internal compiler error occurs using rls_vscode

[cfeitong]

I'm using the latest nightly toolchain installed by rustup. Although autocomplete works fine, go to definition and hover doesn't.

My environment is here.

$ rustup show
Default host: x86_64-apple-darwin

nightly-x86_64-apple-darwin (default)
rustc 1.23.0-nightly (5f44c653c 2017-11-24)

Full log is here.

DEBUG:rls::server: Language Server starting up. Version: 0.123.0-nightly (015073b 2017-11-10)
TRACE:rls::server::io: reading: 1206 bytes
TRACE:rls::server: Read message `{"jsonrpc":"2.0","id":0,"method":"initialize","params":{"processId":4077,"rootPath":"/Users/cfeitong/Algorithm","rootUri":"file:///Users/cfeitong/Algorithm","capabilities":{"workspace":{"didChangeConfiguration":{"dynamicRegistration":true},"didChangeWatchedFiles":{"dynamicRegistration":true},"symbol":{"dynamicRegistration":true},"executeCommand":{"dynamicRegistration":true}},"textDocument":{"synchronization":{"dynamicRegistration":true,"willSave":true,"willSaveWaitUntil":true,"didSave":true},"completion":{"dynamicRegistration":true,"completionItem":{"snippetSupport":true}},"hover":{"dynamicRegistration":true},"signatureHelp":{"dynamicRegistration":true},"definition":{"dynamicRegistration":true},"references":{"dynamicRegistration":true},"documentHighlight":{"dynamicRegistration":true},"documentSymbol":{"dynamicRegistration":true},"codeAction":{"dynamicRegistration":true},"codeLens":{"dynamicRegistration":true},"formatting":{"dynamicRegistration":true},"rangeFormatting":{"dynamicRegistration":true},"onTypeFormatting":{"dynamicRegistration":true},"rename":{"dynamicRegistration":true},"documentLink":{"dynamicRegistration":true}}},"initializationOptions":{"omitInitBuild":true},"trace":"off"}}`
TRACE:rls::server: Parsed message `RawMessage { method: "initialize", id: Some(Num(0)), params: Object({"capabilities": Object({"textDocument": Object({"codeAction": Object({"dynamicRegistration": Bool(true)}), "codeLens": Object({"dynamicRegistration": Bool(true)}), "completion": Object({"completionItem": Object({"snippetSupport": Bool(true)}), "dynamicRegistration": Bool(true)}), "definition": Object({"dynamicRegistration": Bool(true)}), "documentHighlight": Object({"dynamicRegistration": Bool(true)}), "documentLink": Object({"dynamicRegistration": Bool(true)}), "documentSymbol": Object({"dynamicRegistration": Bool(true)}), "formatting": Object({"dynamicRegistration": Bool(true)}), "hover": Object({"dynamicRegistration": Bool(true)}), "onTypeFormatting": Object({"dynamicRegistration": Bool(true)}), "rangeFormatting": Object({"dynamicRegistration": Bool(true)}), "references": Object({"dynamicRegistration": Bool(true)}), "rename": Object({"dynamicRegistration": Bool(true)}), "signatureHelp": Object({"dynamicRegistration": Bool(true)}), "synchronization": Object({"didSave": Bool(true), "dynamicRegistration": Bool(true), "willSave": Bool(true), "willSaveWaitUntil": Bool(true)})}), "workspace": Object({"didChangeConfiguration": Object({"dynamicRegistration": Bool(true)}), "didChangeWatchedFiles": Object({"dynamicRegistration": Bool(true)}), "executeCommand": Object({"dynamicRegistration": Bool(true)}), "symbol": Object({"dynamicRegistration": Bool(true)})})}), "initializationOptions": Object({"omitInitBuild": Bool(true)}), "processId": Number(PosInt(4077)), "rootPath": String("/Users/cfeitong/Algorithm"), "rootUri": String("file:///Users/cfeitong/Algorithm"), "trace": String("off")}) }`
TRACE:rls::server: Handling `initialize`
TRACE:rls::server: init: InitializationOptions { omit_init_build: true }
TRACE:rls::server::io: response: "Content-Length: 500\r\n\r\n{\"jsonrpc\":\"2.0\",\"id\":0,\"result\":{\"capabilities\":{\"textDocumentSync\":2,\"hoverProvider\":true,\"completionProvider\":{\"resolveProvider\":true,\"triggerCharacters\":[\".\",\":\"]},\"definitionProvider\":true,\"referencesProvider\":true,\"documentHighlightProvider\":true,\"documentSymbolProvider\":true,\"workspaceSymbolProvider\":true,\"codeActionProvider\":true,\"documentFormattingProvider\":true,\"documentRangeFormattingProvider\":false,\"renameProvider\":true,\"executeCommandProvider\":{\"commands\":[\"rls.applySuggestion\"]}}}}"
TRACE:rls::config: root manifest_path: "/Users/cfeitong/Algorithm/Cargo.toml"
TRACE:rls::config: infer_config_defaults: Auto-detected `Algorithm` package
TRACE:rls::config: infer_config_defaults: build_lib: true, build_bin: None
TRACE:rls::server::io: reading: 52 bytes
TRACE:rls::server: Read message `{"jsonrpc":"2.0","method":"initialized","params":{}}`
TRACE:rls::server: Parsed message `RawMessage { method: "initialized", id: None, params: Object({}) }`
TRACE:rls::server: Handling `initialized`
TRACE:rls::server::io: response: "Content-Length: 308\r\n\r\n{\"jsonrpc\":\"2.0\",\"id\":1,\"method\":\"client/registerCapability\",\"params\":{\"registrations\":[{\"id\":\"rls-watch\",\"method\":\"workspace/didChangeWatchedFiles\",\"registerOptions\":{\"watchers\":[{\"globPattern\":\"/Users/cfeitong/Algorithm/Cargo{.toml,.lock}\"},{\"globPattern\":\"/Users/cfeitong/Algorithm/target\",\"kind\":4}]}}]}}"
TRACE:rls::server::io: reading: 472 bytes
TRACE:rls::server: Read message `{"jsonrpc":"2.0","method":"workspace/didChangeConfiguration","params":{"settings":{"rust":{"sysroot":null,"target":null,"rustflags":null,"clear_env_rust_log":true,"build_lib":null,"build_bin":null,"cfg_test":false,"unstable_features":true,"wait_to_build":500,"show_warnings":true,"goto_def_racer_fallback":false,"use_crate_blacklist":true,"build_on_save":false,"workspace_mode":false,"analyze_package":null,"features":[],"all_features":true,"no_default_features":false}}}}`
TRACE:rls::server: Parsed message `RawMessage { method: "workspace/didChangeConfiguration", id: None, params: Object({"settings": Object({"rust": Object({"all_features": Bool(true), "analyze_package": Null, "build_bin": Null, "build_lib": Null, "build_on_save": Bool(false), "cfg_test": Bool(false), "clear_env_rust_log": Bool(true), "features": Array([]), "goto_def_racer_fallback": Bool(false), "no_default_features": Bool(false), "rustflags": Null, "show_warnings": Bool(true), "sysroot": Null, "target": Null, "unstable_features": Bool(true), "use_crate_blacklist": Bool(true), "wait_to_build": Number(PosInt(500)), "workspace_mode": Bool(false)})})}) }`
TRACE:rls::server: Handling `workspace/didChangeConfiguration`
TRACE:rls::actions::notifications: config change: Object({"rust": Object({"all_features": Bool(true), "analyze_package": Null, "build_bin": Null, "build_lib": Null, "build_on_save": Bool(false), "cfg_test": Bool(false), "clear_env_rust_log": Bool(true), "features": Array([]), "goto_def_racer_fallback": Bool(false), "no_default_features": Bool(false), "rustflags": Null, "show_warnings": Bool(true), "sysroot": Null, "target": Null, "unstable_features": Bool(true), "use_crate_blacklist": Bool(true), "wait_to_build": Number(PosInt(500)), "workspace_mode": Bool(false)})})
TRACE:rls::actions::notifications: Updated config: Config { sysroot: None, target: None, rustflags: None, build_lib: Inferred(false), build_bin: Inferred(None), cfg_test: false, unstable_features: true, wait_to_build: 500, show_warnings: true, goto_def_racer_fallback: false, workspace_mode: false, analyze_package: None, clear_env_rust_log: true, build_on_save: false, use_crate_blacklist: true, target_dir: None, features: [], all_features: true, no_default_features: false }
TRACE:rls::config: root manifest_path: "/Users/cfeitong/Algorithm/Cargo.toml"
TRACE:rls::config: infer_config_defaults: Auto-detected `Algorithm` package
TRACE:rls::config: infer_config_defaults: build_lib: true, build_bin: None
TRACE:rls::server::io: response: "Content-Length: 66\r\n\r\n{\"jsonrpc\":\"2.0\",\"method\":\"rustDocument/beginBuild\",\"params\":null}"
TRACE:rls::build: request_build Cargo
TRACE:rls::server::io: response: "Content-Length: 183\r\n\r\n{\"jsonrpc\":\"2.0\",\"id\":2,\"method\":\"client/registerCapability\",\"params\":{\"registrations\":[{\"id\":\"rls-range-formatting\",\"method\":\"textDocument/rangeFormatting\",\"registerOptions\":null}]}}"
TRACE:rls::build: run_build, "/Users/cfeitong/Algorithm" Cargo
TRACE:rls::build: running build
TRACE:rls::build::cargo: root manifest_path: "/Users/cfeitong/Algorithm/Cargo.toml"
TRACE:rls::build::cargo: Cargo compilation options:
CargoOptions { package: [], target: None, lib: true, bin: [], bins: false, all: false, exclude: [], all_features: true, no_default_features: false, features: [] }
TRACE:rls::server::io: reading: 4143 bytes
TRACE:rls::server: Read message `{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"file:///Users/cfeitong/Algorithm/src/quick_sort.rs","languageId":"rust","version":1,"text":"use ::rand::Rng;\n\npub fn quick_sort_by<T: Ord + Clone, C: Fn(&T, &T) -> bool>(arr: &mut [T], cmp: C) {\n    quick_sort_impl(arr, &cmp, &median3_select);\n}\n\npub fn quick_sort<T: Ord + Clone>(arr: &mut [T]) {\n    quick_sort_by(arr, |a, b| a < b);\n}\n\n#[allow(dead_code)]\nfn basic_select<T>(arr: &[T]) -> usize {\n    arr.len() - 1\n}\n\n#[allow(dead_code)]\nfn random_select<T>(arr: &[T]) -> usize {\n    let mut rng = ::rand::thread_rng();\n    rng.gen_range(0, arr.len())\n}\n\n#[allow(dead_code)]\nfn median3_select<T: Ord>(arr: &[T]) -> usize {\n    let mut rng = ::rand::thread_rng();\n    let len = arr.len();\n    let ai = rng.gen_range(0, len);\n    let bi = rng.gen_range(0, len);\n    let ci = rng.gen_range(0, len);\n\n    if arr[ai] > arr[bi] && arr[ai] > arr[ci] {\n        if arr[bi] < arr[ci] {\n            ci\n        } else {\n            bi\n        }\n    } else if arr[ai] < arr[bi] && arr[ai] < arr[ci] {\n        if arr[bi] < arr[ci] {\n            bi\n        } else {\n            ci\n        }\n    } else {\n        ai\n    }\n}\n\nfn quick_sort_impl<T, C, S>(arr: &mut [T], cmp: &C, select: &S)\nwhere\n    T: Ord + Clone,\n    C: Fn(&T, &T) -> bool,\n    S: Fn(&[T]) -> usize,\n{\n    if let Some(pivot) = partition(arr, cmp, select) {\n        let len = arr.len();\n        quick_sort_impl(&mut arr[0..pivot], cmp, select);\n        quick_sort_impl(&mut arr[(pivot + 1)..len], cmp, select);\n    }\n}\n\nfn partition<T, C, S>(arr: &mut [T], cmp: &C, select: S) -> Option<usize>\nwhere\n    T: Ord + Clone,\n    C: Fn(&T, &T) -> bool,\n    S: Fn(&[T]) -> usize,\n{\n    if arr.is_empty() {\n        return None;\n    }\n\n    let idx = select(arr);\n    let last_idx = arr.len() - 1;\n    arr.swap(idx, last_idx);\n    let pivot = arr.last().cloned().unwrap();\n    let mut i: isize = -1;\n    for j in 0..(arr.len() - 1) {\n        if cmp(&arr[j], &pivot) {\n            i += 1;\n            arr.swap(i as usize, j);\n        }\n    }\n    i += 1;\n    let pivot_idx = arr.len() - 1;\n    arr.swap(i as usize, pivot_idx);\n\n    Some(i as usize)\n}\n\n#[cfg(test)]\nmod test {\n    use super::*;\n\n    #[test]\n    fn test_quick_sort_by() {\n        let mut arr0 = vec![1, 2, 3, 4, 3, 2, 1];\n        quick_sort_by(&mut arr0, |a, b| a < b);\n        assert_eq!(arr0, vec![1, 1, 2, 2, 3, 3, 4]);\n\n        let mut arr1 = vec![1];\n        quick_sort_by(&mut arr1, |a, b| a < b);\n        assert_eq!(arr1, vec![1]);\n\n        let mut rng = ::rand::thread_rng();\n        let mut arr2: Vec<i64> = vec![];\n        for _ in 0..100000 {\n            arr2.push(rng.gen())\n        }\n        quick_sort_by(&mut arr2, |a, b| a < b);\n        let t = arr2.len() - 1;\n        for i in 0..t {\n            assert!(arr2[i] <= arr2[i + 1]);\n        }\n    }\n\n    #[test]\n    fn test_quick_sort() {\n        let mut arr0 = vec![1, 2, 3, 4, 3, 2, 1];\n        quick_sort(&mut arr0);\n        assert_eq!(arr0, vec![1, 1, 2, 2, 3, 3, 4]);\n\n        let mut arr1 = vec![1];\n        quick_sort(&mut arr1);\n        assert_eq!(arr1, vec![1]);\n\n        let mut rng = ::rand::thread_rng();\n        let mut arr2: Vec<i64> = vec![];\n        for _ in 0..100000 {\n            arr2.push(rng.gen())\n        }\n        quick_sort(&mut arr2);\n        let t = arr2.len() - 1;\n        for i in 0..t {\n            assert!(arr2[i] <= arr2[i + 1]);\n        }\n    }\n\n    #[allow(dead_code)]\n    // #[test]\n    fn quick_sort_worst_case() {\n        // basic quick sort alogirthm has a O(n^2) worse case.\n        // this test case shows how to build the data that slows quick sort\n        // in fact, so simple.\n\n        // generate sorted data\n        let mut arr: Vec<_> = vec![];\n        for i in 0..100000 {\n            arr.push(i);\n        }\n        quick_sort(&mut arr);\n\n        // or an array full of the same value\n        for v in &mut arr {\n            *v = 3;\n        }\n        quick_sort(&mut arr);\n    }\n\n}\n"}}}`
TRACE:rls::server: Parsed message `RawMessage { method: "textDocument/didOpen", id: None, params: Object({"textDocument": Object({"languageId": String("rust"), "text": String("use ::rand::Rng;\n\npub fn quick_sort_by<T: Ord + Clone, C: Fn(&T, &T) -> bool>(arr: &mut [T], cmp: C) {\n    quick_sort_impl(arr, &cmp, &median3_select);\n}\n\npub fn quick_sort<T: Ord + Clone>(arr: &mut [T]) {\n    quick_sort_by(arr, |a, b| a < b);\n}\n\n#[allow(dead_code)]\nfn basic_select<T>(arr: &[T]) -> usize {\n    arr.len() - 1\n}\n\n#[allow(dead_code)]\nfn random_select<T>(arr: &[T]) -> usize {\n    let mut rng = ::rand::thread_rng();\n    rng.gen_range(0, arr.len())\n}\n\n#[allow(dead_code)]\nfn median3_select<T: Ord>(arr: &[T]) -> usize {\n    let mut rng = ::rand::thread_rng();\n    let len = arr.len();\n    let ai = rng.gen_range(0, len);\n    let bi = rng.gen_range(0, len);\n    let ci = rng.gen_range(0, len);\n\n    if arr[ai] > arr[bi] && arr[ai] > arr[ci] {\n        if arr[bi] < arr[ci] {\n            ci\n        } else {\n            bi\n        }\n    } else if arr[ai] < arr[bi] && arr[ai] < arr[ci] {\n        if arr[bi] < arr[ci] {\n            bi\n        } else {\n            ci\n        }\n    } else {\n        ai\n    }\n}\n\nfn quick_sort_impl<T, C, S>(arr: &mut [T], cmp: &C, select: &S)\nwhere\n    T: Ord + Clone,\n    C: Fn(&T, &T) -> bool,\n    S: Fn(&[T]) -> usize,\n{\n    if let Some(pivot) = partition(arr, cmp, select) {\n        let len = arr.len();\n        quick_sort_impl(&mut arr[0..pivot], cmp, select);\n        quick_sort_impl(&mut arr[(pivot + 1)..len], cmp, select);\n    }\n}\n\nfn partition<T, C, S>(arr: &mut [T], cmp: &C, select: S) -> Option<usize>\nwhere\n    T: Ord + Clone,\n    C: Fn(&T, &T) -> bool,\n    S: Fn(&[T]) -> usize,\n{\n    if arr.is_empty() {\n        return None;\n    }\n\n    let idx = select(arr);\n    let last_idx = arr.len() - 1;\n    arr.swap(idx, last_idx);\n    let pivot = arr.last().cloned().unwrap();\n    let mut i: isize = -1;\n    for j in 0..(arr.len() - 1) {\n        if cmp(&arr[j], &pivot) {\n            i += 1;\n            arr.swap(i as usize, j);\n        }\n    }\n    i += 1;\n    let pivot_idx = arr.len() - 1;\n    arr.swap(i as usize, pivot_idx);\n\n    Some(i as usize)\n}\n\n#[cfg(test)]\nmod test {\n    use super::*;\n\n    #[test]\n    fn test_quick_sort_by() {\n        let mut arr0 = vec![1, 2, 3, 4, 3, 2, 1];\n        quick_sort_by(&mut arr0, |a, b| a < b);\n        assert_eq!(arr0, vec![1, 1, 2, 2, 3, 3, 4]);\n\n        let mut arr1 = vec![1];\n        quick_sort_by(&mut arr1, |a, b| a < b);\n        assert_eq!(arr1, vec![1]);\n\n        let mut rng = ::rand::thread_rng();\n        let mut arr2: Vec<i64> = vec![];\n        for _ in 0..100000 {\n            arr2.push(rng.gen())\n        }\n        quick_sort_by(&mut arr2, |a, b| a < b);\n        let t = arr2.len() - 1;\n        for i in 0..t {\n            assert!(arr2[i] <= arr2[i + 1]);\n        }\n    }\n\n    #[test]\n    fn test_quick_sort() {\n        let mut arr0 = vec![1, 2, 3, 4, 3, 2, 1];\n        quick_sort(&mut arr0);\n        assert_eq!(arr0, vec![1, 1, 2, 2, 3, 3, 4]);\n\n        let mut arr1 = vec![1];\n        quick_sort(&mut arr1);\n        assert_eq!(arr1, vec![1]);\n\n        let mut rng = ::rand::thread_rng();\n        let mut arr2: Vec<i64> = vec![];\n        for _ in 0..100000 {\n            arr2.push(rng.gen())\n        }\n        quick_sort(&mut arr2);\n        let t = arr2.len() - 1;\n        for i in 0..t {\n            assert!(arr2[i] <= arr2[i + 1]);\n        }\n    }\n\n    #[allow(dead_code)]\n    // #[test]\n    fn quick_sort_worst_case() {\n        // basic quick sort alogirthm has a O(n^2) worse case.\n        // this test case shows how to build the data that slows quick sort\n        // in fact, so simple.\n\n        // generate sorted data\n        let mut arr: Vec<_> = vec![];\n        for i in 0..100000 {\n            arr.push(i);\n        }\n        quick_sort(&mut arr);\n\n        // or an array full of the same value\n        for v in &mut arr {\n            *v = 3;\n        }\n        quick_sort(&mut arr);\n    }\n\n}\n"), "uri": String("file:///Users/cfeitong/Algorithm/src/quick_sort.rs"), "version": Number(PosInt(1))})}) }`
TRACE:rls::server: Handling `textDocument/didOpen`
TRACE:rls::actions::notifications: on_open: "file:///Users/cfeitong/Algorithm/src/quick_sort.rs"
TRACE:rls::server::io: reading: 38 bytes
TRACE:rls::server: Read message `{"jsonrpc":"2.0","id":1,"result":null}`
TRACE:rls::server::io: reading: 38 bytes
TRACE:rls::server: Read message `{"jsonrpc":"2.0","id":2,"result":null}`
TRACE:rls::server::io: reading: 251 bytes
TRACE:rls::server: Read message `{"jsonrpc":"2.0","id":1,"method":"textDocument/codeAction","params":{"textDocument":{"uri":"file:///Users/cfeitong/Algorithm/src/quick_sort.rs"},"range":{"start":{"line":0,"character":11},"end":{"line":0,"character":11}},"context":{"diagnostics":[]}}}`
TRACE:rls::server: Parsed message `RawMessage { method: "textDocument/codeAction", id: Some(Num(1)), params: Object({"context": Object({"diagnostics": Array([])}), "range": Object({"end": Object({"character": Number(PosInt(11)), "line": Number(PosInt(0))}), "start": Object({"character": Number(PosInt(11)), "line": Number(PosInt(0))})}), "textDocument": Object({"uri": String("file:///Users/cfeitong/Algorithm/src/quick_sort.rs")})}) }`
TRACE:rls::server: Handling `textDocument/codeAction`
TRACE:rls::actions::requests: code_action CodeActionParams { text_document: TextDocumentIdentifier { uri: "file:///Users/cfeitong/Algorithm/src/quick_sort.rs" }, range: Range { start: Position { line: 0, character: 11 }, end: Position { line: 0, character: 11 } }, context: CodeActionContext { diagnostics: [] } }
TRACE:rls::server::io: response: "Content-Length: 36\r\n\r\n{\"jsonrpc\":\"2.0\",\"id\":1,\"result\":[]}"
TRACE:rls::build::cargo: exec: rand
TRACE:rls::build::cargo: rustc not intercepted - rand
error: internal compiler error: unexpected panic

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.23.0-nightly (5f44c653c 2017-11-24) running on x86_64-apple-darwin

note: run with `RUST_BACKTRACE=1` for a backtrace

thread 'rustc' panicked at 'Could not deserialize save-analysis config: MissingFieldError("reachable_only")', src/libcore/result.rs:906:4
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
stack backtrace:
   0: std::sys::imp::backtrace::tracing::imp::unwind_backtrace
   1: std::sys_common::backtrace::_print
   2: std::panicking::default_hook::{{closure}}
   3: std::panicking::default_hook
   4: std::panicking::rust_panic_with_hook
   5: std::panicking::begin_panic
   6: std::panicking::begin_panic_fmt
   7: rust_begin_unwind
   8: core::panicking::panic_fmt
   9: core::result::unwrap_failed
  10: rustc_save_analysis::find_config
  11: rustc_save_analysis::process_crate
  12: _ZN12rustc_driver20enable_save_analysis28_$u7b$$u7b$closure$u7d$$u7d$28_$u7b$$u7b$closure$u7d$$u7d$17h4a9c6eeb3520bf6aE.llvm.2B161E4
  13: _ZN12rustc_driver20enable_save_analysis28_$u7b$$u7b$closure$u7d$$u7d$17h739d1602f809ea6eE.llvm.FCC0CF03
  14: _ZN12rustc_driver6driver13compile_input28_$u7b$$u7b$closure$u7d$$u7d$17h8fe802d0dc808fedE.llvm.F1122271
  15: <std::thread::local::LocalKey<T>>::with
  16: <std::thread::local::LocalKey<T>>::with
  17: rustc::ty::context::TyCtxt::create_and_enter
  18: rustc_driver::driver::compile_input
  19: rustc_driver::run_compiler

INFO:rls::build::cargo: cargo failed
cause: Could not compile `rand`.
stdout: 
TRACE:rls::server::io: response: "Content-Length: 72\r\n\r\n{\"jsonrpc\":\"2.0\",\"method\":\"rustDocument/diagnosticsBegin\",\"params\":null}"
TRACE:rls::actions::post_build: build - Error
TRACE:rls::server::io: response: "Content-Length: 70\r\n\r\n{\"jsonrpc\":\"2.0\",\"method\":\"rustDocument/diagnosticsEnd\",\"params\":null}"
TRACE:rls::server::io: reading: 179 bytes
TRACE:rls::server: Read message `{"jsonrpc":"2.0","id":2,"method":"textDocument/hover","params":{"textDocument":{"uri":"file:///Users/cfeitong/Algorithm/src/quick_sort.rs"},"position":{"line":16,"character":18}}}`
TRACE:rls::server: Parsed message `RawMessage { method: "textDocument/hover", id: Some(Num(2)), params: Object({"position": Object({"character": Number(PosInt(18)), "line": Number(PosInt(16))}), "textDocument": Object({"uri": String("file:///Users/cfeitong/Algorithm/src/quick_sort.rs")})}) }`
TRACE:rls::server: Handling `textDocument/hover`
TRACE:rls::actions: convert_pos_to_span: "/Users/cfeitong/Algorithm/src/quick_sort.rs" Position { line: 16, character: 18 }
TRACE:rls::actions: line: `fn random_select<T>(arr: &[T]) -> usize {
`
TRACE:rls::actions: start: 17, end: 18
TRACE:rls::actions::requests: hover: Span { file: "/Users/cfeitong/Algorithm/src/quick_sort.rs", range: Range { row_start: Row(16, PhantomData), row_end: Row(16, PhantomData), col_start: Column(17, PhantomData), col_end: Column(18, PhantomData) } }
TRACE:rls::server::io: response: "Content-Length: 62\r\n\r\n{\"jsonrpc\":\"2.0\",\"id\":2,\"result\":{\"contents\":[],\"range\":null}}"

[KillTheMule]

I'm seeing this as well, here is a full backtrace. Environment:

Default host: x86_64-unknown-linux-gnu

installed toolchains
--------------------

stable-x86_64-unknown-linux-gnu
nightly-x86_64-unknown-linux-gnu (default)

installed targets for active toolchain
--------------------------------------

x86_64-unknown-linux-gnu
x86_64-unknown-linux-musl

active toolchain
----------------

nightly-x86_64-unknown-linux-gnu (default)
rustc 1.23.0-nightly (5f44c653c 2017-11-24)

If there's anything else you'd like to know, let me know :)

[yamafaktory]

See rust-lang/rust#46244

[cfeitong]

This is resolved in nightly-2017-12-01.