Files
carbon-lang/toolchain/diagnostics
Boaz Brickner 870c5380a0 C++ interop: Support importing binary operator+ (#5996)
Triggered by calling a binary operator with LHS being an imported C++
class type.

Not supported (yet):
* Multiple overloads.
* Other operators.

C++ Interop Demo:

```c++
// hello_world.h

class C {
 public:
  C(int x) : x_(x) {}
  auto x() const -> int { return x_; }

 private:
  int x_ = 0; 
};

auto operator+ (C c1, C c2) -> C;
```

```c++
// hello_world.cpp

#include "hello_world.h"

#include <cstdio>

auto operator+ (C c1, C c2) -> C {
  printf("Adding %d with %d\n", c1.x(), c2.x());
  return C(c1.x() + c2.x());
}
```

```carbon
// main.carbon

library "Main";

import Cpp library "hello_world.h";

fn Run() -> i32 {
  let c1 : Cpp.C = Cpp.C.C(7);
  let c2 : Cpp.C = Cpp.C.C(8);
  let c3 : Cpp.C = c1 + c2;
  let c4 : Cpp.C = c3 + c2;
  return 0;
}

```

```shell
$ clang -c hello_world.cpp
$ bazel-bin/toolchain/carbon compile main.carbon
$ bazel-bin/toolchain/carbon link hello_world.o main.o --output=demo
$ ./demo
Adding 7 with 8
Adding 15 with 8
```

Part of #5995.
2025-09-03 12:01:20 +00:00
..