C++26 Is Finalized at the Croydon ISO Meeting
With reflection and Contracts locked into the standard after a week of fit-and-finish work, committee chair Herb Sutter calls it the biggest upgrade to C++ since templates.
The ISO C++ committee, WG21, completed its technical work on the C++26 Draft International Standard at a meeting in London/Croydon, UK, running March 23–28, 2026. Roughly 210 people attended — about 130 in person and 80 remote — formally representing 24 nations, one of the larger turnouts on record for a WG21 meeting.
This meeting didn't add or remove any features; it resolved the remaining 411 national-body comments from the summer 2025 international comment ballot, the fit-and-finish work that closes out a standard's feature set before it moves to formal ISO publication. The draft now proceeds to the formal ISO approval ballot and a final editorial pass.
The headline feature locked in is reflection, based on proposal P2996, which lets code introspect types, members, and program structure at compile time without external tooling or heavy template metaprogramming. Committee chair and longtime C++ standards officer Herb Sutter described it as "the biggest upgrade for C++ development... since the invention of templates."
Contracts — preconditions via a [[pre:]] attribute, postconditions via [[post:]], and a contract_assert statement — were also confirmed, though not without real debate: the final plenary vote was 114 in favor, 12 opposed, and 3 abstaining, a notably higher opposition count than is typical for a feature finalizing at this stage.
C++26 also locks in memory-safety improvements — eliminating undefined behavior for uninitialized local variables and adding a hardened, bounds-safe standard library profile — and std::execution, a unified framework for asynchronous and concurrent code that had been in development across multiple standards cycles.
Toolchains are already moving fast: GCC had merged both reflection and Contracts to trunk and shipped them in GCC 16.1 by April 2026, weeks after this meeting and well ahead of the standard's formal publication — a sign C++26 is landing in real compilers faster than past standards typically have.
Source: Herb Sutter (WG21) — C++26 is done! Trip report: March 2026 ISO C++ meeting