John McCall has worked on programming languages at Apple for fifteen years. He is a language designer for Swift, for which he serves as the Chair of the Language Workgroup in charge of language and standard library evolution, as well as on Objective-C and many of Apple's language extensions to C. He is also a compiler and runtime implementor on both Swift and Clang and is a code owner of LLVM IR generation in both compilers. John helped bring up C++ support in Clang, including implementing core language features such as access control and exceptions. He also led the design and implementation of a number of memory safety and security features, such as automatic reference counting (ARC) in Objective-C, Apple's ABI adoption of ARMv8.3 pointer authentication in C, Objective-C, and C++, and the basic implementation design of Swift.
Interest in memory-safe programming has never been higher, but how can you adopt it in an existing, large C++ code base without rewriting massive amounts of code at once? One tempting approach is to incrementally improve C++ by bringing the ideas from memory-safe languages back to C++. However, this path has inherent hard limitations forced by the language and library design. New languages offer the chance to start fresh with a memory-safe model, providing language affordances to make memory-safe programming the ergonomic and high-performance default. But the introduction of a new programming language in an existing code base typically requires […]