Just finished running some initial tests on the new C++ support in Claude Code. I've been waiting for this, as a significant portion of our legacy microservices and some high-performance compute components are written in C++. The early results are promising, especially for the kind of incremental refactoring and modernization work we often face.
I tested it against a few common scenarios:
* **Modernizing old C++98/03 code to C++17/20 standards.** It correctly handled replacing `auto_ptr` with `unique_ptr` and suggesting `std::optional` for nullable returns.
* **Adding basic gRPC service stubs.** It generated a clean service implementation skeleton from a `.proto` file.
* **Debugging a tricky memory issue.** I fed it a snippet with a potential use-after-free, and it not only identified the risk but suggested the correct fix using a smart pointer.
Here's a quick example of the modernization output I got:
```cpp
// OLD (Claude Code input)
std::auto_ptr create_conn(const std::string& host) {
std::auto_ptr conn(new Connection(host));
if (!conn->open()) {
return std::auto_ptr(nullptr);
}
return conn;
}
// NEW (Claude Code suggestion)
std::unique_ptr create_conn(const std::string& host) {
auto conn = std::make_unique(host);
if (!conn->open()) {
return nullptr; // Implicit conversion to nullptr
}
return conn;
}
```
The suggestions are sensible and safe, which is crucial. It avoids overly aggressive or clever transformations that could break things.
For those of us managing polyglot K8s environments, this is a solid step forward. I'm planning to use it to help containerize some older C++ applications—thinking about generating Dockerfiles, CMakeLists.txt updates, and even basic Helm chart snippets. The key will be how it handles larger, more complex codebases with custom build systems.
Has anyone else started testing it with real production code? I'm particularly interested in its performance with:
* Template-heavy libraries
* Interfacing C++ with other languages (e.g., Python bindings)
* Understanding and refactoring CMake or Bazel build files