Update to newer rustc

[nhynes]

new features, but there's also a security vulnerability in the old version.

This isn't a priority so maybe someone new might want to learn how to do this all-too-common task :)

[kostko]

We need to do this due to rust-lang/libc#1136 (comment).

[kostko]

Actually we seem to have already bumped the version in #1167 without referencing this issue, so we may need an even newer version?

[kostko]

It seems that the 2018-11-01 nightly is not recent enough and 2018-11-25 is too recent as rust-sgx-sdk fails to compile due to the panic_implementation feature being removed (actually subsumed by panic_handler so it may be a simple change).

[nhynes]

This issue was actually resolved by #1167. Sorry for not noticing.

[kostko]

Yeah but we need to bump it further due to the build failing with newer libc, at least that is my understanding of the comment linked above.

[kostko]

E.g., the build is now failing with:

error[E0432]: unresolved import `core::ffi::c_void`                                                                                                        
    --> /root/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/libc-0.2.44/src/unix/mod.rs:1151:17                                                          
     |                                                                                                                                                     
1151 |         pub use core::ffi::c_void;                                                                                                                  
     |                 ^^^^^^^^^^^^^^^^^ no `c_void` in `ffi`                                                                                              
                                                                                                                                                           

[nhynes]

Weird, that's even in stable: https://doc.rust-lang.org/stable/core/ffi/enum.c_void.html

Also, we don't use the libc crate when building SGX (or at least we're not supposed to). What exactly are you trying to compile?

[kostko]

So our enclave builds are failing, e.g., try to build an enclave in master. I think the issue is that since 1.30 the c_void type is (a stable) part of libcore and the libc crate has changed to use that but for some reason that is not available under SGX.

Note that libc is explicitly made so that it compiles even in environments which lack a libc - in those cases it is merely an empty stub.

In any case, this does not seem to be an issue with the toolchain as the current version (nightly 2018-10-01) should be recent enough.

[kostko]

Ok I see what the issues is. SGX std does not simply re-export all of core's ffi but it introduces a new module and libc uses extern crate std as core. So the solution is to re-export core::ffi::* in std::ffi.