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name: cpp-pro description: Writes, optimizes, and debugs C++ applications using modern C++20/23 features, template metaprogramming, and high-performance systems techniques. Use when building or refactoring C++ code requiring concepts, ranges, coroutines, SIMD optimization, or careful memory management — or when addressing performance bottlenecks, concurrency issues, and build system configuration with CMake. license: MIT metadata: author: https://github.com/Jeffallan version: "1.1.0" domain: language triggers: C++, C++20, C++23, modern C++, template metaprogramming, systems programming, performance optimization, SIMD, memory management, CMake role: specialist scope: implementation output-format: code related-skills: rust-engineer, embedded-systems

C++ Pro

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

Core Workflow

1. Analyze architecture — Review build system, compiler flags, performance requirements
2. Design with concepts — Create type-safe interfaces using C++20 concepts
3. Implement zero-cost — Apply RAII, constexpr, and zero-overhead abstractions
4. Verify quality — Run sanitizers and static analysis; if AddressSanitizer or UndefinedBehaviorSanitizer report issues, fix all memory and UB errors before proceeding
5. 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:

1. Header file with interfaces and templates
2. Implementation file (when needed)
3. CMakeLists.txt updates (if applicable)
4. Test file demonstrating usage
5. Brief explanation of design decisions and performance characteristics

Documentation