rust-analyzer no longer updates on save, starting with commit c7e3f1a

[AaronM04]

Information

VIM version

VIM - Vi IMproved 8.2 (2019 Dec 12, compiled Jun 15 2021 08:22:17)
macOS version - x86_64

Operating System: macOS Catalina

What went wrong

When I add code to a Rust file that adds a warning or an error, the warning/error never shows up. Any warnings or errors present when the file was opened never go away regardless of any changes I save.

Reproducing the bug

1. Setup ALE to use rust-analyzer
2. create an empty project with cargo new --bin foobar
3. cd foobar
4. vim src/main.rs
5. Wait until the rust-analyzer process drops to single digit percentage CPU usage
6. Add a line let x = 3; below the fn main line
7. Wait a second.
8. Observe no warning about an unused variable x (a warning is expected here).

:ALEInfo

 Current Filetype: rust
Available Linters: ['analyzer', 'cargo', 'rls', 'rustc']
  Enabled Linters: ['analyzer']
  Ignored Linters: []
 Suggested Fixers: 
  'remove_trailing_lines' - Remove all blank lines at the end of a file.
  'rustfmt' - Fix Rust files with Rustfmt.
  'trim_whitespace' - Remove all trailing whitespace characters at the end of every line.
 Linter Variables:

let g:ale_rust_analyzer_config = {}
let g:ale_rust_analyzer_executable = 'rust-analyzer'
 Global Variables:

let g:ale_cache_executable_check_failures = v:null
let g:ale_change_sign_column_color = 0
let g:ale_command_wrapper = ''
let g:ale_completion_delay = v:null
let g:ale_completion_enabled = 0
let g:ale_completion_max_suggestions = v:null
let g:ale_disable_lsp = 0
let g:ale_echo_cursor = 1
let g:ale_echo_msg_error_str = 'E'
let g:ale_echo_msg_format = '[%linter%] %s [%severity%]'
let g:ale_echo_msg_info_str = 'Info'
let g:ale_echo_msg_warning_str = 'W'
let g:ale_enabled = 1
let g:ale_fix_on_save = 1
let g:ale_fixers = {}
let g:ale_history_enabled = 1
let g:ale_history_log_output = 1
let g:ale_keep_list_window_open = 0
let g:ale_lint_delay = 200
let g:ale_lint_on_enter = 1
let g:ale_lint_on_filetype_changed = 1
let g:ale_lint_on_insert_leave = 1
let g:ale_lint_on_save = 1
let g:ale_lint_on_text_changed = 'normal'
let g:ale_linter_aliases = {}
let g:ale_linters = {'go': ['gofmt', 'golangci-lint', 'gopls', 'govet'], 'rust': ['analyzer']}
let g:ale_linters_explicit = 0
let g:ale_linters_ignore = {}
let g:ale_list_vertical = 0
let g:ale_list_window_size = 10
let g:ale_loclist_msg_format = '[%linter%] %s [%severity%]'
let g:ale_max_buffer_history_size = 20
let g:ale_max_signs = -1
let g:ale_maximum_file_size = v:null
let g:ale_open_list = 0
let g:ale_pattern_options = v:null
let g:ale_pattern_options_enabled = v:null
let g:ale_root = {}
let g:ale_set_balloons = 1
let g:ale_set_highlights = 1
let g:ale_set_loclist = 1
let g:ale_set_quickfix = 0
let g:ale_set_signs = 1
let g:ale_sign_column_always = 1
let g:ale_sign_error = '=>'
let g:ale_sign_info = '->'
let g:ale_sign_offset = 1000000
let g:ale_sign_style_error = '=>'
let g:ale_sign_style_warning = '->'
let g:ale_sign_warning = '->'
let g:ale_sign_highlight_linenrs = 0
let g:ale_statusline_format = v:null
let g:ale_type_map = {}
let g:ale_use_global_executables = v:null
let g:ale_virtualtext_cursor = 0
let g:ale_warn_about_trailing_blank_lines = 1
let g:ale_warn_about_trailing_whitespace = 1
  Command History:

(executable check - success) rust-analyzer
(started) ['/usr/local/bin/bash', '-c', '''rust-analyzer''']

Cause

After bisecting, I found that this is the commit that broke this functionality:

c7e3f1a0dd447eeafcbbd158974860c1918dbdd5 is the first bad commit
commit c7e3f1a0dd447eeafcbbd158974860c1918dbdd5
Author: Horacio Sanson <hsanson@gmail.com>
Date:   Fri Oct 15 08:42:07 2021 +0900

    Fix 3207 - do not send didSave notification if not supported (#3930)

 autoload/ale/lsp.vim               | 19 ++++++++++++-------
 autoload/ale/lsp_linter.vim        |  1 +
 test/lsp/test_did_save_event.vader | 24 ++++++++++++++++++++++++
 3 files changed, 37 insertions(+), 7 deletions(-)

[AaronM04]

This happens on Linux and OpenBSD as well, and doesn't seem to depend on the rust-analyzer version. I reproed it on macOS with this version though:

❯ rust-analyzer --version
rust-analyzer b641a6607 2021-08-17 dev

The commit message suggests it might be a bug in rust-analyzer though? I am happy to create an issue for that project if you all think that is appropriate.

[hsanson]

@AaronM04 thanks for the report and for tracking the commit that caused the issue. This helped me unveil a silly mistake I made on that commit. I merged a fix so let me know if things are working back again for you.