expose diffline origin value (as enum)

[extrawurst]

so i do not need to hardcode char's but can use actual typed enum values.

Just one question: do I have to write a wrapper enum for these things instead of exposing the one from raw?

[weihanglo]

I think we should not expose raw values from libgit2 to git2 consumer. raw::git_diff_line_t is just an u32 not even a char, and exposing it won't gain supports from Rust's strong type system.

Your enum wrapper idea sounds more suitable to me for this case. 😄

[alexcrichton]

Yeah if possible I think it'd be good to have a wrapper type for the return value.

[extrawurst]

ok updated and wrapped in rust idiomatic enum DiffLineType. Just one thing: how do you think about the acronyms? right now I left ContextEOFNL pretty much like in libgit2. Alternative would be ContextEndOfFileNewLine 🤔

[alexcrichton]

Looks reasonable to me! Could you add a test exercising this as well?

[extrawurst]

@alexcrichton good call, the unittest uncovered the lack of pub use the new type in lib.rs

[alexcrichton]

Thanks!