Closes https://github.com/zed-industries/zed/issues/9458
When flying in a plane being totally offline, I've discovered that my
Rust projects do not have any LSP support and rust-analyzer disappeared
out of `~/Library/Application Support/Zed/languages/rust-analyzer/`
directory.
Looking at the
[bad.log](https://github.com/zed-industries/zed/files/14627508/bad.log),
it appears that `get_language_server_command` tries to find a newer LSP
server version and fails on
80bc6c8cc8/crates/language/src/language.rs (L339)
bailing out of all installation related-methods up to here:
80bc6c8cc8/crates/project/src/project.rs (L2916)
where the code thinks that the binary installation process had failed,
cleans the existing directory and tries to install the language server
again:
```log
[2024-03-17T15:14:13+02:00 WARN isahc::handler] request completed with error: failed to resolve host name
[2024-03-17T15:14:13+02:00 ERROR project] failed to start language server "rust-analyzer": error fetching latest release
[2024-03-17T15:14:13+02:00 ERROR project] server stderr: Some("")
[2024-03-17T15:14:13+02:00 INFO project] retrying installation of language server "rust-analyzer" in 1s
[2024-03-17T15:14:13+02:00 ERROR util] crates/lsp/src/lsp.rs:720: oneshot canceled
[2024-03-17T15:14:14+02:00 INFO project] About to spawn test binary
[2024-03-17T15:14:14+02:00 WARN project] test binary failed to launch
[2024-03-17T15:14:14+02:00 WARN project] test binary check failed
[2024-03-17T15:14:14+02:00 INFO project] beginning to reinstall server
[2024-03-17T15:14:14+02:00 INFO language::language_registry] deleting server container
[2024-03-17T15:14:14+02:00 INFO language::language_registry] starting language server "rust-analyzer", path: "/Users/someonetoignore/work/other/local_test", id: 2
[2024-03-17T15:14:14+02:00 INFO language] fetching latest version of language server "rust-analyzer"
[2024-03-17T15:14:14+02:00 WARN isahc::handler] request completed with error: failed to resolve host name
[2024-03-17T15:14:14+02:00 ERROR project] failed to start language server "rust-analyzer": error fetching latest release
[2024-03-17T15:14:14+02:00 ERROR project] server stderr: Some("")
[2024-03-17T15:14:14+02:00 INFO project] retrying installation of language server "rust-analyzer" in 1s
[2024-03-17T15:14:15+02:00 ERROR util] crates/languages/src/rust.rs:335: no cached binary
[2024-03-17T15:14:15+02:00 INFO project] About to spawn test binary
............
```
The PR extracts away all binary fetching-related code into a single
method that does not fail the entire `get_language_server_command` and
allows it to recover and reuse the existing binary:
[good.log](https://github.com/zed-industries/zed/files/14627507/good.log)
```log
[2024-03-17T15:12:24+02:00 INFO language::language_registry] starting language server "rust-analyzer", path: "/Users/someonetoignore/work/other/local_test", id: 1
[2024-03-17T15:12:24+02:00 INFO language] fetching latest version of language server "rust-analyzer"
[2024-03-17T15:12:24+02:00 WARN isahc::handler] request completed with error: failed to resolve host name
[2024-03-17T15:12:24+02:00 INFO language] failed to fetch newest version of language server LanguageServerName("rust-analyzer"). falling back to using "/Users/someonetoignore/Library/Application Support/Zed/languages/rust-analyzer/rust-analyzer-2024-03-11"
[2024-03-17T15:12:24+02:00 INFO lsp] starting language server. binary path: "/Users/someonetoignore/Library/Application Support/Zed/languages/rust-analyzer/rust-analyzer-2024-03-11", working directory: "/Users/someonetoignore/work/other/local_test", args: []
```
Release Notes:
- Fixed language servers erased from the disk when project is opened
offline
9df92c3fb6