C Constructs That Still Don’t Work in C++ — and a Few That Changed
The post, published on May 23, 2026, on Lobsters, explores C features that still fail to compile in C++ mode, including variable-length arrays (VLAs), compound literals, and flexible array members. It also notes that designated initializers, once problematic, now work in C++20. The author highlights that while C++ has adopted some C features over time, others remain unsupported, leading to practical challenges. For example, codebases that mix C and C++ must use conditional compilation or alternative implementations to handle VLAs, which are a common C idiom but illegal in standard C++. The post references specific C standards (C99, C11) and C++ standards (C++20, C++23) to illustrate the evolution. A concrete consequence is that developers porting C libraries to C++ often need to refactor array handling, potentially impacting performance or readability.
C/C++ interop remains a pain point, forcing workarounds for basic C features.