tweak

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

@@ -44,7 +44,13 @@ export function IfBlock(node, context) {
 
 			// Wrap complex expressions (anything beyond a simple identifier) in $.derived() for memoization.
 			// TODO check expression content more thoroughly to avoid wrapping for stuff like `foo > 1` or `foo.length`
-			if (branch.test.type !== 'Identifier') {
+			if (
+				branch.test.type !== 'Identifier' &&
+				branch.test.type !== 'Literal' &&
+				(branch.test.type !== 'MemberExpression' ||
+					// foo.bar is fine but foo[bar] is not
+					branch.metadata.expression.dependencies.size > 1)
+			) {
 				const derived_id = b.id(context.state.scope.generate('d'));
 				statements.push(b.var(derived_id, b.call('$.derived', b.arrow([], expression))));
 				test = b.call('$.get', derived_id);

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

@@ -10,6 +10,7 @@ import {
 } from '../hydration.js';
 import { block } from '../../reactivity/effects.js';
 import { BranchManager } from './branches.js';
+import { HYDRATION_START, HYDRATION_START_ELSE } from '../../../../constants.js';
 
 /**
  * @param {TemplateNode} node
@@ -33,15 +34,16 @@ export function if_block(node, fn, elseif = false) {
 		if (hydrating) {
 			const data = read_hydration_instruction(node);
 
-			// Parse the hydration comment to determine which branch was server-rendered:
-			//   "[" = branch 0, "[1" = branch 1, "[2" = branch 2, ..., "[!" = else (false)
-			/** @type {number | false} */
+			/**
+			 * @type {number | false}
+			 * "[" = branch 0, "[1" = branch 1, "[2" = branch 2, ..., "[!" = else (false)
+			 */
 			var hydrated_key;
 
-			if (data.length === 1) {
-				hydrated_key = 0; // "["
-			} else if (data[1] === '!') {
-				hydrated_key = false; // "[!"
+			if (data === HYDRATION_START) {
+				hydrated_key = 0;
+			} else if (data === HYDRATION_START_ELSE) {
+				hydrated_key = false;
 			} else {
 				hydrated_key = parseInt(data.substring(1)); // "[1", "[2", etc.
 			}

packages/svelte/tests/snapshot/samples/async-const/_expected/client/index.svelte.js

@@ -26,10 +26,8 @@ export default function Async_const($$anchor) {
 			$.append($$anchor, p);
 		};
 
-		var d = $.derived(() => true);
-
 		$.if(node, ($$render) => {
-			if ($.get(d)) $$render(consequent, 0);
+			if (true) $$render(consequent, 0);
 		});
 	}
 

packages/svelte/tests/snapshot/samples/async-in-derived/_expected/client/index.svelte.js

@@ -42,10 +42,8 @@ export default function Async_in_derived($$anchor, $$props) {
 			]);
 		};
 
-		var d = $.derived(() => true);
-
 		$.if(node, ($$render) => {
-			if ($.get(d)) $$render(consequent, 0);
+			if (true) $$render(consequent, 0);
 		});
 	}