Hi! Thank you for creating an issue. We're aware of this problem and we forced to disable beta channel on Travis because of it.
However, the only solution I can suggest to you is to switch to stable compiler.
The reason is that this issue will never appear in stable, according to https://doc.rust-lang.org/nightly/src/core/array.rs.html#385

[unstable(feature = "const_generic_impls_guard", issue = "0",

reason = "will never be stable, just a temporary step until const generics are stable")]

@vitvakatu oh ok, thank you! I'll use the working nightly until 1.39 goes to stable as I still need await/async.
I'll close this issue since there's nothing you can do about it.

I cannot build librocksdb-sys on beta (I also need beta for the async/await stuff) either on MacOS Mojave, Xcode 11.1 (I have MacPorts, not brew).

I'm getting this error:

error[E0277]: arrays only have std trait implementations for lengths 0..=32
   --> /Users/calin/src/ec/photon/target/release/build/librocksdb-sys-d77172d3d1e61d8b/out/bindings.rs:243:5
    |
243 |     pub __opaque: [libc::c_char; 56usize],
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `std::array::LengthAtMost32` is not implemented for `[i8; 56]`
    |
    = note: required because of the requirements on the impl of `std::fmt::Debug` for `[i8; 56]`
    = note: required because of the requirements on the impl of `std::fmt::Debug` for `&[i8; 56]`
    = note: required for the cast to the object type `dyn std::fmt::Debug`

error[E0277]: arrays only have std trait implementations for lengths 0..=32
   --> /Users/calin/src/ec/photon/target/release/build/librocksdb-sys-d77172d3d1e61d8b/out/bindings.rs:282:5
    |
282 |     pub __opaque: [libc::c_char; 40usize],
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `std::array::LengthAtMost32` is not implemented for `[i8; 40]`
    |
    = note: required because of the requirements on the impl of `std::fmt::Debug` for `[i8; 40]`
    = note: required because of the requirements on the impl of `std::fmt::Debug` for `&[i8; 40]`
    = note: required for the cast to the object type `dyn std::fmt::Debug`

error[E0277]: arrays only have std trait implementations for lengths 0..=32
   --> /Users/calin/src/ec/photon/target/release/build/librocksdb-sys-d77172d3d1e61d8b/out/bindings.rs:364:5
    |
364 |     pub __opaque: [libc::c_char; 56usize],
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `std::array::LengthAtMost32` is not implemented for `[i8; 56]`
    |
    = note: required because of the requirements on the impl of `std::fmt::Debug` for `[i8; 56]`
    = note: required because of the requirements on the impl of `std::fmt::Debug` for `&[i8; 56]`
    = note: required for the cast to the object type `dyn std::fmt::Debug`

error[E0277]: arrays only have std trait implementations for lengths 0..=32
   --> /Users/calin/src/ec/photon/target/release/build/librocksdb-sys-d77172d3d1e61d8b/out/bindings.rs:487:5
    |
487 |     pub __opaque: [libc::c_char; 192usize],
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `std::array::LengthAtMost32` is not implemented for `[i8; 192]`
    |
    = note: required because of the requirements on the impl of `std::fmt::Debug` for `[i8; 192]`
    = note: required because of the requirements on the impl of `std::fmt::Debug` for `&[i8; 192]`
    = note: required for the cast to the object type `dyn std::fmt::Debug`

error[E0277]: arrays only have std trait implementations for lengths 0..=32
   --> /Users/calin/src/ec/photon/target/release/build/librocksdb-sys-d77172d3d1e61d8b/out/bindings.rs:572:5
    |
572 |     pub __opaque: [libc::c_char; 8176usize],
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `std::array::LengthAtMost32` is not implemented for `[i8; 8176]`
    |
    = note: required because of the requirements on the impl of `std::fmt::Debug` for `[i8; 8176]`
    = note: required because of the requirements on the impl of `std::fmt::Debug` for `&[i8; 8176]`
    = note: required for the cast to the object type `dyn std::fmt::Debug`

error: aborting due to 5 previous errors

For more information about this error, try `rustc --explain E0277`.

Please advise?

@cculianu Yes. It's a known issue. Try to use librocksdb-sys from master.

I see. So it will work then?

Apologies but: I'm a nub to the rust world -- I am literally just trying to compile a project a collaborator of mine created so I can get it to work on my macos system (he's doing the server side and I am doing the client in an entirely different language). I just want his server to compile so I can run it here... without having to use a Linux VM (in Linux it compiles perfectly).

I know I can google this but it's intimidating -- the Rust world is literally very new to me. I'm a C++ dev. :) How do I get his build spec to use master and not download the crate that it wants? When I do cargo build in the source directory for his project, it downloads the crate and tries building that. Can I override that?

Maybe I should ask him.. :)

I think I figured it out - I am pointing his rocksdb dependency to your repository here rather than 0.12.4.

It's building now...

ZOMG it compiled! THANK YOU FOR THE REPLY. Literally had no idea what to do. Thanks.