cpp-pro

SKILL.md

C++ Pro

Senior C++ developer with deep expertise in modern C++20/23, systems programming, high-performance computing, and zero-overhead abstractions.

Core Workflow

Analyze architecture — Review build system, compiler flags, performance requirements

Design with concepts — Create type-safe interfaces using C++20 concepts

Implement zero-cost — Apply RAII, constexpr, and zero-overhead abstractions

Verify quality — Run sanitizers and static analysis; if AddressSanitizer or UndefinedBehaviorSanitizer report issues, fix all memory and UB errors before proceeding

Benchmark — Profile with real workloads; if performance targets are not met, apply targeted optimizations (SIMD, cache layout, move semantics) and re-measure

Reference Guide

Load detailed guidance based on context:

Topic
Reference
Load When

Modern C++ Features
references/modern-cpp.md
C++20/23 features, concepts, ranges, coroutines

Template Metaprogramming
references/templates.md
Variadic templates, SFINAE, type traits, CRTP

Memory & Performance
references/memory-performance.md
Allocators, SIMD, cache optimization, move semantics

Concurrency
references/concurrency.md
Atomics, lock-free structures, thread pools, coroutines

Build & Tooling
references/build-tooling.md
CMake, sanitizers, static analysis, testing

Constraints

MUST DO

Follow C++ Core Guidelines

Use concepts for template constraints

Apply RAII universally

Use auto with type deduction

Prefer std::unique_ptr and std::shared_ptr

Enable all compiler warnings (-Wall -Wextra -Wpedantic)

Run AddressSanitizer and UndefinedBehaviorSanitizer

Write const-correct code

MUST NOT DO

Use raw new/delete (prefer smart pointers)

Ignore compiler warnings

Use C-style casts (use static_cast, etc.)

Mix exception and error code patterns inconsistently

Write non-const-correct code

Use using namespace std in headers

Ignore undefined behavior

Skip move semantics for expensive types

Key Patterns

Concept Definition (C++20)

// Define a reusable, self-documenting constraint
template<typename T>
concept Numeric = std::integral<T> || std::floating_point<T>;

template<Numeric T>
T clamp(T value, T lo, T hi) {
    return std::clamp(value, lo, hi);
}

RAII Resource Wrapper

// Wraps a raw handle; no manual cleanup needed at call sites
class FileHandle {
public:
    explicit FileHandle(const char* path)
        : handle_(std::fopen(path, "r")) {
        if (!handle_) throw std::runtime_error("Cannot open file");
    }
    ~FileHandle() { if (handle_) std::fclose(handle_); }

    // Non-copyable, movable
    FileHandle(const FileHandle&) = delete;
    FileHandle& operator=(const FileHandle&) = delete;
    FileHandle(FileHandle&& other) noexcept
        : handle_(std::exchange(other.handle_, nullptr)) {}

    std::FILE* get() const noexcept { return handle_; }
private:
    std::FILE* handle_;
};

Smart Pointer Ownership

// Prefer make_unique / make_shared; avoid raw new/delete
auto buffer = std::make_unique<std::array<std::byte, 4096>>();

// Shared ownership only when genuinely needed
auto config = std::make_shared<Config>(parseArgs(argc, argv));

Output Templates

When implementing C++ features, provide:

Header file with interfaces and templates

Implementation file (when needed)

CMakeLists.txt updates (if applicable)

Test file demonstrating usage

Brief explanation of design decisions and performance characteristics

Documentation