ReSharper C++ 2025.3 introduces significant enhancements, including support for C++26 language features, improved constexpr evaluation, and compatibility with Visual Studio 2026, while also offering performance boosts in Unreal Engine development. This update incorporates new C++26 features such as pack indexing, expansion statements, structured bindings with packs, and template-template parameters, alongside contracts for asserting conditions within the code. Unreal Engine developers benefit from a 30% faster warm startup and other improvements like support for the latest Sparse Class Data system and optimized formatter settings. The release also refines the Out-of-Process mode with features like Peek Definition and Unit Testing now available, running on the more efficient .NET Core runtime. Additionally, the coding assistance and tooling have been updated with the latest Clang-Tidy and Clang-Format binaries, improved Extract Method refactoring, and enhanced performance in the Change Signature dialog.