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Add support for importing access from C++ to Carbon (#5858)

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Better access control with inheritance should come with better
inheritance support (actually importing inheritance).

C++ Interop Demo:

```c++
// hello_world.h

class HelloWorld {
 public:
  static auto Pub() -> void;

 protected:
  static auto Pro() -> void;

 private:
  static auto Pri() -> void;
};
```

```c++
// hello_world.cpp

#include "hello_world.h"

#include <cstdio>

auto HelloWorld::Pub() -> void { printf("Public!\n"); }
auto HelloWorld::Pro() -> void { printf("Protected!\n"); }
auto HelloWorld::Pri() -> void { printf("Private!\n"); }
```

```carbon
// main.carbon

library "Main";

import Cpp library "hello_world.h";

fn Run() -> i32 {
  Cpp.HelloWorld.Pub();
  Cpp.HelloWorld.Pro();
  Cpp.HelloWorld.Pri();
  return 0;
}
```

```shell
$ clang -c hello_world.cpp
$ bazel-bin/toolchain/carbon compile main.carbon
main.carbon:9:3: error: cannot access protected member `Pro` of type `Cpp.HelloWorld`
  Cpp.HelloWorld.Pro();
  ^~~~~~~~~~~~~~~~~~
main.carbon: note: declared here

main.carbon:10:3: error: cannot access private member `Pri` of type `Cpp.HelloWorld`
  Cpp.HelloWorld.Pri();
  ^~~~~~~~~~~~~~~~~~
main.carbon: note: declared here
```

Before this change (no access checks):
```shell
$ bazel-bin/toolchain/carbon compile main.carbon
$ bazel-bin/toolchain/carbon link hello_world.o main.o --output=demo
$ ./demo
Public!
Protected!
Private!
```

Part of #5859.
This commit is contained in:
Boaz Brickner
2025-07-29 08:25:15 +00:00
committed by GitHub
parent 6d6e0d0418
commit 30f0ddab71
8 changed files with 487 additions and 148 deletions
Download Patch File Download Diff File Expand all files Collapse all files
toolchain/check/testdata/interop/cpp/class/struct.carbon
Vendored
+24 -42
View File
@@ -82,20 +82,20 @@ fn MyF(bar: Cpp.Bar*);
//@dump-sem-ir-end
// ============================================================================
// Public static member function
// Static member function
// ============================================================================
// --- public_static_member_function.h
// --- static_member_function.h
struct Bar {
static auto foo() -> void;
};
// --- import_public_static_member_function.carbon
// --- import_static_member_function.carbon
library "[[@TEST_NAME]]";
import Cpp library "public_static_member_function.h";
import Cpp library "static_member_function.h";
fn MyF() {
//@dump-sem-ir-begin
@@ -104,53 +104,31 @@ fn MyF() {
}
// ============================================================================
// Private static member function
// Static data member
// ============================================================================
// --- private_static_member_function.h
struct Bar {
private:
static auto foo() -> void;
};
// --- todo_fail_import_private_static_member_function.carbon
library "[[@TEST_NAME]]";
import Cpp library "private_static_member_function.h";
fn MyF() {
// TODO: Should fail because `foo` is inaccessible.
Cpp.Bar.foo();
}
// ============================================================================
// Public static data member
// ============================================================================
// --- public_static_data_member.h
// --- static_data_member.h
struct Bar {
static Bar* _Nonnull foo;
};
// --- fail_todo_import_public_static_data_member.carbon
// --- fail_todo_import_static_data_member.carbon
library "[[@TEST_NAME]]";
import Cpp library "public_static_data_member.h";
import Cpp library "static_data_member.h";
fn MyF() {
//@dump-sem-ir-begin
// CHECK:STDERR: fail_todo_import_public_static_data_member.carbon:[[@LINE+11]]:23: error: semantics TODO: `Unsupported: Declaration type Var` [SemanticsTodo]
// CHECK:STDERR: fail_todo_import_static_data_member.carbon:[[@LINE+11]]:23: error: semantics TODO: `Unsupported: Declaration type Var` [SemanticsTodo]
// CHECK:STDERR: let bar: Cpp.Bar* = Cpp.Bar.foo();
// CHECK:STDERR: ^~~~~~~~~~~
// CHECK:STDERR: fail_todo_import_public_static_data_member.carbon:[[@LINE+8]]:23: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
// CHECK:STDERR: fail_todo_import_static_data_member.carbon:[[@LINE+8]]:23: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
// CHECK:STDERR: let bar: Cpp.Bar* = Cpp.Bar.foo();
// CHECK:STDERR: ^~~~~~~~~~~
// CHECK:STDERR:
// CHECK:STDERR: fail_todo_import_public_static_data_member.carbon:[[@LINE+4]]:23: error: member name `foo` not found in `Cpp.Bar` [MemberNameNotFoundInInstScope]
// CHECK:STDERR: fail_todo_import_static_data_member.carbon:[[@LINE+4]]:23: error: member name `foo` not found in `Cpp.Bar` [MemberNameNotFoundInInstScope]
// CHECK:STDERR: let bar: Cpp.Bar* = Cpp.Bar.foo();
// CHECK:STDERR: ^~~~~~~~~~~
// CHECK:STDERR:
@@ -159,20 +137,20 @@ fn MyF() {
}
// ============================================================================
// Public data member
// Data member
// ============================================================================
// --- public_data_member.h
// --- data_member.h
struct Bar {
Bar* _Nonnull foo;
};
// --- import_public_data_member.carbon
// --- import_data_member.carbon
library "[[@TEST_NAME]]";
import Cpp library "public_data_member.h";
import Cpp library "data_member.h";
//@dump-sem-ir-begin
fn MyF(bar : Cpp.Bar*) {
@@ -254,7 +232,7 @@ struct Bar {
static auto foo() -> void;
};
// --- todo_fail_to_inherit_private.carbon
// --- fail_to_inherit_private.carbon
library "[[@TEST_NAME]]";
@@ -265,7 +243,11 @@ class Derived {
}
fn MyF() {
// TODO: Should fail because `foo` is inaccessible.
// CHECK:STDERR: fail_to_inherit_private.carbon:[[@LINE+5]]:3: error: cannot access private member `foo` of type `Cpp.Bar` [ClassInvalidMemberAccess]
// CHECK:STDERR: Derived.foo();
// CHECK:STDERR: ^~~~~~~~~~~
// CHECK:STDERR: fail_to_inherit_private.carbon: note: declared here [ClassMemberDeclaration]
// CHECK:STDERR:
Derived.foo();
}
@@ -404,7 +386,7 @@ fn MyF(bar: Cpp.Bar*);
// CHECK:STDOUT:
// CHECK:STDOUT: fn @MyF(%bar.param: %ptr);
// CHECK:STDOUT:
// CHECK:STDOUT: --- import_public_static_member_function.carbon
// CHECK:STDOUT: --- import_static_member_function.carbon
// CHECK:STDOUT:
// CHECK:STDOUT: constants {
// CHECK:STDOUT: %empty_tuple.type: type = tuple_type () [concrete]
@@ -431,7 +413,7 @@ fn MyF(bar: Cpp.Bar*);
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: --- fail_todo_import_public_static_data_member.carbon
// CHECK:STDOUT: --- fail_todo_import_static_data_member.carbon
// CHECK:STDOUT:
// CHECK:STDOUT: constants {
// CHECK:STDOUT: %Bar: type = class_type @Bar [concrete]
@@ -464,7 +446,7 @@ fn MyF(bar: Cpp.Bar*);
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: --- import_public_data_member.carbon
// CHECK:STDOUT: --- import_data_member.carbon
// CHECK:STDOUT:
// CHECK:STDOUT: constants {
// CHECK:STDOUT: %Bar: type = class_type @Bar [concrete]