Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

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

1 files changed, 59 insertions, 0 deletions

diff --git a/third_party/rust/futures-util/src/io/empty.rs b/third_party/rust/futures-util/src/io/empty.rs
new file mode 100644
index 0000000000..02f6103f54
--- /dev/null
+++ b/third_party/rust/futures-util/src/io/empty.rs
@@ -0,0 +1,59 @@
+use futures_core::task::{Context, Poll};
+use futures_io::{AsyncBufRead, AsyncRead};
+use std::fmt;
+use std::io;
+use std::pin::Pin;
+
+/// Reader for the [`empty()`] function.
+#[must_use = "readers do nothing unless polled"]
+pub struct Empty {
+    _priv: (),
+}
+
+/// Constructs a new handle to an empty reader.
+///
+/// All reads from the returned reader will return `Poll::Ready(Ok(0))`.
+///
+/// # Examples
+///
+/// A slightly sad example of not reading anything into a buffer:
+///
+/// ```
+/// # futures::executor::block_on(async {
+/// use futures::io::{self, AsyncReadExt};
+///
+/// let mut buffer = String::new();
+/// let mut reader = io::empty();
+/// reader.read_to_string(&mut buffer).await?;
+/// assert!(buffer.is_empty());
+/// # Ok::<(), Box<dyn std::error::Error>>(()) }).unwrap();
+/// ```
+pub fn empty() -> Empty {
+    Empty { _priv: () }
+}
+
+impl AsyncRead for Empty {
+    #[inline]
+    fn poll_read(
+        self: Pin<&mut Self>,
+        _: &mut Context<'_>,
+        _: &mut [u8],
+    ) -> Poll<io::Result<usize>> {
+        Poll::Ready(Ok(0))
+    }
+}
+
+impl AsyncBufRead for Empty {
+    #[inline]
+    fn poll_fill_buf(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<io::Result<&[u8]>> {
+        Poll::Ready(Ok(&[]))
+    }
+    #[inline]
+    fn consume(self: Pin<&mut Self>, _: usize) {}
+}
+
+impl fmt::Debug for Empty {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.pad("Empty { .. }")
+    }
+}