Collect layout_compatible specializations defined in other crates

cc_bindings_from_rs/generate_bindings/lib.rs

@@ -195,8 +195,8 @@ fn specializations<'tcx>(db: &crate::BindingsGenerator<'tcx>) -> Rc<[CppTypeSpec
     let tcx = db.tcx();
     let mut specializations = Vec::new();
 
-    let defs_in_crate = db.public_paths_by_def_id(db.source_crate_num());
-    for (adt_or_alias_def_id, paths) in defs_in_crate {
+    let all_public_paths = db.all_public_paths_by_def_id();
+    for (adt_or_alias_def_id, paths) in all_public_paths {
         specializations.extend(
             std::iter::once(adt_or_alias_def_id)
                 .chain(

cc_bindings_from_rs/test/bazel/cross_crate/BUILD

@@ -5,6 +5,7 @@ load(
     "@rules_rust//rust:defs.bzl",
     "rust_library",
 )
+load("//cc_bindings_from_rs/bazel_support:cc_bindings_from_rust_library_config_aspect_hint.bzl", "cc_bindings_from_rust_library_config")
 load(
     "//cc_bindings_from_rs/bazel_support:cc_bindings_from_rust_rule.bzl",
     "cc_bindings_from_rust",
@@ -13,10 +14,27 @@ load("//common:crubit_wrapper_macros_oss.bzl", "crubit_cc_test")
 
 package(default_applicable_licenses = ["//:license"])
 
+cc_bindings_from_rust_library_config(
+    name = "other_crate_hint",
+    extra_cc_hdrs = ["other_crate_types.h"],
+)
+
 rust_library(
     name = "other_crate",
     testonly = 1,
     srcs = ["other_crate.rs"],
+    aspect_hints = [
+        ":other_crate_hint",
+    ],
+    proc_macro_deps = [
+        "//support:crubit_annotate",
+    ],
+)
+
+cc_bindings_from_rust(
+    name = "other_crate_cc_api",
+    testonly = 1,
+    crate = ":other_crate",
 )
 
 rust_library(
@@ -36,6 +54,7 @@ crubit_cc_test(
     name = "cross_crate_test",
     srcs = ["cross_crate_test.cc"],
     deps = [
+        ":other_crate_cc_api",
         ":test_api_cc_api",
         "//testing/base/public:gunit_main",
     ],

cc_bindings_from_rs/test/bazel/cross_crate/cross_crate_test.cc

@@ -6,6 +6,7 @@
 
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include "cc_bindings_from_rs/test/bazel/cross_crate/other_crate_types.h"
 #include "cc_bindings_from_rs/test/bazel/cross_crate/test_api.h"
 
 namespace crubit {
@@ -17,6 +18,11 @@ TEST(CrossCrateTests, BasicEndToEndTest) {
   EXPECT_EQ(123, i);
 }
 
+TEST(CrossCrateTests, SpecializationTest) {
+  crubit::test::MyStatus s = test_api::return_status_from_other_crate();
+  EXPECT_TRUE(s.ok);
+}
+
 // b/292231336
 // TEST(CrossCrateTests, RustToolchainCrate) {
 //   ::alloc::string::String s =

cc_bindings_from_rs/test/bazel/cross_crate/other_crate.rs

@@ -6,3 +6,19 @@
 //! `other_crate.rs` are used in public API exposed by `test_api.rs`.
 
 pub struct SomeStruct(pub i32);
+
+#[crubit_annotate::cpp_layout_equivalent(
+    cpp_type = "crubit::test::MyStatusOr<{T}>",
+    include_path = "cc_bindings_from_rs/test/bazel/cross_crate/other_crate_types.h"
+)]
+#[repr(C)]
+pub struct MyStatusOr<T> {
+    pub has_value: bool,
+    pub value: T,
+}
+
+#[crubit_annotate::cpp_specialization(
+    cpp_type = "crubit::test::MyStatus",
+    include_path = "cc_bindings_from_rs/test/bazel/cross_crate/other_crate_types.h"
+)]
+pub type MyStatus = MyStatusOr<()>;

cc_bindings_from_rs/test/bazel/cross_crate/other_crate_types.h

@@ -0,0 +1,24 @@
+// 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_CC_BINDINGS_FROM_RS_TEST_BAZEL_CROSS_CRATE_OTHER_CRATE_TYPES_H_
+#define THIRD_PARTY_CRUBIT_CC_BINDINGS_FROM_RS_TEST_BAZEL_CROSS_CRATE_OTHER_CRATE_TYPES_H_
+
+namespace crubit {
+namespace test {
+
+struct MyStatus {
+  bool ok;
+};
+
+template <typename T>
+struct MyStatusOr {
+  bool has_value;
+  T value;
+};
+
+}  // namespace test
+}  // namespace crubit
+
+#endif  // THIRD_PARTY_CRUBIT_CC_BINDINGS_FROM_RS_TEST_BAZEL_CROSS_CRATE_OTHER_CRATE_TYPES_H_

cc_bindings_from_rs/test/bazel/cross_crate/test_api.rs

@@ -22,3 +22,7 @@ pub fn extract_int(s: other_crate::SomeStruct) -> i32 {
 pub fn return_a_type_from_a_rust_toolchain_crate() -> String {
     "String".to_owned()
 }
+
+pub fn return_status_from_other_crate() -> other_crate::MyStatus {
+    other_crate::MyStatusOr { has_value: true, value: () }
+}