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    use crate::io::util::read_line::finish_string_read;
    use crate::io::util::read_to_end::read_to_end_internal;
    use crate::io::util::vec_with_initialized::VecWithInitialized;
    use crate::io::AsyncRead;

    use pin_project_lite::pin_project;
    use std::future::Future;
    use std::marker::PhantomPinned;
    use std::pin::Pin;
    use std::task::{Context, Poll};
    use std::{io, mem};

    pin_project! {
        /// Future for the [`read_to_string`](super::AsyncReadExt::read_to_string) method.
        #[derive(Debug)]
        #[must_use = "futures do nothing unless you `.await` or poll them"]
        pub struct ReadToString<'a, R: ?Sized> {
            reader: &'a mut R,
            // This is the buffer we were provided. It will be replaced with an empty string
            // while reading to postpone utf-8 handling until after reading.
            output: &'a mut String,
            // The actual allocation of the string is moved into this vector instead.
            buf: VecWithInitialized<Vec<u8>>,
            // The number of bytes appended to buf. This can be less than buf.len() if
            // the buffer was not empty when the operation was started.
            read: usize,
            // Make this future `!Unpin` for compatibility with async trait methods.
            #[pin]
            _pin: PhantomPinned,
        }
    }

    pub(crate) fn read_to_string<'a, R>(
        reader: &'a mut R,
        string: &'a mut String,
    ) -> ReadToString<'a, R>
    where
        R: AsyncRead + ?Sized + Unpin,
    {
        let buf = mem::replace(string, String::new()).into_bytes();
        ReadToString {
            reader,
            buf: VecWithInitialized::new(buf),
            output: string,
            read: 0,
            _pin: PhantomPinned,
        }
    }

    fn read_to_string_internal<R: AsyncRead + ?Sized>(
        reader: Pin<&mut R>,
        output: &mut String,
        buf: &mut VecWithInitialized<Vec<u8>>,
        read: &mut usize,
        cx: &mut Context<'_>,
    ) -> Poll<io::Result<usize>> {
        let io_res = ready!(read_to_end_internal(buf, reader, read, cx));
        let utf8_res = String::from_utf8(buf.take());

        // At this point both buf and output are empty. The allocation is in utf8_res.

        debug_assert!(buf.is_empty());
        debug_assert!(output.is_empty());
        finish_string_read(io_res, utf8_res, *read, output, true)
    }

    impl<A> Future for ReadToString<'_, A>
    where
        A: AsyncRead + ?Sized + Unpin,
    {
        type Output = io::Result<usize>;

        fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
            let me = self.project();

            read_to_string_internal(Pin::new(*me.reader), me.output, me.buf, me.read, cx)
        }
    }