make label optional

packages/svelte/src/compiler/phases/2-analyze/visitors/CallExpression.js

@@ -1,11 +1,11 @@
-/** @import { CallExpression, VariableDeclarator } from 'estree' */
+/** @import { ArrowFunctionExpression, CallExpression, FunctionDeclaration, FunctionExpression, Identifier, VariableDeclarator } from 'estree' */
 /** @import { AST } from '#compiler' */
 /** @import { Context } from '../types' */
 import { get_rune } from '../../scope.js';
 import * as e from '../../../errors.js';
 import { get_parent, unwrap_optional } from '../../../utils/ast.js';
 import { is_pure, is_safe_identifier } from './shared/utils.js';
-import { dev } from '../../../state.js';
+import { dev, locate_node, source } from '../../../state.js';
 
 /**
  * @param {CallExpression} node
@@ -137,21 +137,27 @@ export function CallExpression(node, context) {
 			break;
 
 		case '$inspect.trace': {
-			if (node.arguments.length !== 1) {
-				e.rune_invalid_arguments_length(node, rune, 'exactly one argument');
+			if (node.arguments.length > 1) {
+				e.rune_invalid_arguments_length(node, rune, 'zero or one arguments');
 			}
-			if (node.arguments[0].type !== 'Literal' || typeof node.arguments[0].value !== 'string') {
+
+			if (
+				node.arguments[0] &&
+				(node.arguments[0].type !== 'Literal' || typeof node.arguments[0].value !== 'string')
+			) {
 				e.trace_rune_invalid_argument(node);
 			}
+
 			const grand_parent = context.path.at(-2);
+			const fn = context.path.at(-3);
 
 			if (
 				parent.type !== 'ExpressionStatement' ||
 				grand_parent?.type !== 'BlockStatement' ||
 				!(
-					context.path.at(-3)?.type === 'FunctionDeclaration' ||
-					context.path.at(-3)?.type === 'FunctionExpression' ||
-					context.path.at(-3)?.type === 'ArrowFunctionExpression'
+					fn?.type === 'FunctionDeclaration' ||
+					fn?.type === 'FunctionExpression' ||
+					fn?.type === 'ArrowFunctionExpression'
 				) ||
 				grand_parent.body[0] !== parent
 			) {
@@ -159,7 +165,14 @@ export function CallExpression(node, context) {
 			}
 
 			if (dev) {
-				context.state.scope.tracing = node.arguments[0].value;
+				if (node.arguments[0]) {
+					context.state.scope.tracing = /** @type {string} */ (node.arguments[0].value);
+				} else {
+					const label = get_function_label(context.path.slice(0, -2));
+					const loc = `(${locate_node(fn)})`;
+
+					context.state.scope.tracing = label ? label + ' ' + loc : loc;
+				}
 			}
 
 			break;
@@ -210,3 +223,27 @@ export function CallExpression(node, context) {
 		}
 	}
 }
+
+/**
+ * @param {AST.SvelteNode[]} nodes
+ */
+function get_function_label(nodes) {
+	const fn = /** @type {FunctionExpression | FunctionDeclaration | ArrowFunctionExpression} */ (
+		nodes.at(-1)
+	);
+
+	if ((fn.type === 'FunctionDeclaration' || fn.type === 'FunctionExpression') && fn.id != null) {
+		return fn.id.name;
+	}
+
+	const parent = nodes.at(-2);
+	if (!parent) return;
+
+	if (parent.type === 'CallExpression') {
+		return source.slice(parent.callee.start, parent.callee.end) + '(...)';
+	}
+
+	if (parent.type === 'Property' && !parent.computed) {
+		return /** @type {Identifier} */ (parent.key).name;
+	}
+}

packages/svelte/src/compiler/phases/3-transform/client/visitors/AssignmentExpression.js

@@ -8,7 +8,7 @@ import {
 	get_attribute_expression,
 	is_event_attribute
 } from '../../../../utils/ast.js';
-import { dev, filename, is_ignored, locator } from '../../../../state.js';
+import { dev, filename, is_ignored, locate_node, locator } from '../../../../state.js';
 import { build_proxy_reassignment, should_proxy } from '../utils.js';
 import { visit_assignment_expression } from '../../shared/assignments.js';
 
@@ -183,9 +183,6 @@ function build_assignment(operator, left, right, context) {
 	if (left.type === 'MemberExpression' && should_transform) {
 		const callee = callees[operator];
 
-		const loc = /** @type {Location} */ (locator(/** @type {number} */ (left.start)));
-		const location = `${filename}:${loc.line}:${loc.column}`;
-
 		return /** @type {Expression} */ (
 			context.visit(
 				b.call(
@@ -197,7 +194,7 @@ function build_assignment(operator, left, right, context) {
 							: b.literal(/** @type {Identifier} */ (left.property).name)
 					),
 					right,
-					b.literal(location)
+					b.literal(locate_node(left))
 				)
 			)
 		);

packages/svelte/src/compiler/state.js

@@ -1,6 +1,8 @@
+/** @import { Location } from 'locate-character' */
 /** @import { CompileOptions } from './types' */
 /** @import { AST, Warning } from '#compiler' */
 import { getLocator } from 'locate-character';
+import { sanitize_location } from '../utils.js';
 
 /** @typedef {{ start?: number, end?: number }} NodeLike */
 
@@ -28,6 +30,14 @@ export let dev;
 
 export let locator = getLocator('', { offsetLine: 1 });
 
+/**
+ * @param {AST.SvelteNode & { start?: number | undefined }} node
+ */
+export function locate_node(node) {
+	const loc = /** @type {Location} */ (locator(/** @type {number} */ (node.start)));
+	return `${sanitize_location(filename)}:${loc?.line}:${loc.column}`;
+}
+
 /** @type {NonNullable<CompileOptions['warningFilter']>} */
 export let warning_filter;
 

packages/svelte/src/internal/client/dev/assign.js

@@ -1,6 +1,6 @@
+import { sanitize_location } from '../../../utils.js';
 import { untrack } from '../runtime.js';
 import * as w from '../warnings.js';
-import { sanitize_location } from './location.js';
 
 /**
  *

packages/svelte/src/internal/client/dev/location.js

@@ -1,25 +0,0 @@
-import { DEV } from 'esm-env';
-import { FILENAME } from '../../../constants.js';
-import { dev_current_component_function } from '../runtime.js';
-
-/**
- *
- * @param {number} [line]
- * @param {number} [column]
- */
-export function get_location(line, column) {
-	if (!DEV || line === undefined) return undefined;
-
-	var filename = dev_current_component_function?.[FILENAME];
-	var location = filename && `${filename}:${line}:${column}`;
-
-	return sanitize_location(location);
-}
-
-/**
- * Prevent devtools trying to make `location` a clickable link by inserting a zero-width space
- * @param {string | undefined} location
- */
-export function sanitize_location(location) {
-	return location?.replace(/\//g, '/\u200b');
-}

packages/svelte/src/internal/client/dom/blocks/html.js

@@ -5,11 +5,10 @@ import { hydrate_next, hydrate_node, hydrating, set_hydrate_node } from '../hydr
 import { create_fragment_from_html } from '../reconciler.js';
 import { assign_nodes } from '../template.js';
 import * as w from '../../warnings.js';
-import { hash } from '../../../../utils.js';
+import { hash, sanitize_location } from '../../../../utils.js';
 import { DEV } from 'esm-env';
 import { dev_current_component_function } from '../../runtime.js';
 import { get_first_child, get_next_sibling } from '../operations.js';
-import { sanitize_location } from '../../dev/location.js';
 
 /**
  * @param {Element} element

packages/svelte/src/internal/client/reactivity/effects.js

@@ -1,4 +1,4 @@
-/** @import { ComponentContext, ComponentContextLegacy, Derived, Effect, Reaction, TemplateNode, TransitionManager } from '#client' */
+/** @import { ComponentContext, ComponentContextLegacy, Derived, Effect, TemplateNode, TransitionManager } from '#client' */
 import {
 	check_dirtiness,
 	component_context,
@@ -16,8 +16,7 @@ import {
 	set_is_flushing_effect,
 	set_signal_status,
 	untrack,
-	skip_reaction,
-	capture_signals
+	skip_reaction
 } from '../runtime.js';
 import {
 	DIRTY,
@@ -40,13 +39,10 @@ import {
 } from '../constants.js';
 import { set } from './sources.js';
 import * as e from '../errors.js';
-import * as w from '../warnings.js';
 import { DEV } from 'esm-env';
 import { define_property } from '../../shared/utils.js';
 import { get_next_sibling } from '../dom/operations.js';
 import { destroy_derived } from './deriveds.js';
-import { FILENAME } from '../../../constants.js';
-import { get_location } from '../dev/location.js';
 
 /**
  * @param {'$effect' | '$effect.pre' | '$inspect'} rune

packages/svelte/src/utils.js

@@ -450,3 +450,11 @@ const RAW_TEXT_ELEMENTS = /** @type {const} */ (['textarea', 'script', 'style',
 export function is_raw_text_element(name) {
 	return RAW_TEXT_ELEMENTS.includes(/** @type {RAW_TEXT_ELEMENTS[number]} */ (name));
 }
+
+/**
+ * Prevent devtools trying to make `location` a clickable link by inserting a zero-width space
+ * @param {string | undefined} location
+ */
+export function sanitize_location(location) {
+	return location?.replace(/\//g, '/\u200b');
+}