Override Clang class layout for Carbon class types. (#7071)

Use the Carbon-determined size and alignment for Carbon-defined classes,
rather than allowing Clang to work one out for itself using the C++
rules.
This commit is contained in:
Richard Smith
2026-04-17 00:03:29 +00:00
committed by GitHub
parent e7626f46cc
commit f91990aa87
5 changed files with 352 additions and 166 deletions
@@ -97,24 +97,3 @@ inline Cpp '''
// CHECK:STDERR:
Carbon::T t;
''';
// --- fail_todo_fields.carbon
library "[[@TEST_NAME]]";
import Cpp;
class A {
var a: i32;
var b: i32;
}
inline Cpp '''
// CHECK:STDERR: fail_todo_fields.carbon:[[@LINE+7]]:15: error: static assertion failed due to requirement 'sizeof(Carbon::A) == 2 * sizeof(int)' [CppInteropParseError]
// CHECK:STDERR: 18 | static_assert(sizeof(Carbon::A) == 2 * sizeof(int));
// CHECK:STDERR: | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR: fail_todo_fields.carbon:[[@LINE+4]]:33: note: expression evaluates to '1 == 8' [CppInteropParseNote]
// CHECK:STDERR: 18 | static_assert(sizeof(Carbon::A) == 2 * sizeof(int));
// CHECK:STDERR: | ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
// CHECK:STDERR:
static_assert(sizeof(Carbon::A) == 2 * sizeof(int));
''';
@@ -0,0 +1,49 @@
// Part of the Carbon Language 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-FILE: toolchain/testing/testdata/min_prelude/int.carbon
//
// AUTOUPDATE
// TIP: To test this file alone, run:
// TIP: bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/check/testdata/interop/cpp/class/export/layout.carbon
// TIP: To dump output, run:
// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/interop/cpp/class/export/layout.carbon
// --- simple.carbon
library "[[@TEST_NAME]]";
import Cpp;
class C {
var a: i32;
var b: i32;
var c: i32;
}
inline Cpp '''c++
static_assert(sizeof(Carbon::C) == 12);
static_assert(alignof(Carbon::C) == 4);
''';
// --- packed.carbon
library "[[@TEST_NAME]]";
import Cpp;
class C {
var a: ()*;
var b: i32;
}
class D {
var c: C;
var d: i32;
}
inline Cpp '''c++
static_assert(sizeof(Carbon::C) == 12);
static_assert(alignof(Carbon::C) == 8);
static_assert(sizeof(Carbon::D) == 16);
static_assert(alignof(Carbon::D) == 8);
''';