od: simplify a match in input_decoder.rs

[Devel08]

No description provided.

[Devel08]

@xtqqczze what do you think

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/cut/bounded-memory (fails in this run but passes in the 'main' branch)
Skip an intermittent issue tests/misc/io-errors (fails in this run but passes in the 'main' branch)
Skip an intermittent issue tests/tail/retry (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/date/date-locale-hour (passes in this run but fails in the 'main' branch)
Skipping an intermittent issue tests/tail/tail-n0f (passes in this run but fails in the 'main' branch)
Note: The gnu test tests/cut/cut-huge-range is now being skipped but was previously passing.
Note: The gnu test tests/printf/printf-surprise is now being skipped but was previously passing.

[xtqqczze]

The map feels a bit unusual here since we’re updating two fields as a side effect.

How about using the ? operator to return early instead?

    let (n, p) = self
        .input
        .peek_read(self.data.as_mut_slice(), self.reserved_peek_length)?;

[Devel08]

so like that?

    pub fn peek_read(&mut self) -> io::Result<MemoryDecoder<'_>> {
        let (n, p) = self
            .input
            .peek_read(self.data.as_mut_slice(), self.reserved_peek_length)?;
        self.used_normal_length = n;
        self.used_peek_length = p;
        Ok(MemoryDecoder {
            data: &mut self.data,
            used_normal_length: self.used_normal_length,
            used_peek_length: self.used_peek_length,
            byte_order: self.byte_order,
        })
    }

[cakebaker]

Thanks!