Code Review Checklist

When reviewing workerd C++ code, check for each of these items.

• Always check for STL leaking in: std::string, std::vector, std::optional, std::unique_ptr, etc.
• Never allow raw new/delete**. Should be kj::heap<T>() or similar
• Never use throw statements. Should use KJ_ASSERT/KJ_REQUIRE/KJ_FAIL_ASSERT/etc
• Never use noexcept
• Always use noexcept(false) on explicit destructors
• Never use [=] lambda captures
• Never use nullable raw pointers. Should be kj::Maybe<T&>
• Never mixed interface and implementation classes. No data members in interfaces, no non-final virtuals in implementations. Intermediate subclasses are ok
• Never use singletons or mutable globals
• Always verify proper use of .attach() on promises. Objects must stay alive for the promise duration
• Always use .eagerlyEvaluate() with background promises. Lazy continuations may never execute. Co-routines are eager by default.
• Never use manual errno checks. Should use KJ_SYSCALL / KJ_SYSCALL_HANDLE_ERRORS
• Avoid static_cast for downcasting where possible. Should be kj::downcast<T> (debug-checked)
• Avoid dynamic_cast for dispatch where possible. Extend the interface instead
• Never use std::to_string or + string concatenation**
• Never use /* */ block comments. Use // line comments
• Always verify naming convention conformance. TitleCase types, camelCase functions/variables, CAPS constants
• Always check for missing braces around blocks. Required unless entire statement is on one line
• Always avoid bool function parameters. Prefer enum class or WD_STRONG_BOOL for clarity at call sites. E.g., void connect(bool secure) should be void connect(SecureMode mode)
• Always use [[nodiscard]] with functions returning error codes, kj::Maybe, or success booleans that callers must check should be [[nodiscard]]
• Always prefer coroutines over kj::Promise chains. Nested .then() chains with complex error handling that would be more readable as a coroutine with co_await. But always avoid suggesting sweeping rewrites
• Always check for missing constexpr / consteval where they would be appropriate
• Always avoid reinventing utility with custom code duplicating functionality already in src/workerd/util/ (e.g., custom ring buffer, small set, state machine, weak reference pattern). Always check the util directory before suggesting a new abstraction.
• Always check for missing override on virtual method overrides.
• Always flag magic numbers (Numeric literals) without explanation or named constants.
• Always check for copyright header on new files. Every new .c++ and .h file must begin with the project copyright/license header using the current year (not copied from older files). Expected format:
  Copy

  // Copyright (c) <current-year> Cloudflare, Inc.
  // Licensed under the Apache 2.0 license found in the LICENSE file or at:
  //     https://opensource.org/licenses/Apache-2.0
  

  Flag any new file that uses a stale year (e.g., 2017-2022 in a file created in 2026) or omits the header entirely.