fix: resolve performance issue when throwing errors with stackTraceLimit = 0 (#8531)

Copilot · sheremet-va · AriPerkkio · web-flow · commit 6d5b5b1a5ea3 · 2025-09-08T13:39:43.000+02:00
Co-authored-by: copilot-swe-agent[bot] &lt;198982749+Copilot@users.noreply.github.com&gt;
Co-authored-by: sheremet-va &lt;16173870+sheremet-va@users.noreply.github.com&gt;
Co-authored-by: Ari Perkki&ouml; &lt;ari.perkkio@gmail.com&gt;
diff --git a/packages/utils/src/source-map.ts b/packages/utils/src/source-map.ts
@@ -91,17 +91,38 @@ export function parseSingleFFOrSafariStack(raw: string): ParsedStack | null {
     )
   }
 
-  if (!line.includes('@') && !line.includes(':')) {
+  // Early return for lines that don't look like Firefox/Safari stack traces
+  // Firefox/Safari stack traces must contain '@' and should have location info after it
+  if (!line.includes('@')) {
     return null
   }
 
-  // eslint-disable-next-line regexp/no-super-linear-backtracking, regexp/optimal-quantifier-concatenation
-  const functionNameRegex = /((.*".+"[^@]*)?[^@]*)(@)/
-  const matches = line.match(functionNameRegex)
-  const functionName = matches && matches[1] ? matches[1] : undefined
-  const [url, lineNumber, columnNumber] = extractLocation(
-    line.replace(functionNameRegex, ''),
-  )
+  // Find the correct @ that separates function name from location
+  // For cases like '@https://@fs/path' or 'functionName@https://@fs/path'
+  // we need to find the first @ that precedes a valid location (containing :)
+  let atIndex = -1
+  let locationPart = ''
+  let functionName: string | undefined
+
+  // Try each @ from left to right to find the one that gives us a valid location
+  for (let i = 0; i < line.length; i++) {
+    if (line[i] === '@') {
+      const candidateLocation = line.slice(i + 1)
+      // Minimum length 3 for valid location: 1 for filename + 1 for colon + 1 for line number (e.g., "a:1")
+      if (candidateLocation.includes(':') && candidateLocation.length >= 3) {
+        atIndex = i
+        locationPart = candidateLocation
+        functionName = i > 0 ? line.slice(0, i) : undefined
+        break
+      }
+    }
+  }
+
+  // Validate we found a valid location with minimum length (filename:line format)
+  if (atIndex === -1 || !locationPart.includes(':') || locationPart.length < 3) {
+    return null
+  }
+  const [url, lineNumber, columnNumber] = extractLocation(locationPart)
 
   if (!url || !lineNumber || !columnNumber) {
     return null
diff --git a/test/core/test/utils.spec.ts b/test/core/test/utils.spec.ts
@@ -1,4 +1,5 @@
 import { assertTypes, deepClone, deepMerge, isNegativeNaN, objDisplay, objectAttr, toArray } from '@vitest/utils'
+import { parseSingleFFOrSafariStack } from '@vitest/utils/source-map'
 import { EvaluatedModules } from 'vite/module-runner'
 import { beforeAll, describe, expect, test } from 'vitest'
 import { deepMergeSnapshot } from '../../../packages/snapshot/src/port/utils'
@@ -306,3 +307,88 @@ describe('isNegativeNaN', () => {
     expect(isNegativeNaN(value)).toBe(expected)
   })
 })
+
+describe('parseSingleFFOrSafariStack', () => {
+  test('should parse valid Firefox/Safari stack traces with file protocol', () => {
+    const validStackLine = 'functionName@file:///path/to/file.js:123:45'
+
+    const result = parseSingleFFOrSafariStack(validStackLine)
+
+    expect(result).toEqual({
+      file: 'file:///path/to/file.js',
+      method: 'functionName',
+      line: 123,
+      column: 45,
+    })
+  })
+
+  test('should parse valid Firefox/Safari stack traces with https protocol', () => {
+    const validStackLine = 'functionName@https://example.com/path/to/file.js:123:45'
+
+    const result = parseSingleFFOrSafariStack(validStackLine)
+
+    expect(result).toEqual({
+      file: '/path/to/file.js',
+      method: 'functionName',
+      line: 123,
+      column: 45,
+    })
+  })
+
+  test('should handle stack lines without function names', () => {
+    const stackLineWithoutFunction = '@file:///path/to/file.js:123:45'
+
+    const result = parseSingleFFOrSafariStack(stackLineWithoutFunction)
+
+    expect(result).toEqual({
+      file: 'file:///path/to/file.js',
+      method: '',
+      line: 123,
+      column: 45,
+    })
+  })
+
+  test('should parse https URLs with @fs prefix without function name', () => {
+    const stackLine = '@https://@fs/path/to/file.js:123:4'
+
+    const result = parseSingleFFOrSafariStack(stackLine)
+
+    expect(result).toEqual({
+      file: '/path/to/file.js',
+      method: '',
+      line: 123,
+      column: 4,
+    })
+  })
+
+  test('should parse https URLs with @fs prefix with function name', () => {
+    const stackLine = 'functionName@https://@fs/path/to/file.js:123:4'
+
+    const result = parseSingleFFOrSafariStack(stackLine)
+
+    expect(result).toEqual({
+      file: '/path/to/file.js',
+      method: 'functionName',
+      line: 123,
+      column: 4,
+    })
+  })
+
+  test('should not hang when `Error.stackTraceLimit = 0` (#6039)', { timeout: 5_000 }, async () => {
+    // 40 takes ~30s on M2 CPU when fix is reverted
+    const size = 40
+
+    const obj = Object.fromEntries(
+      [...Array.from({ length: size }).keys()].map(i => [`prop${i}`, i]),
+    )
+
+    class PrettyError extends globalThis.Error {
+      constructor(e: unknown) {
+        Error.stackTraceLimit = 0
+        super(JSON.stringify(e))
+      }
+    }
+
+    parseSingleFFOrSafariStack(new PrettyError(obj).stack!)
+  })
+})
