Merging upstream version 1.66.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

5 files changed, 67 insertions, 15 deletions

diff --git a/library/std/src/io/error.rs b/library/std/src/io/error.rs
index 29b09fcc5..3cabf2449 100644
--- a/library/std/src/io/error.rs
+++ b/library/std/src/io/error.rs
@@ -76,7 +76,6 @@ impl fmt::Debug for Error {
     }
 }
 
-#[cfg(not(bootstrap))]
 #[stable(feature = "rust1", since = "1.0.0")]
 impl From<alloc::ffi::NulError> for Error {
     /// Converts a [`alloc::ffi::NulError`] into a [`Error`].
@@ -388,7 +387,7 @@ pub enum ErrorKind {
 impl ErrorKind {
     pub(crate) fn as_str(&self) -> &'static str {
         use ErrorKind::*;
-        // Strictly alphabetical, please.  (Sadly rustfmt cannot do this yet.)
+        // tidy-alphabetical-start
         match *self {
             AddrInUse => "address in use",
             AddrNotAvailable => "address not available",
@@ -432,6 +431,7 @@ impl ErrorKind {
             WouldBlock => "operation would block",
             WriteZero => "write zero",
         }
+        // tidy-alphabetical-end
     }
 }
 
@@ -482,6 +482,7 @@ impl Error {
     /// originate from the OS itself. The `error` argument is an arbitrary
     /// payload which will be contained in this [`Error`].
     ///
+    /// Note that this function allocates memory on the heap.
     /// If no extra payload is required, use the `From` conversion from
     /// `ErrorKind`.
     ///
@@ -496,7 +497,7 @@ impl Error {
     /// // errors can also be created from other errors
     /// let custom_error2 = Error::new(ErrorKind::Interrupted, custom_error);
     ///
-    /// // creating an error without payload
+    /// // creating an error without payload (and without memory allocation)
     /// let eof_error = Error::from(ErrorKind::UnexpectedEof);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
diff --git a/library/std/src/io/error/tests.rs b/library/std/src/io/error/tests.rs
index c897a5e87..16c634e9a 100644
--- a/library/std/src/io/error/tests.rs
+++ b/library/std/src/io/error/tests.rs
@@ -86,7 +86,7 @@ fn test_errorkind_packing() {
     assert_eq!(Error::from(ErrorKind::NotFound).kind(), ErrorKind::NotFound);
     assert_eq!(Error::from(ErrorKind::PermissionDenied).kind(), ErrorKind::PermissionDenied);
     assert_eq!(Error::from(ErrorKind::Uncategorized).kind(), ErrorKind::Uncategorized);
-    // Check that the innards look like like what we want.
+    // Check that the innards look like what we want.
     assert_matches!(
         Error::from(ErrorKind::OutOfMemory).repr.data(),
         ErrorData::Simple(ErrorKind::OutOfMemory),
diff --git a/library/std/src/io/mod.rs b/library/std/src/io/mod.rs
index eeace2c43..23a13523f 100644
--- a/library/std/src/io/mod.rs
+++ b/library/std/src/io/mod.rs
@@ -262,9 +262,12 @@ use crate::sys_common::memchr;
 
 #[stable(feature = "bufwriter_into_parts", since = "1.56.0")]
 pub use self::buffered::WriterPanicked;
+pub(crate) use self::stdio::attempt_print_to_stderr;
 #[unstable(feature = "internal_output_capture", issue = "none")]
 #[doc(no_inline, hidden)]
 pub use self::stdio::set_output_capture;
+#[unstable(feature = "is_terminal", issue = "98070")]
+pub use self::stdio::IsTerminal;
 #[unstable(feature = "print_internals", issue = "none")]
 pub use self::stdio::{_eprint, _print};
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -580,7 +583,7 @@ pub trait Read {
     /// `n > buf.len()`.
     ///
     /// No guarantees are provided about the contents of `buf` when this
-    /// function is called, implementations cannot rely on any property of the
+    /// function is called, so implementations cannot rely on any property of the
     /// contents of `buf` being true. It is recommended that *implementations*
     /// only write data to `buf` instead of reading its contents.
     ///
@@ -756,7 +759,7 @@ pub trait Read {
     /// specified buffer `buf`.
     ///
     /// No guarantees are provided about the contents of `buf` when this
-    /// function is called, implementations cannot rely on any property of the
+    /// function is called, so implementations cannot rely on any property of the
     /// contents of `buf` being true. It is recommended that implementations
     /// only write data to `buf` instead of reading its contents. The
     /// documentation on [`read`] has a more detailed explanation on this
diff --git a/library/std/src/io/readbuf.rs b/library/std/src/io/readbuf.rs
index b1a84095f..4800eeda0 100644
--- a/library/std/src/io/readbuf.rs
+++ b/library/std/src/io/readbuf.rs
@@ -3,10 +3,10 @@
 #[cfg(test)]
 mod tests;
 
-use crate::cmp;
 use crate::fmt::{self, Debug, Formatter};
 use crate::io::{Result, Write};
 use crate::mem::{self, MaybeUninit};
+use crate::{cmp, ptr};
 
 /// A borrowed byte buffer which is incrementally filled and initialized.
 ///
@@ -250,8 +250,11 @@ impl<'a> BorrowedCursor<'a> {
     /// Initializes all bytes in the cursor.
     #[inline]
     pub fn ensure_init(&mut self) -> &mut Self {
-        for byte in self.uninit_mut() {
-            byte.write(0);
+        let uninit = self.uninit_mut();
+        // SAFETY: 0 is a valid value for MaybeUninit<u8> and the length matches the allocation
+        // since it is comes from a slice reference.
+        unsafe {
+            ptr::write_bytes(uninit.as_mut_ptr(), 0, uninit.len());
         }
         self.buf.init = self.buf.capacity();
 
diff --git a/library/std/src/io/stdio.rs b/library/std/src/io/stdio.rs
index 2dc12a18a..1141a957d 100644
--- a/library/std/src/io/stdio.rs
+++ b/library/std/src/io/stdio.rs
@@ -7,6 +7,7 @@ use crate::io::prelude::*;
 
 use crate::cell::{Cell, RefCell};
 use crate::fmt;
+use crate::fs::File;
 use crate::io::{self, BufReader, IoSlice, IoSliceMut, LineWriter, Lines};
 use crate::sync::atomic::{AtomicBool, Ordering};
 use crate::sync::{Arc, Mutex, MutexGuard, OnceLock};
@@ -999,7 +1000,18 @@ fn print_to<T>(args: fmt::Arguments<'_>, global_s: fn() -> T, label: &str)
 where
     T: Write,
 {
-    if OUTPUT_CAPTURE_USED.load(Ordering::Relaxed)
+    if print_to_buffer_if_capture_used(args) {
+        // Successfully wrote to capture buffer.
+        return;
+    }
+
+    if let Err(e) = global_s().write_fmt(args) {
+        panic!("failed printing to {label}: {e}");
+    }
+}
+
+fn print_to_buffer_if_capture_used(args: fmt::Arguments<'_>) -> bool {
+    OUTPUT_CAPTURE_USED.load(Ordering::Relaxed)
         && OUTPUT_CAPTURE.try_with(|s| {
             // Note that we completely remove a local sink to write to in case
             // our printing recursively panics/prints, so the recursive
@@ -1009,16 +1021,49 @@ where
                 s.set(Some(w));
             })
         }) == Ok(Some(()))
-    {
-        // Successfully wrote to capture buffer.
+}
+
+/// Used by impl Termination for Result to print error after `main` or a test
+/// has returned. Should avoid panicking, although we can't help it if one of
+/// the Display impls inside args decides to.
+pub(crate) fn attempt_print_to_stderr(args: fmt::Arguments<'_>) {
+    if print_to_buffer_if_capture_used(args) {
         return;
     }
 
-    if let Err(e) = global_s().write_fmt(args) {
-        panic!("failed printing to {label}: {e}");
-    }
+    // Ignore error if the write fails, for example because stderr is already
+    // closed. There is not much point panicking at this point.
+    let _ = stderr().write_fmt(args);
 }
 
+/// Trait to determine if a descriptor/handle refers to a terminal/tty.
+#[unstable(feature = "is_terminal", issue = "98070")]
+pub trait IsTerminal: crate::sealed::Sealed {
+    /// Returns `true` if the descriptor/handle refers to a terminal/tty.
+    ///
+    /// On platforms where Rust does not know how to detect a terminal yet, this will return
+    /// `false`. This will also return `false` if an unexpected error occurred, such as from
+    /// passing an invalid file descriptor.
+    fn is_terminal(&self) -> bool;
+}
+
+macro_rules! impl_is_terminal {
+    ($($t:ty),*$(,)?) => {$(
+        #[unstable(feature = "sealed", issue = "none")]
+        impl crate::sealed::Sealed for $t {}
+
+        #[unstable(feature = "is_terminal", issue = "98070")]
+        impl IsTerminal for $t {
+            #[inline]
+            fn is_terminal(&self) -> bool {
+                crate::sys::io::is_terminal(self)
+            }
+        }
+    )*}
+}
+
+impl_is_terminal!(File, Stdin, StdinLock<'_>, Stdout, StdoutLock<'_>, Stderr, StderrLock<'_>);
+
 #[unstable(
     feature = "print_internals",
     reason = "implementation detail which may disappear or be replaced at any time",