Auto merge of #110648 - Dylan-DPC:rollup-em3ovcq, r=Dylan-DPC

Rollup of 5 pull requests

Successful merges:

 - #110333 (rustc_metadata: Split `children` into multiple tables)
 - #110501 (rustdoc: fix ICE from rustc_resolve and librustdoc parse divergence)
 - #110608 (Specialize some `io::Read` and `io::Write` methods for `VecDeque<u8>` and `&[u8]`)
 - #110632 (Panic instead of truncating if the incremental on-disk cache is too big)
 - #110633 (More `mem::take` in `library`)

Failed merges:

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

3 files changed, 59 insertions, 5 deletions

diff --git a/library/std/src/io/impls.rs b/library/std/src/io/impls.rs
index e5048dcc8ac..a7428776d8f 100644
--- a/library/std/src/io/impls.rs
+++ b/library/std/src/io/impls.rs
@@ -9,6 +9,7 @@ use crate::io::{
     self, BorrowedCursor, BufRead, ErrorKind, IoSlice, IoSliceMut, Read, Seek, SeekFrom, Write,
 };
 use crate::mem;
+use crate::str;
 
 // =============================================================================
 // Forwarding implementations
@@ -307,6 +308,17 @@ impl Read for &[u8] {
         *self = &self[len..];
         Ok(len)
     }
+
+    #[inline]
+    fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
+        let content = str::from_utf8(self).map_err(|_| {
+            io::const_io_error!(ErrorKind::InvalidData, "stream did not contain valid UTF-8")
+        })?;
+        buf.push_str(content);
+        let len = self.len();
+        *self = &self[len..];
+        Ok(len)
+    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -336,7 +348,7 @@ impl Write for &mut [u8] {
     #[inline]
     fn write(&mut self, data: &[u8]) -> io::Result<usize> {
         let amt = cmp::min(data.len(), self.len());
-        let (a, b) = mem::replace(self, &mut []).split_at_mut(amt);
+        let (a, b) = mem::take(self).split_at_mut(amt);
         a.copy_from_slice(&data[..amt]);
         *self = b;
         Ok(amt)
@@ -434,6 +446,33 @@ impl<A: Allocator> Read for VecDeque<u8, A> {
         self.drain(..n);
         Ok(())
     }
+
+    #[inline]
+    fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
+        // The total len is known upfront so we can reserve it in a single call.
+        let len = self.len();
+        buf.reserve(len);
+
+        let (front, back) = self.as_slices();
+        buf.extend_from_slice(front);
+        buf.extend_from_slice(back);
+        self.clear();
+        Ok(len)
+    }
+
+    #[inline]
+    fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
+        // We have to use a single contiguous slice because the `VecDequeue` might be split in the
+        // middle of an UTF-8 character.
+        let len = self.len();
+        let content = self.make_contiguous();
+        let string = str::from_utf8(content).map_err(|_| {
+            io::const_io_error!(ErrorKind::InvalidData, "stream did not contain valid UTF-8")
+        })?;
+        buf.push_str(string);
+        self.clear();
+        Ok(len)
+    }
 }
 
 /// Write is implemented for `VecDeque<u8>` by appending to the `VecDeque`, growing it as needed.
@@ -446,6 +485,21 @@ impl<A: Allocator> Write for VecDeque<u8, A> {
     }
 
     #[inline]
+    fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
+        let len = bufs.iter().map(|b| b.len()).sum();
+        self.reserve(len);
+        for buf in bufs {
+            self.extend(&**buf);
+        }
+        Ok(len)
+    }
+
+    #[inline]
+    fn is_write_vectored(&self) -> bool {
+        true
+    }
+
+    #[inline]
     fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
         self.extend(buf);
         Ok(())
diff --git a/library/std/src/io/mod.rs b/library/std/src/io/mod.rs
index 020c723925a..8c1c8cac0ef 100644
--- a/library/std/src/io/mod.rs
+++ b/library/std/src/io/mod.rs
@@ -253,7 +253,7 @@ mod tests;
 
 use crate::cmp;
 use crate::fmt;
-use crate::mem::replace;
+use crate::mem::take;
 use crate::ops::{Deref, DerefMut};
 use crate::slice;
 use crate::str;
@@ -1186,7 +1186,7 @@ impl<'a> IoSliceMut<'a> {
             }
         }
 
-        *bufs = &mut replace(bufs, &mut [])[remove..];
+        *bufs = &mut take(bufs)[remove..];
         if bufs.is_empty() {
             assert!(n == accumulated_len, "advancing io slices beyond their length");
         } else {
@@ -1329,7 +1329,7 @@ impl<'a> IoSlice<'a> {
             }
         }
 
-        *bufs = &mut replace(bufs, &mut [])[remove..];
+        *bufs = &mut take(bufs)[remove..];
         if bufs.is_empty() {
             assert!(n == accumulated_len, "advancing io slices beyond their length");
         } else {
diff --git a/library/std/src/sys/unsupported/io.rs b/library/std/src/sys/unsupported/io.rs
index 82610ffab7e..6372fca74e0 100644
--- a/library/std/src/sys/unsupported/io.rs
+++ b/library/std/src/sys/unsupported/io.rs
@@ -30,7 +30,7 @@ impl<'a> IoSliceMut<'a> {
 
     #[inline]
     pub fn advance(&mut self, n: usize) {
-        let slice = mem::replace(&mut self.0, &mut []);
+        let slice = mem::take(&mut self.0);
         let (_, remaining) = slice.split_at_mut(n);
         self.0 = remaining;
     }