Failed to fetch region: fetch converts u64 to i64.

[SebastianDall]

Hello,

Thank you for this awesome crate.

I ran into an issue yesterday where I want to fetch an entire region from bed.gz file with a tabix file. As I always want to fetch the entire reference I set the end to be u64::MAX, however this creates a "Failed to fetch region" error.

use rust_htslib::tbx::{Reader};

let mut reader = Reader::from_path("sample.bed.gz");

const UNREASONABLE_MAX: u64 = i64::MAX as u64;
reader
   .fetch(tid, 0, UNREASONABLE_MAX)
   .map_err(|e| anyhow!("Failed to fetch contig '{}': {}", contig, e.to_string()))?;

The error arises from:

/// Fetch region given by numeric sequence number and 0-based begin and end position.
    pub fn fetch(&mut self, tid: u64, start: u64, end: u64) -> Result<()> {
        self.tid = tid as i64; <-    HERE
        self.start = start as i64; <-    HERE
        self.end = end as i64; <-   HERE

        if let Some(itr) = self.itr {
            unsafe {
                htslib::hts_itr_destroy(itr);
            }
        }
        let itr = unsafe {
            htslib::hts_itr_query(
                (*self.tbx).idx,
                tid as i32,
                start as i64,
                end as i64,
                Some(htslib::tbx_readrec),
            )
        };
        if itr.is_null() {
            self.itr = None;
            Err(Error::Fetch)
        } else {
            self.itr = Some(itr);
            Ok(())
        }
    }

Is there a particular reason why the arguments are u64 but converted to i64 right after? In my case I could simply do i64::MAX as u64 and the error would be resolved.

Also do let me know if I can query more efficiently.

Kind regards, Sebastian