             Some(id as u64)
-        } else if #[cfg(target_os = "netbsd")] {
+        }
+        target_os = "netbsd" => {
             // SAFETY: FFI call with no preconditions.
             let id: libc::lwpid_t = unsafe { libc::_lwp_self() };
             Some(id as u64)
-        } else if #[cfg(any(target_os = "illumos", target_os = "solaris"))] {
+        }
+        any(target_os = "illumos", target_os = "solaris") => {
             // On Illumos and Solaris, the `pthread_t` is the same as the OS thread ID.
             // SAFETY: FFI call with no preconditions.
             let id: libc::pthread_t = unsafe { libc::pthread_self() };
             Some(id as u64)
-        } else if #[cfg(target_vendor = "apple")] {
+        }
+        target_vendor = "apple" => {
             // Apple allows querying arbitrary thread IDs, `thread=NULL` queries the current thread.
             let mut id = 0u64;
             // SAFETY: `thread_id` is a valid pointer, no other preconditions.
@@ -458,10 +465,9 @@ pub(crate) fn current_os_id() -> Option<u64> {
             } else {
                 None
             }
-        } else {
-            // Other platforms don't have an OS thread ID or don't have a way to access it.
-            None
         }
+        // Other platforms don't have an OS thread ID or don't have a way to access it.
+        _ => None,
     }
 }
 
@@ -483,8 +489,8 @@ fn truncate_cstr<const MAX_WITH_NUL: usize>(cstr: &CStr) -> [libc::c_char; MAX_W
 }
 
 pub fn available_parallelism() -> io::Result<NonZero<usize>> {
-    cfg_if::cfg_if! {
-        if #[cfg(any(
+    cfg_select! {
+        any(
             target_os = "android",
             target_os = "emscripten",
             target_os = "fuchsia",
@@ -493,7 +499,7 @@ pub fn available_parallelism() -> io::Result<NonZero<usize>> {
             target_os = "aix",
             target_vendor = "apple",
             target_os = "cygwin",
-        ))] {
+        ) => {
             #[allow(unused_assignments)]
             #[allow(unused_mut)]
             let mut quota = usize::MAX;
@@ -527,12 +533,13 @@ pub fn available_parallelism() -> io::Result<NonZero<usize>> {
                     Ok(unsafe { NonZero::new_unchecked(count) })
                 }
             }
-        } else if #[cfg(any(
-                   target_os = "freebsd",
-                   target_os = "dragonfly",
-                   target_os = "openbsd",
-                   target_os = "netbsd",
-               ))] {
+        }
+        any(
+           target_os = "freebsd",
+           target_os = "dragonfly",
+           target_os = "openbsd",
+           target_os = "netbsd",
+        ) => {
             use crate::ptr;
 
             #[cfg(target_os = "freebsd")]
@@ -607,7 +614,8 @@ pub fn available_parallelism() -> io::Result<NonZero<usize>> {
             }
 
             Ok(unsafe { NonZero::new_unchecked(cpus as usize) })
-        } else if #[cfg(target_os = "nto")] {
+        }
+        target_os = "nto" => {
             unsafe {
                 use libc::_syspage_ptr;
                 if _syspage_ptr.is_null() {
@@ -618,13 +626,15 @@ pub fn available_parallelism() -> io::Result<NonZero<usize>> {
                         .ok_or(io::Error::UNKNOWN_THREAD_COUNT)
                 }
             }
-        } else if #[cfg(any(target_os = "solaris", target_os = "illumos"))] {
+        }
+        any(target_os = "solaris", target_os = "illumos") => {
             let mut cpus = 0u32;
             if unsafe { libc::pset_info(libc::PS_MYID, core::ptr::null_mut(), &mut cpus, core::ptr::null_mut()) } != 0 {
                 return Err(io::Error::UNKNOWN_THREAD_COUNT);
             }
             Ok(unsafe { NonZero::new_unchecked(cpus as usize) })
-        } else if #[cfg(target_os = "haiku")] {
+        }
+        target_os = "haiku" => {
             // system_info cpu_count field gets the static data set at boot time with `smp_set_num_cpus`
             // `get_system_info` calls then `smp_get_num_cpus`
             unsafe {
@@ -637,7 +647,8 @@ pub fn available_parallelism() -> io::Result<NonZero<usize>> {
 
                 Ok(NonZero::new_unchecked(sinfo.cpu_count as usize))
             }
-        } else if #[cfg(target_os = "vxworks")] {
+        }
+        target_os = "vxworks" => {
             // Note: there is also `vxCpuConfiguredGet`, closer to _SC_NPROCESSORS_CONF
             // expectations than the actual cores availability.
             unsafe extern "C" {
@@ -649,7 +660,8 @@ pub fn available_parallelism() -> io::Result<NonZero<usize>> {
                 let set = vxCpuEnabledGet();
                 Ok(NonZero::new_unchecked(set.count_ones() as usize))
             }
-        } else {
+        }
+        _ => {
             // FIXME: implement on Redox, l4re
             Err(io::const_error!(io::ErrorKind::Unsupported, "getting the number of hardware threads is not supported on the target platform"))
         }
diff --git a/library/std/src/sys/pal/wasi/thread.rs b/library/std/src/sys/pal/wasi/thread.rs
index 4755e2ef5da..e062b49bd7a 100644
--- a/library/std/src/sys/pal/wasi/thread.rs
+++ b/library/std/src/sys/pal/wasi/thread.rs
@@ -5,8 +5,8 @@ use crate::num::NonZero;
 use crate::time::{Duration, Instant};
 use crate::{io, mem};
 
-cfg_if::cfg_if! {
-    if #[cfg(target_feature = "atomics")] {
+cfg_select! {
+    target_feature = "atomics" => {
         use crate::cmp;
         use crate::ptr;
         use crate::sys::os;
@@ -62,7 +62,8 @@ cfg_if::cfg_if! {
                 debug_assert_eq!(ret, 0);
             }
         }
-    } else {
+    }
+    _ => {
         pub struct Thread(!);
     }
 }
@@ -71,8 +72,8 @@ pub const DEFAULT_MIN_STACK_SIZE: usize = 1024 * 1024;
 
 impl Thread {
     // unsafe: see thread::Builder::spawn_unchecked for safety requirements
-    cfg_if::cfg_if! {
-        if #[cfg(target_feature = "atomics")] {
+    cfg_select! {
+        target_feature = "atomics" => {
             pub unsafe fn new(stack: usize, _name: Option<&str>, p: Box<dyn FnOnce()>) -> io::Result<Thread> {
                 let p = Box::into_raw(Box::new(p));
                 let mut native: libc::pthread_t = unsafe { mem::zeroed() };
@@ -119,7 +120,8 @@ impl Thread {
                     ptr::null_mut()
                 }
             }
-        } else {
+        }
+        _ => {
             pub unsafe fn new(_stack: usize, _name: Option<&str>, _p: Box<dyn FnOnce()>) -> io::Result<Thread> {
                 crate::sys::unsupported()
             }
@@ -180,14 +182,15 @@ impl Thread {
     }
 
     pub fn join(self) {
-        cfg_if::cfg_if! {
-            if #[cfg(target_feature = "atomics")] {
+        cfg_select! {
+            target_feature = "atomics" => {
                 let id = mem::ManuallyDrop::new(self).id;
                 let ret = unsafe { libc::pthread_join(id, ptr::null_mut()) };
                 if ret != 0 {
                     rtabort!("failed to join thread: {}", io::Error::from_raw_os_error(ret));
                 }
-            } else {
+            }
+            _ => {
                 self.0
             }
         }
@@ -199,14 +202,13 @@ pub(crate) fn current_os_id() -> Option<u64> {
 }
 
 pub fn available_parallelism() -> io::Result<NonZero<usize>> {
-    cfg_if::cfg_if! {
-        if #[cfg(target_feature = "atomics")] {
+    cfg_select! {
+        target_feature = "atomics" => {
             match unsafe { libc::sysconf(libc::_SC_NPROCESSORS_ONLN) } {
                 -1 => Err(io::Error::last_os_error()),
                 cpus => NonZero::new(cpus as usize).ok_or(io::Error::UNKNOWN_THREAD_COUNT),
             }
-        } else {
-            crate::sys::unsupported()
         }
+        _ => crate::sys::unsupported(),
     }
 }
diff --git a/library/std/src/sys/pal/wasm/mod.rs b/library/std/src/sys/pal/wasm/mod.rs
index 37cb46a8f6b..346c9ff88c9 100644
--- a/library/std/src/sys/pal/wasm/mod.rs
+++ b/library/std/src/sys/pal/wasm/mod.rs
@@ -23,13 +23,14 @@ pub mod pipe;
 #[path = "../unsupported/time.rs"]
 pub mod time;
 
-cfg_if::cfg_if! {
-    if #[cfg(target_feature = "atomics")] {
+cfg_select! {
+    target_feature = "atomics" => {
         #[path = "atomics/futex.rs"]
         pub mod futex;
         #[path = "atomics/thread.rs"]
         pub mod thread;
-    } else {
+    }
+    _ => {
         #[path = "../unsupported/thread.rs"]
         pub mod thread;
     }
diff --git a/library/std/src/sys/pal/windows/c.rs b/library/std/src/sys/pal/windows/c.rs
index edac5262a4e..25c1a82cc42 100644
--- a/library/std/src/sys/pal/windows/c.rs
+++ b/library/std/src/sys/pal/windows/c.rs
@@ -95,11 +95,8 @@ pub struct MOUNT_POINT_REPARSE_BUFFER {
 }
 
 // Desktop specific functions & types
-cfg_if::cfg_if! {
-if #[cfg(not(target_vendor = "uwp"))] {
-    pub const EXCEPTION_CONTINUE_SEARCH: i32 = 0;
-}
-}
+#[cfg(not(target_vendor = "uwp"))]
+pub const EXCEPTION_CONTINUE_SEARCH: i32 = 0;
 
 // Use raw-dylib to import ProcessPrng as we can't rely on there being an import library.
 #[cfg(not(target_vendor = "win7"))]
@@ -230,12 +227,13 @@ compat_fn_with_fallback! {
     }
 }
 
-cfg_if::cfg_if! {
-    if #[cfg(target_vendor = "uwp")] {
+cfg_select! {
+    target_vendor = "uwp" => {
         windows_targets::link_raw_dylib!("ntdll.dll" "system" fn NtCreateFile(filehandle : *mut HANDLE, desiredaccess : FILE_ACCESS_RIGHTS, objectattributes : *const OBJECT_ATTRIBUTES, iostatusblock : *mut IO_STATUS_BLOCK, allocationsize : *const i64, fileattributes : FILE_FLAGS_AND_ATTRIBUTES, shareaccess : FILE_SHARE_MODE, createdisposition : NTCREATEFILE_CREATE_DISPOSITION, createoptions : NTCREATEFILE_CREATE_OPTIONS, eabuffer : *const core::ffi::c_void, ealength : u32) -> NTSTATUS);
         windows_targets::link_raw_dylib!("ntdll.dll" "system" fn NtOpenFile(filehandle : *mut HANDLE, desiredaccess : u32, objectattributes : *const OBJECT_ATTRIBUTES, iostatusblock : *mut IO_STATUS_BLOCK, shareaccess : u32, openoptions : u32) -> NTSTATUS);
         windows_targets::link_raw_dylib!("ntdll.dll" "system" fn NtReadFile(filehandle : HANDLE, event : HANDLE, apcroutine : PIO_APC_ROUTINE, apccontext : *const core::ffi::c_void, iostatusblock : *mut IO_STATUS_BLOCK, buffer : *mut core::ffi::c_void, length : u32, byteoffset : *const i64, key : *const u32) -> NTSTATUS);
         windows_targets::link_raw_dylib!("ntdll.dll" "system" fn NtWriteFile(filehandle : HANDLE, event : HANDLE, apcroutine : PIO_APC_ROUTINE, apccontext : *const core::ffi::c_void, iostatusblock : *mut IO_STATUS_BLOCK, buffer : *const core::ffi::c_void, length : u32, byteoffset : *const i64, key : *const u32) -> NTSTATUS);
         windows_targets::link_raw_dylib!("ntdll.dll" "system" fn RtlNtStatusToDosError(status : NTSTATUS) -> u32);
     }
+    _ => {}
 }
diff --git a/library/std/src/sys/pal/windows/mod.rs b/library/std/src/sys/pal/windows/mod.rs
index 8f54e2376eb..10ad4541bed 100644
--- a/library/std/src/sys/pal/windows/mod.rs
+++ b/library/std/src/sys/pal/windows/mod.rs
@@ -22,10 +22,11 @@ pub mod os;
 pub mod pipe;
 pub mod thread;
 pub mod time;
-cfg_if::cfg_if! {
-    if #[cfg(not(target_vendor = "uwp"))] {
+cfg_select! {
+    not(target_vendor = "uwp") => {
         pub mod stack_overflow;
-    } else {
+    }
+    _ => {
         pub mod stack_overflow_uwp;
         pub use self::stack_overflow_uwp as stack_overflow;
     }
@@ -337,14 +338,17 @@ pub fn dur2timeout(dur: Duration) -> u32 {
 #[cfg(not(miri))] // inline assembly does not work in Miri
 pub fn abort_internal() -> ! {
     unsafe {
-        cfg_if::cfg_if! {
-            if #[cfg(any(target_arch = "x86", target_arch = "x86_64"))] {
+        cfg_select! {
+            any(target_arch = "x86", target_arch = "x86_64") => {
                 core::arch::asm!("int $$0x29", in("ecx") c::FAST_FAIL_FATAL_APP_EXIT, options(noreturn, nostack));
-            } else if #[cfg(all(target_arch = "arm", target_feature = "thumb-mode"))] {
+            }
+            all(target_arch = "arm", target_feature = "thumb-mode") => {
                 core::arch::asm!(".inst 0xDEFB", in("r0") c::FAST_FAIL_FATAL_APP_EXIT, options(noreturn, nostack));
-            } else if #[cfg(any(target_arch = "aarch64", target_arch = "arm64ec"))] {
+            }
+            any(target_arch = "aarch64", target_arch = "arm64ec") => {
                 core::arch::asm!("brk 0xF003", in("x0") c::FAST_FAIL_FATAL_APP_EXIT, options(noreturn, nostack));
-            } else {
+            }
+            _ => {
                 core::intrinsics::abort();
             }
         }
diff --git a/library/std/src/sys/path/mod.rs b/library/std/src/sys/path/mod.rs
index a4ff4338cf5..254683bc83f 100644
--- a/library/std/src/sys/path/mod.rs
+++ b/library/std/src/sys/path/mod.rs
@@ -1,22 +1,27 @@
-cfg_if::cfg_if! {
-    if #[cfg(target_os = "windows")] {
+cfg_select! {
+    target_os = "windows" => {
         mod windows;
         mod windows_prefix;
         pub use windows::*;
-    } else if #[cfg(all(target_vendor = "fortanix", target_env = "sgx"))] {
+    }
+    all(target_vendor = "fortanix", target_env = "sgx") => {
         mod sgx;
         pub use sgx::*;
-    } else if #[cfg(target_os = "solid_asp3")] {
+    }
+    target_os = "solid_asp3" => {
         mod unsupported_backslash;
         pub use unsupported_backslash::*;
-    } else if #[cfg(target_os = "uefi")] {
+    }
+    target_os = "uefi" => {
         mod uefi;
         pub use uefi::*;
-    } else if #[cfg(target_os = "cygwin")] {
+    }
+    target_os = "cygwin" => {
         mod cygwin;
         mod windows_prefix;
         pub use cygwin::*;
-    } else {
+    }
+    _ => {
         mod unix;
         pub use unix::*;
     }
diff --git a/library/std/src/sys/personality/gcc.rs b/library/std/src/sys/personality/gcc.rs
index 75e793f18b8..019d5629d6d 100644
--- a/library/std/src/sys/personality/gcc.rs
+++ b/library/std/src/sys/personality/gcc.rs
@@ -93,12 +93,12 @@ const UNWIND_DATA_REG: (i32, i32) = (4, 5); // a0, a1
 // https://github.com/gcc-mirror/gcc/blob/master/libstdc++-v3/libsupc++/eh_personality.cc
 // https://github.com/gcc-mirror/gcc/blob/trunk/libgcc/unwind-c.c
 
-cfg_if::cfg_if! {
-    if #[cfg(all(
+cfg_select! {
+    all(
         target_arch = "arm",
         not(target_vendor = "apple"),
         not(target_os = "netbsd"),
-    ))] {
+    ) => {
         /// personality fn called by [ARM EHABI][armeabi-eh]
         ///
         /// 32-bit ARM on iOS/tvOS/watchOS does not use ARM EHABI, it uses
@@ -202,7 +202,8 @@ cfg_if::cfg_if! {
                 }
             }
         }
-    } else {
+    }
+    _ => {
         /// Default personality routine, which is used directly on most targets
         /// and indirectly on Windows x86_64 and AArch64 via SEH.
         unsafe extern "C" fn rust_eh_personality_impl(
@@ -247,11 +248,11 @@ cfg_if::cfg_if! {
             }
         }
 
-        cfg_if::cfg_if! {
-            if #[cfg(any(
-                    all(windows, any(target_arch = "aarch64", target_arch = "x86_64"), target_env = "gnu"),
-                    target_os = "cygwin",
-                ))] {
+        cfg_select! {
+            any(
+                all(windows, any(target_arch = "aarch64", target_arch = "x86_64"), target_env = "gnu"),
+                target_os = "cygwin",
+            ) => {
                 /// personality fn called by [Windows Structured Exception Handling][windows-eh]
                 ///
                 /// On x86_64 and AArch64 MinGW targets, the unwinding mechanism is SEH,
@@ -279,7 +280,8 @@ cfg_if::cfg_if! {
                         )
                     }
                 }
-            } else {
+            }
+            _ => {
                 /// personality fn called by [Itanium C++ ABI Exception Handling][itanium-eh]
                 ///
                 /// The personality routine for most non-Windows targets. This will be called by
diff --git a/library/std/src/sys/personality/mod.rs b/library/std/src/sys/personality/mod.rs
index 2e1d2e53a29..158e44e1764 100644
--- a/library/std/src/sys/personality/mod.rs
+++ b/library/std/src/sys/personality/mod.rs
@@ -13,10 +13,11 @@
 mod dwarf;
 
 #[cfg(not(any(test, doctest)))]
-cfg_if::cfg_if! {
-    if #[cfg(target_os = "emscripten")] {
+cfg_select! {
+    target_os = "emscripten" => {
         mod emcc;
-    } else if #[cfg(any(target_env = "msvc", target_family = "wasm"))] {
+    }
+    any(target_env = "msvc", target_family = "wasm") => {
         // This is required by the compiler to exist (e.g., it's a lang item),
         // but it's never actually called by the compiler because
         // __CxxFrameHandler3 (msvc) / __gxx_wasm_personality_v0 (wasm) is the
@@ -26,16 +27,18 @@ cfg_if::cfg_if! {
         fn rust_eh_personality() {
             core::intrinsics::abort()
         }
-    } else if #[cfg(any(
+    }
+    any(
         all(target_family = "windows", target_env = "gnu"),
         target_os = "psp",
         target_os = "xous",
         target_os = "solid_asp3",
         all(target_family = "unix", not(target_os = "espidf"), not(target_os = "l4re"), not(target_os = "nuttx")),
         all(target_vendor = "fortanix", target_env = "sgx"),
-    ))] {
+    ) => {
         mod gcc;
-    } else {
+    }
+    _ => {
         // Targets that don't support unwinding.
         // - os=none ("bare metal" targets)
         // - os=uefi
diff --git a/library/std/src/sys/process/mod.rs b/library/std/src/sys/process/mod.rs
index 91c7005a328..9ef5496e57a 100644
--- a/library/std/src/sys/process/mod.rs
+++ b/library/std/src/sys/process/mod.rs
@@ -1,14 +1,17 @@
-cfg_if::cfg_if! {
-    if #[cfg(target_family = "unix")] {
+cfg_select! {
+    target_family = "unix" => {
         mod unix;
         use unix as imp;
-    } else if #[cfg(target_os = "windows")] {
+    }
+    target_os = "windows" => {
         mod windows;
         use windows as imp;
-    } else if #[cfg(target_os = "uefi")] {
+    }
+    target_os = "uefi" => {
         mod uefi;
         use uefi as imp;
-    } else {
+    }
+    _ => {
         mod unsupported;
         use unsupported as imp;
     }
diff --git a/library/std/src/sys/process/unix/common.rs b/library/std/src/sys/process/unix/common.rs
index 6219be60caf..ea45b08e90a 100644
--- a/library/std/src/sys/process/unix/common.rs
+++ b/library/std/src/sys/process/unix/common.rs
@@ -20,12 +20,14 @@ use crate::{fmt, io};
 
 mod cstring_array;
 
-cfg_if::cfg_if! {
-    if #[cfg(target_os = "fuchsia")] {
+cfg_select! {
+    target_os = "fuchsia" => {
         // fuchsia doesn't have /dev/null
-    } else if #[cfg(target_os = "vxworks")] {
+    }
+    target_os = "vxworks" => {
         const DEV_NULL: &CStr = c"/null";
-    } else {
+    }
+    _ => {
         const DEV_NULL: &CStr = c"/dev/null";
     }
 }
@@ -35,8 +37,8 @@ cfg_if::cfg_if! {
 // to support older Android version (independent of libc version).
 // The following implementations are based on
 // https://github.com/aosp-mirror/platform_bionic/blob/ad8dcd6023294b646e5a8288c0ed431b0845da49/libc/include/android/legacy_signal_inlines.h
-cfg_if::cfg_if! {
-    if #[cfg(target_os = "android")] {
+cfg_select! {
+    target_os = "android" => {
         #[allow(dead_code)]
         pub unsafe fn sigemptyset(set: *mut libc::sigset_t) -> libc::c_int {
             set.write_bytes(0u8, 1);
@@ -69,7 +71,8 @@ cfg_if::cfg_if! {
             raw[bit / LONG_BIT] |= 1 << (bit % LONG_BIT);
             return 0;
         }
-    } else {
+    }
+    _ => {
         #[allow(unused_imports)]
         pub use libc::{sigemptyset, sigaddset};
     }
diff --git a/library/std/src/sys/process/unix/mod.rs b/library/std/src/sys/process/unix/mod.rs
index ee8fd8b2ca3..b4cf060fba9 100644
--- a/library/std/src/sys/process/unix/mod.rs
+++ b/library/std/src/sys/process/unix/mod.rs
@@ -1,18 +1,21 @@
 #[cfg_attr(any(target_os = "espidf", target_os = "horizon", target_os = "nuttx"), allow(unused))]
 mod common;
 
-cfg_if::cfg_if! {
-    if #[cfg(target_os = "fuchsia")] {
+cfg_select! {
+    target_os = "fuchsia" => {
         mod fuchsia;
         use fuchsia as imp;
-    } else if #[cfg(target_os = "vxworks")] {
+    }
+    target_os = "vxworks" => {
         mod vxworks;
         use vxworks as imp;
-    } else if #[cfg(any(target_os = "espidf", target_os = "horizon", target_os = "vita", target_os = "nuttx"))] {
+    }
+    any(target_os = "espidf", target_os = "horizon", target_os = "vita", target_os = "nuttx") => {
         mod unsupported;
         use unsupported as imp;
         pub use unsupported::output;
-    } else {
+    }
+    _ => {
         mod unix;
         use unix as imp;
     }
diff --git a/library/std/src/sys/process/unix/unix.rs b/library/std/src/sys/process/unix/unix.rs
index 5d13d6da185..11d48878727 100644
--- a/library/std/src/sys/process/unix/unix.rs
+++ b/library/std/src/sys/process/unix/unix.rs
@@ -18,8 +18,8 @@ use crate::sys::cvt;
 use crate::sys::pal::linux::pidfd::PidFd;
 use crate::{fmt, mem, sys};
 
-cfg_if::cfg_if! {
-    if #[cfg(target_os = "nto")] {
+cfg_select! {
+    target_os = "nto" => {
         use crate::thread;
         use libc::{c_char, posix_spawn_file_actions_t, posix_spawnattr_t};
         use crate::time::Duration;
@@ -43,6 +43,7 @@ cfg_if::cfg_if! {
         // Maximum duration of sleeping before giving up and returning an error
         const MAX_FORKSPAWN_SLEEP: Duration = Duration::from_millis(1000);
     }
+    _ => {}
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -465,8 +466,8 @@ impl Command {
             return Ok(None);
         }
 
-        cfg_if::cfg_if! {
-            if #[cfg(target_os = "linux")] {
+        cfg_select! {
+            target_os = "linux" => {
                 use crate::sys::weak::weak;
 
                 weak!(
@@ -526,7 +527,8 @@ impl Command {
                     }
                     core::assert_matches::debug_assert_matches!(support, SPAWN | NO);
                 }
-            } else {
+            }
+            _ => {
                 if self.get_create_pidfd() {
                     unreachable!("only implemented on linux")
                 }
@@ -746,10 +748,11 @@ impl Command {
             }
 
             if self.get_setsid() {
-                cfg_if::cfg_if! {
-                    if #[cfg(all(target_os = "linux", target_env = "gnu"))] {
+                cfg_select! {
+                    all(target_os = "linux", target_env = "gnu") => {
                         flags |= libc::POSIX_SPAWN_SETSID;
-                    } else {
+                    }
+                    _ => {
                         return Ok(None);
                     }
                 }
diff --git a/library/std/src/sys/random/mod.rs b/library/std/src/sys/random/mod.rs
index fc85797dcc2..a7fbae86099 100644
--- a/library/std/src/sys/random/mod.rs
+++ b/library/std/src/sys/random/mod.rs
@@ -1,16 +1,19 @@
-cfg_if::cfg_if! {
+cfg_select! {
     // Tier 1
-    if #[cfg(any(target_os = "linux", target_os = "android"))] {
+    any(target_os = "linux", target_os = "android") => {
         mod linux;
         pub use linux::{fill_bytes, hashmap_random_keys};
-    } else if #[cfg(target_os = "windows")] {
+    }
+    target_os = "windows" => {
         mod windows;
         pub use windows::fill_bytes;
-    } else if #[cfg(target_vendor = "apple")] {
+    }
+    target_vendor = "apple" => {
         mod apple;
         pub use apple::fill_bytes;
     // Others, in alphabetical ordering.
-    } else if #[cfg(any(
+    }
+    any(
         target_os = "dragonfly",
         target_os = "freebsd",
         target_os = "haiku",
@@ -21,69 +24,86 @@ cfg_if::cfg_if! {
         target_os = "solaris",
         target_os = "vita",
         target_os = "nuttx",
-    ))] {
+    ) => {
         mod arc4random;
         pub use arc4random::fill_bytes;
-    } else if #[cfg(target_os = "emscripten")] {
+    }
+    target_os = "emscripten" => {
         mod getentropy;
         pub use getentropy::fill_bytes;
-    } else if #[cfg(target_os = "espidf")] {
+    }
+    target_os = "espidf" => {
         mod espidf;
         pub use espidf::fill_bytes;
-    } else if #[cfg(target_os = "fuchsia")] {
+    }
+    target_os = "fuchsia" => {
         mod fuchsia;
         pub use fuchsia::fill_bytes;
-    } else if #[cfg(target_os = "hermit")] {
+    }
+    target_os = "hermit" => {
         mod hermit;
         pub use hermit::fill_bytes;
-    } else if #[cfg(any(target_os = "horizon", target_os = "cygwin"))] {
+    }
+    any(target_os = "horizon", target_os = "cygwin") => {
         // FIXME(horizon): add arc4random_buf to shim-3ds
         mod getrandom;
         pub use getrandom::fill_bytes;
-    } else if #[cfg(any(
+    }
+    any(
         target_os = "aix",
         target_os = "hurd",
         target_os = "l4re",
         target_os = "nto",
-    ))] {
+    ) => {
         mod unix_legacy;
         pub use unix_legacy::fill_bytes;
-    } else if #[cfg(target_os = "redox")] {
+    }
+    target_os = "redox" => {
         mod redox;
         pub use redox::fill_bytes;
-    } else if #[cfg(all(target_vendor = "fortanix", target_env = "sgx"))] {
+    }
+    all(target_vendor = "fortanix", target_env = "sgx") => {
         mod sgx;
         pub use sgx::fill_bytes;
-    } else if #[cfg(target_os = "solid_asp3")] {
+    }
+    target_os = "solid_asp3" => {
         mod solid;
         pub use solid::fill_bytes;
-    } else if #[cfg(target_os = "teeos")] {
+    }
+    target_os = "teeos" => {
         mod teeos;
         pub use teeos::fill_bytes;
-    } else if #[cfg(target_os = "trusty")] {
+    }
+    target_os = "trusty" => {
         mod trusty;
         pub use trusty::fill_bytes;
-    } else if #[cfg(target_os = "uefi")] {
+    }
+    target_os = "uefi" => {
         mod uefi;
         pub use uefi::fill_bytes;
-    } else if #[cfg(target_os = "vxworks")] {
+    }
+    target_os = "vxworks" => {
         mod vxworks;
         pub use vxworks::fill_bytes;
-    } else if #[cfg(target_os = "wasi")] {
+    }
+    target_os = "wasi" => {
         mod wasi;
         pub use wasi::fill_bytes;
-    } else if #[cfg(target_os = "zkvm")] {
+    }
+    target_os = "zkvm" => {
         mod zkvm;
         pub use zkvm::fill_bytes;
-    } else if #[cfg(any(
+    }
+    any(
         all(target_family = "wasm", target_os = "unknown"),
         target_os = "xous",
-    ))] {
+    ) => {
         // FIXME: finally remove std support for wasm32-unknown-unknown
         // FIXME: add random data generation to xous
         mod unsupported;
         pub use unsupported::{fill_bytes, hashmap_random_keys};
     }
+    _ => {}
 }
 
 #[cfg(not(any(
diff --git a/library/std/src/sys/random/uefi.rs b/library/std/src/sys/random/uefi.rs
index 4a71d32fffe..697933f197b 100644
--- a/library/std/src/sys/random/uefi.rs
+++ b/library/std/src/sys/random/uefi.rs
@@ -55,12 +55,13 @@ mod rng_protocol {
 /// Port from [getrandom](https://github.com/rust-random/getrandom/blob/master/src/backends/rdrand.rs)
 #[cfg(any(target_arch = "x86_64", target_arch = "x86"))]
 mod rdrand {
-    cfg_if::cfg_if! {
-        if #[cfg(target_arch = "x86_64")] {
+    cfg_select! {
+        target_arch = "x86_64" => {
             use crate::arch::x86_64 as arch;
             use arch::_rdrand64_step as rdrand_step;
             type Word = u64;
-        } else if #[cfg(target_arch = "x86")] {
+        }
+        target_arch = "x86" => {
             use crate::arch::x86 as arch;
             use arch::_rdrand32_step as rdrand_step;
             type Word = u32;
diff --git a/library/std/src/sys/stdio/mod.rs b/library/std/src/sys/stdio/mod.rs
index 336d4c8527d..314f226f07b 100644
--- a/library/std/src/sys/stdio/mod.rs
+++ b/library/std/src/sys/stdio/mod.rs
@@ -1,40 +1,47 @@
 #![forbid(unsafe_op_in_unsafe_fn)]
 
-cfg_if::cfg_if! {
-    if #[cfg(any(
-        target_family = "unix",
-        target_os = "hermit"
-    ))] {
+cfg_select! {
+    any(target_family = "unix", target_os = "hermit") => {
         mod unix;
         pub use unix::*;
-    } else if #[cfg(target_os = "windows")] {
+    }
+    target_os = "windows" => {
         mod windows;
         pub use windows::*;
-    } else if #[cfg(all(target_vendor = "fortanix", target_env = "sgx"))] {
+    }
+    all(target_vendor = "fortanix", target_env = "sgx") => {
         mod sgx;
         pub use sgx::*;
-    } else if #[cfg(target_os = "solid_asp3")] {
+    }
+    target_os = "solid_asp3" => {
         mod solid;
         pub use solid::*;
-    } else if #[cfg(target_os = "teeos")] {
+    }
+    target_os = "teeos" => {
         mod teeos;
         pub use teeos::*;
-    } else if #[cfg(target_os = "trusty")] {
+    }
+    target_os = "trusty" => {
         mod trusty;
         pub use trusty::*;
-    } else if #[cfg(target_os = "uefi")] {
+    }
+    target_os = "uefi" => {
         mod uefi;
         pub use uefi::*;
-    } else if #[cfg(target_os = "wasi")] {
+    }
+    target_os = "wasi" => {
         mod wasi;
         pub use wasi::*;
-    } else if #[cfg(target_os = "xous")] {
+    }
+    target_os = "xous" => {
         mod xous;
         pub use xous::*;
-    } else if #[cfg(target_os = "zkvm")] {
+    }
+    target_os = "zkvm" => {
         mod zkvm;
         pub use zkvm::*;
-    } else {
+    }
+    _ => {
         mod unsupported;
         pub use unsupported::*;
     }
diff --git a/library/std/src/sys/sync/condvar/mod.rs b/library/std/src/sys/sync/condvar/mod.rs
index d0c998a5597..cb67d273759 100644
--- a/library/std/src/sys/sync/condvar/mod.rs
+++ b/library/std/src/sys/sync/condvar/mod.rs
@@ -1,5 +1,5 @@
-cfg_if::cfg_if! {
-    if #[cfg(any(
+cfg_select! {
+    any(
         all(target_os = "windows", not(target_vendor="win7")),
         target_os = "linux",
         target_os = "android",
@@ -9,28 +9,34 @@ cfg_if::cfg_if! {
         target_os = "fuchsia",
         all(target_family = "wasm", target_feature = "atomics"),
         target_os = "hermit",
-    ))] {
+    ) => {
         mod futex;
         pub use futex::Condvar;
-    } else if #[cfg(any(
+    }
+    any(
         target_family = "unix",
         target_os = "teeos",
-    ))] {
+    ) => {
         mod pthread;
         pub use pthread::Condvar;
-    } else if #[cfg(all(target_os = "windows", target_vendor = "win7"))] {
+    }
+    all(target_os = "windows", target_vendor = "win7") => {
         mod windows7;
         pub use windows7::Condvar;
-    } else if #[cfg(all(target_vendor = "fortanix", target_env = "sgx"))] {
+    }
+    all(target_vendor = "fortanix", target_env = "sgx") => {
         mod sgx;
         pub use sgx::Condvar;
-    } else if #[cfg(target_os = "solid_asp3")] {
+    }
+    target_os = "solid_asp3" => {
         mod itron;
         pub use itron::Condvar;
-    } else if #[cfg(target_os = "xous")] {
+    }
+    target_os = "xous" => {
         mod xous;
         pub use xous::Condvar;
-    } else {
+    }
+    _ => {
         mod no_threads;
         pub use no_threads::Condvar;
     }
diff --git a/library/std/src/sys/sync/mutex/mod.rs b/library/std/src/sys/sync/mutex/mod.rs
index 360df3fc4b5..c885b0eabae 100644
--- a/library/std/src/sys/sync/mutex/mod.rs
+++ b/library/std/src/sys/sync/mutex/mod.rs
@@ -1,5 +1,5 @@
-cfg_if::cfg_if! {
-    if #[cfg(any(
+cfg_select! {
+    any(
         all(target_os = "windows", not(target_vendor = "win7")),
         target_os = "linux",
         target_os = "android",
@@ -8,31 +8,38 @@ cfg_if::cfg_if! {
         target_os = "dragonfly",
         all(target_family = "wasm", target_feature = "atomics"),
         target_os = "hermit",
-    ))] {
+    ) => {
         mod futex;
         pub use futex::Mutex;
-    } else if #[cfg(target_os = "fuchsia")] {
+    }
+    target_os = "fuchsia" => {
         mod fuchsia;
         pub use fuchsia::Mutex;
-    } else if #[cfg(any(
+    }
+    any(
         target_family = "unix",
         target_os = "teeos",
-    ))] {
+    ) => {
         mod pthread;
         pub use pthread::Mutex;
-    } else if #[cfg(all(target_os = "windows", target_vendor = "win7"))] {
+    }
+    all(target_os = "windows", target_vendor = "win7") => {
         mod windows7;
         pub use windows7::{Mutex, raw};
-    } else if #[cfg(all(target_vendor = "fortanix", target_env = "sgx"))] {
+    }
+    all(target_vendor = "fortanix", target_env = "sgx") => {
         mod sgx;
         pub use sgx::Mutex;
-    } else if #[cfg(target_os = "solid_asp3")] {
+    }
+    target_os = "solid_asp3" => {
         mod itron;
         pub use itron::Mutex;
-    } else if #[cfg(target_os = "xous")] {
+    }
+    target_os = "xous" => {
         mod xous;
         pub use xous::Mutex;
-    } else {
+    }
+    _ => {
         mod no_threads;
         pub use no_threads::Mutex;
     }
diff --git a/library/std/src/sys/sync/once/mod.rs b/library/std/src/sys/sync/once/mod.rs
index 0e38937b121..8adeb1f259d 100644
--- a/library/std/src/sys/sync/once/mod.rs
+++ b/library/std/src/sys/sync/once/mod.rs
@@ -7,8 +7,8 @@
 // This also gives us the opportunity to optimize the implementation a bit which
 // should help the fast path on call sites.
 
-cfg_if::cfg_if! {
-    if #[cfg(any(
+cfg_select! {
+    any(
         all(target_os = "windows", not(target_vendor="win7")),
         target_os = "linux",
         target_os = "android",
@@ -18,19 +18,21 @@ cfg_if::cfg_if! {
         target_os = "dragonfly",
         target_os = "fuchsia",
         target_os = "hermit",
-    ))] {
+    ) => {
         mod futex;
         pub use futex::{Once, OnceState};
-    } else if #[cfg(any(
+    }
+    any(
         windows,
         target_family = "unix",
         all(target_vendor = "fortanix", target_env = "sgx"),
         target_os = "solid_asp3",
         target_os = "xous",
-    ))] {
+    ) => {
         mod queue;
         pub use queue::{Once, OnceState};
-    } else {
+    }
+    _ => {
         mod no_threads;
         pub use no_threads::{Once, OnceState};
     }
diff --git a/library/std/src/sys/sync/rwlock/mod.rs b/library/std/src/sys/sync/rwlock/mod.rs
index 70ba6bf38ef..82f1dd18dee 100644
--- a/library/std/src/sys/sync/rwlock/mod.rs
+++ b/library/std/src/sys/sync/rwlock/mod.rs
@@ -1,5 +1,5 @@
-cfg_if::cfg_if! {
-    if #[cfg(any(
+cfg_select! {
+    any(
         all(target_os = "windows", not(target_vendor = "win7")),
         target_os = "linux",
         target_os = "android",
@@ -9,24 +9,28 @@ cfg_if::cfg_if! {
         target_os = "fuchsia",
         all(target_family = "wasm", target_feature = "atomics"),
         target_os = "hermit",
-    ))] {
+    ) => {
         mod futex;
         pub use futex::RwLock;
-    } else if #[cfg(any(
+    }
+    any(
         target_family = "unix",
         all(target_os = "windows", target_vendor = "win7"),
         all(target_vendor = "fortanix", target_env = "sgx"),
         target_os = "xous",
-    ))] {
+    ) => {
         mod queue;
         pub use queue::RwLock;
-    } else if #[cfg(target_os = "solid_asp3")] {
+    }
+    target_os = "solid_asp3" => {
         mod solid;
         pub use solid::RwLock;
-    } else if #[cfg(target_os = "teeos")] {
+    }
+    target_os = "teeos" => {
         mod teeos;
         pub use teeos::RwLock;
-    } else {
+    }
+    _ => {
         mod no_threads;
         pub use no_threads::RwLock;
     }
diff --git a/library/std/src/sys/sync/thread_parking/mod.rs b/library/std/src/sys/sync/thread_parking/mod.rs
index f4d8fa0a58c..b9fb27b4eef 100644
--- a/library/std/src/sys/sync/thread_parking/mod.rs
+++ b/library/std/src/sys/sync/thread_parking/mod.rs
@@ -1,5 +1,5 @@
-cfg_if::cfg_if! {
-    if #[cfg(any(
+cfg_select! {
+    any(
         all(target_os = "windows", not(target_vendor = "win7")),
         target_os = "linux",
         target_os = "android",
@@ -9,30 +9,36 @@ cfg_if::cfg_if! {
         target_os = "dragonfly",
         target_os = "fuchsia",
         target_os = "hermit",
-    ))] {
+    ) => {
         mod futex;
         pub use futex::Parker;
-    } else if #[cfg(any(
+    }
+    any(
         target_os = "netbsd",
         all(target_vendor = "fortanix", target_env = "sgx"),
         target_os = "solid_asp3",
-    ))] {
+    ) => {
         mod id;
         pub use id::Parker;
-    } else if #[cfg(target_vendor = "win7")] {
+    }
+    target_vendor = "win7" => {
         mod windows7;
         pub use windows7::Parker;
-    } else if #[cfg(all(target_vendor = "apple", not(miri)))] {
+    }
+    all(target_vendor = "apple", not(miri)) => {
         // Doesn't work in Miri, see <https://github.com/rust-lang/miri/issues/2589>.
         mod darwin;
         pub use darwin::Parker;
-    } else if #[cfg(target_os = "xous")] {
+    }
+    target_os = "xous" => {
         mod xous;
         pub use xous::Parker;
-    } else if #[cfg(target_family = "unix")] {
+    }
+    target_family = "unix" => {
         mod pthread;
         pub use pthread::Parker;
-    } else {
+    }
+    _ => {
         mod unsupported;
         pub use unsupported::Parker;
     }
diff --git a/library/std/src/sys/thread_local/mod.rs b/library/std/src/sys/thread_local/mod.rs
index 9fafac3aa5b..cff74857c47 100644
--- a/library/std/src/sys/thread_local/mod.rs
+++ b/library/std/src/sys/thread_local/mod.rs
@@ -23,21 +23,23 @@
     issue = "none"
 )]
 
-cfg_if::cfg_if! {
-    if #[cfg(any(
+cfg_select! {
+    any(
         all(target_family = "wasm", not(target_feature = "atomics")),
         target_os = "uefi",
         target_os = "zkvm",
         target_os = "trusty",
-    ))] {
+    ) => {
         mod no_threads;
         pub use no_threads::{EagerStorage, LazyStorage, thread_local_inner};
         pub(crate) use no_threads::{LocalPointer, local_pointer};
-    } else if #[cfg(target_thread_local)] {
+    }
+    target_thread_local => {
         mod native;
         pub use native::{EagerStorage, LazyStorage, thread_local_inner};
         pub(crate) use native::{LocalPointer, local_pointer};
-    } else {
+    }
+    _ => {
         mod os;
         pub use os::{Storage, thread_local_inner};
         pub(crate) use os::{LocalPointer, local_pointer};
@@ -53,8 +55,8 @@ cfg_if::cfg_if! {
 /// single callback that runs all of the destructors in the list.
 #[cfg(all(target_thread_local, not(all(target_family = "wasm", not(target_feature = "atomics")))))]
 pub(crate) mod destructors {
-    cfg_if::cfg_if! {
-        if #[cfg(any(
+    cfg_select! {
+        any(
             target_os = "linux",
             target_os = "android",
             target_os = "fuchsia",
@@ -62,12 +64,13 @@ pub(crate) mod destructors {
             target_os = "hurd",
             target_os = "netbsd",
             target_os = "dragonfly"
-        ))] {
+        ) => {
             mod linux_like;
             mod list;
             pub(super) use linux_like::register;
             pub(super) use list::run;
-        } else {
+        }
+        _ => {
             mod list;
             pub(super) use list::register;
             pub(crate) use list::run;
@@ -79,21 +82,23 @@ pub(crate) mod destructors {
 /// and the [runtime cleanup](crate::rt::thread_cleanup) function. Calling `enable`
 /// should ensure that these functions are called at the right times.
 pub(crate) mod guard {
-    cfg_if::cfg_if! {
-        if #[cfg(all(target_thread_local, target_vendor = "apple"))] {
+    cfg_select! {
+        all(target_thread_local, target_vendor = "apple") => {
             mod apple;
             pub(crate) use apple::enable;
-        } else if #[cfg(target_os = "windows")] {
+        }
+        target_os = "windows" => {
             mod windows;
             pub(crate) use windows::enable;
-        } else if #[cfg(any(
+        }
+        any(
             all(target_family = "wasm", not(
                 all(target_os = "wasi", target_env = "p1", target_feature = "atomics")
             )),
             target_os = "uefi",
             target_os = "zkvm",
             target_os = "trusty",
-        ))] {
+        ) => {
             pub(crate) fn enable() {
                 // FIXME: Right now there is no concept of "thread exit" on
                 // wasm, but this is likely going to show up at some point in
@@ -107,17 +112,20 @@ pub(crate) mod guard {
                 #[allow(unused)]
                 use crate::rt::thread_cleanup;
             }
-        } else if #[cfg(any(
+        }
+        any(
             target_os = "hermit",
             target_os = "xous",
-        ))] {
+        ) => {
             // `std` is the only runtime, so it just calls the destructor functions
             // itself when the time comes.
             pub(crate) fn enable() {}
-        } else if #[cfg(target_os = "solid_asp3")] {
+        }
+        target_os = "solid_asp3" => {
             mod solid;
             pub(crate) use solid::enable;
-        } else {
+        }
+        _ => {
             mod key;
             pub(crate) use key::enable;
         }
@@ -131,8 +139,8 @@ pub(crate) mod guard {
 /// reference an entry in a thread-local table. This then associates each key
 /// with a pointer which we can get and set to store our data.
 pub(crate) mod key {
-    cfg_if::cfg_if! {
-        if #[cfg(any(
+    cfg_select! {
+        any(
             all(
                 not(target_vendor = "apple"),
                 not(target_family = "wasm"),
@@ -141,7 +149,7 @@ pub(crate) mod key {
             all(not(target_thread_local), target_vendor = "apple"),
             target_os = "teeos",
             all(target_os = "wasi", target_env = "p1", target_feature = "atomics"),
-        ))] {
+        ) => {
             mod racy;
             mod unix;
             #[cfg(test)]
@@ -151,12 +159,14 @@ pub(crate) mod key {
             #[cfg(any(not(target_thread_local), test))]
             pub(super) use unix::get;
             use unix::{create, destroy};
-        } else if #[cfg(all(not(target_thread_local), target_os = "windows"))] {
+        }
+        all(not(target_thread_local), target_os = "windows") => {
             #[cfg(test)]
             mod tests;
             mod windows;
             pub(super) use windows::{Key, LazyKey, get, run_dtors, set};
-        } else if #[cfg(all(target_vendor = "fortanix", target_env = "sgx"))] {
+        }
+        all(target_vendor = "fortanix", target_env = "sgx") => {
             mod racy;
             mod sgx;
             #[cfg(test)]
@@ -164,7 +174,8 @@ pub(crate) mod key {
             pub(super) use racy::LazyKey;
             pub(super) use sgx::{Key, get, set};
             use sgx::{create, destroy};
-        } else if #[cfg(target_os = "xous")] {
+        }
+        target_os = "xous" => {
             mod racy;
             #[cfg(test)]
             mod tests;
@@ -174,6 +185,7 @@ pub(crate) mod key {
             pub(super) use xous::{Key, get, set};
             use xous::{create, destroy};
         }
+        _ => {}
     }
 }
 
diff --git a/library/std/src/thread/current.rs b/library/std/src/thread/current.rs
index 5c879903526..7da1621da45 100644
--- a/library/std/src/thread/current.rs
+++ b/library/std/src/thread/current.rs
@@ -18,8 +18,8 @@ local_pointer! {
 pub(super) mod id {
     use super::*;
 
-    cfg_if::cfg_if! {
-        if #[cfg(target_thread_local)] {
+    cfg_select! {
+        target_thread_local => {
             use crate::cell::Cell;
 
             #[thread_local]
@@ -34,7 +34,8 @@ pub(super) mod id {
             pub(super) fn set(id: ThreadId) {
                 ID.set(Some(id))
             }
-        } else if #[cfg(target_pointer_width = "16")] {
+        }
+        target_pointer_width = "16" => {
             local_pointer! {
                 static ID0;
                 static ID16;
@@ -59,7 +60,8 @@ pub(super) mod id {
                 ID32.set(ptr::without_provenance_mut((val >> 32) as usize));
                 ID48.set(ptr::without_provenance_mut((val >> 48) as usize));
             }
-        } else if #[cfg(target_pointer_width = "32")] {
+        }
+        target_pointer_width = "32" => {
             local_pointer! {
                 static ID0;
                 static ID32;
@@ -78,7 +80,8 @@ pub(super) mod id {
                 ID0.set(ptr::without_provenance_mut(val as usize));
                 ID32.set(ptr::without_provenance_mut((val >> 32) as usize));
             }
-        } else {
+        }
+        _ => {
             local_pointer! {
                 static ID;
             }
diff --git a/library/std/src/thread/mod.rs b/library/std/src/thread/mod.rs
index 292323d0118..b6059c28cec 100644
--- a/library/std/src/thread/mod.rs
+++ b/library/std/src/thread/mod.rs
@@ -1212,8 +1212,8 @@ impl ThreadId {
             panic!("failed to generate unique thread ID: bitspace exhausted")
         }
 
-        cfg_if::cfg_if! {
-            if #[cfg(target_has_atomic = "64")] {
+        cfg_select! {
+            target_has_atomic = "64" => {
                 use crate::sync::atomic::{Atomic, AtomicU64};
 
                 static COUNTER: Atomic<u64> = AtomicU64::new(0);
@@ -1229,7 +1229,8 @@ impl ThreadId {
                         Err(id) => last = id,
                     }
                 }
-            } else {
+            }
+            _ => {
                 use crate::sync::{Mutex, PoisonError};
 
                 static COUNTER: Mutex<u64> = Mutex::new(0);
@@ -1318,8 +1319,8 @@ use thread_name_string::ThreadNameString;
 /// Note however that this also means that the name reported in pre-main functions
 /// will be incorrect, but that's just something we have to live with.
 pub(crate) mod main_thread {
-    cfg_if::cfg_if! {
-        if #[cfg(target_has_atomic = "64")] {
+    cfg_select! {
+        target_has_atomic = "64" => {
             use super::ThreadId;
             use crate::sync::atomic::{Atomic, AtomicU64};
             use crate::sync::atomic::Ordering::Relaxed;
@@ -1335,7 +1336,8 @@ pub(crate) mod main_thread {
             pub(crate) unsafe fn set(id: ThreadId) {
                 MAIN.store(id.as_u64().get(), Relaxed)
             }
-        } else {
+        }
+        _ => {
             use super::ThreadId;
             use crate::mem::MaybeUninit;
             use crate::sync::atomic::{Atomic, AtomicBool};
diff --git a/library/std/tests/env_modify.rs b/library/std/tests/env_modify.rs
index ba84978b35f..fe0ae68806e 100644
--- a/library/std/tests/env_modify.rs
+++ b/library/std/tests/env_modify.rs
@@ -1,5 +1,6 @@
 // These tests are in a separate integration test as they modify the environment,
 // and would otherwise cause some other tests to fail.
+#![feature(cfg_select)]
 
 use std::env::*;
 use std::ffi::{OsStr, OsString};
@@ -110,8 +111,8 @@ fn env_home_dir() {
         }
     }
 
-    cfg_if::cfg_if! {
-        if #[cfg(unix)] {
+    cfg_select! {
+        unix => {
             let oldhome = var_to_os_string(var("HOME"));
 
             unsafe {
@@ -130,7 +131,8 @@ fn env_home_dir() {
             }
 
             if let Some(oldhome) = oldhome { unsafe { set_var("HOME", oldhome); } }
-        } else if #[cfg(windows)] {
+        }
+        windows => {
             let oldhome = var_to_os_string(var("HOME"));
             let olduserprofile = var_to_os_string(var("USERPROFILE"));
 
@@ -159,6 +161,7 @@ fn env_home_dir() {
                 if let Some(olduserprofile) = olduserprofile { set_var("USERPROFILE", olduserprofile); }
             }
         }
+        _ => {}
     }
 }
 
diff --git a/library/std_detect/Cargo.toml b/library/std_detect/Cargo.toml
index 8d91454726b..33e6617c381 100644
--- a/library/std_detect/Cargo.toml
+++ b/library/std_detect/Cargo.toml
@@ -21,7 +21,6 @@ is-it-maintained-open-issues = { repository = "rust-lang/stdarch" }
 maintenance = { status = "experimental" }
 
 [dependencies]
-cfg-if = "1.0.0"
 core = { path = "../core" }
 alloc = { path = "../alloc" }
 
diff --git a/library/std_detect/src/detect/arch/loongarch.rs b/library/std_detect/src/detect/arch/loongarch.rs
index 68fc600fa8e..d5a442fbbb8 100644
--- a/library/std_detect/src/detect/arch/loongarch.rs
+++ b/library/std_detect/src/detect/arch/loongarch.rs
@@ -8,6 +8,7 @@ features! {
     /// Checks if `loongarch` feature is enabled.
     /// Supported arguments are:
     ///
+    /// * `"32s"`
     /// * `"f"`
     /// * `"d"`
     /// * `"frecipe"`
@@ -22,6 +23,8 @@ features! {
     /// * `"lvz"`
     /// * `"ual"`
     #[stable(feature = "stdarch_loongarch_feature", since = "1.89.0")]
+    @FEATURE: #[unstable(feature = "stdarch_loongarch_feature_detection", issue = "117425")] _32s: "32s";
+    /// 32S
     @FEATURE: #[stable(feature = "stdarch_loongarch_feature", since = "1.89.0")] f: "f";
     /// F
     @FEATURE: #[stable(feature = "stdarch_loongarch_feature", since = "1.89.0")] d: "d";
diff --git a/library/std_detect/src/detect/arch/mod.rs b/library/std_detect/src/detect/arch/mod.rs
index b0be554ed89..c066b9cc681 100644
--- a/library/std_detect/src/detect/arch/mod.rs
+++ b/library/std_detect/src/detect/arch/mod.rs
@@ -1,7 +1,5 @@
 #![allow(dead_code)]
 
-use cfg_if::cfg_if;
-
 // Export the macros for all supported architectures.
 #[macro_use]
 mod x86;
@@ -24,38 +22,48 @@ mod loongarch;
 #[macro_use]
 mod s390x;
 
-cfg_if! {
-    if #[cfg(any(target_arch = "x86", target_arch = "x86_64"))] {
+cfg_select! {
+    any(target_arch = "x86", target_arch = "x86_64") => {
         #[stable(feature = "simd_x86", since = "1.27.0")]
         pub use x86::*;
-    } else if #[cfg(target_arch = "arm")] {
+    }
+    target_arch = "arm" => {
         #[unstable(feature = "stdarch_arm_feature_detection", issue = "111190")]
         pub use arm::*;
-    } else if #[cfg(any(target_arch = "aarch64", target_arch = "arm64ec"))] {
+    }
+    any(target_arch = "aarch64", target_arch = "arm64ec") => {
         #[stable(feature = "simd_aarch64", since = "1.60.0")]
         pub use aarch64::*;
-    } else if #[cfg(any(target_arch = "riscv32", target_arch = "riscv64"))] {
+    }
+    any(target_arch = "riscv32", target_arch = "riscv64") => {
         #[unstable(feature = "stdarch_riscv_feature_detection", issue = "111192")]
         pub use riscv::*;
-    } else if #[cfg(target_arch = "powerpc")] {
+    }
+    target_arch = "powerpc" => {
         #[unstable(feature = "stdarch_powerpc_feature_detection", issue = "111191")]
         pub use powerpc::*;
-    } else if #[cfg(target_arch = "powerpc64")] {
+    }
+    target_arch = "powerpc64" => {
         #[unstable(feature = "stdarch_powerpc_feature_detection", issue = "111191")]
         pub use powerpc64::*;
-    } else if #[cfg(target_arch = "mips")] {
+    }
+    target_arch = "mips" => {
         #[unstable(feature = "stdarch_mips_feature_detection", issue = "111188")]
         pub use mips::*;
-    } else if #[cfg(target_arch = "mips64")] {
+    }
+    target_arch = "mips64" => {
         #[unstable(feature = "stdarch_mips_feature_detection", issue = "111188")]
         pub use mips64::*;
-    } else if #[cfg(any(target_arch = "loongarch32", target_arch = "loongarch64"))] {
+    }
+    any(target_arch = "loongarch32", target_arch = "loongarch64") => {
         #[stable(feature = "stdarch_loongarch_feature", since = "1.89.0")]
         pub use loongarch::*;
-    } else if #[cfg(target_arch = "s390x")] {
+    }
+    target_arch = "s390x" => {
         #[unstable(feature = "stdarch_s390x_feature_detection", issue = "135413")]
         pub use s390x::*;
-    } else {
+    }
+    _ => {
         // Unimplemented architecture:
         #[doc(hidden)]
         pub(crate) enum Feature {
diff --git a/library/std_detect/src/detect/cache.rs b/library/std_detect/src/detect/cache.rs
index 1a42e091463..c0c0b7b7f86 100644
--- a/library/std_detect/src/detect/cache.rs
+++ b/library/std_detect/src/detect/cache.rs
@@ -101,8 +101,8 @@ impl Cache {
     }
 }
 
-cfg_if::cfg_if! {
-    if #[cfg(feature = "std_detect_env_override")] {
+cfg_select! {
+    feature = "std_detect_env_override" => {
         #[inline]
         fn disable_features(disable: &[u8], value: &mut Initializer) {
             if let Ok(disable) = core::str::from_utf8(disable) {
@@ -116,8 +116,8 @@ cfg_if::cfg_if! {
         fn initialize(mut value: Initializer) -> Initializer {
             use core::ffi::CStr;
             const RUST_STD_DETECT_UNSTABLE: &CStr = c"RUST_STD_DETECT_UNSTABLE";
-            cfg_if::cfg_if! {
-                if #[cfg(windows)] {
+            cfg_select! {
+                windows => {
                     use alloc::vec;
                     #[link(name = "kernel32")]
                     unsafe extern "system" {
@@ -132,7 +132,8 @@ cfg_if::cfg_if! {
                             disable_features(&env[..len as usize], &mut value);
                         }
                     }
-                } else {
+                }
+                _ => {
                     let env = unsafe {
                         libc::getenv(RUST_STD_DETECT_UNSTABLE.as_ptr())
                     };
@@ -146,7 +147,8 @@ cfg_if::cfg_if! {
             do_initialize(value);
             value
         }
-    } else {
+    }
+    _ => {
         #[inline]
         fn initialize(value: Initializer) -> Initializer {
             do_initialize(value);
diff --git a/library/std_detect/src/detect/mod.rs b/library/std_detect/src/detect/mod.rs
index f936a5a1345..2bc6e9a24db 100644
--- a/library/std_detect/src/detect/mod.rs
+++ b/library/std_detect/src/detect/mod.rs
@@ -17,8 +17,6 @@
 //! due to security concerns (x86 is the big exception). These functions are
 //! implemented in the `os/{target_os}.rs` modules.
 
-use cfg_if::cfg_if;
-
 #[macro_use]
 mod macros;
 
@@ -34,8 +32,8 @@ pub(crate) use self::arch::Feature;
 mod bit;
 mod cache;
 
-cfg_if! {
-    if #[cfg(miri)] {
+cfg_select! {
+    miri => {
         // When running under miri all target-features that are not enabled at
         // compile-time are reported as disabled at run-time.
         //
@@ -43,35 +41,42 @@ cfg_if! {
         // this run-time detection logic is never called.
         #[path = "os/other.rs"]
         mod os;
-    } else if #[cfg(any(target_arch = "x86", target_arch = "x86_64"))] {
+    }
+    any(target_arch = "x86", target_arch = "x86_64") => {
         // On x86/x86_64 no OS specific functionality is required.
         #[path = "os/x86.rs"]
         mod os;
-    } else if #[cfg(all(any(target_os = "linux", target_os = "android"), feature = "libc"))] {
+    }
+    all(any(target_os = "linux", target_os = "android"), feature = "libc") => {
         #[cfg(any(target_arch = "riscv32", target_arch = "riscv64"))]
         #[path = "os/riscv.rs"]
         mod riscv;
         #[path = "os/linux/mod.rs"]
         mod os;
-    } else if #[cfg(all(target_os = "freebsd", feature = "libc"))] {
+    }
+    all(target_os = "freebsd", feature = "libc") => {
         #[cfg(target_arch = "aarch64")]
         #[path = "os/aarch64.rs"]
         mod aarch64;
         #[path = "os/freebsd/mod.rs"]
         mod os;
-    } else if #[cfg(all(target_os = "openbsd", target_arch = "aarch64", feature = "libc"))] {
+    }
+    all(target_os = "openbsd", target_arch = "aarch64", feature = "libc") => {
         #[allow(dead_code)] // we don't use code that calls the mrs instruction.
         #[path = "os/aarch64.rs"]
         mod aarch64;
         #[path = "os/openbsd/aarch64.rs"]
         mod os;
-    } else if #[cfg(all(target_os = "windows", any(target_arch = "aarch64", target_arch = "arm64ec")))] {
+    }
+    all(target_os = "windows", any(target_arch = "aarch64", target_arch = "arm64ec")) => {
         #[path = "os/windows/aarch64.rs"]
         mod os;
-    } else if #[cfg(all(target_vendor = "apple", target_arch = "aarch64", feature = "libc"))] {
+    }
+    all(target_vendor = "apple", target_arch = "aarch64", feature = "libc") => {
         #[path = "os/darwin/aarch64.rs"]
         mod os;
-    } else {
+    }
+    _ => {
         #[path = "os/other.rs"]
         mod os;
     }
@@ -89,8 +94,8 @@ fn check_for(x: Feature) -> bool {
 /// is `true` if the feature is supported by the host and `false` otherwise.
 #[unstable(feature = "stdarch_internal", issue = "none")]
 pub fn features() -> impl Iterator<Item = (&'static str, bool)> {
-    cfg_if! {
-        if #[cfg(any(
+    cfg_select! {
+        any(
             target_arch = "x86",
             target_arch = "x86_64",
             target_arch = "arm",
@@ -105,7 +110,7 @@ pub fn features() -> impl Iterator<Item = (&'static str, bool)> {
             target_arch = "loongarch32",
             target_arch = "loongarch64",
             target_arch = "s390x",
-        ))] {
+        ) => {
             (0_u8..Feature::_last as u8).map(|discriminant: u8| {
                 #[allow(bindings_with_variant_name)] // RISC-V has Feature::f
                 let f: Feature = unsafe { core::mem::transmute(discriminant) };
@@ -113,8 +118,7 @@ pub fn features() -> impl Iterator<Item = (&'static str, bool)> {
                 let enabled: bool = check_for(f);
                 (name, enabled)
             })
-        } else {
-            None.into_iter()
         }
+        _ => None.into_iter(),
     }
 }
diff --git a/library/std_detect/src/detect/os/freebsd/mod.rs b/library/std_detect/src/detect/os/freebsd/mod.rs
index ade7fb6269d..7de9250e835 100644
--- a/library/std_detect/src/detect/os/freebsd/mod.rs
+++ b/library/std_detect/src/detect/os/freebsd/mod.rs
@@ -2,17 +2,20 @@
 
 mod auxvec;
 
-cfg_if::cfg_if! {
-    if #[cfg(target_arch = "aarch64")] {
+cfg_select! {
+    target_arch = "aarch64" => {
         mod aarch64;
         pub(crate) use self::aarch64::detect_features;
-    } else if #[cfg(target_arch = "arm")] {
+    }
+    target_arch = "arm" => {
         mod arm;
         pub(crate) use self::arm::detect_features;
-    } else if #[cfg(target_arch = "powerpc64")] {
+    }
+    target_arch = "powerpc64" => {
         mod powerpc;
         pub(crate) use self::powerpc::detect_features;
-    } else {
+    }
+    _ => {
         use crate::detect::cache;
         /// Performs run-time feature detection.
         pub(crate) fn detect_features() -> cache::Initializer {
diff --git a/library/std_detect/src/detect/os/linux/auxvec.rs b/library/std_detect/src/detect/os/linux/auxvec.rs
index 443caaaa186..75e01bdc449 100644
--- a/library/std_detect/src/detect/os/linux/auxvec.rs
+++ b/library/std_detect/src/detect/os/linux/auxvec.rs
@@ -131,15 +131,15 @@ pub(crate) fn auxv() -> Result<AuxVec, ()> {
 /// `getauxval` function. If the function is not linked, this function return `Err`.
 fn getauxval(key: usize) -> Result<usize, ()> {
     type F = unsafe extern "C" fn(libc::c_ulong) -> libc::c_ulong;
-    cfg_if::cfg_if! {
-        if #[cfg(all(
+    cfg_select! {
+        all(
             feature = "std_detect_dlsym_getauxval",
             not(all(
                 target_os = "linux",
                 any(target_env = "gnu", target_env = "musl", target_env = "ohos"),
             )),
             not(target_os = "android"),
-        ))] {
+        ) => {
             let ffi_getauxval: F = unsafe {
                 let ptr = libc::dlsym(libc::RTLD_DEFAULT, c"getauxval".as_ptr());
                 if ptr.is_null() {
@@ -147,7 +147,8 @@ fn getauxval(key: usize) -> Result<usize, ()> {
                 }
                 core::mem::transmute(ptr)
             };
-        } else {
+        }
+        _ => {
             let ffi_getauxval: F = libc::getauxval;
         }
     }
diff --git a/library/std_detect/src/detect/os/linux/auxvec/tests.rs b/library/std_detect/src/detect/os/linux/auxvec/tests.rs
index 536615fa272..631a3e5e9ef 100644
--- a/library/std_detect/src/detect/os/linux/auxvec/tests.rs
+++ b/library/std_detect/src/detect/os/linux/auxvec/tests.rs
@@ -42,8 +42,8 @@ fn auxv_dump() {
 }
 
 #[cfg(feature = "std_detect_file_io")]
-cfg_if::cfg_if! {
-    if #[cfg(target_arch = "arm")] {
+cfg_select! {
+    target_arch = "arm" => {
         // The tests below can be executed under qemu, where we do not have access to the test
         // files on disk, so we need to embed them with `include_bytes!`.
         #[test]
@@ -62,7 +62,8 @@ cfg_if::cfg_if! {
             assert_eq!(v.hwcap, 126614527);
             assert_eq!(v.hwcap2, 0);
         }
-    } else if #[cfg(target_arch = "aarch64")] {
+    }
+    target_arch = "aarch64" => {
         #[cfg(target_endian = "little")]
         #[test]
         fn linux_artificial_aarch64() {
@@ -81,6 +82,7 @@ cfg_if::cfg_if! {
             assert_eq!(v.hwcap2, 0);
         }
     }
+    _ => {}
 }
 
 #[test]
diff --git a/library/std_detect/src/detect/os/linux/loongarch.rs b/library/std_detect/src/detect/os/linux/loongarch.rs
index e97fda11d08..74415266f8b 100644
--- a/library/std_detect/src/detect/os/linux/loongarch.rs
+++ b/library/std_detect/src/detect/os/linux/loongarch.rs
@@ -17,22 +17,21 @@ pub(crate) fn detect_features() -> cache::Initializer {
     // The values are part of the platform-specific [cpucfg]
     //
     // [cpucfg]: LoongArch Reference Manual Volume 1: Basic Architecture v1.1
+    let cpucfg1: usize;
     let cpucfg2: usize;
-    unsafe {
-        asm!(
-            "cpucfg {}, {}",
-            out(reg) cpucfg2, in(reg) 2,
-            options(pure, nomem, preserves_flags, nostack)
-        );
-    }
     let cpucfg3: usize;
     unsafe {
         asm!(
             "cpucfg {}, {}",
+            "cpucfg {}, {}",
+            "cpucfg {}, {}",
+            out(reg) cpucfg1, in(reg) 1,
+            out(reg) cpucfg2, in(reg) 2,
             out(reg) cpucfg3, in(reg) 3,
             options(pure, nomem, preserves_flags, nostack)
         );
     }
+    enable_feature(&mut value, Feature::_32s, bit::test(cpucfg1, 0) || bit::test(cpucfg1, 1));
     enable_feature(&mut value, Feature::frecipe, bit::test(cpucfg2, 25));
     enable_feature(&mut value, Feature::div32, bit::test(cpucfg2, 26));
     enable_feature(&mut value, Feature::lam_bh, bit::test(cpucfg2, 27));
diff --git a/library/std_detect/src/detect/os/linux/mod.rs b/library/std_detect/src/detect/os/linux/mod.rs
index 5ae2aaeab5b..5273c16c089 100644
--- a/library/std_detect/src/detect/os/linux/mod.rs
+++ b/library/std_detect/src/detect/os/linux/mod.rs
@@ -37,29 +37,36 @@ fn read_file(orig_path: &str) -> Result<Vec<u8>, alloc::string::String> {
     }
 }
 
-cfg_if::cfg_if! {
-    if #[cfg(target_arch = "aarch64")] {
+cfg_select! {
+    target_arch = "aarch64" => {
         mod aarch64;
         pub(crate) use self::aarch64::detect_features;
-    } else if #[cfg(target_arch = "arm")] {
+    }
+    target_arch = "arm" => {
         mod arm;
         pub(crate) use self::arm::detect_features;
-    } else if #[cfg(any(target_arch = "riscv32", target_arch = "riscv64"))] {
+    }
+    any(target_arch = "riscv32", target_arch = "riscv64") => {
         mod riscv;
         pub(crate) use self::riscv::detect_features;
-    } else if #[cfg(any(target_arch = "mips", target_arch = "mips64"))] {
+    }
+    any(target_arch = "mips", target_arch = "mips64") => {
         mod mips;
         pub(crate) use self::mips::detect_features;
-    } else if #[cfg(any(target_arch = "powerpc", target_arch = "powerpc64"))] {
+    }
+    any(target_arch = "powerpc", target_arch = "powerpc64") => {
         mod powerpc;
         pub(crate) use self::powerpc::detect_features;
-    } else if #[cfg(any(target_arch = "loongarch32", target_arch = "loongarch64"))] {
+    }
+    any(target_arch = "loongarch32", target_arch = "loongarch64") => {
         mod loongarch;
         pub(crate) use self::loongarch::detect_features;
-    } else if #[cfg(target_arch = "s390x")] {
+    }
+    target_arch = "s390x" => {
         mod s390x;
         pub(crate) use self::s390x::detect_features;
-    } else {
+    }
+    _ => {
         use crate::detect::cache;
         /// Performs run-time feature detection.
         pub(crate) fn detect_features() -> cache::Initializer {
diff --git a/library/std_detect/src/lib.rs b/library/std_detect/src/lib.rs
index ab1b77bad5b..73e2f5dd964 100644
--- a/library/std_detect/src/lib.rs
+++ b/library/std_detect/src/lib.rs
@@ -15,7 +15,7 @@
 //! * `s390x`: [`is_s390x_feature_detected`]
 
 #![unstable(feature = "stdarch_internal", issue = "none")]
-#![feature(staged_api, doc_cfg, allow_internal_unstable)]
+#![feature(staged_api, cfg_select, doc_cfg, allow_internal_unstable)]
 #![deny(rust_2018_idioms)]
 #![allow(clippy::shadow_reuse)]
 #![cfg_attr(test, allow(unused_imports))]
diff --git a/library/std_detect/tests/macro_trailing_commas.rs b/library/std_detect/tests/macro_trailing_commas.rs
index 2fee0abdd57..6072ddf5ac4 100644
--- a/library/std_detect/tests/macro_trailing_commas.rs
+++ b/library/std_detect/tests/macro_trailing_commas.rs
@@ -69,6 +69,8 @@ fn aarch64() {
 #[test]
 #[cfg(any(target_arch = "loongarch32", target_arch = "loongarch64"))]
 fn loongarch() {
+    let _ = is_loongarch_feature_detected!("32s");
+    let _ = is_loongarch_feature_detected!("32s",);
     let _ = is_loongarch_feature_detected!("lsx");
     let _ = is_loongarch_feature_detected!("lsx",);
 }
diff --git a/library/unwind/Cargo.toml b/library/unwind/Cargo.toml
index b9ce676eb3f..f02744a1070 100644
--- a/library/unwind/Cargo.toml
+++ b/library/unwind/Cargo.toml
@@ -14,7 +14,6 @@ bench = false
 doc = false
 
 [dependencies]
-cfg-if = "1.0"
 core = { path = "../rustc-std-workspace-core", package = "rustc-std-workspace-core" }
 
 [target.'cfg(not(all(windows, target_env = "msvc")))'.dependencies]
diff --git a/library/unwind/src/lib.rs b/library/unwind/src/lib.rs
index 5451a38a674..cd3a2f33ffa 100644
--- a/library/unwind/src/lib.rs
+++ b/library/unwind/src/lib.rs
@@ -1,6 +1,7 @@
 #![no_std]
 #![unstable(feature = "panic_unwind", issue = "32837")]
 #![feature(cfg_emscripten_wasm_eh)]
+#![feature(cfg_select)]
 #![feature(link_cfg)]
 #![feature(staged_api)]
 #![cfg_attr(not(target_env = "msvc"), feature(libc))]
@@ -15,32 +16,37 @@
 #[cfg(not(all(windows, target_env = "msvc")))]
 extern crate libc as _;
 
-cfg_if::cfg_if! {
-    if #[cfg(target_env = "msvc")] {
+cfg_select! {
+    target_env = "msvc" => {
         // Windows MSVC no extra unwinder support needed
-    } else if #[cfg(any(
+    }
+    any(
         target_os = "l4re",
         target_os = "none",
         target_os = "espidf",
         target_os = "nuttx",
-    ))] {
+    ) => {
         // These "unix" family members do not have unwinder.
-    } else if #[cfg(any(
+    }
+    any(
         unix,
         windows,
         target_os = "psp",
         target_os = "solid_asp3",
         all(target_vendor = "fortanix", target_env = "sgx"),
-    ))] {
+    ) => {
         mod libunwind;
         pub use libunwind::*;
-    } else if #[cfg(target_os = "xous")] {
+    }
+    target_os = "xous" => {
         mod unwinding;
         pub use unwinding::*;
-    } else if #[cfg(target_family = "wasm")] {
+    }
+    target_family = "wasm" => {
         mod wasm;
         pub use wasm::*;
-    } else {
+    }
+    _ => {
         // no unwinder on the system!
         // - os=none ("bare metal" targets)
         // - os=hermit
@@ -52,17 +58,20 @@ cfg_if::cfg_if! {
 }
 
 #[cfg(target_env = "musl")]
-cfg_if::cfg_if! {
-    if #[cfg(all(feature = "llvm-libunwind", feature = "system-llvm-libunwind"))] {
+cfg_select! {
+    all(feature = "llvm-libunwind", feature = "system-llvm-libunwind") => {
         compile_error!("`llvm-libunwind` and `system-llvm-libunwind` cannot be enabled at the same time");
-    } else if #[cfg(feature = "llvm-libunwind")] {
+    }
+    feature = "llvm-libunwind" => {
         #[link(name = "unwind", kind = "static", modifiers = "-bundle")]
         unsafe extern "C" {}
-    } else if #[cfg(feature = "system-llvm-libunwind")] {
+    }
+    feature = "system-llvm-libunwind" => {
         #[link(name = "unwind", kind = "static", modifiers = "-bundle", cfg(target_feature = "crt-static"))]
         #[link(name = "unwind", cfg(not(target_feature = "crt-static")))]
         unsafe extern "C" {}
-    } else {
+    }
+    _ => {
         #[link(name = "unwind", kind = "static", modifiers = "-bundle", cfg(target_feature = "crt-static"))]
         #[link(name = "gcc_s", cfg(not(target_feature = "crt-static")))]
         unsafe extern "C" {}
@@ -72,13 +81,15 @@ cfg_if::cfg_if! {
 // This is the same as musl except that we default to using the system libunwind
 // instead of libgcc.
 #[cfg(target_env = "ohos")]
-cfg_if::cfg_if! {
-    if #[cfg(all(feature = "llvm-libunwind", feature = "system-llvm-libunwind"))] {
+cfg_select! {
+    all(feature = "llvm-libunwind", feature = "system-llvm-libunwind") => {
         compile_error!("`llvm-libunwind` and `system-llvm-libunwind` cannot be enabled at the same time");
-    } else if #[cfg(feature = "llvm-libunwind")] {
+    }
+    feature = "llvm-libunwind" => {
         #[link(name = "unwind", kind = "static", modifiers = "-bundle")]
         unsafe extern "C" {}
-    } else {
+    }
+    _ => {
         #[link(name = "unwind", kind = "static", modifiers = "-bundle", cfg(target_feature = "crt-static"))]
         #[link(name = "unwind", cfg(not(target_feature = "crt-static")))]
         unsafe extern "C" {}
@@ -86,10 +97,11 @@ cfg_if::cfg_if! {
 }
 
 #[cfg(target_os = "android")]
-cfg_if::cfg_if! {
-    if #[cfg(feature = "llvm-libunwind")] {
+cfg_select! {
+    feature = "llvm-libunwind" => {
         compile_error!("`llvm-libunwind` is not supported for Android targets");
-    } else {
+    }
+    _ => {
         #[link(name = "unwind", kind = "static", modifiers = "-bundle", cfg(target_feature = "crt-static"))]
         #[link(name = "unwind", cfg(not(target_feature = "crt-static")))]
         unsafe extern "C" {}
@@ -166,11 +178,12 @@ unsafe extern "C" {}
 unsafe extern "C" {}
 
 #[cfg(target_os = "nto")]
-cfg_if::cfg_if! {
-    if #[cfg(target_env = "nto70")] {
+cfg_select! {
+    target_env = "nto70" => {
         #[link(name = "gcc")]
         unsafe extern "C" {}
-    } else {
+    }
+    _ => {
         #[link(name = "gcc_s")]
         unsafe extern "C" {}
     }
diff --git a/library/unwind/src/libunwind.rs b/library/unwind/src/libunwind.rs
index b350003cbb1..9ac9b54ed4a 100644
--- a/library/unwind/src/libunwind.rs
+++ b/library/unwind/src/libunwind.rs
@@ -122,198 +122,205 @@ unsafe extern "C" {
     pub fn _Unwind_GetDataRelBase(ctx: *mut _Unwind_Context) -> _Unwind_Ptr;
 }
 
-cfg_if::cfg_if! {
-if #[cfg(any(target_vendor = "apple", target_os = "netbsd", not(target_arch = "arm")))] {
-    // Not ARM EHABI
-    //
-    // 32-bit ARM on iOS/tvOS/watchOS use either DWARF/Compact unwinding or
-    // "setjmp-longjmp" / SjLj unwinding.
-    pub type _Unwind_Action = c_int;
-
-    pub const _UA_SEARCH_PHASE: c_int = 1;
-    pub const _UA_CLEANUP_PHASE: c_int = 2;
-    pub const _UA_HANDLER_FRAME: c_int = 4;
-    pub const _UA_FORCE_UNWIND: c_int = 8;
-    pub const _UA_END_OF_STACK: c_int = 16;
-
-    #[cfg_attr(
-        all(feature = "llvm-libunwind", any(target_os = "fuchsia", target_os = "linux", target_os = "xous")),
-        link(name = "unwind", kind = "static", modifiers = "-bundle")
-    )]
-    unsafe extern "C" {
-        pub fn _Unwind_GetGR(ctx: *mut _Unwind_Context, reg_index: c_int) -> _Unwind_Word;
-        pub fn _Unwind_SetGR(ctx: *mut _Unwind_Context, reg_index: c_int, value: _Unwind_Word);
-        pub fn _Unwind_GetIP(ctx: *mut _Unwind_Context) -> _Unwind_Word;
-        pub fn _Unwind_SetIP(ctx: *mut _Unwind_Context, value: _Unwind_Word);
-        pub fn _Unwind_GetIPInfo(ctx: *mut _Unwind_Context, ip_before_insn: *mut c_int)
-                                 -> _Unwind_Word;
-        pub fn _Unwind_FindEnclosingFunction(pc: *mut c_void) -> *mut c_void;
-    }
+cfg_select! {
+    any(target_vendor = "apple", target_os = "netbsd", not(target_arch = "arm")) => {
+        // Not ARM EHABI
+        //
+        // 32-bit ARM on iOS/tvOS/watchOS use either DWARF/Compact unwinding or
+        // "setjmp-longjmp" / SjLj unwinding.
+        pub type _Unwind_Action = c_int;
+
+        pub const _UA_SEARCH_PHASE: c_int = 1;
+        pub const _UA_CLEANUP_PHASE: c_int = 2;
+        pub const _UA_HANDLER_FRAME: c_int = 4;
+        pub const _UA_FORCE_UNWIND: c_int = 8;
+        pub const _UA_END_OF_STACK: c_int = 16;
+
+        #[cfg_attr(
+            all(feature = "llvm-libunwind", any(target_os = "fuchsia", target_os = "linux", target_os = "xous")),
+            link(name = "unwind", kind = "static", modifiers = "-bundle")
+        )]
+        unsafe extern "C" {
+            pub fn _Unwind_GetGR(ctx: *mut _Unwind_Context, reg_index: c_int) -> _Unwind_Word;
+            pub fn _Unwind_SetGR(ctx: *mut _Unwind_Context, reg_index: c_int, value: _Unwind_Word);
+            pub fn _Unwind_GetIP(ctx: *mut _Unwind_Context) -> _Unwind_Word;
+            pub fn _Unwind_SetIP(ctx: *mut _Unwind_Context, value: _Unwind_Word);
+            pub fn _Unwind_GetIPInfo(ctx: *mut _Unwind_Context, ip_before_insn: *mut c_int)
+                                     -> _Unwind_Word;
+            pub fn _Unwind_FindEnclosingFunction(pc: *mut c_void) -> *mut c_void;
+        }
 
-} else {
-    // ARM EHABI
-    #[repr(C)]
-    #[derive(Copy, Clone, PartialEq)]
-    pub enum _Unwind_State {
-        _US_VIRTUAL_UNWIND_FRAME = 0,
-        _US_UNWIND_FRAME_STARTING = 1,
-        _US_UNWIND_FRAME_RESUME = 2,
-        _US_ACTION_MASK = 3,
-        _US_FORCE_UNWIND = 8,
-        _US_END_OF_STACK = 16,
     }
-    pub use _Unwind_State::*;
+    _ => {
+        // ARM EHABI
+        #[repr(C)]
+        #[derive(Copy, Clone, PartialEq)]
+        pub enum _Unwind_State {
+            _US_VIRTUAL_UNWIND_FRAME = 0,
+            _US_UNWIND_FRAME_STARTING = 1,
+            _US_UNWIND_FRAME_RESUME = 2,
+            _US_ACTION_MASK = 3,
+            _US_FORCE_UNWIND = 8,
+            _US_END_OF_STACK = 16,
+        }
+        pub use _Unwind_State::*;
 
-    #[repr(C)]
-    enum _Unwind_VRS_Result {
-        _UVRSR_OK = 0,
-        _UVRSR_NOT_IMPLEMENTED = 1,
-        _UVRSR_FAILED = 2,
-    }
-    #[repr(C)]
-    enum _Unwind_VRS_RegClass {
-        _UVRSC_CORE = 0,
-        _UVRSC_VFP = 1,
-        _UVRSC_FPA = 2,
-        _UVRSC_WMMXD = 3,
-        _UVRSC_WMMXC = 4,
-    }
-    use _Unwind_VRS_RegClass::*;
-    #[repr(C)]
-    enum _Unwind_VRS_DataRepresentation {
-        _UVRSD_UINT32 = 0,
-        _UVRSD_VFPX = 1,
-        _UVRSD_FPAX = 2,
-        _UVRSD_UINT64 = 3,
-        _UVRSD_FLOAT = 4,
-        _UVRSD_DOUBLE = 5,
-    }
-    use _Unwind_VRS_DataRepresentation::*;
-
-    pub const UNWIND_POINTER_REG: c_int = 12;
-    pub const UNWIND_SP_REG: c_int = 13;
-    pub const UNWIND_IP_REG: c_int = 15;
-
-    #[cfg_attr(
-        all(feature = "llvm-libunwind", any(target_os = "fuchsia", target_os = "linux", target_os = "xous")),
-        link(name = "unwind", kind = "static", modifiers = "-bundle")
-    )]
-    unsafe extern "C" {
-        fn _Unwind_VRS_Get(ctx: *mut _Unwind_Context,
-                           regclass: _Unwind_VRS_RegClass,
-                           regno: _Unwind_Word,
-                           repr: _Unwind_VRS_DataRepresentation,
-                           data: *mut c_void)
-                           -> _Unwind_VRS_Result;
-
-        fn _Unwind_VRS_Set(ctx: *mut _Unwind_Context,
-                           regclass: _Unwind_VRS_RegClass,
-                           regno: _Unwind_Word,
-                           repr: _Unwind_VRS_DataRepresentation,
-                           data: *mut c_void)
-                           -> _Unwind_VRS_Result;
-    }
+        #[repr(C)]
+        enum _Unwind_VRS_Result {
+            _UVRSR_OK = 0,
+            _UVRSR_NOT_IMPLEMENTED = 1,
+            _UVRSR_FAILED = 2,
+        }
+        #[repr(C)]
+        enum _Unwind_VRS_RegClass {
+            _UVRSC_CORE = 0,
+            _UVRSC_VFP = 1,
+            _UVRSC_FPA = 2,
+            _UVRSC_WMMXD = 3,
+            _UVRSC_WMMXC = 4,
+        }
+        use _Unwind_VRS_RegClass::*;
+        #[repr(C)]
+        enum _Unwind_VRS_DataRepresentation {
+            _UVRSD_UINT32 = 0,
+            _UVRSD_VFPX = 1,
+            _UVRSD_FPAX = 2,
+            _UVRSD_UINT64 = 3,
+            _UVRSD_FLOAT = 4,
+            _UVRSD_DOUBLE = 5,
+        }
+        use _Unwind_VRS_DataRepresentation::*;
+
+        pub const UNWIND_POINTER_REG: c_int = 12;
+        pub const UNWIND_SP_REG: c_int = 13;
+        pub const UNWIND_IP_REG: c_int = 15;
+
+        #[cfg_attr(
+            all(feature = "llvm-libunwind", any(target_os = "fuchsia", target_os = "linux", target_os = "xous")),
+            link(name = "unwind", kind = "static", modifiers = "-bundle")
+        )]
+        unsafe extern "C" {
+            fn _Unwind_VRS_Get(ctx: *mut _Unwind_Context,
+                               regclass: _Unwind_VRS_RegClass,
+                               regno: _Unwind_Word,
+                               repr: _Unwind_VRS_DataRepresentation,
+                               data: *mut c_void)
+                               -> _Unwind_VRS_Result;
+
+            fn _Unwind_VRS_Set(ctx: *mut _Unwind_Context,
+                               regclass: _Unwind_VRS_RegClass,
+                               regno: _Unwind_Word,
+                               repr: _Unwind_VRS_DataRepresentation,
+                               data: *mut c_void)
+                               -> _Unwind_VRS_Result;
+        }
 
-    // On Android or ARM/Linux, these are implemented as macros:
+        // On Android or ARM/Linux, these are implemented as macros:
 
-    pub unsafe fn _Unwind_GetGR(ctx: *mut _Unwind_Context, reg_index: c_int) -> _Unwind_Word {
-        let mut val: _Unwind_Word = core::ptr::null();
-        unsafe { _Unwind_VRS_Get(ctx, _UVRSC_CORE, reg_index as _Unwind_Word, _UVRSD_UINT32,
-                        (&raw mut val) as *mut c_void); }
-        val
-    }
+        pub unsafe fn _Unwind_GetGR(ctx: *mut _Unwind_Context, reg_index: c_int) -> _Unwind_Word {
+            let mut val: _Unwind_Word = core::ptr::null();
+            unsafe { _Unwind_VRS_Get(ctx, _UVRSC_CORE, reg_index as _Unwind_Word, _UVRSD_UINT32,
+                            (&raw mut val) as *mut c_void); }
+            val
+        }
 
-    pub unsafe fn _Unwind_SetGR(ctx: *mut _Unwind_Context, reg_index: c_int, value: _Unwind_Word) {
-        let mut value = value;
-        unsafe { _Unwind_VRS_Set(ctx, _UVRSC_CORE, reg_index as _Unwind_Word, _UVRSD_UINT32,
-                        (&raw mut value) as *mut c_void); }
-    }
+        pub unsafe fn _Unwind_SetGR(
+            ctx: *mut _Unwind_Context,
+            reg_index: c_int,
+            value: _Unwind_Word
+        ) {
+            let mut value = value;
+            unsafe { _Unwind_VRS_Set(ctx, _UVRSC_CORE, reg_index as _Unwind_Word, _UVRSD_UINT32,
+                            (&raw mut value) as *mut c_void); }
+        }
 
-    pub unsafe fn _Unwind_GetIP(ctx: *mut _Unwind_Context)
-                                -> _Unwind_Word {
-        let val = unsafe { _Unwind_GetGR(ctx, UNWIND_IP_REG) };
-        val.map_addr(|v| v & !1)
-    }
+        pub unsafe fn _Unwind_GetIP(ctx: *mut _Unwind_Context)
+                                    -> _Unwind_Word {
+            let val = unsafe { _Unwind_GetGR(ctx, UNWIND_IP_REG) };
+            val.map_addr(|v| v & !1)
+        }
 
-    pub unsafe fn _Unwind_SetIP(ctx: *mut _Unwind_Context,
-                                value: _Unwind_Word) {
-        // Propagate thumb bit to instruction pointer
-        let thumb_state = unsafe { _Unwind_GetGR(ctx, UNWIND_IP_REG).addr() & 1 };
-        let value = value.map_addr(|v| v | thumb_state);
-        unsafe { _Unwind_SetGR(ctx, UNWIND_IP_REG, value); }
-    }
+        pub unsafe fn _Unwind_SetIP(ctx: *mut _Unwind_Context,
+                                    value: _Unwind_Word) {
+            // Propagate thumb bit to instruction pointer
+            let thumb_state = unsafe { _Unwind_GetGR(ctx, UNWIND_IP_REG).addr() & 1 };
+            let value = value.map_addr(|v| v | thumb_state);
+            unsafe { _Unwind_SetGR(ctx, UNWIND_IP_REG, value); }
+        }
 
-    pub unsafe fn _Unwind_GetIPInfo(ctx: *mut _Unwind_Context,
-                                    ip_before_insn: *mut c_int)
-                                    -> _Unwind_Word {
-        unsafe {
-            *ip_before_insn = 0;
-            _Unwind_GetIP(ctx)
+        pub unsafe fn _Unwind_GetIPInfo(ctx: *mut _Unwind_Context,
+                                        ip_before_insn: *mut c_int)
+                                        -> _Unwind_Word {
+            unsafe {
+                *ip_before_insn = 0;
+                _Unwind_GetIP(ctx)
+            }
         }
-    }
 
-    // This function also doesn't exist on Android or ARM/Linux, so make it a no-op
-    pub unsafe fn _Unwind_FindEnclosingFunction(pc: *mut c_void) -> *mut c_void {
-        pc
+        // This function also doesn't exist on Android or ARM/Linux, so make it a no-op
+        pub unsafe fn _Unwind_FindEnclosingFunction(pc: *mut c_void) -> *mut c_void {
+            pc
+        }
     }
 }
-} // cfg_if!
-
-cfg_if::cfg_if! {
-if #[cfg(all(target_vendor = "apple", not(target_os = "watchos"), target_arch = "arm"))] {
-    // 32-bit ARM Apple (except for watchOS armv7k specifically) uses SjLj and
-    // does not provide _Unwind_Backtrace()
-    unsafe extern "C-unwind" {
-        pub fn _Unwind_SjLj_RaiseException(e: *mut _Unwind_Exception) -> _Unwind_Reason_Code;
-    }
 
-    pub use _Unwind_SjLj_RaiseException as _Unwind_RaiseException;
-} else {
-    #[cfg_attr(
-        all(feature = "llvm-libunwind", any(target_os = "fuchsia", target_os = "linux", target_os = "xous")),
-        link(name = "unwind", kind = "static", modifiers = "-bundle")
-    )]
-    unsafe extern "C-unwind" {
-        pub fn _Unwind_RaiseException(exception: *mut _Unwind_Exception) -> _Unwind_Reason_Code;
+cfg_select! {
+    all(target_vendor = "apple", not(target_os = "watchos"), target_arch = "arm") => {
+        // 32-bit ARM Apple (except for watchOS armv7k specifically) uses SjLj and
+        // does not provide _Unwind_Backtrace()
+        unsafe extern "C-unwind" {
+            pub fn _Unwind_SjLj_RaiseException(e: *mut _Unwind_Exception) -> _Unwind_Reason_Code;
+        }
+
+        pub use _Unwind_SjLj_RaiseException as _Unwind_RaiseException;
     }
-    #[cfg_attr(
-        all(feature = "llvm-libunwind", any(target_os = "fuchsia", target_os = "linux", target_os = "xous")),
-        link(name = "unwind", kind = "static", modifiers = "-bundle")
-    )]
-    unsafe extern "C" {
-        pub fn _Unwind_Backtrace(trace: _Unwind_Trace_Fn,
-                                 trace_argument: *mut c_void)
-                                 -> _Unwind_Reason_Code;
+    _ => {
+        #[cfg_attr(
+            all(feature = "llvm-libunwind", any(target_os = "fuchsia", target_os = "linux", target_os = "xous")),
+            link(name = "unwind", kind = "static", modifiers = "-bundle")
+        )]
+        unsafe extern "C-unwind" {
+            pub fn _Unwind_RaiseException(exception: *mut _Unwind_Exception) -> _Unwind_Reason_Code;
+        }
+        #[cfg_attr(
+            all(feature = "llvm-libunwind", any(target_os = "fuchsia", target_os = "linux", target_os = "xous")),
+            link(name = "unwind", kind = "static", modifiers = "-bundle")
+        )]
+        unsafe extern "C" {
+            pub fn _Unwind_Backtrace(trace: _Unwind_Trace_Fn,
+                                     trace_argument: *mut c_void)
+                                     -> _Unwind_Reason_Code;
+        }
     }
 }
-} // cfg_if!
 
-cfg_if::cfg_if! {
-if #[cfg(any(
+cfg_select! {
+    any(
         all(windows, any(target_arch = "aarch64", target_arch = "x86_64"), target_env = "gnu"),
         target_os = "cygwin",
-    ))] {
-    // We declare these as opaque types. This is fine since you just need to
-    // pass them to _GCC_specific_handler and forget about them.
-    pub enum EXCEPTION_RECORD {}
-    pub type LPVOID = *mut c_void;
-    pub enum CONTEXT {}
-    pub enum DISPATCHER_CONTEXT {}
-    pub type EXCEPTION_DISPOSITION = c_int;
-    type PersonalityFn = unsafe extern "C" fn(version: c_int,
-                                              actions: _Unwind_Action,
-                                              exception_class: _Unwind_Exception_Class,
-                                              exception_object: *mut _Unwind_Exception,
-                                              context: *mut _Unwind_Context)
-                                              -> _Unwind_Reason_Code;
-
-    unsafe extern "C" {
-        pub fn _GCC_specific_handler(exceptionRecord: *mut EXCEPTION_RECORD,
-                                establisherFrame: LPVOID,
-                                contextRecord: *mut CONTEXT,
-                                dispatcherContext: *mut DISPATCHER_CONTEXT,
-                                personality: PersonalityFn)
-                                -> EXCEPTION_DISPOSITION;
+    ) => {
+        // We declare these as opaque types. This is fine since you just need to
+        // pass them to _GCC_specific_handler and forget about them.
+        pub enum EXCEPTION_RECORD {}
+        pub type LPVOID = *mut c_void;
+        pub enum CONTEXT {}
+        pub enum DISPATCHER_CONTEXT {}
+        pub type EXCEPTION_DISPOSITION = c_int;
+        type PersonalityFn = unsafe extern "C" fn(version: c_int,
+                                                  actions: _Unwind_Action,
+                                                  exception_class: _Unwind_Exception_Class,
+                                                  exception_object: *mut _Unwind_Exception,
+                                                  context: *mut _Unwind_Context)
+                                                  -> _Unwind_Reason_Code;
+
+        unsafe extern "C" {
+            pub fn _GCC_specific_handler(exceptionRecord: *mut EXCEPTION_RECORD,
+                                    establisherFrame: LPVOID,
+                                    contextRecord: *mut CONTEXT,
+                                    dispatcherContext: *mut DISPATCHER_CONTEXT,
+                                    personality: PersonalityFn)
+                                    -> EXCEPTION_DISPOSITION;
+        }
     }
+    _ => {}
 }
-} // cfg_if!
diff --git a/library/unwind/src/wasm.rs b/library/unwind/src/wasm.rs
index 2d36a8be004..3341e54759a 100644
--- a/library/unwind/src/wasm.rs
+++ b/library/unwind/src/wasm.rs
@@ -45,18 +45,19 @@ pub unsafe fn _Unwind_RaiseException(exception: *mut _Unwind_Exception) -> _Unwi
     // via integers, with 0 corresponding to C++ exceptions and 1 to C setjmp()/longjmp().
     // Ideally, we'd be able to choose something unique for Rust, but for now,
     // we pretend to be C++ and implement the Itanium exception-handling ABI.
-    cfg_if::cfg_if! {
+    cfg_select! {
         // panic=abort is default for wasm targets. Because an unknown instruction is a load-time
         // error on wasm, instead of a runtime error like on traditional architectures, we never
         // want to codegen a `throw` instruction, as that would break users using runtimes that
         // don't yet support exceptions. The only time this first branch would be selected is if
         // the user explicitly opts in to wasm exceptions, via -Zbuild-std with -Cpanic=unwind.
-        if #[cfg(panic = "unwind")] {
+        panic = "unwind" => {
             // corresponds with llvm::WebAssembly::Tag::CPP_EXCEPTION
             //     in llvm-project/llvm/include/llvm/CodeGen/WasmEHFuncInfo.h
             const CPP_EXCEPTION_TAG: i32 = 0;
             core::arch::wasm::throw::<CPP_EXCEPTION_TAG>(exception.cast())
-        } else {
+        }
+        _ => {
             let _ = exception;
             core::arch::wasm::unreachable()
         }