make autofix configurable through in-editor configuration

VS Code and Sublime Text offer their own setting to configure code actions on save. `editor.codeActionsOnSave` and `lsp_code_actions_on_save` respectively.
These options should be preferred over `enable_autofix` if possible. The `enable_autofix` gets renamed to `force_autofix` to reflect that it should only be used on editors that don't support code actions on save. Some further research is necessary to identify which editors support these features to make the transition as smooth as possible for all users.

See #1093

schema.json

@@ -27,8 +27,8 @@
             },
             "default": []
         },
-        "enable_autofix": {
-            "description": "Whether to automatically fix errors on save. Currently supports adding and removing discards.",
+        "force_autofix": {
+            "description": "TODO",
             "type": "boolean",
             "default": false
         },

src/Config.zig

@@ -18,8 +18,8 @@ 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,
+/// TODO
+force_autofix: bool = false,
 
 /// Set level of semantic tokens. `partial` only includes information that requires semantic analysis.
 semantic_tokens: enum {

src/Server.zig

@@ -74,7 +74,7 @@ const ClientCapabilities = struct {
     supports_will_save: bool = false,
     supports_will_save_wait_until: bool = false,
     supports_publish_diagnostics: bool = false,
-    supports_code_action_fixall: bool = false,
+    supports_code_actions: bool = false,
     hover_supports_md: bool = false,
     signature_help_supports_md: bool = false,
     completion_doc_supports_md: bool = false,
@@ -332,15 +332,19 @@ fn initAnalyser(server: *Server, handle: ?*DocumentStore.Handle) Analyser {
     );
 }
 
-fn getAutofixMode(server: *Server) enum {
-    on_save,
-    will_save_wait_until,
+pub fn getAutofixMode(server: *Server) enum {
+    /// Autofix is implemented by providing `source.fixall` code actions.
     fixall,
+    /// Autofix is implemented using `textDocument/willSaveWaitUntil`.
+    /// Requires `force_autofix` to be enabled.
+    will_save_wait_until,
+    /// 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_actions) return .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;
@@ -392,19 +396,11 @@ fn autofix(server: *Server, arena: std.mem.Allocator, handle: *DocumentStore.Han
 }
 
 fn initializeHandler(server: *Server, arena: std.mem.Allocator, request: types.InitializeParams) Error!types.InitializeResult {
-    var skip_set_fixall = false;
-
     if (request.clientInfo) |clientInfo| {
         server.client_capabilities.client_name = try server.allocator.dupe(u8, clientInfo.name);
 
         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
-            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;
         }
     }
 
@@ -481,17 +477,8 @@ 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) |_| {
+            server.client_capabilities.supports_code_actions = true;
         }
         if (textDocument.definition) |definition| {
             server.client_capabilities.supports_textDocument_definition_linkSupport = definition.linkSupport orelse false;
@@ -1026,8 +1013,8 @@ 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"});
     }
 }
 

src/features/diagnostics.zig

@@ -44,7 +44,7 @@ pub fn generateDiagnostics(server: *Server, arena: std.mem.Allocator, handle: *D
         try getAstCheckDiagnostics(server, arena, handle, &diagnostics);
     }
 
-    if (server.config.enable_autofix) {
+    if (server.getAutofixMode() != .none) {
         try code_actions.collectAutoDiscardDiagnostics(tree, arena, &diagnostics, server.offset_encoding);
     }
 

src/tools/config.json

@@ -25,8 +25,8 @@
             "default": []
         },
         {
-            "name": "enable_autofix",
-            "description": "Whether to automatically fix errors on save. Currently supports adding and removing discards.",
+            "name": "force_autofix",
+            "description": "TODO",
             "type": "bool",
             "default": false
         },

tests/lsp_features/code_actions.zig

@@ -593,7 +593,6 @@ fn testAutofix(before: []const u8, after: []const u8) !void {
 fn testAutofixOptions(before: []const u8, after: []const u8, want_zir: bool) !void {
     var ctx = try Context.init();
     defer ctx.deinit();
-    ctx.server.config.enable_autofix = true;
     ctx.server.config.prefer_ast_check_as_child_process = !want_zir;
 
     const uri = try ctx.addDocument(.{ .source = before });
@@ -641,7 +640,6 @@ fn testAutofixOptions(before: []const u8, after: []const u8, want_zir: bool) !vo
 fn testDiagnostic(before: []const u8, after: []const u8) !void {
     var ctx = try Context.init();
     defer ctx.deinit();
-    ctx.server.config.enable_autofix = true;
 
     const uri = try ctx.addDocument(.{ .source = before });
     const handle = ctx.server.document_store.getHandle(uri).?;