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-rw-r--r--compiler/rustc_codegen_llvm/src/allocator.rs30
-rw-r--r--compiler/rustc_expand/src/mbe/macro_check.rs11
-rw-r--r--compiler/rustc_mir_transform/src/patch.rs30
-rw-r--r--compiler/rustc_mir_transform/src/simplify_branches.rs19
-rw-r--r--library/std/src/net/hostname.rs22
-rw-r--r--library/std/src/net/mod.rs6
-rw-r--r--library/std/src/sys/net/connection/socket/windows.rs80
-rw-r--r--library/std/src/sys/net/hostname/mod.rs14
-rw-r--r--library/std/src/sys/net/hostname/unix.rs62
-rw-r--r--library/std/src/sys/net/hostname/unsupported.rs6
-rw-r--r--library/std/src/sys/net/hostname/windows.rs24
-rw-r--r--library/std/src/sys/net/mod.rs3
-rw-r--r--library/std/src/sys/pal/windows/c/bindings.txt2
-rw-r--r--library/std/src/sys/pal/windows/c/windows_sys.rs2
-rw-r--r--library/std/src/sys/pal/windows/mod.rs1
-rw-r--r--library/std/src/sys/pal/windows/winsock.rs80
-rw-r--r--src/librustdoc/clean/types.rs16
17 files changed, 296 insertions, 112 deletions
diff --git a/compiler/rustc_codegen_llvm/src/allocator.rs b/compiler/rustc_codegen_llvm/src/allocator.rs
index abd63120397..896d6755c75 100644
--- a/compiler/rustc_codegen_llvm/src/allocator.rs
+++ b/compiler/rustc_codegen_llvm/src/allocator.rs
@@ -5,9 +5,10 @@ use rustc_ast::expand::allocator::{
 };
 use rustc_codegen_ssa::traits::BaseTypeCodegenMethods as _;
 use rustc_middle::bug;
-use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs;
+use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
 use rustc_middle::ty::TyCtxt;
 use rustc_session::config::{DebugInfo, OomStrategy};
+use rustc_span::sym;
 use rustc_symbol_mangling::mangle_internal_symbol;
 
 use crate::attributes::llfn_attrs_from_instance;
@@ -59,7 +60,26 @@ pub(crate) unsafe fn codegen(
             let from_name = mangle_internal_symbol(tcx, &global_fn_name(method.name));
             let to_name = mangle_internal_symbol(tcx, &default_fn_name(method.name));
 
-            create_wrapper_function(tcx, &cx, &from_name, Some(&to_name), &args, output, false);
+            let alloc_attr_flag = match method.name {
+                sym::alloc => CodegenFnAttrFlags::ALLOCATOR,
+                sym::dealloc => CodegenFnAttrFlags::DEALLOCATOR,
+                sym::realloc => CodegenFnAttrFlags::REALLOCATOR,
+                sym::alloc_zeroed => CodegenFnAttrFlags::ALLOCATOR_ZEROED,
+                _ => unreachable!("Unknown allocator method!"),
+            };
+
+            let mut attrs = CodegenFnAttrs::new();
+            attrs.flags |= alloc_attr_flag;
+            create_wrapper_function(
+                tcx,
+                &cx,
+                &from_name,
+                Some(&to_name),
+                &args,
+                output,
+                false,
+                &attrs,
+            );
         }
     }
 
@@ -72,6 +92,7 @@ pub(crate) unsafe fn codegen(
         &[usize, usize], // size, align
         None,
         true,
+        &CodegenFnAttrs::new(),
     );
 
     unsafe {
@@ -93,6 +114,7 @@ pub(crate) unsafe fn codegen(
             &[],
             None,
             false,
+            &CodegenFnAttrs::new(),
         );
     }
 
@@ -139,6 +161,7 @@ fn create_wrapper_function(
     args: &[&Type],
     output: Option<&Type>,
     no_return: bool,
+    attrs: &CodegenFnAttrs,
 ) {
     let ty = cx.type_func(args, output.unwrap_or_else(|| cx.type_void()));
     let llfn = declare_simple_fn(
@@ -150,8 +173,7 @@ fn create_wrapper_function(
         ty,
     );
 
-    let attrs = CodegenFnAttrs::new();
-    llfn_attrs_from_instance(cx, tcx, llfn, &attrs, None);
+    llfn_attrs_from_instance(cx, tcx, llfn, attrs, None);
 
     let no_return = if no_return {
         // -> ! DIFlagNoReturn
diff --git a/compiler/rustc_expand/src/mbe/macro_check.rs b/compiler/rustc_expand/src/mbe/macro_check.rs
index ebd6e887f7d..0eae44a05e7 100644
--- a/compiler/rustc_expand/src/mbe/macro_check.rs
+++ b/compiler/rustc_expand/src/mbe/macro_check.rs
@@ -210,8 +210,7 @@ pub(super) fn check_meta_variables(
     guar.map_or(Ok(()), Err)
 }
 
-/// Checks `lhs` as part of the LHS of a macro definition, extends `binders` with new binders, and
-/// sets `valid` to false in case of errors.
+/// Checks `lhs` as part of the LHS of a macro definition.
 ///
 /// Arguments:
 /// - `psess` is used to emit diagnostics and lints
@@ -306,8 +305,7 @@ fn get_binder_info<'a>(
     binders.get(&name).or_else(|| macros.find_map(|state| state.binders.get(&name)))
 }
 
-/// Checks `rhs` as part of the RHS of a macro definition and sets `valid` to false in case of
-/// errors.
+/// Checks `rhs` as part of the RHS of a macro definition.
 ///
 /// Arguments:
 /// - `psess` is used to emit diagnostics and lints
@@ -372,7 +370,7 @@ enum NestedMacroState {
 }
 
 /// Checks `tts` as part of the RHS of a macro definition, tries to recognize nested macro
-/// definitions, and sets `valid` to false in case of errors.
+/// definitions.
 ///
 /// Arguments:
 /// - `psess` is used to emit diagnostics and lints
@@ -491,8 +489,7 @@ fn check_nested_occurrences(
     }
 }
 
-/// Checks the body of nested macro, returns where the check stopped, and sets `valid` to false in
-/// case of errors.
+/// Checks the body of nested macro, returns where the check stopped.
 ///
 /// The token trees are checked as long as they look like a list of (LHS) => {RHS} token trees. This
 /// check is a best-effort to detect a macro definition. It returns the position in `tts` where we
diff --git a/compiler/rustc_mir_transform/src/patch.rs b/compiler/rustc_mir_transform/src/patch.rs
index d831ab50b1a..cc8ea76011b 100644
--- a/compiler/rustc_mir_transform/src/patch.rs
+++ b/compiler/rustc_mir_transform/src/patch.rs
@@ -11,6 +11,8 @@ use tracing::debug;
 /// once with `apply`. This is useful for MIR transformation passes.
 pub(crate) struct MirPatch<'tcx> {
     term_patch_map: FxHashMap<BasicBlock, TerminatorKind<'tcx>>,
+    /// Set of statements that should be replaced by `Nop`.
+    nop_statements: Vec<Location>,
     new_blocks: Vec<BasicBlockData<'tcx>>,
     new_statements: Vec<(Location, StatementKind<'tcx>)>,
     new_locals: Vec<LocalDecl<'tcx>>,
@@ -33,6 +35,7 @@ impl<'tcx> MirPatch<'tcx> {
     pub(crate) fn new(body: &Body<'tcx>) -> Self {
         let mut result = MirPatch {
             term_patch_map: Default::default(),
+            nop_statements: vec![],
             new_blocks: vec![],
             new_statements: vec![],
             new_locals: vec![],
@@ -212,6 +215,15 @@ impl<'tcx> MirPatch<'tcx> {
         self.term_patch_map.insert(block, new);
     }
 
+    /// Mark given statement to be replaced by a `Nop`.
+    ///
+    /// This method only works on statements from the initial body, and cannot be used to remove
+    /// statements from `add_statement` or `add_assign`.
+    #[tracing::instrument(level = "debug", skip(self))]
+    pub(crate) fn nop_statement(&mut self, loc: Location) {
+        self.nop_statements.push(loc);
+    }
+
     /// Queues the insertion of a statement at a given location. The statement
     /// currently at that location, and all statements that follow, are shifted
     /// down. If multiple statements are queued for addition at the same
@@ -257,11 +269,8 @@ impl<'tcx> MirPatch<'tcx> {
         bbs.extend(self.new_blocks);
         body.local_decls.extend(self.new_locals);
 
-        // The order in which we patch terminators does not change the result.
-        #[allow(rustc::potential_query_instability)]
-        for (src, patch) in self.term_patch_map {
-            debug!("MirPatch: patching block {:?}", src);
-            bbs[src].terminator_mut().kind = patch;
+        for loc in self.nop_statements {
+            bbs[loc.block].statements[loc.statement_index].make_nop();
         }
 
         let mut new_statements = self.new_statements;
@@ -285,6 +294,17 @@ impl<'tcx> MirPatch<'tcx> {
                 .insert(loc.statement_index, Statement::new(source_info, stmt));
             delta += 1;
         }
+
+        // The order in which we patch terminators does not change the result.
+        #[allow(rustc::potential_query_instability)]
+        for (src, patch) in self.term_patch_map {
+            debug!("MirPatch: patching block {:?}", src);
+            let bb = &mut bbs[src];
+            if let TerminatorKind::Unreachable = patch {
+                bb.statements.clear();
+            }
+            bb.terminator_mut().kind = patch;
+        }
     }
 
     fn source_info_for_index(data: &BasicBlockData<'_>, loc: Location) -> SourceInfo {
diff --git a/compiler/rustc_mir_transform/src/simplify_branches.rs b/compiler/rustc_mir_transform/src/simplify_branches.rs
index 886f4d6e509..ed94a058ec6 100644
--- a/compiler/rustc_mir_transform/src/simplify_branches.rs
+++ b/compiler/rustc_mir_transform/src/simplify_branches.rs
@@ -2,6 +2,8 @@ use rustc_middle::mir::*;
 use rustc_middle::ty::TyCtxt;
 use tracing::trace;
 
+use crate::patch::MirPatch;
+
 pub(super) enum SimplifyConstCondition {
     AfterConstProp,
     Final,
@@ -19,8 +21,10 @@ impl<'tcx> crate::MirPass<'tcx> for SimplifyConstCondition {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
         trace!("Running SimplifyConstCondition on {:?}", body.source);
         let typing_env = body.typing_env(tcx);
-        'blocks: for block in body.basic_blocks_mut() {
-            for stmt in block.statements.iter_mut() {
+        let mut patch = MirPatch::new(body);
+
+        'blocks: for (bb, block) in body.basic_blocks.iter_enumerated() {
+            for (statement_index, stmt) in block.statements.iter().enumerate() {
                 // Simplify `assume` of a known value: either a NOP or unreachable.
                 if let StatementKind::Intrinsic(box ref intrinsic) = stmt.kind
                     && let NonDivergingIntrinsic::Assume(discr) = intrinsic
@@ -28,17 +32,16 @@ impl<'tcx> crate::MirPass<'tcx> for SimplifyConstCondition {
                     && let Some(constant) = c.const_.try_eval_bool(tcx, typing_env)
                 {
                     if constant {
-                        stmt.make_nop();
+                        patch.nop_statement(Location { block: bb, statement_index });
                     } else {
-                        block.statements.clear();
-                        block.terminator_mut().kind = TerminatorKind::Unreachable;
+                        patch.patch_terminator(bb, TerminatorKind::Unreachable);
                         continue 'blocks;
                     }
                 }
             }
 
-            let terminator = block.terminator_mut();
-            terminator.kind = match terminator.kind {
+            let terminator = block.terminator();
+            let terminator = match terminator.kind {
                 TerminatorKind::SwitchInt {
                     discr: Operand::Constant(ref c), ref targets, ..
                 } => {
@@ -58,7 +61,9 @@ impl<'tcx> crate::MirPass<'tcx> for SimplifyConstCondition {
                 },
                 _ => continue,
             };
+            patch.patch_terminator(bb, terminator);
         }
+        patch.apply(body);
     }
 
     fn is_required(&self) -> bool {
diff --git a/library/std/src/net/hostname.rs b/library/std/src/net/hostname.rs
new file mode 100644
index 00000000000..b1010cec600
--- /dev/null
+++ b/library/std/src/net/hostname.rs
@@ -0,0 +1,22 @@
+use crate::ffi::OsString;
+
+/// Returns the system hostname.
+///
+/// This can error out in platform-specific error cases;
+/// for example, uefi and wasm, where hostnames aren't
+/// supported.
+///
+/// # Underlying system calls
+///
+/// | Platform | System call                                                                                             |
+/// |----------|---------------------------------------------------------------------------------------------------------|
+/// | UNIX     | [`gethostname`](https://www.man7.org/linux/man-pages/man2/gethostname.2.html)                           |
+/// | Windows  | [`GetHostNameW`](https://learn.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-gethostnamew) |
+///
+/// Note that platform-specific behavior [may change in the future][changes].
+///
+/// [changes]: crate::io#platform-specific-behavior
+#[unstable(feature = "gethostname", issue = "135142")]
+pub fn hostname() -> crate::io::Result<OsString> {
+    crate::sys::net::hostname()
+}
diff --git a/library/std/src/net/mod.rs b/library/std/src/net/mod.rs
index 40f1a93e39d..3e4447eb33f 100644
--- a/library/std/src/net/mod.rs
+++ b/library/std/src/net/mod.rs
@@ -1,7 +1,8 @@
 //! Networking primitives for TCP/UDP communication.
 //!
 //! This module provides networking functionality for the Transmission Control and User
-//! Datagram Protocols, as well as types for IP and socket addresses.
+//! Datagram Protocols, as well as types for IP and socket addresses and functions related
+//! to network properties.
 //!
 //! # Organization
 //!
@@ -24,6 +25,8 @@
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::net::AddrParseError;
 
+#[unstable(feature = "gethostname", issue = "135142")]
+pub use self::hostname::hostname;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::ip_addr::{IpAddr, Ipv4Addr, Ipv6Addr, Ipv6MulticastScope};
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -35,6 +38,7 @@ pub use self::tcp::{Incoming, TcpListener, TcpStream};
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::udp::UdpSocket;
 
+mod hostname;
 mod ip_addr;
 mod socket_addr;
 mod tcp;
diff --git a/library/std/src/sys/net/connection/socket/windows.rs b/library/std/src/sys/net/connection/socket/windows.rs
index b71d8b1357b..5b6f4cedf1b 100644
--- a/library/std/src/sys/net/connection/socket/windows.rs
+++ b/library/std/src/sys/net/connection/socket/windows.rs
@@ -8,9 +8,8 @@ use crate::net::{Shutdown, SocketAddr};
 use crate::os::windows::io::{
     AsRawSocket, AsSocket, BorrowedSocket, FromRawSocket, IntoRawSocket, OwnedSocket, RawSocket,
 };
-use crate::sync::atomic::Atomic;
-use crate::sync::atomic::Ordering::{AcqRel, Relaxed};
 use crate::sys::c;
+use crate::sys::pal::winsock::last_error;
 use crate::sys_common::{AsInner, FromInner, IntoInner};
 use crate::time::Duration;
 use crate::{cmp, mem, ptr, sys};
@@ -112,84 +111,11 @@ pub(super) mod netc {
     }
 }
 
+pub use crate::sys::pal::winsock::{cleanup, cvt, cvt_gai, cvt_r, startup as init};
+
 #[expect(missing_debug_implementations)]
 pub struct Socket(OwnedSocket);
 
-static WSA_INITIALIZED: Atomic<bool> = Atomic::<bool>::new(false);
-
-/// Checks whether the Windows socket interface has been started already, and
-/// if not, starts it.
-#[inline]
-pub fn init() {
-    if !WSA_INITIALIZED.load(Relaxed) {
-        wsa_startup();
-    }
-}
-
-#[cold]
-fn wsa_startup() {
-    unsafe {
-        let mut data: c::WSADATA = mem::zeroed();
-        let ret = c::WSAStartup(
-            0x202, // version 2.2
-            &mut data,
-        );
-        assert_eq!(ret, 0);
-        if WSA_INITIALIZED.swap(true, AcqRel) {
-            // If another thread raced with us and called WSAStartup first then call
-            // WSACleanup so it's as though WSAStartup was only called once.
-            c::WSACleanup();
-        }
-    }
-}
-
-pub fn cleanup() {
-    // We don't need to call WSACleanup here because exiting the process will cause
-    // the OS to clean everything for us, which is faster than doing it manually.
-    // See #141799.
-}
-
-/// Returns the last error from the Windows socket interface.
-fn last_error() -> io::Error {
-    io::Error::from_raw_os_error(unsafe { c::WSAGetLastError() })
-}
-
-#[doc(hidden)]
-pub trait IsMinusOne {
-    fn is_minus_one(&self) -> bool;
-}
-
-macro_rules! impl_is_minus_one {
-    ($($t:ident)*) => ($(impl IsMinusOne for $t {
-        fn is_minus_one(&self) -> bool {
-            *self == -1
-        }
-    })*)
-}
-
-impl_is_minus_one! { i8 i16 i32 i64 isize }
-
-/// Checks if the signed integer is the Windows constant `SOCKET_ERROR` (-1)
-/// and if so, returns the last error from the Windows socket interface. This
-/// function must be called before another call to the socket API is made.
-pub fn cvt<T: IsMinusOne>(t: T) -> io::Result<T> {
-    if t.is_minus_one() { Err(last_error()) } else { Ok(t) }
-}
-
-/// A variant of `cvt` for `getaddrinfo` which return 0 for a success.
-pub fn cvt_gai(err: c_int) -> io::Result<()> {
-    if err == 0 { Ok(()) } else { Err(last_error()) }
-}
-
-/// Just to provide the same interface as sys/pal/unix/net.rs
-pub fn cvt_r<T, F>(mut f: F) -> io::Result<T>
-where
-    T: IsMinusOne,
-    F: FnMut() -> T,
-{
-    cvt(f())
-}
-
 impl Socket {
     pub fn new(addr: &SocketAddr, ty: c_int) -> io::Result<Socket> {
         let family = match *addr {
diff --git a/library/std/src/sys/net/hostname/mod.rs b/library/std/src/sys/net/hostname/mod.rs
new file mode 100644
index 00000000000..a4b5b76059d
--- /dev/null
+++ b/library/std/src/sys/net/hostname/mod.rs
@@ -0,0 +1,14 @@
+cfg_select! {
+    target_family = "unix" => {
+        mod unix;
+        pub use unix::hostname;
+    }
+    target_os = "windows" => {
+        mod windows;
+        pub use windows::hostname;
+    }
+    _ => {
+        mod unsupported;
+        pub use unsupported::hostname;
+    }
+}
diff --git a/library/std/src/sys/net/hostname/unix.rs b/library/std/src/sys/net/hostname/unix.rs
new file mode 100644
index 00000000000..bc6fa82a38f
--- /dev/null
+++ b/library/std/src/sys/net/hostname/unix.rs
@@ -0,0 +1,62 @@
+use crate::ffi::OsString;
+use crate::io;
+use crate::os::unix::ffi::OsStringExt;
+use crate::sys::pal::os::errno;
+
+pub fn hostname() -> io::Result<OsString> {
+    // Query the system for the maximum host name length.
+    let host_name_max = match unsafe { libc::sysconf(libc::_SC_HOST_NAME_MAX) } {
+        // If this fails (possibly because there is no maximum length), then
+        // assume a maximum length of _POSIX_HOST_NAME_MAX (255).
+        -1 => 255,
+        max => max as usize,
+    };
+
+    // Reserve space for the nul terminator too.
+    let mut buf = Vec::<u8>::try_with_capacity(host_name_max + 1)?;
+    loop {
+        // SAFETY: `buf.capacity()` bytes of `buf` are writable.
+        let r = unsafe { libc::gethostname(buf.as_mut_ptr().cast(), buf.capacity()) };
+        match (r != 0).then(errno) {
+            None => {
+                // Unfortunately, the UNIX specification says that the name will
+                // be truncated if it does not fit in the buffer, without returning
+                // an error. As additionally, the truncated name may still be null-
+                // terminated, there is no reliable way to  detect truncation.
+                // Fortunately, most platforms ignore what the specification says
+                // and return an error (mostly ENAMETOOLONG). Should that not be
+                // the case, the following detects truncation if the null-terminator
+                // was omitted. Note that this check does not impact performance at
+                // all as we need to find the length of the string anyways.
+                //
+                // Use `strnlen` as it does not place an initialization requirement
+                // on the bytes after the nul terminator.
+                //
+                // SAFETY: `buf.capacity()` bytes of `buf` are accessible, and are
+                // initialized up to and including a possible nul terminator.
+                let len = unsafe { libc::strnlen(buf.as_ptr().cast(), buf.capacity()) };
+                if len < buf.capacity() {
+                    // If the string is nul-terminated, we assume that is has not
+                    // been truncated, as the capacity *should be* enough to hold
+                    // `HOST_NAME_MAX` bytes.
+                    // SAFETY: `len + 1` bytes have been initialized (we exclude
+                    // the nul terminator from the string).
+                    unsafe { buf.set_len(len) };
+                    return Ok(OsString::from_vec(buf));
+                }
+            }
+            // As `buf.capacity()` is always less than or equal to `isize::MAX`
+            // (Rust allocations cannot exceed that limit), the only way `EINVAL`
+            // can be returned is if the system uses `EINVAL` to report that the
+            // name does not fit in the provided buffer. In that case (or in the
+            // case of `ENAMETOOLONG`), resize the buffer and try again.
+            Some(libc::EINVAL | libc::ENAMETOOLONG) => {}
+            // Other error codes (e.g. EPERM) have nothing to do with the buffer
+            // size and should be returned to the user.
+            Some(err) => return Err(io::Error::from_raw_os_error(err)),
+        }
+
+        // Resize the buffer (according to `Vec`'s resizing rules) and try again.
+        buf.try_reserve(buf.capacity() + 1)?;
+    }
+}
diff --git a/library/std/src/sys/net/hostname/unsupported.rs b/library/std/src/sys/net/hostname/unsupported.rs
new file mode 100644
index 00000000000..d868f68f32d
--- /dev/null
+++ b/library/std/src/sys/net/hostname/unsupported.rs
@@ -0,0 +1,6 @@
+use crate::ffi::OsString;
+use crate::io::{Error, Result};
+
+pub fn hostname() -> Result<OsString> {
+    Err(Error::UNSUPPORTED_PLATFORM)
+}
diff --git a/library/std/src/sys/net/hostname/windows.rs b/library/std/src/sys/net/hostname/windows.rs
new file mode 100644
index 00000000000..24eed100f32
--- /dev/null
+++ b/library/std/src/sys/net/hostname/windows.rs
@@ -0,0 +1,24 @@
+use crate::ffi::OsString;
+use crate::io::Result;
+use crate::mem::MaybeUninit;
+use crate::os::windows::ffi::OsStringExt;
+use crate::sys::pal::c;
+use crate::sys::pal::winsock::{self, cvt};
+
+pub fn hostname() -> Result<OsString> {
+    winsock::startup();
+
+    // The documentation of GetHostNameW says that a buffer size of 256 is
+    // always enough.
+    let mut buffer = [const { MaybeUninit::<u16>::uninit() }; 256];
+    // SAFETY: these parameters specify a valid, writable region of memory.
+    cvt(unsafe { c::GetHostNameW(buffer.as_mut_ptr().cast(), buffer.len() as i32) })?;
+    // Use `lstrlenW` here as it does not require the bytes after the nul
+    // terminator to be initialized.
+    // SAFETY: if `GetHostNameW` returns successfully, the name is nul-terminated.
+    let len = unsafe { c::lstrlenW(buffer.as_ptr().cast()) };
+    // SAFETY: the length of the name is `len`, hence `len` bytes have been
+    //         initialized by `GetHostNameW`.
+    let name = unsafe { buffer[..len as usize].assume_init_ref() };
+    Ok(OsString::from_wide(name))
+}
diff --git a/library/std/src/sys/net/mod.rs b/library/std/src/sys/net/mod.rs
index dffc4ea7f81..bfe5cf53128 100644
--- a/library/std/src/sys/net/mod.rs
+++ b/library/std/src/sys/net/mod.rs
@@ -2,3 +2,6 @@
 /// `UdpSocket` as well as related functionality like DNS resolving.
 mod connection;
 pub use connection::*;
+
+mod hostname;
+pub use hostname::hostname;
diff --git a/library/std/src/sys/pal/windows/c/bindings.txt b/library/std/src/sys/pal/windows/c/bindings.txt
index abc1c19827f..9009aa09f48 100644
--- a/library/std/src/sys/pal/windows/c/bindings.txt
+++ b/library/std/src/sys/pal/windows/c/bindings.txt
@@ -2170,6 +2170,7 @@ GetFileType
 GETFINALPATHNAMEBYHANDLE_FLAGS
 GetFinalPathNameByHandleW
 GetFullPathNameW
+GetHostNameW
 GetLastError
 GetModuleFileNameW
 GetModuleHandleA
@@ -2270,6 +2271,7 @@ LPPROGRESS_ROUTINE
 LPPROGRESS_ROUTINE_CALLBACK_REASON
 LPTHREAD_START_ROUTINE
 LPWSAOVERLAPPED_COMPLETION_ROUTINE
+lstrlenW
 M128A
 MAX_PATH
 MAXIMUM_REPARSE_DATA_BUFFER_SIZE
diff --git a/library/std/src/sys/pal/windows/c/windows_sys.rs b/library/std/src/sys/pal/windows/c/windows_sys.rs
index 989a1246650..98f277b3378 100644
--- a/library/std/src/sys/pal/windows/c/windows_sys.rs
+++ b/library/std/src/sys/pal/windows/c/windows_sys.rs
@@ -49,6 +49,7 @@ windows_targets::link!("kernel32.dll" "system" fn GetFileSizeEx(hfile : HANDLE,
 windows_targets::link!("kernel32.dll" "system" fn GetFileType(hfile : HANDLE) -> FILE_TYPE);
 windows_targets::link!("kernel32.dll" "system" fn GetFinalPathNameByHandleW(hfile : HANDLE, lpszfilepath : PWSTR, cchfilepath : u32, dwflags : GETFINALPATHNAMEBYHANDLE_FLAGS) -> u32);
 windows_targets::link!("kernel32.dll" "system" fn GetFullPathNameW(lpfilename : PCWSTR, nbufferlength : u32, lpbuffer : PWSTR, lpfilepart : *mut PWSTR) -> u32);
+windows_targets::link!("ws2_32.dll" "system" fn GetHostNameW(name : PWSTR, namelen : i32) -> i32);
 windows_targets::link!("kernel32.dll" "system" fn GetLastError() -> WIN32_ERROR);
 windows_targets::link!("kernel32.dll" "system" fn GetModuleFileNameW(hmodule : HMODULE, lpfilename : PWSTR, nsize : u32) -> u32);
 windows_targets::link!("kernel32.dll" "system" fn GetModuleHandleA(lpmodulename : PCSTR) -> HMODULE);
@@ -134,6 +135,7 @@ windows_targets::link!("ws2_32.dll" "system" fn getsockname(s : SOCKET, name : *
 windows_targets::link!("ws2_32.dll" "system" fn getsockopt(s : SOCKET, level : i32, optname : i32, optval : PSTR, optlen : *mut i32) -> i32);
 windows_targets::link!("ws2_32.dll" "system" fn ioctlsocket(s : SOCKET, cmd : i32, argp : *mut u32) -> i32);
 windows_targets::link!("ws2_32.dll" "system" fn listen(s : SOCKET, backlog : i32) -> i32);
+windows_targets::link!("kernel32.dll" "system" fn lstrlenW(lpstring : PCWSTR) -> i32);
 windows_targets::link!("ws2_32.dll" "system" fn recv(s : SOCKET, buf : PSTR, len : i32, flags : SEND_RECV_FLAGS) -> i32);
 windows_targets::link!("ws2_32.dll" "system" fn recvfrom(s : SOCKET, buf : PSTR, len : i32, flags : i32, from : *mut SOCKADDR, fromlen : *mut i32) -> i32);
 windows_targets::link!("ws2_32.dll" "system" fn select(nfds : i32, readfds : *mut FD_SET, writefds : *mut FD_SET, exceptfds : *mut FD_SET, timeout : *const TIMEVAL) -> i32);
diff --git a/library/std/src/sys/pal/windows/mod.rs b/library/std/src/sys/pal/windows/mod.rs
index b7578b01584..18ab3498267 100644
--- a/library/std/src/sys/pal/windows/mod.rs
+++ b/library/std/src/sys/pal/windows/mod.rs
@@ -31,6 +31,7 @@ cfg_select! {
         pub use self::stack_overflow_uwp as stack_overflow;
     }
 }
+pub mod winsock;
 
 /// Map a [`Result<T, WinError>`] to [`io::Result<T>`](crate::io::Result<T>).
 pub trait IoResult<T> {
diff --git a/library/std/src/sys/pal/windows/winsock.rs b/library/std/src/sys/pal/windows/winsock.rs
new file mode 100644
index 00000000000..b110a43ef3a
--- /dev/null
+++ b/library/std/src/sys/pal/windows/winsock.rs
@@ -0,0 +1,80 @@
+use super::c;
+use crate::ffi::c_int;
+use crate::sync::atomic::Atomic;
+use crate::sync::atomic::Ordering::{AcqRel, Relaxed};
+use crate::{io, mem};
+
+static WSA_STARTED: Atomic<bool> = Atomic::<bool>::new(false);
+
+/// Checks whether the Windows socket interface has been started already, and
+/// if not, starts it.
+#[inline]
+pub fn startup() {
+    if !WSA_STARTED.load(Relaxed) {
+        wsa_startup();
+    }
+}
+
+#[cold]
+fn wsa_startup() {
+    unsafe {
+        let mut data: c::WSADATA = mem::zeroed();
+        let ret = c::WSAStartup(
+            0x202, // version 2.2
+            &mut data,
+        );
+        assert_eq!(ret, 0);
+        if WSA_STARTED.swap(true, AcqRel) {
+            // If another thread raced with us and called WSAStartup first then call
+            // WSACleanup so it's as though WSAStartup was only called once.
+            c::WSACleanup();
+        }
+    }
+}
+
+pub fn cleanup() {
+    // We don't need to call WSACleanup here because exiting the process will cause
+    // the OS to clean everything for us, which is faster than doing it manually.
+    // See #141799.
+}
+
+/// Returns the last error from the Windows socket interface.
+pub fn last_error() -> io::Error {
+    io::Error::from_raw_os_error(unsafe { c::WSAGetLastError() })
+}
+
+#[doc(hidden)]
+pub trait IsMinusOne {
+    fn is_minus_one(&self) -> bool;
+}
+
+macro_rules! impl_is_minus_one {
+    ($($t:ident)*) => ($(impl IsMinusOne for $t {
+        fn is_minus_one(&self) -> bool {
+            *self == -1
+        }
+    })*)
+}
+
+impl_is_minus_one! { i8 i16 i32 i64 isize }
+
+/// Checks if the signed integer is the Windows constant `SOCKET_ERROR` (-1)
+/// and if so, returns the last error from the Windows socket interface. This
+/// function must be called before another call to the socket API is made.
+pub fn cvt<T: IsMinusOne>(t: T) -> io::Result<T> {
+    if t.is_minus_one() { Err(last_error()) } else { Ok(t) }
+}
+
+/// A variant of `cvt` for `getaddrinfo` which return 0 for a success.
+pub fn cvt_gai(err: c_int) -> io::Result<()> {
+    if err == 0 { Ok(()) } else { Err(last_error()) }
+}
+
+/// Just to provide the same interface as sys/pal/unix/net.rs
+pub fn cvt_r<T, F>(mut f: F) -> io::Result<T>
+where
+    T: IsMinusOne,
+    F: FnMut() -> T,
+{
+    cvt(f())
+}
diff --git a/src/librustdoc/clean/types.rs b/src/librustdoc/clean/types.rs
index 4eb32585ffb..6e3dfa0ac22 100644
--- a/src/librustdoc/clean/types.rs
+++ b/src/librustdoc/clean/types.rs
@@ -1084,8 +1084,8 @@ pub(crate) fn extract_cfg_from_attrs<'a, I: Iterator<Item = &'a hir::Attribute>
 
     let mut changed_auto_active_status = None;
 
-    // First we get all `doc(auto_cfg)` attributes.
-    for attr in attrs.clone() {
+    // We get all `doc(auto_cfg)`, `cfg` and `target_feature` attributes.
+    for attr in attrs {
         if let Some(ident) = attr.ident()
             && ident.name == sym::doc
             && let Some(attrs) = attr.meta_item_list()
@@ -1146,15 +1146,9 @@ pub(crate) fn extract_cfg_from_attrs<'a, I: Iterator<Item = &'a hir::Attribute>
                     }
                 }
             }
-        }
-    }
-
-    // If there is no `doc(cfg())`, then we retrieve the `cfg()` attributes (because
-    // `doc(cfg())` overrides `cfg()`).
-    for attr in attrs {
-        if let hir::Attribute::Parsed(AttributeKind::TargetFeature { features, .. }) = attr {
-            // treat #[target_feature(enable = "feat")] attributes as if they were
-            // #[doc(cfg(target_feature = "feat"))] attributes as well
+        } else if let hir::Attribute::Parsed(AttributeKind::TargetFeature { features, .. }) = attr {
+            // Treat `#[target_feature(enable = "feat")]` attributes as if they were
+            // `#[doc(cfg(target_feature = "feat"))]` attributes as well.
             for (feature, _) in features {
                 cfg_info.current_cfg &= Cfg::Cfg(sym::target_feature, Some(*feature));
             }