From 61be37b6aad87d1a71d924208f9c23b7b42e0ba5 Mon Sep 17 00:00:00 2001
From: Lukas Stracke <lukas.stracke@sentry.io>
Date: Wed, 10 Jan 2024 11:56:46 +0100
Subject: [PATCH 1/7] wip

---
 packages/core/src/tracing/span.ts             |  1 +
 packages/core/src/utils/spanUtils.ts          | 12 +++++++
 .../core/test/lib/utils/spanUtils.test.ts     | 35 ++++++++++++++++++-
 packages/types/src/span.ts                    |  1 +
 4 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/packages/core/src/tracing/span.ts b/packages/core/src/tracing/span.ts
index c3cd71e87699..c22f6a06bd5f 100644
--- a/packages/core/src/tracing/span.ts
+++ b/packages/core/src/tracing/span.ts
@@ -105,6 +105,7 @@ export class Span implements SpanInterface {
 
   /**
    * @inheritDoc
+   * @deprecated Use top level `Sentry.getRootSpan()` instead
    */
   public transaction?: Transaction;
 
diff --git a/packages/core/src/utils/spanUtils.ts b/packages/core/src/utils/spanUtils.ts
index cbf8ce6d7f5b..0561d7dde5a8 100644
--- a/packages/core/src/utils/spanUtils.ts
+++ b/packages/core/src/utils/spanUtils.ts
@@ -107,3 +107,15 @@ export function spanIsSampled(span: Span): boolean {
   // eslint-disable-next-line no-bitwise
   return Boolean(traceFlags & TRACE_FLAG_SAMPLED);
 }
+
+/**
+ * Returns the root span of a given span.
+ *
+ * As long as we use `Transaction`s internally, the returned root span
+ * will be a `Transaction` but be aware that this might change in the future.
+ *
+ * If the given span has no root span or transaction, `undefined` is returned.
+ */
+export function getRootSpan(span: Span): Span | undefined {
+  return span.transaction;
+}
diff --git a/packages/core/test/lib/utils/spanUtils.test.ts b/packages/core/test/lib/utils/spanUtils.test.ts
index e521df7c2dc9..bddfe11fdcf4 100644
--- a/packages/core/test/lib/utils/spanUtils.test.ts
+++ b/packages/core/test/lib/utils/spanUtils.test.ts
@@ -1,6 +1,7 @@
 import { TRACEPARENT_REGEXP, timestampInSeconds } from '@sentry/utils';
+import { Transaction } from '../../../build/types';
 import { Span, spanToTraceHeader } from '../../../src';
-import { spanIsSampled, spanTimeInputToSeconds, spanToJSON } from '../../../src/utils/spanUtils';
+import { getRootSpan, spanIsSampled, spanTimeInputToSeconds, spanToJSON } from '../../../src/utils/spanUtils';
 
 describe('spanToTraceHeader', () => {
   test('simple', () => {
@@ -127,3 +128,35 @@ describe('spanIsSampled', () => {
     expect(spanIsSampled(span)).toBe(false);
   });
 });
+
+describe('getRootSpan', () => {
+  it('returns the root span of a span (Span)', () => {
+    const root = new Span({ name: 'test' });
+    // @ts-expect-error this is highly illegal and shouldn't happen IRL
+    root.transaction = root;
+
+    // eslint-disable-next-line deprecation/deprecation
+    const childSpan = root.startChild({ name: 'child' });
+    expect(getRootSpan(childSpan)).toBe(root);
+  });
+
+  it('returns the root span of a span (Transaction)', () => {
+    const root = new Transaction({ name: 'test' });
+
+    // eslint-disable-next-line deprecation/deprecation
+    const childSpan = root.startChild({ name: 'child' });
+    expect(getRootSpan(childSpan)).toBe(root);
+  });
+
+  it('returns the span itself if it is a root span', () => {
+    const span = new Transaction({ name: 'test' });
+
+    expect(getRootSpan(span)).toBe(span);
+  });
+
+  it('returns undefined if span has no root span', () => {
+    const span = new Span({ name: 'test' });
+
+    expect(getRootSpan(span)).toBe(undefined);
+  });
+});
diff --git a/packages/types/src/span.ts b/packages/types/src/span.ts
index 662cfb57a155..164e7c47f741 100644
--- a/packages/types/src/span.ts
+++ b/packages/types/src/span.ts
@@ -216,6 +216,7 @@ export interface Span extends SpanContext {
 
   /**
    * The transaction containing this span
+   * @deprecated Use top level `Sentry.getRootSpan()` instead
    */
   transaction?: Transaction;
 

From a0efb9bd2ff7d6e653252b7871876465ca34c86a Mon Sep 17 00:00:00 2001
From: Lukas Stracke <lukas.stracke@sentry.io>
Date: Wed, 10 Jan 2024 13:15:32 +0100
Subject: [PATCH 2/7] replace usages/add eslint ignores in core

---
 packages/core/src/scope.ts                       |  3 +++
 packages/core/src/server-runtime-client.ts       |  4 ++--
 .../core/src/tracing/dynamicSamplingContext.ts   |  7 +++----
 packages/core/src/tracing/span.ts                | 16 +++++++++++-----
 packages/core/src/tracing/transaction.ts         |  2 ++
 packages/core/src/utils/applyScopeDataToEvent.ts |  8 ++++----
 packages/core/src/utils/spanUtils.ts             |  2 ++
 .../lib/tracing/dynamicSamplingContext.test.ts   | 11 +++++------
 packages/core/test/lib/utils/spanUtils.test.ts   |  6 ++++--
 9 files changed, 36 insertions(+), 23 deletions(-)

diff --git a/packages/core/src/scope.ts b/packages/core/src/scope.ts
index 255af68dd48e..fe682bf02661 100644
--- a/packages/core/src/scope.ts
+++ b/packages/core/src/scope.ts
@@ -334,6 +334,9 @@ export class Scope implements ScopeInterface {
     // Often, this span (if it exists at all) will be a transaction, but it's not guaranteed to be. Regardless, it will
     // have a pointer to the currently-active transaction.
     const span = this._span;
+    // Cannot replace with getRootSpan because getRootSpan returns a span, not a transaction
+    // Also, this method will be removed anyway.
+    // eslint-disable-next-line deprecation/deprecation
     return span && span.transaction;
   }
 
diff --git a/packages/core/src/server-runtime-client.ts b/packages/core/src/server-runtime-client.ts
index 00f23be2dc0a..785ad0c4f94b 100644
--- a/packages/core/src/server-runtime-client.ts
+++ b/packages/core/src/server-runtime-client.ts
@@ -26,7 +26,7 @@ import {
   getDynamicSamplingContextFromClient,
   getDynamicSamplingContextFromSpan,
 } from './tracing';
-import { spanToTraceContext } from './utils/spanUtils';
+import { getRootSpan, spanToTraceContext } from './utils/spanUtils';
 
 export interface ServerRuntimeClientOptions extends ClientOptions<BaseTransportOptions> {
   platform?: string;
@@ -262,7 +262,7 @@ export class ServerRuntimeClient<
     // eslint-disable-next-line deprecation/deprecation
     const span = scope.getSpan();
     if (span) {
-      const samplingContext = span.transaction ? getDynamicSamplingContextFromSpan(span) : undefined;
+      const samplingContext = getRootSpan(span) ? getDynamicSamplingContextFromSpan(span) : undefined;
       return [samplingContext, spanToTraceContext(span)];
     }
 
diff --git a/packages/core/src/tracing/dynamicSamplingContext.ts b/packages/core/src/tracing/dynamicSamplingContext.ts
index 318c232eb43b..e9b93ef96ac8 100644
--- a/packages/core/src/tracing/dynamicSamplingContext.ts
+++ b/packages/core/src/tracing/dynamicSamplingContext.ts
@@ -3,7 +3,7 @@ import { dropUndefinedKeys } from '@sentry/utils';
 
 import { DEFAULT_ENVIRONMENT } from '../constants';
 import { getClient, getCurrentScope } from '../exports';
-import { spanIsSampled, spanToJSON } from '../utils/spanUtils';
+import { getRootSpan, spanIsSampled, spanToJSON } from '../utils/spanUtils';
 
 /**
  * Creates a dynamic sampling context from a client.
@@ -54,9 +54,8 @@ export function getDynamicSamplingContextFromSpan(span: Span): Readonly<Partial<
   // passing emit=false here to only emit later once the DSC is actually populated
   const dsc = getDynamicSamplingContextFromClient(spanToJSON(span).trace_id || '', client, getCurrentScope());
 
-  // As long as we use `Transaction`s internally, this should be fine.
-  // TODO: We need to replace this with a `getRootSpan(span)` function though
-  const txn = span.transaction as TransactionWithV7FrozenDsc | undefined;
+  // TODO (v8): Remove v7FrozenDsc as a Transaction will no longer have _frozenDynamicSamplingContext
+  const txn = getRootSpan(span) as TransactionWithV7FrozenDsc | undefined;
   if (!txn) {
     return dsc;
   }
diff --git a/packages/core/src/tracing/span.ts b/packages/core/src/tracing/span.ts
index c22f6a06bd5f..5fc4beedc682 100644
--- a/packages/core/src/tracing/span.ts
+++ b/packages/core/src/tracing/span.ts
@@ -19,6 +19,7 @@ import { DEBUG_BUILD } from '../debug-build';
 import {
   TRACE_FLAG_NONE,
   TRACE_FLAG_SAMPLED,
+  getRootSpan,
   spanTimeInputToSeconds,
   spanToJSON,
   spanToTraceContext,
@@ -305,12 +306,16 @@ export class Span implements SpanInterface {
       childSpan.spanRecorder.add(childSpan);
     }
 
-    childSpan.transaction = this.transaction;
+    const rootSpan = getRootSpan(this);
+    // TODO: still set span.transaction here until we have a more permanent solution
+    // Probably similarly to the weakmap we hold in node-experimental
+    // eslint-disable-next-line deprecation/deprecation
+    childSpan.transaction = rootSpan as Transaction;
 
-    if (DEBUG_BUILD && childSpan.transaction) {
+    if (DEBUG_BUILD && rootSpan) {
       const opStr = (spanContext && spanContext.op) || '< unknown op >';
       const nameStr = spanToJSON(childSpan).description || '< unknown name >';
-      const idStr = childSpan.transaction.spanContext().spanId;
+      const idStr = rootSpan.spanContext().spanId;
 
       const logMessage = `[Tracing] Starting '${opStr}' span on transaction '${nameStr}' (${idStr}).`;
       logger.log(logMessage);
@@ -417,11 +422,12 @@ export class Span implements SpanInterface {
 
   /** @inheritdoc */
   public end(endTimestamp?: SpanTimeInput): void {
+    const rootSpan = getRootSpan(this);
     if (
       DEBUG_BUILD &&
       // Don't call this for transactions
-      this.transaction &&
-      this.transaction.spanContext().spanId !== this._spanId
+      rootSpan &&
+      rootSpan.spanContext().spanId !== this._spanId
     ) {
       const logMessage = this._logMessage;
       if (logMessage) {
diff --git a/packages/core/src/tracing/transaction.ts b/packages/core/src/tracing/transaction.ts
index 738e98e418a3..90d2c1ad4a92 100644
--- a/packages/core/src/tracing/transaction.ts
+++ b/packages/core/src/tracing/transaction.ts
@@ -66,6 +66,8 @@ export class Transaction extends SpanClass implements TransactionInterface {
     this._trimEnd = transactionContext.trimEnd;
 
     // this is because transactions are also spans, and spans have a transaction pointer
+    // TODO (v8): Replace this with another way to set the root span
+    // eslint-disable-next-line deprecation/deprecation
     this.transaction = this;
 
     // If Dynamic Sampling Context is provided during the creation of the transaction, we freeze it as it usually means
diff --git a/packages/core/src/utils/applyScopeDataToEvent.ts b/packages/core/src/utils/applyScopeDataToEvent.ts
index f834776ac9ba..57cc00053be9 100644
--- a/packages/core/src/utils/applyScopeDataToEvent.ts
+++ b/packages/core/src/utils/applyScopeDataToEvent.ts
@@ -1,7 +1,7 @@
 import type { Breadcrumb, Event, PropagationContext, ScopeData, Span } from '@sentry/types';
 import { arrayify } from '@sentry/utils';
 import { getDynamicSamplingContextFromSpan } from '../tracing/dynamicSamplingContext';
-import { spanToJSON, spanToTraceContext } from './spanUtils';
+import { getRootSpan, spanToJSON, spanToTraceContext } from './spanUtils';
 
 /**
  * Applies data from the scope to the event and runs all event processors on it.
@@ -174,13 +174,13 @@ function applySdkMetadataToEvent(
 
 function applySpanToEvent(event: Event, span: Span): void {
   event.contexts = { trace: spanToTraceContext(span), ...event.contexts };
-  const transaction = span.transaction;
-  if (transaction) {
+  const rootSpan = getRootSpan(span);
+  if (rootSpan) {
     event.sdkProcessingMetadata = {
       dynamicSamplingContext: getDynamicSamplingContextFromSpan(span),
       ...event.sdkProcessingMetadata,
     };
-    const transactionName = spanToJSON(transaction).description;
+    const transactionName = spanToJSON(rootSpan).description;
     if (transactionName) {
       event.tags = { transaction: transactionName, ...event.tags };
     }
diff --git a/packages/core/src/utils/spanUtils.ts b/packages/core/src/utils/spanUtils.ts
index 0561d7dde5a8..1a80f3d29397 100644
--- a/packages/core/src/utils/spanUtils.ts
+++ b/packages/core/src/utils/spanUtils.ts
@@ -117,5 +117,7 @@ export function spanIsSampled(span: Span): boolean {
  * If the given span has no root span or transaction, `undefined` is returned.
  */
 export function getRootSpan(span: Span): Span | undefined {
+  // TODO (v8): Remove this check and just return span
+  // eslint-disable-next-line deprecation/deprecation
   return span.transaction;
 }
diff --git a/packages/core/test/lib/tracing/dynamicSamplingContext.test.ts b/packages/core/test/lib/tracing/dynamicSamplingContext.test.ts
index da8bf1595e21..91158d36ff01 100644
--- a/packages/core/test/lib/tracing/dynamicSamplingContext.test.ts
+++ b/packages/core/test/lib/tracing/dynamicSamplingContext.test.ts
@@ -20,7 +20,7 @@ describe('getDynamicSamplingContextFromSpan', () => {
   });
 
   test('returns the DSC provided during transaction creation', () => {
-    // eslint-disable-next-line deprecation/deprecation
+    // eslint-disable-next-line deprecation/deprecation -- using old API on purpose
     const transaction = new Transaction({
       name: 'tx',
       metadata: { dynamicSamplingContext: { environment: 'myEnv' } },
@@ -68,7 +68,7 @@ describe('getDynamicSamplingContextFromSpan', () => {
   });
 
   test('returns a new DSC, if no DSC was provided during transaction creation (via new Txn and deprecated metadata)', () => {
-    // eslint-disable-next-line deprecation/deprecation
+    // eslint-disable-next-line deprecation/deprecation -- using old API on purpose
     const transaction = new Transaction({
       name: 'tx',
       metadata: {
@@ -92,7 +92,7 @@ describe('getDynamicSamplingContextFromSpan', () => {
 
   describe('Including transaction name in DSC', () => {
     test('is not included if transaction source is url', () => {
-      // eslint-disable-next-line deprecation/deprecation
+      // eslint-disable-next-line deprecation/deprecation -- using old API on purpose
       const transaction = new Transaction({
         name: 'tx',
         metadata: {
@@ -109,8 +109,7 @@ describe('getDynamicSamplingContextFromSpan', () => {
       ['is included if transaction source is parameterized route/url', 'route'],
       ['is included if transaction source is a custom name', 'custom'],
     ])('%s', (_: string, source) => {
-      // eslint-disable-next-line deprecation/deprecation
-      const transaction = new Transaction({
+      const transaction = startInactiveSpan({
         name: 'tx',
         metadata: {
           ...(source && { source: source as TransactionSource }),
@@ -120,7 +119,7 @@ describe('getDynamicSamplingContextFromSpan', () => {
       // Only setting the attribute manually because we're directly calling new Transaction()
       transaction?.setAttribute(SEMANTIC_ATTRIBUTE_SENTRY_SOURCE, source);
 
-      const dsc = getDynamicSamplingContextFromSpan(transaction);
+      const dsc = getDynamicSamplingContextFromSpan(transaction!);
 
       expect(dsc.transaction).toEqual('tx');
     });
diff --git a/packages/core/test/lib/utils/spanUtils.test.ts b/packages/core/test/lib/utils/spanUtils.test.ts
index bddfe11fdcf4..116124130cf0 100644
--- a/packages/core/test/lib/utils/spanUtils.test.ts
+++ b/packages/core/test/lib/utils/spanUtils.test.ts
@@ -1,6 +1,5 @@
 import { TRACEPARENT_REGEXP, timestampInSeconds } from '@sentry/utils';
-import { Transaction } from '../../../build/types';
-import { Span, spanToTraceHeader } from '../../../src';
+import { Span, Transaction, spanToTraceHeader } from '../../../src';
 import { getRootSpan, spanIsSampled, spanTimeInputToSeconds, spanToJSON } from '../../../src/utils/spanUtils';
 
 describe('spanToTraceHeader', () => {
@@ -133,6 +132,7 @@ describe('getRootSpan', () => {
   it('returns the root span of a span (Span)', () => {
     const root = new Span({ name: 'test' });
     // @ts-expect-error this is highly illegal and shouldn't happen IRL
+    // eslint-disable-next-line deprecation/deprecation
     root.transaction = root;
 
     // eslint-disable-next-line deprecation/deprecation
@@ -141,6 +141,7 @@ describe('getRootSpan', () => {
   });
 
   it('returns the root span of a span (Transaction)', () => {
+    // eslint-disable-next-line deprecation/deprecation
     const root = new Transaction({ name: 'test' });
 
     // eslint-disable-next-line deprecation/deprecation
@@ -149,6 +150,7 @@ describe('getRootSpan', () => {
   });
 
   it('returns the span itself if it is a root span', () => {
+    // eslint-disable-next-line deprecation/deprecation
     const span = new Transaction({ name: 'test' });
 
     expect(getRootSpan(span)).toBe(span);

From 31126f3c726b4e2e6aa4031f01d404c49dea4615 Mon Sep 17 00:00:00 2001
From: Lukas Stracke <lukas.stracke@sentry.io>
Date: Wed, 10 Jan 2024 13:23:28 +0100
Subject: [PATCH 3/7] move to dedicated file

---
 packages/core/src/index.ts                    |  1 +
 packages/core/src/server-runtime-client.ts    |  3 +-
 .../src/tracing/dynamicSamplingContext.ts     |  3 +-
 packages/core/src/tracing/span.ts             |  2 +-
 .../core/src/utils/applyScopeDataToEvent.ts   |  3 +-
 packages/core/src/utils/getRootSpan.ts        | 15 +++++++
 packages/core/src/utils/spanUtils.ts          | 14 -------
 packages/core/test/lib/utils/getRootSpan.ts   | 36 +++++++++++++++++
 .../core/test/lib/utils/spanUtils.test.ts     | 39 +------------------
 .../tracing-internal/src/browser/request.ts   |  3 +-
 packages/tracing-internal/src/common/fetch.ts |  2 +-
 11 files changed, 64 insertions(+), 57 deletions(-)
 create mode 100644 packages/core/src/utils/getRootSpan.ts
 create mode 100644 packages/core/test/lib/utils/getRootSpan.ts

diff --git a/packages/core/src/index.ts b/packages/core/src/index.ts
index e277c01f2dbe..67ce93ce33fa 100644
--- a/packages/core/src/index.ts
+++ b/packages/core/src/index.ts
@@ -81,6 +81,7 @@ export {
   spanToJSON,
   spanIsSampled,
 } from './utils/spanUtils';
+export { getRootSpan } from './utils/getRootSpan';
 export { DEFAULT_ENVIRONMENT } from './constants';
 export { ModuleMetadata } from './integrations/metadata';
 export { RequestData } from './integrations/requestdata';
diff --git a/packages/core/src/server-runtime-client.ts b/packages/core/src/server-runtime-client.ts
index 785ad0c4f94b..aed69369fc5d 100644
--- a/packages/core/src/server-runtime-client.ts
+++ b/packages/core/src/server-runtime-client.ts
@@ -26,7 +26,8 @@ import {
   getDynamicSamplingContextFromClient,
   getDynamicSamplingContextFromSpan,
 } from './tracing';
-import { getRootSpan, spanToTraceContext } from './utils/spanUtils';
+import { getRootSpan } from './utils/getRootSpan';
+import { spanToTraceContext } from './utils/spanUtils';
 
 export interface ServerRuntimeClientOptions extends ClientOptions<BaseTransportOptions> {
   platform?: string;
diff --git a/packages/core/src/tracing/dynamicSamplingContext.ts b/packages/core/src/tracing/dynamicSamplingContext.ts
index e9b93ef96ac8..f27052c8cfbc 100644
--- a/packages/core/src/tracing/dynamicSamplingContext.ts
+++ b/packages/core/src/tracing/dynamicSamplingContext.ts
@@ -3,7 +3,8 @@ import { dropUndefinedKeys } from '@sentry/utils';
 
 import { DEFAULT_ENVIRONMENT } from '../constants';
 import { getClient, getCurrentScope } from '../exports';
-import { getRootSpan, spanIsSampled, spanToJSON } from '../utils/spanUtils';
+import { getRootSpan } from '../utils/getRootSpan';
+import { spanIsSampled, spanToJSON } from '../utils/spanUtils';
 
 /**
  * Creates a dynamic sampling context from a client.
diff --git a/packages/core/src/tracing/span.ts b/packages/core/src/tracing/span.ts
index 5fc4beedc682..170f2d4b60be 100644
--- a/packages/core/src/tracing/span.ts
+++ b/packages/core/src/tracing/span.ts
@@ -16,10 +16,10 @@ import type {
 import { dropUndefinedKeys, logger, timestampInSeconds, uuid4 } from '@sentry/utils';
 
 import { DEBUG_BUILD } from '../debug-build';
+import { getRootSpan } from '../utils/getRootSpan';
 import {
   TRACE_FLAG_NONE,
   TRACE_FLAG_SAMPLED,
-  getRootSpan,
   spanTimeInputToSeconds,
   spanToJSON,
   spanToTraceContext,
diff --git a/packages/core/src/utils/applyScopeDataToEvent.ts b/packages/core/src/utils/applyScopeDataToEvent.ts
index 57cc00053be9..426f2295fbb0 100644
--- a/packages/core/src/utils/applyScopeDataToEvent.ts
+++ b/packages/core/src/utils/applyScopeDataToEvent.ts
@@ -1,7 +1,8 @@
 import type { Breadcrumb, Event, PropagationContext, ScopeData, Span } from '@sentry/types';
 import { arrayify } from '@sentry/utils';
 import { getDynamicSamplingContextFromSpan } from '../tracing/dynamicSamplingContext';
-import { getRootSpan, spanToJSON, spanToTraceContext } from './spanUtils';
+import { getRootSpan } from './getRootSpan';
+import { spanToJSON, spanToTraceContext } from './spanUtils';
 
 /**
  * Applies data from the scope to the event and runs all event processors on it.
diff --git a/packages/core/src/utils/getRootSpan.ts b/packages/core/src/utils/getRootSpan.ts
new file mode 100644
index 000000000000..9a0f5d642a77
--- /dev/null
+++ b/packages/core/src/utils/getRootSpan.ts
@@ -0,0 +1,15 @@
+import type { Span } from '@sentry/types';
+
+/**
+ * Returns the root span of a given span.
+ *
+ * As long as we use `Transaction`s internally, the returned root span
+ * will be a `Transaction` but be aware that this might change in the future.
+ *
+ * If the given span has no root span or transaction, `undefined` is returned.
+ */
+export function getRootSpan(span: Span): Span | undefined {
+  // TODO (v8): Remove this check and just return span
+  // eslint-disable-next-line deprecation/deprecation
+  return span.transaction;
+}
diff --git a/packages/core/src/utils/spanUtils.ts b/packages/core/src/utils/spanUtils.ts
index 1a80f3d29397..cbf8ce6d7f5b 100644
--- a/packages/core/src/utils/spanUtils.ts
+++ b/packages/core/src/utils/spanUtils.ts
@@ -107,17 +107,3 @@ export function spanIsSampled(span: Span): boolean {
   // eslint-disable-next-line no-bitwise
   return Boolean(traceFlags & TRACE_FLAG_SAMPLED);
 }
-
-/**
- * Returns the root span of a given span.
- *
- * As long as we use `Transaction`s internally, the returned root span
- * will be a `Transaction` but be aware that this might change in the future.
- *
- * If the given span has no root span or transaction, `undefined` is returned.
- */
-export function getRootSpan(span: Span): Span | undefined {
-  // TODO (v8): Remove this check and just return span
-  // eslint-disable-next-line deprecation/deprecation
-  return span.transaction;
-}
diff --git a/packages/core/test/lib/utils/getRootSpan.ts b/packages/core/test/lib/utils/getRootSpan.ts
new file mode 100644
index 000000000000..eba622a2d884
--- /dev/null
+++ b/packages/core/test/lib/utils/getRootSpan.ts
@@ -0,0 +1,36 @@
+import { Span, Transaction, getRootSpan } from '../../../src';
+
+describe('getRootSpan', () => {
+  it('returns the root span of a span (Span)', () => {
+    const root = new Span({ name: 'test' });
+    // @ts-expect-error this is highly illegal and shouldn't happen IRL
+    // eslint-disable-next-line deprecation/deprecation
+    root.transaction = root;
+
+    // eslint-disable-next-line deprecation/deprecation
+    const childSpan = root.startChild({ name: 'child' });
+    expect(getRootSpan(childSpan)).toBe(root);
+  });
+
+  it('returns the root span of a span (Transaction)', () => {
+    // eslint-disable-next-line deprecation/deprecation
+    const root = new Transaction({ name: 'test' });
+
+    // eslint-disable-next-line deprecation/deprecation
+    const childSpan = root.startChild({ name: 'child' });
+    expect(getRootSpan(childSpan)).toBe(root);
+  });
+
+  it('returns the span itself if it is a root span', () => {
+    // eslint-disable-next-line deprecation/deprecation
+    const span = new Transaction({ name: 'test' });
+
+    expect(getRootSpan(span)).toBe(span);
+  });
+
+  it('returns undefined if span has no root span', () => {
+    const span = new Span({ name: 'test' });
+
+    expect(getRootSpan(span)).toBe(undefined);
+  });
+});
diff --git a/packages/core/test/lib/utils/spanUtils.test.ts b/packages/core/test/lib/utils/spanUtils.test.ts
index 116124130cf0..e521df7c2dc9 100644
--- a/packages/core/test/lib/utils/spanUtils.test.ts
+++ b/packages/core/test/lib/utils/spanUtils.test.ts
@@ -1,6 +1,6 @@
 import { TRACEPARENT_REGEXP, timestampInSeconds } from '@sentry/utils';
-import { Span, Transaction, spanToTraceHeader } from '../../../src';
-import { getRootSpan, spanIsSampled, spanTimeInputToSeconds, spanToJSON } from '../../../src/utils/spanUtils';
+import { Span, spanToTraceHeader } from '../../../src';
+import { spanIsSampled, spanTimeInputToSeconds, spanToJSON } from '../../../src/utils/spanUtils';
 
 describe('spanToTraceHeader', () => {
   test('simple', () => {
@@ -127,38 +127,3 @@ describe('spanIsSampled', () => {
     expect(spanIsSampled(span)).toBe(false);
   });
 });
-
-describe('getRootSpan', () => {
-  it('returns the root span of a span (Span)', () => {
-    const root = new Span({ name: 'test' });
-    // @ts-expect-error this is highly illegal and shouldn't happen IRL
-    // eslint-disable-next-line deprecation/deprecation
-    root.transaction = root;
-
-    // eslint-disable-next-line deprecation/deprecation
-    const childSpan = root.startChild({ name: 'child' });
-    expect(getRootSpan(childSpan)).toBe(root);
-  });
-
-  it('returns the root span of a span (Transaction)', () => {
-    // eslint-disable-next-line deprecation/deprecation
-    const root = new Transaction({ name: 'test' });
-
-    // eslint-disable-next-line deprecation/deprecation
-    const childSpan = root.startChild({ name: 'child' });
-    expect(getRootSpan(childSpan)).toBe(root);
-  });
-
-  it('returns the span itself if it is a root span', () => {
-    // eslint-disable-next-line deprecation/deprecation
-    const span = new Transaction({ name: 'test' });
-
-    expect(getRootSpan(span)).toBe(span);
-  });
-
-  it('returns undefined if span has no root span', () => {
-    const span = new Span({ name: 'test' });
-
-    expect(getRootSpan(span)).toBe(undefined);
-  });
-});
diff --git a/packages/tracing-internal/src/browser/request.ts b/packages/tracing-internal/src/browser/request.ts
index abde36a88488..5d37c7ed49be 100644
--- a/packages/tracing-internal/src/browser/request.ts
+++ b/packages/tracing-internal/src/browser/request.ts
@@ -21,6 +21,7 @@ import {
   stringMatchesSomePattern,
 } from '@sentry/utils';
 
+import { getRootSpan } from '@sentry/core/build/types/utils/spanUtils';
 import { instrumentFetchRequest } from '../common/fetch';
 import { addPerformanceInstrumentationHandler } from './instrument';
 
@@ -298,7 +299,7 @@ export function xhrCallback(
 
   if (xhr.setRequestHeader && shouldAttachHeaders(sentryXhrData.url)) {
     if (span) {
-      const transaction = span && span.transaction;
+      const transaction = span && getRootSpan(span);
       const dynamicSamplingContext = transaction && getDynamicSamplingContextFromSpan(transaction);
       const sentryBaggageHeader = dynamicSamplingContextToSentryBaggageHeader(dynamicSamplingContext);
       setHeaderOnXhr(xhr, spanToTraceHeader(span), sentryBaggageHeader);
diff --git a/packages/tracing-internal/src/common/fetch.ts b/packages/tracing-internal/src/common/fetch.ts
index 14cf242cbf51..b5b104f6f3c6 100644
--- a/packages/tracing-internal/src/common/fetch.ts
+++ b/packages/tracing-internal/src/common/fetch.ts
@@ -134,7 +134,7 @@ export function addTracingHeadersToFetchRequest(
   // eslint-disable-next-line deprecation/deprecation
   const span = requestSpan || scope.getSpan();
 
-  const transaction = span && span.transaction;
+  const transaction = span && getRootSpan(span);
 
   const { traceId, sampled, dsc } = scope.getPropagationContext();
 

From 9298b763d6db809b9455d29a7df76fd23355cf33 Mon Sep 17 00:00:00 2001
From: Lukas Stracke <lukas.stracke@sentry.io>
Date: Wed, 10 Jan 2024 13:31:27 +0100
Subject: [PATCH 4/7] replace span.transaction usages in other packages

---
 packages/astro/src/server/meta.ts                | 7 ++++---
 packages/opentelemetry-node/src/propagator.ts    | 4 ++--
 packages/opentelemetry-node/src/utils/spanMap.ts | 3 ++-
 packages/svelte/src/performance.ts               | 3 ++-
 packages/tracing-internal/src/browser/request.ts | 2 +-
 packages/tracing-internal/src/common/fetch.ts    | 1 +
 6 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/packages/astro/src/server/meta.ts b/packages/astro/src/server/meta.ts
index 1a908acc9ceb..dd591c15d966 100644
--- a/packages/astro/src/server/meta.ts
+++ b/packages/astro/src/server/meta.ts
@@ -1,6 +1,7 @@
 import {
   getDynamicSamplingContextFromClient,
   getDynamicSamplingContextFromSpan,
+  getRootSpan,
   spanToTraceHeader,
 } from '@sentry/core';
 import type { Client, Scope, Span } from '@sentry/types';
@@ -32,12 +33,12 @@ export function getTracingMetaTags(
   client: Client | undefined,
 ): { sentryTrace: string; baggage?: string } {
   const { dsc, sampled, traceId } = scope.getPropagationContext();
-  const transaction = span?.transaction;
+  const rootSpan = span && getRootSpan(span);
 
   const sentryTrace = span ? spanToTraceHeader(span) : generateSentryTraceHeader(traceId, undefined, sampled);
 
-  const dynamicSamplingContext = transaction
-    ? getDynamicSamplingContextFromSpan(transaction)
+  const dynamicSamplingContext = rootSpan
+    ? getDynamicSamplingContextFromSpan(rootSpan)
     : dsc
       ? dsc
       : client
diff --git a/packages/opentelemetry-node/src/propagator.ts b/packages/opentelemetry-node/src/propagator.ts
index 9052ede7e966..ead43afdb8f5 100644
--- a/packages/opentelemetry-node/src/propagator.ts
+++ b/packages/opentelemetry-node/src/propagator.ts
@@ -1,7 +1,7 @@
 import type { Baggage, Context, TextMapGetter, TextMapSetter } from '@opentelemetry/api';
 import { TraceFlags, isSpanContextValid, propagation, trace } from '@opentelemetry/api';
 import { W3CBaggagePropagator, isTracingSuppressed } from '@opentelemetry/core';
-import { getDynamicSamplingContextFromSpan, spanToTraceHeader } from '@sentry/core';
+import { getDynamicSamplingContextFromSpan, getRootSpan, spanToTraceHeader } from '@sentry/core';
 import {
   SENTRY_BAGGAGE_KEY_PREFIX,
   baggageHeaderToDynamicSamplingContext,
@@ -35,7 +35,7 @@ export class SentryPropagator extends W3CBaggagePropagator {
     if (span) {
       setter.set(carrier, SENTRY_TRACE_HEADER, spanToTraceHeader(span));
 
-      if (span.transaction) {
+      if (getRootSpan(span)) {
         const dynamicSamplingContext = getDynamicSamplingContextFromSpan(span);
         baggage = Object.entries(dynamicSamplingContext).reduce<Baggage>((b, [dscKey, dscValue]) => {
           if (dscValue) {
diff --git a/packages/opentelemetry-node/src/utils/spanMap.ts b/packages/opentelemetry-node/src/utils/spanMap.ts
index eee8e923ccbf..9cbdba4460ab 100644
--- a/packages/opentelemetry-node/src/utils/spanMap.ts
+++ b/packages/opentelemetry-node/src/utils/spanMap.ts
@@ -1,3 +1,4 @@
+import { getRootSpan } from '@sentry/core';
 import type { Span as SentrySpan } from '@sentry/types';
 
 interface SpanMapEntry {
@@ -31,7 +32,7 @@ export function getSentrySpan(spanId: string): SentrySpan | undefined {
 export function setSentrySpan(spanId: string, sentrySpan: SentrySpan): void {
   let ref: SpanRefType = SPAN_REF_ROOT;
 
-  const rootSpanId = sentrySpan.transaction?.spanContext().spanId;
+  const rootSpanId = getRootSpan(sentrySpan)?.spanContext().spanId;
 
   if (rootSpanId && rootSpanId !== spanId) {
     const root = SPAN_MAP.get(rootSpanId);
diff --git a/packages/svelte/src/performance.ts b/packages/svelte/src/performance.ts
index f0aa16d0c961..38d68468ffd6 100644
--- a/packages/svelte/src/performance.ts
+++ b/packages/svelte/src/performance.ts
@@ -3,6 +3,7 @@ import type { Span, Transaction } from '@sentry/types';
 import { afterUpdate, beforeUpdate, onMount } from 'svelte';
 import { current_component } from 'svelte/internal';
 
+import { getRootSpan } from '@sentry/core';
 import { DEFAULT_COMPONENT_NAME, UI_SVELTE_INIT, UI_SVELTE_UPDATE } from './constants';
 import type { TrackComponentOptions } from './types';
 
@@ -74,7 +75,7 @@ function recordUpdateSpans(componentName: string, initSpan?: Span): void {
     // If we are initializing the component when the update span is started, we start it as child
     // of the init span. Else, we start it as a child of the transaction.
     const parentSpan =
-      initSpan && !initSpan.endTimestamp && initSpan.transaction === transaction ? initSpan : transaction;
+      initSpan && !initSpan.endTimestamp && getRootSpan(initSpan) === transaction ? initSpan : transaction;
 
     // eslint-disable-next-line deprecation/deprecation
     updateSpan = parentSpan.startChild({
diff --git a/packages/tracing-internal/src/browser/request.ts b/packages/tracing-internal/src/browser/request.ts
index 5d37c7ed49be..461171ec1e25 100644
--- a/packages/tracing-internal/src/browser/request.ts
+++ b/packages/tracing-internal/src/browser/request.ts
@@ -5,6 +5,7 @@ import {
   getCurrentScope,
   getDynamicSamplingContextFromClient,
   getDynamicSamplingContextFromSpan,
+  getRootSpan,
   hasTracingEnabled,
   spanToJSON,
   spanToTraceHeader,
@@ -21,7 +22,6 @@ import {
   stringMatchesSomePattern,
 } from '@sentry/utils';
 
-import { getRootSpan } from '@sentry/core/build/types/utils/spanUtils';
 import { instrumentFetchRequest } from '../common/fetch';
 import { addPerformanceInstrumentationHandler } from './instrument';
 
diff --git a/packages/tracing-internal/src/common/fetch.ts b/packages/tracing-internal/src/common/fetch.ts
index b5b104f6f3c6..a6f7d68ac920 100644
--- a/packages/tracing-internal/src/common/fetch.ts
+++ b/packages/tracing-internal/src/common/fetch.ts
@@ -4,6 +4,7 @@ import {
   getCurrentScope,
   getDynamicSamplingContextFromClient,
   getDynamicSamplingContextFromSpan,
+  getRootSpan,
   hasTracingEnabled,
   spanToTraceHeader,
 } from '@sentry/core';

From 9b721b1cc27d43eb6ecf7966cde14286b6647819 Mon Sep 17 00:00:00 2001
From: Lukas Stracke <lukas.stracke@sentry.io>
Date: Wed, 10 Jan 2024 13:33:01 +0100
Subject: [PATCH 5/7] migration

---
 MIGRATION.md | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/MIGRATION.md b/MIGRATION.md
index 0fb51fd6c4c7..382a0d142f91 100644
--- a/MIGRATION.md
+++ b/MIGRATION.md
@@ -151,7 +151,11 @@ In v8, the Span class is heavily reworked. The following properties & methods ar
 - `span.data`: Use `spanToJSON(span).data` instead.
 - `span.setTag()`: Use `span.setAttribute()` instead or set tags on the surrounding scope.
 - `span.setData()`: Use `span.setAttribute()` instead.
+<<<<<<< HEAD
 - `span.instrumenter` This field was removed and will be replaced internally.
+=======
+- `span.transaction`: Use `getRootSpan` utility function instead.
+>>>>>>> 167fa756a (migration)
 - `transaction.setContext()`: Set context on the surrounding scope instead.
 
 ## Deprecate `pushScope` & `popScope` in favor of `withScope`

From c2c20b1dfffc7e2b9fd1935dd5dd73e1a64f6170 Mon Sep 17 00:00:00 2001
From: Lukas Stracke <lukas.stracke@sentry.io>
Date: Wed, 10 Jan 2024 13:55:13 +0100
Subject: [PATCH 6/7] add core as a dep of @sentry/svelte

---
 packages/svelte/package.json | 1 +
 1 file changed, 1 insertion(+)

diff --git a/packages/svelte/package.json b/packages/svelte/package.json
index 0add4e5758ee..aff3a68ab70a 100644
--- a/packages/svelte/package.json
+++ b/packages/svelte/package.json
@@ -30,6 +30,7 @@
   },
   "dependencies": {
     "@sentry/browser": "7.93.0",
+    "@sentry/core": "7.93.0",
     "@sentry/types": "7.93.0",
     "@sentry/utils": "7.93.0",
     "magic-string": "^0.30.0"

From 5131d0267031ad0ba25fa940b3deae19a3d416ad Mon Sep 17 00:00:00 2001
From: Lukas Stracke <lukas.stracke@sentry.io>
Date: Thu, 11 Jan 2024 12:50:20 +0100
Subject: [PATCH 7/7] fix rebase ??

---
 MIGRATION.md | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/MIGRATION.md b/MIGRATION.md
index 382a0d142f91..330601046734 100644
--- a/MIGRATION.md
+++ b/MIGRATION.md
@@ -151,11 +151,8 @@ In v8, the Span class is heavily reworked. The following properties & methods ar
 - `span.data`: Use `spanToJSON(span).data` instead.
 - `span.setTag()`: Use `span.setAttribute()` instead or set tags on the surrounding scope.
 - `span.setData()`: Use `span.setAttribute()` instead.
-<<<<<<< HEAD
 - `span.instrumenter` This field was removed and will be replaced internally.
-=======
 - `span.transaction`: Use `getRootSpan` utility function instead.
->>>>>>> 167fa756a (migration)
 - `transaction.setContext()`: Set context on the surrounding scope instead.
 
 ## Deprecate `pushScope` & `popScope` in favor of `withScope`