mvp

demo/Cargo.toml

@@ -9,7 +9,7 @@ publish = false
 repository = "https://github.com/dtolnay/cxx"
 
 [dependencies]
-cxx = "1.0"
+cxx = {version="1.0", features=["c++17"]}
 
 [build-dependencies]
 cxx-build = "1.0"

demo/build.rs

@@ -1,7 +1,7 @@
 fn main() {
     cxx_build::bridge("src/main.rs")
         .file("src/blobstore.cc")
-        .flag_if_supported("-std=c++14")
+        .flag("-std=c++17")
         .compile("cxxbridge-demo");
 
     println!("cargo:rerun-if-changed=src/main.rs");

demo/include/blobstore.h

@@ -22,5 +22,10 @@ class BlobstoreClient {
 
 std::unique_ptr<BlobstoreClient> new_blobstore_client();
 
+::rust::Option<::rust::Box<BlobMetadata>> c_take_option_box(::rust::Option<::rust::Box<BlobMetadata>>);
+::rust::Option<const BlobMetadata*> c_take_option_ref(::rust::Option<const BlobMetadata *>);
+::rust::Option<BlobMetadata*> c_take_option_ref_mut(::rust::Option<BlobMetadata *>);
+void c_take_rust_ref_option_opaque(rust::Option<const MultiBuf*>);
+
 } // namespace blobstore
 } // namespace org

demo/src/blobstore.cc

@@ -2,9 +2,11 @@
 #include "demo/src/main.rs.h"
 #include <algorithm>
 #include <functional>
+#include <vector>
 #include <set>
 #include <string>
 #include <unordered_map>
+#include <iostream>
 
 namespace org {
 namespace blobstore {
@@ -27,6 +29,19 @@ BlobstoreClient::BlobstoreClient() : impl(new class BlobstoreClient::impl) {}
 // Upload a new blob and return a blobid that serves as a handle to the blob.
 uint64_t BlobstoreClient::put(MultiBuf &buf) const {
   std::string contents;
+  BlobMetadata metadata{};
+  metadata.tags.push_back("cpp");
+  metadata.size = 1;
+  auto rrob = r_return_option_box();
+  std::cout << "rrob.inner.empty: " << rrob.inner.empty << std::endl;
+  std::cout << "rrob.has_value(): " << rrob.has_value() << std::endl;
+  std::cout << "rrob.value().size: " << rrob.value()->size << std::endl;
+  std::cout << "rrob.value().tags[0]: " << rrob.value()->tags[0] << std::endl;
+
+  // auto rror = r_return_option_ref(metadata);
+  // std::cout << "rror.has_value(): " << rror.has_value() << std::endl;
+  // std::cout << "rror.value().size: " << rror.value()->size << std::endl;
+  // std::cout << "rror.value().tags[0]: " << rror.value()->tags[0] << std::endl;
 
   // Traverse the caller's chunk iterator.
   //
@@ -67,5 +82,28 @@ std::unique_ptr<BlobstoreClient> new_blobstore_client() {
   return std::make_unique<BlobstoreClient>();
 }
 
+rust::Option<rust::Box<BlobMetadata>>c_take_option_box(rust::Option<rust::Box<BlobMetadata>> r) {
+  std::cout << "r.inner.empty: " << r.inner.empty << std::endl;
+  std::cout << "r.has_value(): " << r.has_value() << std::endl;
+  std::cout << "r.value().size: " << r.value()->size << std::endl;
+  std::cout << "r.value().tags[0]: " << r.value()->tags[0] << std::endl;
+  return r;
+}
+
+rust::Option<const BlobMetadata *> c_take_option_ref(rust::Option<const BlobMetadata *> r) {
+  std::cout << "r.has_value(): " << r.has_value() << std::endl;
+  std::cout << "r.value().size: " << r.value()->size << std::endl;
+  std::cout << "r.value().tags[0]: " << r.value()->tags[0] << std::endl;
+  return r;
+}
+
+rust::Option<BlobMetadata *> c_take_option_ref_mut(rust::Option<BlobMetadata *> r) {
+  std::cout << "r.has_value(): " << r.has_value() << std::endl;
+  std::cout << "r.value().size: " << r.value()->size << std::endl;
+  std::cout << "r.value().tags[0]: " << r.value()->tags[0] << std::endl;
+  r.value()->tags[0] = "cpp";
+  return r;
+}
+
 } // namespace blobstore
 } // namespace org

demo/src/main.rs

@@ -1,3 +1,6 @@
+use cxx::{CxxVector, UniquePtr};
+use std::pin::Pin;
+
 #[cxx::bridge(namespace = "org::blobstore")]
 mod ffi {
     // Shared structs with fields visible to both languages.
@@ -10,7 +13,20 @@ mod ffi {
     extern "Rust" {
         type MultiBuf;
 
+        fn r_return_str() -> &'static str;
         fn next_chunk(buf: &mut MultiBuf) -> &[u8];
+        fn r_return_option_box() -> Option<Box<BlobMetadata>>;
+        fn r_return_option_ref() -> Option<&'static u8>;
+        fn r_take_option_box(o: Option<Box<BlobMetadata>>);
+        unsafe fn r_take_option_pin<'a>(
+            o: Option<Pin<&'a mut BlobMetadata>>,
+        ) -> Option<Pin<&'a mut BlobMetadata>>;
+
+        fn r_take_vec(v: Vec<BlobMetadata>);
+        fn r_return_vec() -> Vec<BlobMetadata>;
+        fn r_return_box() -> Box<BlobMetadata>;
+
+        fn foo(_: UniquePtr<CxxVector<BlobMetadata>>) -> u32;
     }
 
     // C++ types and signatures exposed to Rust.
@@ -23,6 +39,10 @@ mod ffi {
         fn put(&self, parts: &mut MultiBuf) -> u64;
         fn tag(&self, blobid: u64, tag: &str);
         fn metadata(&self, blobid: u64) -> BlobMetadata;
+
+        fn c_take_option_box(rust: Option<Box<BlobMetadata>>) -> Option<Box<BlobMetadata>>;
+        fn c_take_option_ref(rust: Option<&BlobMetadata>) -> Option<&BlobMetadata>;
+        fn c_take_option_ref_mut(rust: Option<&mut BlobMetadata>) -> Option<&mut BlobMetadata>;
     }
 }
 
@@ -41,7 +61,64 @@ pub fn next_chunk(buf: &mut MultiBuf) -> &[u8] {
     next.map_or(&[], Vec::as_slice)
 }
 
+pub fn r_return_str() -> &'static str {
+    "rust"
+}
+
+fn r_return_option_box() -> Option<Box<ffi::BlobMetadata>> {
+    Some(Box::new(ffi::BlobMetadata {
+        size: 42,
+        tags: vec!["rust".to_owned()],
+    }))
+}
+
+fn r_return_option_ref() -> Option<&'static u8> {
+    Some(&42)
+}
+
+fn r_take_option_box(o: Option<Box<ffi::BlobMetadata>>) {
+    let _ = o;
+}
+
+unsafe fn r_take_option_pin<'a>(
+    o: Option<Pin<&'a mut ffi::BlobMetadata>>,
+) -> Option<Pin<&'a mut ffi::BlobMetadata>> {
+    o
+}
+
+pub fn foo(cpp: UniquePtr<CxxVector<ffi::BlobMetadata>>) -> u32 {
+    cpp.len() as u32
+}
+
+fn r_take_vec(v: Vec<ffi::BlobMetadata>) {
+    let _ = v;
+}
+
+fn r_return_vec() -> Vec<ffi::BlobMetadata> {
+    Vec::new()
+}
+
+fn r_return_box() -> Box<ffi::BlobMetadata> {
+    Box::new(ffi::BlobMetadata {
+        size: 0,
+        tags: vec![],
+    })
+}
+
 fn main() {
+    let opt = ffi::c_take_option_box(Some(Box::new(ffi::BlobMetadata {
+        size: 42,
+        tags: vec!["rust".to_owned()],
+    })));
+    println!("opt.unwrap().tags: {:?}", opt.unwrap().tags);
+    let mut metadata = ffi::BlobMetadata {
+        size: 42,
+        tags: vec!["rust".to_owned()],
+    };
+    let opt = ffi::c_take_option_ref(Some(&metadata));
+    println!("opt.unwrap().tags: {:?}", opt.unwrap().tags);
+    let opt = ffi::c_take_option_ref_mut(Some(&mut metadata));
+    println!("opt.unwrap().tags: {:?}", opt.unwrap().tags);
     let client = ffi::new_blobstore_client();
 
     // Upload a blob.

gen/src/builtin.rs

@@ -10,6 +10,7 @@ pub(crate) struct Builtins<'a> {
     pub rust_slice: bool,
     pub rust_box: bool,
     pub rust_vec: bool,
+    pub rust_option: bool,
     pub rust_fn: bool,
     pub rust_isize: bool,
     pub opaque: bool,