cppcourse/.agents/skills/cpp-code-review/references/correctness-idioms.md

Correctness & Modern Idioms

Docs: cppreference language/library pages; C++ Core Guidelines.

Errors & exceptions

• Errors aren't silently ignored (unchecked return codes, empty catch (...)).
• Mark functions whose result must be used [[nodiscard]].
• Exception safety: on throw, no leaks and objects stay valid (RAII gives this for free).
• Destructors and move operations are noexcept; no throwing from destructors.
• Catch exceptions by const reference (catch (std::exception const& e)).
• Consider std::optional / std::expected (C++23) for expected failures, per project style.

Types & integers

• Fixed-width integers: use the project's aliases (u32, i64, ...) instead of std::uint32_t etc., e.g. for sizes in protocols, files, and hardware.
• Signed/unsigned comparison and mixing (int vs size_t); use std::cmp_less etc. (C++20) or std::ssize.
• Narrowing conversions are explicit and checked; prefer {} initialization to catch them.
• No implicit conversions via single-arg constructors; mark them explicit.
• enum class over plain enum.

API & classes

• const correctness: methods, references, and parameters.
• Pass cheap types by value, large read-only by const&, sinks by value + std::move.
• override on virtual overrides; final where intended.
• No object slicing (passing derived by value as base).
• Header hygiene: include what you use, no using namespace in headers.

Modern idioms

• Prefer standard algorithms and range-for over hand-rolled loops.
• constexpr for compile-time constants instead of macros.
• std::string_view / std::span for non-owning parameters (watch lifetimes).
• New logic has tests; edge cases (empty, max, error path) are covered.