fix: change the type to c_char so it can be compiled for aarch64

[cschin]

The PR changes the pointer type to i8 to a pointer type to c_char. When I tested to compile this on AWS graviton CPU, the c_char is actually u8 type. The hard-coded pointer type to i8 causes compiling errors. This should work on Intel and aarch64. (I did not test compiling the code on macOS though.)

[brainstorm]

Thanks @cschin for these changes, there seem to be formatting issues, just cargo fmt and commit/push again? ;)

[coveralls]

Pull Request Test Coverage Report for Build 1383999223

• 37 of 37 (100.0%) changed or added relevant lines in 4 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.004%) to 94.8%

---

Totals
Change from base Build 1383851418:	0.004%
Covered Lines:	11523
Relevant Lines:	12155

---

💛 - Coveralls

[brainstorm]

Can you rebase against master? CI does not seem to be happy with MacOS, it doesn't seem to be your fault though, I've pushed a couple of commits fixing rust.yml CI recipe for OSX now and it's green on HEAD.

[cschin]

Can you rebase against master? CI does not seem to be happy with MacOS, it doesn't seem to be your fault though, I've pushed a couple of commits fixing rust.yml CI recipe for OSX now and it's green on HEAD.

just did. sorry the commits are a bit messy.

[brainstorm]

just did. sorry the commits are a bit messy.

Yeah, thanks, I noticed, would you mind cleaning (squashing) them up a bit?

[brainstorm]

The PR changes the pointer type to i8 to a pointer type to c_char. When I tested to compile this on AWS graviton CPU, the c_char is actually u8 type. The hard-coded pointer type to i8 causes compiling errors. This should work on Intel and aarch64. (I did not test compiling the code on macOS though.)

Also, could you paste the compile errors you were seeing over here for future reference? I'll probably test your changes with my toy example: https://github.com/brainstorm/s3-rust-htslib-bam

[cschin]

This is the errors when I compile the master branch:

   Compiling rust-htslib v0.38.2 (/wd/rust-htslib)
error[E0308]: mismatched types
   --> src/bam/record.rs:152:16
    |
152 |             s: sam_copy.as_ptr() as *mut i8,
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `u8`, found `i8`
    |
    = note: expected raw pointer `*mut u8`
               found raw pointer `*mut i8`

error[E0308]: mismatched types
   --> src/bam/record.rs:583:17
    |
583 |                 c_str.as_ptr() as *mut i8,
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^ expected `u8`, found `i8`
    |
    = note: expected raw pointer `*const u8`
               found raw pointer `*mut i8`

error[E0308]: mismatched types
   --> src/bam/record.rs:678:49
    |
678 |                 let c_str = ffi::CStr::from_ptr(aux.offset(TYPE_ID_LEN).cast::<i8>());
    |                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `u8`, found `i8`
    |
    = note: expected raw pointer `*const u8`
               found raw pointer `*const i8`

error[E0308]: mismatched types
   --> src/bam/record.rs:798:21
    |
798 |                     ctag,
    |                     ^^^^ expected `u8`, found `i8`
    |
    = note: expected raw pointer `*const u8`
               found raw pointer `*mut i8`

[tedil]

Makes sense to go from i8 to c_char. Just a byte in a CStr ;)
Thanks for the PR, very much appreciated!

[cschin]

@brainstorm @tedil Thanks. It will make my Cargo.toml a bit cleaner (no need to point to my own fork in the future).