#modules
4 posts tagged #modules.
228 of 2,613 tracked C++ projects now ship a module
The arewemodulesyet tracker lists 228 projects with a C++20 module, up from 62 in November 2025. That is 8.7% of the 2,613 it follows, and a tick means a module exists, not that it is on: two of three well-known entries keep it behind a build option that defaults to off. A single-file import std; builds on Compiler Explorer only with GCC 16 and one extra flag.
LLVM 23.1 shipped, and one of its changes is silent
Clang 23.1 landed on 25 August with partial expansion statements, modules dependency discovery, and a batch of core-issue fixes. It also elides more dead stores than 22 did, which is the one change that alters behaviour without saying anything at build time.
C++ modules in 2026: import std works, import boost is coming, your IDE still can't
import std compiles on GCC 16.1, Clang 18+, and MSVC. Boost has a per-library module prototype showing 45% build-time reductions. But CMake support is still experimental, clangd needs a full rebuild on module changes, IntelliSense has been 'experimental' for seven years, and almost no libraries ship module definitions. For reflection users: PCH is faster than modules on GCC 16.1 today.
The hidden cost of <meta> -- and the three-line fix
Vittorio Romeo measured what C++26 reflection actually costs: the <meta> header adds ~181ms per TU on GCC 16.1, but the reflection algorithm itself is ~0.07ms per enumerator. The header is 2500x more expensive than the logic. A three-line CMake PCH stanza cuts the header cost by 2.3x. Modules, surprisingly, make it worse.