this code doesn't appear to do anything useful, and no tests fail without it

Author: Rich-Harris

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

@@ -20,23 +20,6 @@ function log_entry(signal, traces = []) {
 		return;
 	}
 
-	if (signal.trace) {
-		var previous_captured_signals = captured_signals;
-		var captured = new Set();
-		set_captured_signals(captured);
-
-		try {
-			untrack(signal.trace);
-		} finally {
-			set_captured_signals(previous_captured_signals);
-		}
-
-		if (captured.size > 0) {
-			for (const dep of captured) log_entry(dep);
-			return;
-		}
-	}
-
 	const type = (signal.f & DERIVED) !== 0 ? '$derived' : '$state';
 	const current_reaction = /** @type {Reaction} */ (active_reaction);
 	const dirty = signal.wv > current_reaction.wv || current_reaction.wv === 0;

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

@@ -524,16 +524,6 @@ function create_item(
 	var v = reactive ? (mutable ? mutable_source(value) : source(value)) : value;
 	var i = (flags & EACH_INDEX_REACTIVE) === 0 ? index : source(index);
 
-	if (DEV && reactive) {
-		// For tracing purposes, we need to link the source signal we create with the
-		// collection + index so that tracing works as intended
-		/** @type {Value} */ (v).trace = () => {
-			var collection_index = typeof i === 'number' ? index : i.v;
-			// eslint-disable-next-line @typescript-eslint/no-unused-expressions
-			get_collection()[collection_index];
-		};
-	}
-
 	/** @type {EachItem} */
 	var item = {
 		i,

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

@@ -66,7 +66,6 @@ export function source(v, stack) {
 
 	if (DEV && tracing_mode_flag) {
 		signal.created = stack ?? get_stack('CreatedAt');
-		signal.trace = null;
 	}
 
 	return signal;

packages/svelte/src/internal/client/reactivity/types.d.ts

@@ -22,7 +22,6 @@ export interface Value<V = unknown> extends Signal {
 	updated?: Error | null;
 	trace_need_increase?: boolean;
 	trace_v?: V;
-	trace?: null | (() => void);
 }
 
 export interface Reaction extends Signal {

packages/svelte/src/internal/client/runtime.js

@@ -779,26 +779,21 @@ export function get(signal) {
 		active_reaction !== null &&
 		tracing_expressions.reaction === active_reaction
 	) {
-		// Used when mapping state between special blocks like `each`
-		if (signal.trace) {
-			signal.trace();
-		} else {
-			var trace = get_stack('TracedAt');
+		var trace = get_stack('TracedAt');
 
-			if (trace) {
-				var traces = tracing_expressions.entries.get(signal);
+		if (trace) {
+			var traces = tracing_expressions.entries.get(signal);
 
-				if (traces === undefined) {
-					tracing_expressions.entries.set(signal, (traces = []));
-				}
+			if (traces === undefined) {
+				tracing_expressions.entries.set(signal, (traces = []));
+			}
 
-				var last = traces.at(-1);
+			var last = traces.at(-1);
 
-				// traces can be duplicated, e.g. by `snapshot` invoking both
-				// both `getOwnPropertyDescriptor` and `get` traps at once
-				if (trace.stack !== last?.stack) {
-					traces.push(trace);
-				}
+			// traces can be duplicated, e.g. by `snapshot` invoking both
+			// both `getOwnPropertyDescriptor` and `get` traps at once
+			if (trace.stack !== last?.stack) {
+				traces.push(trace);
 			}
 		}
 	}