From b141f60a7f45770939011605115ec41516dfdb58 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Mon, 30 Jun 2025 21:53:24 -0400
Subject: [PATCH] simplify

---
 packages/svelte/src/internal/client/constants.js  |  2 --
 .../src/internal/client/reactivity/props.js       | 15 ++++-----------
 packages/svelte/src/internal/client/runtime.js    | 13 +------------
 3 files changed, 5 insertions(+), 25 deletions(-)

diff --git a/packages/svelte/src/internal/client/constants.js b/packages/svelte/src/internal/client/constants.js
index dd3d1b2df6..cd5e0d2244 100644
--- a/packages/svelte/src/internal/client/constants.js
+++ b/packages/svelte/src/internal/client/constants.js
@@ -15,8 +15,6 @@ export const DESTROYED = 1 << 14;
 export const EFFECT_RAN = 1 << 15;
 /** 'Transparent' effects do not create a transition boundary */
 export const EFFECT_TRANSPARENT = 1 << 16;
-/** Svelte 4 legacy mode props need to be handled with deriveds and be recognized elsewhere, hence the dedicated flag */
-export const LEGACY_DERIVED_PROP = 1 << 17;
 export const INSPECT_EFFECT = 1 << 18;
 export const HEAD_EFFECT = 1 << 19;
 export const EFFECT_HAS_DERIVED = 1 << 20;
diff --git a/packages/svelte/src/internal/client/reactivity/props.js b/packages/svelte/src/internal/client/reactivity/props.js
index 101e8f2dd2..42a905f668 100644
--- a/packages/svelte/src/internal/client/reactivity/props.js
+++ b/packages/svelte/src/internal/client/reactivity/props.js
@@ -8,12 +8,11 @@ import {
 	PROPS_IS_UPDATED
 } from '../../../constants.js';
 import { get_descriptor, is_function } from '../../shared/utils.js';
-import { mutable_source, set, source, update } from './sources.js';
+import { set, source, update } from './sources.js';
 import { derived, derived_safe_equal } from './deriveds.js';
-import { get, captured_signals, untrack } from '../runtime.js';
-import { safe_equals } from './equality.js';
+import { get, untrack } from '../runtime.js';
 import * as e from '../errors.js';
-import { LEGACY_DERIVED_PROP, LEGACY_PROPS, STATE_SYMBOL } from '#client/constants';
+import { LEGACY_PROPS, STATE_SYMBOL } from '#client/constants';
 import { proxy } from '../proxy.js';
 import { capture_store_binding } from './store.js';
 import { legacy_mode_flag } from '../../flags/index.js';
@@ -326,14 +325,8 @@ export function prop(props, key, flags, fallback) {
 			return value;
 		};
 	} else {
-		// Svelte 4 did not trigger updates when a primitive value was updated to the same value.
-		// Replicate that behavior through using a derived
-		var derived_getter = (immutable ? derived : derived_safe_equal)(
-			() => /** @type {V} */ (props[key])
-		);
-		derived_getter.f |= LEGACY_DERIVED_PROP;
 		getter = () => {
-			var value = get(derived_getter);
+			var value = /** @type {V} */ (props[key]);
 			if (value !== undefined) fallback_value = /** @type {V} */ (undefined);
 			return value === undefined ? fallback_value : value;
 		};
diff --git a/packages/svelte/src/internal/client/runtime.js b/packages/svelte/src/internal/client/runtime.js
index 3e70537d7c..5a798ba3e9 100644
--- a/packages/svelte/src/internal/client/runtime.js
+++ b/packages/svelte/src/internal/client/runtime.js
@@ -20,7 +20,6 @@ import {
 	STATE_SYMBOL,
 	BLOCK_EFFECT,
 	ROOT_EFFECT,
-	LEGACY_DERIVED_PROP,
 	DISCONNECTED,
 	EFFECT_IS_UPDATING,
 	STALE_REACTION
@@ -863,17 +862,7 @@ export function invalidate_inner_signals(fn) {
 	var captured = capture_signals(() => untrack(fn));
 
 	for (var signal of captured) {
-		// Go one level up because derived signals created as part of props in legacy mode
-		if ((signal.f & LEGACY_DERIVED_PROP) !== 0) {
-			for (const dep of /** @type {Derived} */ (signal).deps || []) {
-				if ((dep.f & DERIVED) === 0) {
-					// Use internal_set instead of set here and below to avoid mutation validation
-					internal_set(dep, dep.v);
-				}
-			}
-		} else {
-			internal_set(signal, signal.v);
-		}
+		internal_set(signal, signal.v);
 	}
 }