vimrc: standalone .rs files via detachedFiles, added at server start

A .rs file that is a target of its nearest Cargo.toml uses that crate;
any other .rs file is loaded standalone via detachedFiles with
checkOnSave off (cargo check needs a Cargo.toml).

1 files changed, 31 insertions, 53 deletions

diff --git a/core/vimrc b/core/vimrc
index 017e754..22b6b41 100644
--- a/core/vimrc
+++ b/core/vimrc
@@ -186,75 +186,53 @@ endif
 let g:gitgutter_sign_column_always = 0
 
 
-" rust-analyzer root: nearest Cargo.toml dir only if this file is a target of that crate
-" (src/ examples/ tests/ benches/ build.rs, or its path appears in the manifest); else the
-" file's own dir, so rust-analyzer loads it standalone (std resolves) instead of detached-in-a-foreign-project
-" RustCrate(): crate dir if this buffer is a target of its nearest Cargo.toml, else ''
+" rust-analyzer: a file that is a target of its nearest Cargo.toml (src/ examples/ tests/
+" benches/ build.rs, or its path is in the manifest) uses that crate. Any other .rs file is
+" loaded standalone via detachedFiles, with checkOnSave off (cargo check needs a Cargo.toml).
 function! RustCrate() abort
   let l:p = expand('%:p')
   let l:d = lsp#utils#find_nearest_parent_file_directory(l:p, 'Cargo.toml')
-  if !empty(l:d)
-    let l:d = substitute(fnamemodify(l:d, ':p'), '/$', '', '')
-    let l:rel = stridx(l:p, l:d . '/') == 0 ? l:p[len(l:d) + 1:] : ''
-    let l:target = l:rel =~# '^\(src\|examples\|tests\|benches\)/' || l:rel ==# 'build.rs'
-    if !l:target && !empty(l:rel)
-      let l:target = stridx(join(readfile(l:d . '/Cargo.toml'), "\n"), '"' . l:rel . '"') >= 0
-    endif
-    if l:target
-      return l:d
-    endif
+  if empty(l:d) | return '' | endif
+  let l:d = substitute(fnamemodify(l:d, ':p'), '/$', '', '')
+  let l:rel = stridx(l:p, l:d . '/') == 0 ? l:p[len(l:d) + 1:] : ''
+  if l:rel =~# '^\(src\|examples\|tests\|benches\)/\|^build\.rs$'
+    \ || (!empty(l:rel) && stridx(join(readfile(l:d . '/Cargo.toml')), '"' . l:rel . '"') >= 0)
+    return l:d
   endif
   return ''
 endfunction
+function! s:RustAddDetached() abort
+  let l:p = expand('%:p')
+  if empty(l:p) || index(g:ra_init.detachedFiles, l:p) >= 0 | return 0 | endif
+  call add(g:ra_init.detachedFiles, l:p)
+  return 1
+endfunction
+" Called once at server start (root_uri is read just before the init options).
 function! RustRoot() abort
   let l:c = RustCrate()
-  return empty(l:c) ? expand('%:p:h') : l:c
+  let g:ra_init.checkOnSave = empty(l:c) ? v:false : v:true
+  if !empty(l:c) | return l:c | endif
+  call s:RustAddDetached()
+  return expand('%:p:h')
 endfunction
-" Standalone .rs files (no owning crate) must be listed in rust-analyzer's detachedFiles,
-" else it loads nothing for them (no gd/completion). The list is shared by reference with
-" the init options below (covers the first file) and pushed as config for later files.
-let g:ra_detached = []
-" checkOnSave runs `cargo check` on the file, which needs nightly -Zscript for a file with
-" no Cargo.toml; RustDetach turns it off when the server starts on a standalone file.
 let g:ra_init = {
-  \   'completion': {
-  \     'autoimport': { 'enable': v:true },
-  \     'postfix':    { 'enable': v:true },
-  \   },
-  \   'checkOnSave': v:true,
-  \   'detachedFiles': g:ra_detached,
-  \ }
-function! RustDetach() abort
-  if !exists('g:lsp_loaded')
-    return
-  endif
-  let l:p = expand('%:p')
-  if empty(l:p) || !empty(RustCrate()) || index(g:ra_detached, l:p) >= 0
-    return
-  endif
-  call add(g:ra_detached, l:p)
-  if lsp#get_server_status('rust-analyzer') !~# '^\(running\|starting\)$'
-    let g:ra_init['checkOnSave'] = v:false
-  endif
-  if lsp#get_server_status('rust-analyzer') ==# 'running'
-    call lsp#update_workspace_config('rust-analyzer', {'rust-analyzer': {'detachedFiles': copy(g:ra_detached)}})
-  endif
-endfunction
+  \ 'completion': {'autoimport': {'enable': v:true}, 'postfix': {'enable': v:true}},
+  \ 'checkOnSave': v:true, 'detachedFiles': []}
 augroup rust_detached
   au!
-  au BufEnter *.rs call RustDetach()
+  " standalone file opened while the server already runs: add it live (check setting untouched)
+  au BufEnter *.rs if exists('g:lsp_loaded') && lsp#get_server_status('rust-analyzer') ==# 'running'
+    \ && empty(RustCrate()) && s:RustAddDetached()
+    \ | call lsp#update_workspace_config('rust-analyzer', {'rust-analyzer': g:ra_init}) | endif
 augroup END
-
 " rust-analyzer via the rustup proxy shim (portable across toolchains/machines)
 if executable(expand('~/.cargo/bin/rust-analyzer'))
   au User lsp_setup call lsp#register_server({
-  \   'name': 'rust-analyzer',
-  \   'cmd': {server_info -> [expand('~/.cargo/bin/rust-analyzer')]},
-  \   'allowlist': ['rust'],
-  \   'root_uri': {server_info -> lsp#utils#path_to_uri(RustRoot())},
-  \   'initialization_options': g:ra_init,
-  \   'workspace_config': {'rust-analyzer': {'detachedFiles': g:ra_detached}},
-  \ })
+  \ 'name': 'rust-analyzer', 'allowlist': ['rust'],
+  \ 'cmd': {server_info -> [expand('~/.cargo/bin/rust-analyzer')]},
+  \ 'root_uri': {server_info -> lsp#utils#path_to_uri(RustRoot())},
+  \ 'initialization_options': g:ra_init,
+  \ 'workspace_config': {'rust-analyzer': g:ra_init}})
 endif
 if executable(expand('~/.local/bin/ruff'))
   au User lsp_setup call lsp#register_server({