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Support importing C++ _Nonnull pointers as function parameters or return values (#5773)

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We avoid using canonical type before knowing it's not a pointer because
we need the nullability attribute.
No support for pointers to pointers, yet.

C++ Interop Demo:

```c++
// hello_world.h

auto hello_world_param(int* _Nonnull i) -> void;
auto hello_world_return() -> int* _Nonnull;
```

```c++
// hello_world.cpp

#include "hello_world.h"
#include <cstdio>

auto hello_world_param(int* _Nonnull i) -> void {
  printf("hello_world: %d\n", *i);
}

static int x = 5;
auto hello_world_return() -> int* _Nonnull { return &x; }
```

```carbon
// main.carbon

library "Main";

import Core library "io";
import Cpp library "hello_world.h";

fn Run() -> i32 {
  var i: i32 = 10;
  Cpp.hello_world_param(&i);

  let p: i32* = Cpp.hello_world_return();
  Core.Print(*p);

  return 0;
}
```

```shell
$ clang -c hello_world.cpp
$ ./bazel-bin/toolchain/install/prefix_root/bin/carbon compile main.carbon
$ ./bazel-bin/toolchain/install/prefix_root/bin/carbon link hello_world.o main.o --output=demo
$ ./demo
hello_world: 10
5
```

Part of #5772.
This commit is contained in:
Boaz Brickner
2025-07-10 08:00:37 +00:00
committed by GitHub
parent 110af3bfe4
commit a5ddc3e3cd
7 changed files with 899 additions and 145 deletions
Download Patch File Download Diff File Expand all files Collapse all files
toolchain/check/testdata/interop/cpp/function/param_int32.carbon
Vendored
+29 -26
View File
@@ -329,9 +329,9 @@ fn F() {
// --- int_pointer.h
auto foo(int* a) -> void;
auto foo(int* _Nonnull a) -> void;
// --- fail_todo_import_int_pointer.carbon
// --- import_int_pointer.carbon
library "[[@TEST_NAME]]";
@@ -340,13 +340,6 @@ import Cpp library "int_pointer.h";
fn F() {
var a: i32 = 1;
//@dump-sem-ir-begin
// CHECK:STDERR: fail_todo_import_int_pointer.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: int *` [SemanticsTodo]
// CHECK:STDERR: Cpp.foo(&a);
// CHECK:STDERR: ^~~~~~~
// CHECK:STDERR: fail_todo_import_int_pointer.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
// CHECK:STDERR: Cpp.foo(&a);
// CHECK:STDERR: ^~~~~~~
// CHECK:STDERR:
Cpp.foo(&a);
//@dump-sem-ir-end
}
@@ -357,9 +350,9 @@ fn F() {
// --- const_int_pointer.h
auto foo(const int* a) -> int;
auto foo(const int* _Nonnull a) -> int;
// --- fail_todo_import_const_int_pointer.carbon
// --- import_const_int_pointer.carbon
library "[[@TEST_NAME]]";
@@ -368,13 +361,6 @@ import Cpp library "const_int_pointer.h";
fn F() {
var a : i32 = 1;
//@dump-sem-ir-begin
// CHECK:STDERR: fail_todo_import_const_int_pointer.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: const int *` [SemanticsTodo]
// CHECK:STDERR: Cpp.foo(&a);
// CHECK:STDERR: ^~~~~~~
// CHECK:STDERR: fail_todo_import_const_int_pointer.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
// CHECK:STDERR: Cpp.foo(&a);
// CHECK:STDERR: ^~~~~~~
// CHECK:STDERR:
Cpp.foo(&a);
//@dump-sem-ir-end
}
@@ -1077,53 +1063,70 @@ fn F() {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: --- fail_todo_import_int_pointer.carbon
// CHECK:STDOUT: --- import_int_pointer.carbon
// CHECK:STDOUT:
// CHECK:STDOUT: constants {
// CHECK:STDOUT: %empty_tuple.type: type = tuple_type () [concrete]
// CHECK:STDOUT: %int_32: Core.IntLiteral = int_value 32 [concrete]
// CHECK:STDOUT: %i32: type = class_type @Int, @Int(%int_32) [concrete]
// CHECK:STDOUT: %ptr.235: type = ptr_type %i32 [concrete]
// CHECK:STDOUT: %foo.type: type = fn_type @foo [concrete]
// CHECK:STDOUT: %foo: %foo.type = struct_value () [concrete]
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: imports {
// CHECK:STDOUT: %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
// CHECK:STDOUT: .foo = <error>
// CHECK:STDOUT: .foo = %foo.decl
// CHECK:STDOUT: import Cpp//...
// CHECK:STDOUT: }
// CHECK:STDOUT: %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: } {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: }
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: fn @F() {
// CHECK:STDOUT: !entry:
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
// CHECK:STDOUT: %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
// CHECK:STDOUT: %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
// CHECK:STDOUT: %a.ref: ref %i32 = name_ref a, %a
// CHECK:STDOUT: %addr.loc16: %ptr.235 = addr_of %a.ref
// CHECK:STDOUT: %addr.loc9: %ptr.235 = addr_of %a.ref
// CHECK:STDOUT: %foo.call: init %empty_tuple.type = call %foo.ref(%addr.loc9)
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: --- fail_todo_import_const_int_pointer.carbon
// CHECK:STDOUT: --- import_const_int_pointer.carbon
// CHECK:STDOUT:
// CHECK:STDOUT: constants {
// CHECK:STDOUT: %int_32: Core.IntLiteral = int_value 32 [concrete]
// CHECK:STDOUT: %i32: type = class_type @Int, @Int(%int_32) [concrete]
// CHECK:STDOUT: %ptr.235: type = ptr_type %i32 [concrete]
// CHECK:STDOUT: %foo.type: type = fn_type @foo [concrete]
// CHECK:STDOUT: %foo: %foo.type = struct_value () [concrete]
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: imports {
// CHECK:STDOUT: %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
// CHECK:STDOUT: .foo = <error>
// CHECK:STDOUT: .foo = %foo.decl
// CHECK:STDOUT: import Cpp//...
// CHECK:STDOUT: }
// CHECK:STDOUT: %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: } {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: }
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: fn @F() {
// CHECK:STDOUT: !entry:
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
// CHECK:STDOUT: %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
// CHECK:STDOUT: %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
// CHECK:STDOUT: %a.ref: ref %i32 = name_ref a, %a
// CHECK:STDOUT: %addr.loc16: %ptr.235 = addr_of %a.ref
// CHECK:STDOUT: %addr.loc9: %ptr.235 = addr_of %a.ref
// CHECK:STDOUT: %foo.call: init %i32 = call %foo.ref(%addr.loc9)
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: }
// CHECK:STDOUT: