Auto merge of rust-lang#101220 - JohnTitor:rollup-ov7upr7, r=JohnTitor

Rollup of 10 pull requests

Successful merges:

 - rust-lang#100804 (Fix search results color on hover for ayu theme)
 - rust-lang#100892 (Add `AsFd` implementations for stdio types on WASI.)
 - rust-lang#100927 (Adding new Fuchsia rustup docs... reworking walkthrough)
 - rust-lang#101088 (Set DebuginfoKind::Pdb in msvc_base)
 - rust-lang#101159 (add tracking issue number to const_slice_split_at_not_mut)
 - rust-lang#101192 (Remove path string)
 - rust-lang#101193 (Avoid zeroing large stack buffers in stdio on Windows)
 - rust-lang#101197 (:arrow_up: rust-analyzer)
 - rust-lang#101200 (Add test for issue rust-lang#85872)
 - rust-lang#101219 (Update books)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

compiler/rustc_infer/src/infer/error_reporting/mod.rs

@@ -2055,22 +2055,22 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
             (exp_found.expected.kind(), exp_found.found.kind())
         {
             if let ty::Adt(found_def, found_substs) = *found_ty.kind() {
-                let path_str = format!("{:?}", exp_def);
                 if exp_def == &found_def {
-                    let opt_msg = "you can convert from `&Option<T>` to `Option<&T>` using \
-                                       `.as_ref()`";
-                    let result_msg = "you can convert from `&Result<T, E>` to \
-                                          `Result<&T, &E>` using `.as_ref()`";
                     let have_as_ref = &[
-                        ("std::option::Option", opt_msg),
-                        ("core::option::Option", opt_msg),
-                        ("std::result::Result", result_msg),
-                        ("core::result::Result", result_msg),
+                        (
+                            sym::Option,
+                            "you can convert from `&Option<T>` to `Option<&T>` using \
+                        `.as_ref()`",
+                        ),
+                        (
+                            sym::Result,
+                            "you can convert from `&Result<T, E>` to \
+                        `Result<&T, &E>` using `.as_ref()`",
+                        ),
                     ];
-                    if let Some(msg) = have_as_ref
-                        .iter()
-                        .find_map(|(path, msg)| (&path_str == path).then_some(msg))
-                    {
+                    if let Some(msg) = have_as_ref.iter().find_map(|(name, msg)| {
+                        self.tcx.is_diagnostic_item(*name, exp_def.did()).then_some(msg)
+                    }) {
                         let mut show_suggestion = true;
                         for (exp_ty, found_ty) in
                             iter::zip(exp_substs.types(), found_substs.types())

compiler/rustc_target/src/spec/msvc_base.rs

@@ -1,4 +1,4 @@
-use crate::spec::{LinkerFlavor, LldFlavor, SplitDebuginfo, TargetOptions};
+use crate::spec::{DebuginfoKind, LinkerFlavor, LldFlavor, SplitDebuginfo, TargetOptions};
 use std::borrow::Cow;
 
 pub fn opts() -> TargetOptions {
@@ -20,6 +20,7 @@ pub fn opts() -> TargetOptions {
         // where `*.pdb` files show up next to the final artifact.
         split_debuginfo: SplitDebuginfo::Packed,
         supported_split_debuginfo: Cow::Borrowed(&[SplitDebuginfo::Packed]),
+        debuginfo_kind: DebuginfoKind::Pdb,
 
         ..Default::default()
     }

compiler/rustc_target/src/spec/windows_msvc_base.rs

@@ -1,4 +1,4 @@
-use crate::spec::{cvs, DebuginfoKind, TargetOptions};
+use crate::spec::{cvs, TargetOptions};
 
 pub fn opts() -> TargetOptions {
     let base = super::msvc_base::opts();
@@ -28,7 +28,6 @@ pub fn opts() -> TargetOptions {
         // not ever be possible for us to pass this flag.
         no_default_libraries: false,
         has_thread_local: true,
-        debuginfo_kind: DebuginfoKind::Pdb,
 
         ..base
     }

library/core/src/slice/mod.rs

@@ -1541,7 +1541,7 @@ impl<T> [T] {
     /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_unstable(feature = "const_slice_split_at_not_mut", issue = "none")]
+    #[rustc_const_unstable(feature = "const_slice_split_at_not_mut", issue = "101158")]
     #[inline]
     #[track_caller]
     #[must_use]

library/std/src/sys/wasi/stdio.rs

@@ -4,7 +4,7 @@ use super::fd::WasiFd;
 use crate::io::{self, IoSlice, IoSliceMut};
 use crate::mem::ManuallyDrop;
 use crate::os::raw;
-use crate::os::wasi::io::{AsRawFd, FromRawFd};
+use crate::os::wasi::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd};
 
 pub struct Stdin;
 pub struct Stdout;
@@ -23,6 +23,13 @@ impl AsRawFd for Stdin {
     }
 }
 
+impl AsFd for Stdin {
+    #[inline]
+    fn as_fd(&self) -> BorrowedFd<'_> {
+        unsafe { BorrowedFd::borrow_raw(0) }
+    }
+}
+
 impl io::Read for Stdin {
     fn read(&mut self, data: &mut [u8]) -> io::Result<usize> {
         self.read_vectored(&mut [IoSliceMut::new(data)])
@@ -51,6 +58,13 @@ impl AsRawFd for Stdout {
     }
 }
 
+impl AsFd for Stdout {
+    #[inline]
+    fn as_fd(&self) -> BorrowedFd<'_> {
+        unsafe { BorrowedFd::borrow_raw(1) }
+    }
+}
+
 impl io::Write for Stdout {
     fn write(&mut self, data: &[u8]) -> io::Result<usize> {
         self.write_vectored(&[IoSlice::new(data)])
@@ -82,6 +96,13 @@ impl AsRawFd for Stderr {
     }
 }
 
+impl AsFd for Stderr {
+    #[inline]
+    fn as_fd(&self) -> BorrowedFd<'_> {
+        unsafe { BorrowedFd::borrow_raw(2) }
+    }
+}
+
 impl io::Write for Stderr {
     fn write(&mut self, data: &[u8]) -> io::Result<usize> {
         self.write_vectored(&[IoSlice::new(data)])

library/std/src/sys/windows/stdio.rs

@@ -3,6 +3,7 @@
 use crate::char::decode_utf16;
 use crate::cmp;
 use crate::io;
+use crate::mem::MaybeUninit;
 use crate::os::windows::io::{FromRawHandle, IntoRawHandle};
 use crate::ptr;
 use crate::str;
@@ -169,13 +170,14 @@ fn write(
 }
 
 fn write_valid_utf8_to_console(handle: c::HANDLE, utf8: &str) -> io::Result<usize> {
-    let mut utf16 = [0u16; MAX_BUFFER_SIZE / 2];
+    let mut utf16 = [MaybeUninit::<u16>::uninit(); MAX_BUFFER_SIZE / 2];
     let mut len_utf16 = 0;
     for (chr, dest) in utf8.encode_utf16().zip(utf16.iter_mut()) {
-        *dest = chr;
+        *dest = MaybeUninit::new(chr);
         len_utf16 += 1;
     }
-    let utf16 = &utf16[..len_utf16];
+    // Safety: We've initialized `len_utf16` values.
+    let utf16: &[u16] = unsafe { MaybeUninit::slice_assume_init_ref(&utf16[..len_utf16]) };
 
     let mut written = write_u16s(handle, &utf16)?;
 
@@ -250,27 +252,33 @@ impl io::Read for Stdin {
             return Ok(bytes_copied);
         } else if buf.len() - bytes_copied < 4 {
             // Not enough space to get a UTF-8 byte. We will use the incomplete UTF8.
-            let mut utf16_buf = [0u16; 1];
+            let mut utf16_buf = [MaybeUninit::new(0); 1];
             // Read one u16 character.
             let read = read_u16s_fixup_surrogates(handle, &mut utf16_buf, 1, &mut self.surrogate)?;
             // Read bytes, using the (now-empty) self.incomplete_utf8 as extra space.
-            let read_bytes = utf16_to_utf8(&utf16_buf[..read], &mut self.incomplete_utf8.bytes)?;
+            let read_bytes = utf16_to_utf8(
+                unsafe { MaybeUninit::slice_assume_init_ref(&utf16_buf[..read]) },
+                &mut self.incomplete_utf8.bytes,
+            )?;
 
             // Read in the bytes from incomplete_utf8 until the buffer is full.
             self.incomplete_utf8.len = read_bytes as u8;
             // No-op if no bytes.
             bytes_copied += self.incomplete_utf8.read(&mut buf[bytes_copied..]);
             Ok(bytes_copied)
         } else {
-            let mut utf16_buf = [0u16; MAX_BUFFER_SIZE / 2];
+            let mut utf16_buf = [MaybeUninit::<u16>::uninit(); MAX_BUFFER_SIZE / 2];
+
             // In the worst case, a UTF-8 string can take 3 bytes for every `u16` of a UTF-16. So
             // we can read at most a third of `buf.len()` chars and uphold the guarantee no data gets
             // lost.
             let amount = cmp::min(buf.len() / 3, utf16_buf.len());
             let read =
                 read_u16s_fixup_surrogates(handle, &mut utf16_buf, amount, &mut self.surrogate)?;
-
-            match utf16_to_utf8(&utf16_buf[..read], buf) {
+            // Safety `read_u16s_fixup_surrogates` returns the number of items
+            // initialized.
+            let utf16s = unsafe { MaybeUninit::slice_assume_init_ref(&utf16_buf[..read]) };
+            match utf16_to_utf8(utf16s, buf) {
                 Ok(value) => return Ok(bytes_copied + value),
                 Err(e) => return Err(e),
             }
@@ -283,14 +291,14 @@ impl io::Read for Stdin {
 // This is a best effort, and might not work if we are not the only reader on Stdin.
 fn read_u16s_fixup_surrogates(
     handle: c::HANDLE,
-    buf: &mut [u16],
+    buf: &mut [MaybeUninit<u16>],
     mut amount: usize,
     surrogate: &mut u16,
 ) -> io::Result<usize> {
     // Insert possibly remaining unpaired surrogate from last read.
     let mut start = 0;
     if *surrogate != 0 {
-        buf[0] = *surrogate;
+        buf[0] = MaybeUninit::new(*surrogate);
         *surrogate = 0;
         start = 1;
         if amount == 1 {
@@ -303,7 +311,10 @@ fn read_u16s_fixup_surrogates(
     let mut amount = read_u16s(handle, &mut buf[start..amount])? + start;
 
     if amount > 0 {
-        let last_char = buf[amount - 1];
+        // Safety: The returned `amount` is the number of values initialized,
+        // and it is not 0, so we know that `buf[amount - 1]` have been
+        // initialized.
+        let last_char = unsafe { buf[amount - 1].assume_init() };
         if last_char >= 0xD800 && last_char <= 0xDBFF {
             // high surrogate
             *surrogate = last_char;
@@ -313,7 +324,8 @@ fn read_u16s_fixup_surrogates(
     Ok(amount)
 }
 
-fn read_u16s(handle: c::HANDLE, buf: &mut [u16]) -> io::Result<usize> {
+// Returns `Ok(n)` if it initialized `n` values in `buf`.
+fn read_u16s(handle: c::HANDLE, buf: &mut [MaybeUninit<u16>]) -> io::Result<usize> {
     // Configure the `pInputControl` parameter to not only return on `\r\n` but also Ctrl-Z, the
     // traditional DOS method to indicate end of character stream / user input (SUB).
     // See #38274 and https://stackoverflow.com/questions/43836040/win-api-readconsole.
@@ -346,8 +358,9 @@ fn read_u16s(handle: c::HANDLE, buf: &mut [u16]) -> io::Result<usize> {
         }
         break;
     }
-
-    if amount > 0 && buf[amount as usize - 1] == CTRL_Z {
+    // Safety: if `amount > 0`, then that many bytes were written, so
+    // `buf[amount as usize - 1]` has been initialized.
+    if amount > 0 && unsafe { buf[amount as usize - 1].assume_init() } == CTRL_Z {
         amount -= 1;
     }
     Ok(amount as usize)