feat(lsp): target architecture switching command for RustAnalyzer (#541)

Author: borngraced

doc/rustaceanvim.txt

@@ -24,6 +24,9 @@ Commands:
  ':RustAnalyzer stop' - Stop the LSP client.
  ':RustAnalyzer restart' - Restart the LSP client.
  ':RustAnalyzer reloadSettings' - Reload settings for the LSP client.
+ ':RustAnalyzer target <target_arch>' - Set the target architecture for the LSP client.
+
+The ':RustAnalyzer target' command can take a valid rustc target, such as 'wasm32-unknown-unknown', or it can be left empty to set the LSP client to use the default target architecture for the operating system.
 
 The ':RustLsp[!]' command is available after the LSP client has initialized.
 It accepts the following subcommands:

lua/rustaceanvim/init.lua

@@ -16,6 +16,11 @@
 --- ':RustAnalyzer stop' - Stop the LSP client.
 --- ':RustAnalyzer restart' - Restart the LSP client.
 --- ':RustAnalyzer reloadSettings' - Reload settings for the LSP client.
+--- ':RustAnalyzer target <target_arch>' - Set the target architecture for the LSP client.
+
+--- The ':RustAnalyzer target' command can take a valid rustc target,
+--- such as 'wasm32-unknown-unknown', or it can be left empty to set the LSP client
+--- to use the default target architecture for the operating system.
 ---
 ---The ':RustLsp[!]' command is available after the LSP client has initialized.
 ---It accepts the following subcommands:

lua/rustaceanvim/lsp/init.lua

@@ -7,6 +7,9 @@ local server_status = require('rustaceanvim.server_status')
 local cargo = require('rustaceanvim.cargo')
 local os = require('rustaceanvim.os')
 
+---Local rustc targets cache
+local rustc_targets_cache = nil
+
 local function override_apply_text_edits()
   local old_func = vim.lsp.util.apply_text_edits
   ---@diagnostic disable-next-line
@@ -93,6 +96,71 @@ local function configure_file_watcher(server_cfg)
   end
 end
 
+---Handles retrieving rustc target archs and running on_valid callback
+---to perform certain actions using the retrieved targets.
+---@param on_valid function(rustc_targets)
+local function validate_rustc_target(on_valid)
+  local on_exit = function(result)
+    -- use cache if available.
+    if rustc_targets_cache then
+      return on_valid(rustc_targets_cache)
+    end
+
+    if result.code ~= 0 then
+      error('Failed to retrieve rustc targets: ' .. result.stderr)
+    end
+
+    rustc_targets_cache = {}
+    for line in result.stdout:gmatch('[^\r\n]+') do
+      rustc_targets_cache[line] = true
+    end
+
+    return on_valid(rustc_targets_cache)
+  end
+
+  -- Call vim.system with on_exit callback to avoid blocking Neovim's event loop.
+  vim.system({ 'rustc', '--print', 'target-list' }, { text = true }, on_exit)
+end
+
+---LSP restart internal implementations
+---@param bufnr? number
+---@param callback? function(client) Optional callback to run for each client before restarting.
+---@return number|nil client_id
+local function restart(bufnr, callback)
+  bufnr = bufnr or vim.api.nvim_get_current_buf()
+  local clients = M.stop(bufnr)
+  local timer, _, _ = vim.uv.new_timer()
+  if not timer then
+    vim.notify('Failed to init timer for LSP client restart.', vim.log.levels.ERROR)
+    return
+  end
+  local attempts_to_live = 50
+  local stopped_client_count = 0
+  timer:start(200, 100, function()
+    for _, client in ipairs(clients) do
+      if client:is_stopped() then
+        stopped_client_count = stopped_client_count + 1
+        vim.schedule(function()
+          -- Execute the callback, if provided, for additional actions before restarting
+          if callback then
+            callback(client)
+          end
+          M.start(bufnr)
+        end)
+      end
+    end
+    if stopped_client_count >= #clients then
+      timer:stop()
+      attempts_to_live = 0
+    elseif attempts_to_live <= 0 then
+      vim.notify('rustaceanvim.lsp: Could not restart all LSP clients.', vim.log.levels.ERROR)
+      timer:stop()
+      attempts_to_live = 0
+    end
+    attempts_to_live = attempts_to_live - 1
+  end)
+end
+
 ---@class rustaceanvim.lsp.StartConfig: rustaceanvim.lsp.ClientConfig
 ---@field root_dir string | nil
 ---@field init_options? table
@@ -249,39 +317,50 @@ M.reload_settings = function(bufnr)
   return clients
 end
 
+---Updates the target architecture setting for the LSP client associated with the given buffer.
+---@param bufnr? number The buffer number, defaults to the current buffer
+---@param target? string The target architecture. Defaults to nil(the current buffer's target if not provided).
+M.set_target_arch = function(bufnr, target)
+  local on_update_target = function(client)
+    -- Get current user's rust-analyzer target
+    local current_target = vim.tbl_get(client, 'config', 'settings', 'rust-analyzer', 'cargo', 'target')
+
+    if not target then
+      if not current_target then
+        vim.notify('Using default OS target architecture.', vim.log.levels.INFO)
+      else
+        vim.notify('Target architecture is already set to the default OS target.', vim.log.levels.INFO)
+      end
+      return
+    end
+
+    ---on_valid callback handles the main functionality in changing system's arch
+    ---by checking if rustc targets contains user's target or if user's provided target is nil.
+    ---Notifies user on unrecognized target arch request
+    local on_valid = function(rustc_tgs)
+      if target == nil or rustc_tgs[target] then
+        client.settings['rust-analyzer'].cargo.target = target
+        client.notify('workspace/didChangeConfiguration', { settings = client.config.settings })
+        vim.notify('Target architecture updated successfully to: ' .. target, vim.log.levels.INFO)
+        return
+      else
+        vim.notify('Invalid target architecture provided: ' .. tostring(target), vim.log.levels.ERROR)
+        return
+      end
+    end
+
+    return validate_rustc_target(on_valid)
+  end
+
+  restart(bufnr, on_update_target)
+end
+
 ---Restart the LSP client.
 ---Fails silently if the buffer's filetype is not one of the filetypes specified in the config.
 ---@param bufnr? number The buffer number (optional), defaults to the current buffer
 ---@return number|nil client_id The LSP client ID after restart
 M.restart = function(bufnr)
-  bufnr = bufnr or vim.api.nvim_get_current_buf()
-  local clients = M.stop(bufnr)
-  local timer, _, _ = vim.uv.new_timer()
-  if not timer then
-    -- TODO: Log error when logging is implemented
-    return
-  end
-  local attempts_to_live = 50
-  local stopped_client_count = 0
-  timer:start(200, 100, function()
-    for _, client in ipairs(clients) do
-      if client:is_stopped() then
-        stopped_client_count = stopped_client_count + 1
-        vim.schedule(function()
-          M.start(bufnr)
-        end)
-      end
-    end
-    if stopped_client_count >= #clients then
-      timer:stop()
-      attempts_to_live = 0
-    elseif attempts_to_live <= 0 then
-      vim.notify('rustaceanvim.lsp: Could not restart all LSP clients.', vim.log.levels.ERROR)
-      timer:stop()
-      attempts_to_live = 0
-    end
-    attempts_to_live = attempts_to_live - 1
-  end)
+  M.restart(bufnr)
 end
 
 ---@enum RustAnalyzerCmd
@@ -290,11 +369,13 @@ local RustAnalyzerCmd = {
   stop = 'stop',
   restart = 'restart',
   reload_settings = 'reloadSettings',
+  target = 'target',
 }
 
 local function rust_analyzer_cmd(opts)
   local fargs = opts.fargs
   local cmd = fargs[1]
+  local arch = fargs[2]
   ---@cast cmd RustAnalyzerCmd
   if cmd == RustAnalyzerCmd.start then
     M.start()
@@ -304,12 +385,14 @@ local function rust_analyzer_cmd(opts)
     M.restart()
   elseif cmd == RustAnalyzerCmd.reload_settings then
     M.reload_settings()
+  elseif cmd == RustAnalyzerCmd.target then
+    M.set_target_arch(nil, arch)
   end
 end
 
 vim.api.nvim_create_user_command('RustAnalyzer', rust_analyzer_cmd, {
   nargs = '+',
-  desc = 'Starts or stops the rust-analyzer LSP client',
+  desc = 'Starts, stops the rust-analyzer LSP client or changes the target',
   complete = function(arg_lead, cmdline, _)
     local clients = rust_analyzer.get_active_rustaceanvim_clients()
     ---@type RustAnalyzerCmd[]