src/docs/unused_io_amount.txt

   1 ### What it does
   2 Checks for unused written/read amount.
   3
   4 ### Why is this bad?
   5 `io::Write::write(_vectored)` and
   6 `io::Read::read(_vectored)` are not guaranteed to
   7 process the entire buffer. They return how many bytes were processed, which
   8 might be smaller
   9 than a given buffer's length. If you don't need to deal with
  10 partial-write/read, use
  11 `write_all`/`read_exact` instead.
  12
  13 When working with asynchronous code (either with the `futures`
  14 crate or with `tokio`), a similar issue exists for
  15 `AsyncWriteExt::write()` and `AsyncReadExt::read()` : these
  16 functions are also not guaranteed to process the entire
  17 buffer.  Your code should either handle partial-writes/reads, or
  18 call the `write_all`/`read_exact` methods on those traits instead.
  19
  20 ### Known problems
  21 Detects only common patterns.
  22
  23 ### Examples
  24 ```
  25 use std::io;
  26 fn foo<W: io::Write>(w: &mut W) -> io::Result<()> {
  27     // must be `w.write_all(b"foo")?;`
  28     w.write(b"foo")?;
  29     Ok(())
  30 }
  31 ```