Yesterday I successfully updated my current project to build with the 2018 update. The only minor issue seems to be that since updating, RLS in VSCode has started failing and rust build options no longer show up in the list of available tasks. Cargo build/doc/test still all work from the command line though.
I set "rust-client.revealOutputChannelOn": "info" in order to try to debug it. I consistently see the following upon opening any *.rs file.
thread 'main' panicked at 'Could not convert URI to path: ()', src\libcore\result.rs:1009:5
note: Run with `RUST_BACKTRACE=1` for a backtrace.
[Info - 7:21:15 PM] Connection to server got closed. Server will restart.
thread 'main' panicked at 'Could not convert URI to path: ()', src\libcore\result.rs:1009:5
note: Run with `RUST_BACKTRACE=1` for a backtrace.
[Info - 7:21:16 PM] Connection to server got closed. Server will restart.
thread 'main' panicked at 'Could not convert URI to path: ()', src\libcore\result.rs:1009:5
note: Run with `RUST_BACKTRACE=1` for a backtrace.
[Info - 7:21:17 PM] Connection to server got closed. Server will restart.
thread 'main' panicked at 'Could not convert URI to path: ()', src\libcore\result.rs:1009:5
note: Run with `RUST_BACKTRACE=1` for a backtrace.
[Info - 7:21:18 PM] Connection to server got closed. Server will restart.
thread 'main' panicked at 'Could not convert URI to path: ()', src\libcore\result.rs:1009:5
note: Run with `RUST_BACKTRACE=1` for a backtrace.
[Error - 7:21:19 PM] Connection to server got closed. Server will not be restarted.
EDIT: Here it is with backtrace enabled:
thread 'main' panicked at 'Could not convert URI to path: ()', src\libcore\result.rs:1009:5
stack backtrace:
0: std::sys_common::alloc::realloc_fallback
1: std::panicking::take_hook
2: std::panicking::take_hook
3: std::panicking::rust_panic_with_hook
4: std::panicking::begin_panic_fmt
5: rust_begin_unwind
6: core::panicking::panic_fmt
7: <unknown>
8: <unknown>
9: <unknown>
10: <unknown>
11: <unknown>
12: <unknown>
13: <unknown>
14: <unknown>
15: std::panicking::update_panic_count
16: _rust_maybe_catch_panic
17: std::rt::lang_start_internal
18: <unknown>
19: git_libgit2_opts
20: BaseThreadInitThunk
21: RtlUserThreadStart
[Info - 11:10:03 AM] Connection to server got closed. Server will restart.