WIP

Author: trueadm

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

@@ -359,28 +359,32 @@ export function is_inlinable_expression(node_or_nodes, state) {
  */
 export function trace(node, expression, state) {
 	const loc = node.loc;
-	if (!loc) {
-		return expression;
-	}
-	const start = loc.start;
-	const end = loc.end;
 	const source = state.source;
 	let code = '';
 
-	if (start.line === end.line) {
-		code = source[start.line - 1].slice(start.column, end.column);
-	} else {
-		for (let i = start.line; i < end.line + 1; i++) {
-			const loc = source[i - 1];
+	if (loc) {
+		const start = loc.start;
+		const end = loc.end;
 
-			if (i === start.line) {
-				code += loc.slice(start.column) + '\n';
-			} else if (i === end.line) {
-				code += loc.slice(0, end.column);
-			} else {
-				code += loc + '\n';
+		if (start.line === end.line) {
+			code = source[start.line - 1].slice(start.column, end.column);
+		} else {
+			for (let i = start.line; i < end.line + 1; i++) {
+				const loc = source[i - 1];
+
+				if (i === start.line) {
+					code += loc.slice(start.column) + '\n';
+				} else if (i === end.line) {
+					code += loc.slice(0, end.column);
+				} else {
+					code += loc + '\n';
+				}
 			}
 		}
+	} else if (node.start !== undefined && node.end !== undefined) {
+		code = source.join('\n').slice(node.start, node.end);
+	} else {
+		return expression;
 	}
 
 	return b.call(

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

@@ -18,7 +18,17 @@ export function MemberExpression(node, context) {
 		}
 	}
 
-	if (dev) {
+	const parent = context.path.at(-1);
+
+	if (
+		dev &&
+		// Bail out of tracing members if they're used as calees to avoid context issues
+		(parent?.type !== 'CallExpression' || parent.callee !== node) &&
+		parent?.type !== 'BindDirective' &&
+		parent?.type !== 'AssignmentExpression' &&
+		parent?.type !== 'UpdateExpression' &&
+		parent?.type !== 'Component'
+	) {
 		return trace(
 			node,
 			transformed || {
@@ -28,6 +38,8 @@ export function MemberExpression(node, context) {
 			},
 			context.state
 		);
+	} else if (transformed) {
+		return transformed;
 	}
 
 	context.next();

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

@@ -60,11 +60,16 @@ export function log_trace(fn, label) {
 		var start = performance.now();
 		var value = fn();
 		var time = (performance.now() - start).toFixed(2);
-		// eslint-disable-next-line no-console
-		console.group(`${label} %c(${time}ms)`, 'color: grey');
-		log_expressions(tracing_expressions);
-		// eslint-disable-next-line no-console
-		console.groupEnd();
+		if (tracing_expressions.length > 0) {
+			// eslint-disable-next-line no-console
+			console.group(`${label} %c(${time}ms)`, 'color: grey');
+			log_expressions(tracing_expressions);
+			// eslint-disable-next-line no-console
+			console.groupEnd();
+		} else {
+			// eslint-disable-next-line no-console
+			console.log(`${label} %cno reactive dependencies (${time}ms)`, 'color: grey');
+		}
 
 		if (previously_tracing_expressions !== null) {
 			previously_tracing_expressions.push(...tracing_expressions);
@@ -123,9 +128,7 @@ export function trace(fn, label, computed) {
 				if (previously_tracing_expressions !== null) {
 					previously_tracing_expressions.push(...tracing_expressions);
 				}
-			} else if (
-				previously_tracing_expressions.length !== 0
-			) {
+			} else if (tracing_expressions.length !== 0) {
 				previously_tracing_expressions.push({
 					changed: tracing_expressions.some((e) => e.changed),
 					label,