Create the skeleton of a round-trip test for C++ types.

This also functions as a test case for b/271498109.

PiperOrigin-RevId: 542483945

common/test/bidirectional_deps/BUILD

diff --git a/common/test/bidirectional_deps/BUILD b/common/test/bidirectional_deps/BUILD
index 7dc2a10..507aaaf 100644
--- a/common/test/bidirectional_deps/BUILD
+++ b/common/test/bidirectional_deps/BUILD
@@ -33,3 +33,29 @@
         ":leaf_rs_lib",
     ],
 )
+
+crubit_test_cc_library(
+    name = "leaf_cc_lib",
+    hdrs = ["leaf_cc_lib.h"],
+)
+
+rust_library(
+    name = "middle_rs_lib",
+    srcs = ["middle_rs_lib.rs"],
+    cc_deps = [":leaf_cc_lib"],
+)
+
+cc_bindings_from_rust(
+    name = "middle_rs_lib_cc_api",
+    crate = ":middle_rs_lib",
+)
+
+cc_test(
+    name = "cc_test",
+    srcs = ["cc_test.cc"],
+    deps = [
+        ":leaf_cc_lib",
+        "@com_google_googletest//:gtest_main",
+        "//common:rust_allocator_shims",
+    ],
+)

common/test/bidirectional_deps/cc_test.cc

diff --git a/common/test/bidirectional_deps/cc_test.cc b/common/test/bidirectional_deps/cc_test.cc
new file mode 100644
index 0000000..ce47c69
--- /dev/null
+++ b/common/test/bidirectional_deps/cc_test.cc
@@ -0,0 +1,11 @@
+// Part of the Crubit project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#include "common/test/bidirectional_deps/leaf_cc_lib.h"
+
+namespace {
+
+// TODO(b/274834739): Test that CcType(RsType(X)) == X
+
+}  // namespace

common/test/bidirectional_deps/leaf_cc_lib.h

diff --git a/common/test/bidirectional_deps/leaf_cc_lib.h b/common/test/bidirectional_deps/leaf_cc_lib.h
new file mode 100644
index 0000000..4dbd6ef
--- /dev/null
+++ b/common/test/bidirectional_deps/leaf_cc_lib.h
@@ -0,0 +1,16 @@
+// Part of the Crubit project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#ifndef THIRD_PARTY_CRUBIT_COMMON_TEST_BIDIRECTIONAL_DEPS_LEAF_CC_LIB_H_
+#define THIRD_PARTY_CRUBIT_COMMON_TEST_BIDIRECTIONAL_DEPS_LEAF_CC_LIB_H_
+
+struct LeafCcType {
+  unsigned char field;
+};
+
+LeafCcType Wrap(unsigned char x) { return LeafCcType{x}; }
+
+unsigned char Unwrap(LeafCcType x) { return x.field; }
+
+#endif  // THIRD_PARTY_CRUBIT_COMMON_TEST_BIDIRECTIONAL_DEPS_LEAF_CC_LIB_H_

common/test/bidirectional_deps/middle_rs_lib.rs

diff --git a/common/test/bidirectional_deps/middle_rs_lib.rs b/common/test/bidirectional_deps/middle_rs_lib.rs
new file mode 100644
index 0000000..4e7be42
--- /dev/null
+++ b/common/test/bidirectional_deps/middle_rs_lib.rs
@@ -0,0 +1,5 @@
+// Part of the Crubit project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+// TODO(b/274834739): Provide helpers to test that CcType(RsType(X)) == X.