make autofix configurable through in-editor configuration

The `force_autofix` will not work on an editor that supports code actions.

Author: Techatrix

schema.json

@@ -27,11 +27,6 @@
             },
             "default": []
         },
-        "enable_autofix": {
-            "description": "Whether to automatically fix errors on save. Currently supports adding and removing discards.",
-            "type": "boolean",
-            "default": false
-        },
         "semantic_tokens": {
             "description": "Set level of semantic tokens. `partial` only includes information that requires semantic analysis.",
             "type": "string",
@@ -77,6 +72,11 @@
             "type": "boolean",
             "default": false
         },
+        "force_autofix": {
+            "description": "Work around editors that do not support 'source.fixall' code actions on save. This option may delivered a substandard user experience. Please refer to the installation guide to see which editors natively support code actions on save.",
+            "type": "boolean",
+            "default": false
+        },
         "warn_style": {
             "description": "Enables warnings for style guideline mismatches",
             "type": "boolean",

src/Config.zig

@@ -18,9 +18,6 @@ enable_build_on_save: ?bool = null,
 /// If the `build.zig` has declared a 'check' step, it will be preferred over the default 'install' step.
 build_on_save_args: []const []const u8 = &.{},
 
-/// Whether to automatically fix errors on save. Currently supports adding and removing discards.
-enable_autofix: bool = false,
-
 /// Set level of semantic tokens. `partial` only includes information that requires semantic analysis.
 semantic_tokens: enum {
     none,
@@ -49,6 +46,9 @@ inlay_hints_hide_redundant_param_names: bool = false,
 /// Hides inlay hints when parameter name matches the last token of a parameter node (e.g. foo: bar.foo, foo: &foo)
 inlay_hints_hide_redundant_param_names_last_token: bool = false,
 
+/// Work around editors that do not support 'source.fixall' code actions on save. This option may delivered a substandard user experience. Please refer to the installation guide to see which editors natively support code actions on save.
+force_autofix: bool = false,
+
 /// Enables warnings for style guideline mismatches
 warn_style: bool = false,
 

src/Server.zig

@@ -332,15 +332,19 @@ fn initAnalyser(server: *Server, handle: ?*DocumentStore.Handle) Analyser {
     );
 }
 
-fn getAutofixMode(server: *Server) enum {
-    on_save,
+pub fn getAutofixMode(server: *Server) enum {
+    /// Autofix is implemented by providing `source.fixall` code actions.
+    @"source.fixall",
+    /// Autofix is implemented using `textDocument/willSaveWaitUntil`.
+    /// Requires `force_autofix` to be enabled.
     will_save_wait_until,
-    fixall,
+    /// Autofix is implemented by send a `workspace/applyEdit` request after receiving a `textDocument/didSave` notification.
+    /// Requires `force_autofix` to be enabled.
+    on_save,
     none,
 } {
-    if (!server.config.enable_autofix) return .none;
-    // TODO https://github.com/zigtools/zls/issues/1093
-    // if (server.client_capabilities.supports_code_action_fixall) return .fixall;
+    if (server.client_capabilities.supports_code_action_fixall) return .@"source.fixall";
+    if (!server.config.force_autofix) return .none;
     if (server.client_capabilities.supports_apply_edits) {
         if (server.client_capabilities.supports_will_save_wait_until) return .will_save_wait_until;
         return .on_save;
@@ -397,12 +401,12 @@ fn initializeHandler(server: *Server, arena: std.mem.Allocator, request: types.I
 
         if (std.mem.eql(u8, clientInfo.name, "Sublime Text LSP")) {
             server.client_capabilities.max_detail_length = 256;
-            // TODO investigate why fixall doesn't work in sublime text
+        } else if (std.mem.startsWith(u8, clientInfo.name, "emacs")) {
+            // Assumes that `emacs` means `emacs-lsp/lsp-mode`. Eglot uses `Eglot`.
+
+            // https://github.com/emacs-lsp/lsp-mode/issues/1842
             server.client_capabilities.supports_code_action_fixall = false;
             skip_set_fixall = true;
-        } else if (std.mem.eql(u8, clientInfo.name, "Visual Studio Code")) {
-            server.client_capabilities.supports_code_action_fixall = true;
-            skip_set_fixall = true;
         }
     }
 
@@ -479,16 +483,12 @@ fn initializeHandler(server: *Server, arena: std.mem.Allocator, request: types.I
             server.client_capabilities.supports_will_save = synchronization.willSave orelse false;
             server.client_capabilities.supports_will_save_wait_until = synchronization.willSaveWaitUntil orelse false;
         }
-        if (textDocument.codeAction) |codeaction| {
-            if (codeaction.codeActionLiteralSupport) |literalSupport| {
-                if (!skip_set_fixall) {
-                    for (literalSupport.codeActionKind.valueSet) |code_action_kind| {
-                        if (code_action_kind.eql(.@"source.fixAll")) {
-                            server.client_capabilities.supports_code_action_fixall = true;
-                            break;
-                        }
-                    }
-                }
+        if (textDocument.codeAction) |_| {
+            if (!skip_set_fixall) {
+                // Some clients do not specify `source.fixAll` in
+                // `textDocument.codeAction.?.codeActionLiteralSupport.?.codeActionKind.valueSet`
+                // so we assume they support it if they support code actions in general.
+                server.client_capabilities.supports_code_action_fixall = true;
             }
         }
         if (textDocument.definition) |definition| {
@@ -531,6 +531,7 @@ fn initializeHandler(server: *Server, arena: std.mem.Allocator, request: types.I
     if (request.clientInfo) |clientInfo| {
         log.info("Client Info:      {s}-{s}", .{ clientInfo.name, clientInfo.version orelse "<no version>" });
     }
+    log.info("Autofix Mode:     {s}", .{@tagName(server.getAutofixMode())});
     log.debug("Offset Encoding:  {s}", .{@tagName(server.offset_encoding)});
 
     if (request.workspaceFolders) |workspace_folders| {
@@ -879,6 +880,7 @@ pub fn updateConfiguration(
     const new_build_runner_path =
         new_config.build_runner_path != null and
         (server.config.build_runner_path == null or !std.mem.eql(u8, server.config.build_runner_path.?, new_config.build_runner_path.?));
+    const new_force_autofix = new_config.force_autofix != null and server.config.force_autofix != new_config.force_autofix.?;
 
     inline for (std.meta.fields(Config)) |field| {
         if (@field(new_cfg, field.name)) |new_value| {
@@ -1013,8 +1015,10 @@ pub fn updateConfiguration(
         }
     }
 
-    if (server.config.enable_autofix and server.getAutofixMode() == .none) {
-        log.warn("`enable_autofix` is ignored because it is not supported by {s}", .{server.client_capabilities.client_name orelse "your editor"});
+    if (server.config.force_autofix and server.getAutofixMode() == .none) {
+        log.warn("`force_autofix` is ignored because it is not supported by {s}", .{server.client_capabilities.client_name orelse "your editor"});
+    } else if (new_force_autofix) {
+        log.info("Autofix Mode: {s}", .{@tagName(server.getAutofixMode())});
     }
 }
 

src/features/diagnostics.zig

@@ -53,7 +53,7 @@ pub fn generateDiagnostics(server: *Server, arena: std.mem.Allocator, handle: *D
         }
     }
 
-    if (server.config.enable_autofix and tree.mode == .zig) {
+    if (server.getAutofixMode() != .none and tree.mode == .zig) {
         try code_actions.collectAutoDiscardDiagnostics(tree, arena, &diagnostics, server.offset_encoding);
     }
 

src/tools/config.json

@@ -24,12 +24,6 @@
             "type": "[]const []const u8",
             "default": []
         },
-        {
-            "name": "enable_autofix",
-            "description": "Whether to automatically fix errors on save. Currently supports adding and removing discards.",
-            "type": "bool",
-            "default": false
-        },
         {
             "name": "semantic_tokens",
             "description": "Set level of semantic tokens. `partial` only includes information that requires semantic analysis.",
@@ -83,6 +77,12 @@
             "type": "bool",
             "default": false
         },
+        {
+            "name": "force_autofix",
+            "description": "Work around editors that do not support 'source.fixall' code actions on save. This option may delivered a substandard user experience. Please refer to the installation guide to see which editors natively support code actions on save.",
+            "type": "bool",
+            "default": false
+        },
         {
             "name": "warn_style",
             "description": "Enables warnings for style guideline mismatches",

src/tools/config_gen.zig

@@ -261,7 +261,8 @@ fn generateVSCodeConfigFile(allocator: std.mem.Allocator, config: Config, path:
     });
 
     for (config.options) |option| {
-        if (std.mem.eql(u8, option.name, "zig_exe_path")) continue;
+        if (std.mem.eql(u8, option.name, "zig_exe_path")) continue; // vscode-zig has its own option for this
+        if (std.mem.eql(u8, option.name, "force_autofix")) continue; // VS Code supports code actions on save without a workaround
 
         const snake_case_name = try std.fmt.allocPrint(allocator, "zig.zls.{s}", .{option.name});
         defer allocator.free(snake_case_name);

tests/lsp_features/code_actions.zig

@@ -663,7 +663,6 @@ fn testDiagnostic(
 ) !void {
     var ctx = try Context.init();
     defer ctx.deinit();
-    ctx.server.config.enable_autofix = true;
     ctx.server.config.prefer_ast_check_as_child_process = !options.want_zir;
 
     const uri = try ctx.addDocument(.{ .source = before });