C++ Insights is a Clang-based source-to-source transformation tool that reveals the implicit operations and transformations the compiler performs on C++ code.
The tool solves the problem of understanding what the compiler actually does with modern C++ features by transforming source code into a form that shows compiler-generated operations explicitly. It expands constructs like range-based for-loops, lambdas, and structured bindings into their underlying implementations, deduces types hidden behind auto and decltype, and reveals implicit casts and operator invocations. The output is intended to be compilable C++ code rather than assembly or abstract syntax trees, making it readable to developers writing in the language.
C++ Insights suits developers learning C++ who want to understand how language features work under the hood, and educators teaching C++ who need to demonstrate compiler behavior in familiar syntax. It covers C++ standards from C++11 through C++23 and beyond. The tool is available both as a web interface and for local building, making it accessible for quick exploration or integration into development workflows. The README acknowledges that not all transformations can produce compilable code and that the tool's accuracy depends on Clang's AST understanding.
The project maintains active development across multiple C++ standards, with ongoing work to support newer language features. The codebase shows continuous refinement of transformation logic for increasingly complex language constructs. Development appears focused on expanding standard coverage and improving the fidelity of transformations rather than pursuing unrelated feature expansion.
