https://github.com/llvmbot created
https://github.com/llvm/llvm-project/pull/147554
Backport fcc09b6f02676e2a0a2c75460ec0dacc89de7525
Requested by: @ldionne
>From 6bdca0d1e8f5cce13270f74b337b5b819cbdea51 Mon Sep 17 00:00:00 2001
From: itrofimow <i.trofi...@yandex.ru>
Date: Tue, 8 Jul 2025 17:34:42 +0200
Subject: [PATCH] [libc++] Fix std::make_exception_ptr interaction with ObjC
(#135386)
Clang treats throwing/catching ObjC types differently from C++ types,
and omitting the `throw` in `std::make_exception_ptr` breaks ObjC
invariants about how types are thrown/caught.
Fixes #135089
Co-authored-by: Louis Dionne <ldionn...@gmail.com>
(cherry picked from commit fcc09b6f02676e2a0a2c75460ec0dacc89de7525)
---
libcxx/include/__exception/exception_ptr.h | 62 +++++++++++++------
.../make_exception_ptr.objc.pass.mm | 44 +++++++++++++
2 files changed, 88 insertions(+), 18 deletions(-)
create mode 100644
libcxx/test/std/language.support/support.exception/propagation/make_exception_ptr.objc.pass.mm
diff --git a/libcxx/include/__exception/exception_ptr.h
b/libcxx/include/__exception/exception_ptr.h
index 6257e6f729bf3..b007e39db6fcb 100644
--- a/libcxx/include/__exception/exception_ptr.h
+++ b/libcxx/include/__exception/exception_ptr.h
@@ -15,6 +15,7 @@
#include <__memory/addressof.h>
#include <__memory/construct_at.h>
#include <__type_traits/decay.h>
+#include <__type_traits/is_pointer.h>
#include <cstdlib>
#include <typeinfo>
@@ -62,7 +63,7 @@ class _LIBCPP_EXPORTED_FROM_ABI exception_ptr {
static exception_ptr __from_native_exception_pointer(void*) _NOEXCEPT;
template <class _Ep>
- friend _LIBCPP_HIDE_FROM_ABI exception_ptr make_exception_ptr(_Ep) _NOEXCEPT;
+ friend _LIBCPP_HIDE_FROM_ABI exception_ptr
__make_exception_ptr_explicit(_Ep&) _NOEXCEPT;
public:
// exception_ptr is basically a COW string.
@@ -89,25 +90,21 @@ class _LIBCPP_EXPORTED_FROM_ABI exception_ptr {
friend _LIBCPP_EXPORTED_FROM_ABI void rethrow_exception(exception_ptr);
};
-template <class _Ep>
-_LIBCPP_HIDE_FROM_ABI exception_ptr make_exception_ptr(_Ep __e) _NOEXCEPT {
# if _LIBCPP_HAS_EXCEPTIONS
-# if _LIBCPP_AVAILABILITY_HAS_INIT_PRIMARY_EXCEPTION && __cplusplus >=
201103L
+# if _LIBCPP_AVAILABILITY_HAS_INIT_PRIMARY_EXCEPTION
+template <class _Ep>
+_LIBCPP_HIDE_FROM_ABI exception_ptr __make_exception_ptr_explicit(_Ep& __e)
_NOEXCEPT {
using _Ep2 = __decay_t<_Ep>;
-
void* __ex = __cxxabiv1::__cxa_allocate_exception(sizeof(_Ep));
# ifdef __wasm__
- // In Wasm, a destructor returns its argument
- (void)__cxxabiv1::__cxa_init_primary_exception(
- __ex, const_cast<std::type_info*>(&typeid(_Ep)), [](void* __p) -> void* {
+ auto __cleanup = [](void* __p) -> void* {
+ std::__destroy_at(static_cast<_Ep2*>(__p));
+ return __p;
+ };
# else
- (void)__cxxabiv1::__cxa_init_primary_exception(__ex,
const_cast<std::type_info*>(&typeid(_Ep)), [](void* __p) {
-# endif
- std::__destroy_at(static_cast<_Ep2*>(__p));
-# ifdef __wasm__
- return __p;
+ auto __cleanup = [](void* __p) { std::__destroy_at(static_cast<_Ep2*>(__p));
};
# endif
- });
+ (void)__cxxabiv1::__cxa_init_primary_exception(__ex,
const_cast<std::type_info*>(&typeid(_Ep)), __cleanup);
try {
::new (__ex) _Ep2(__e);
@@ -116,18 +113,47 @@ _LIBCPP_HIDE_FROM_ABI exception_ptr
make_exception_ptr(_Ep __e) _NOEXCEPT {
__cxxabiv1::__cxa_free_exception(__ex);
return current_exception();
}
-# else
+}
+# endif
+
+template <class _Ep>
+_LIBCPP_HIDE_FROM_ABI exception_ptr __make_exception_ptr_via_throw(_Ep& __e)
_NOEXCEPT {
try {
throw __e;
} catch (...) {
return current_exception();
}
+}
+
+template <class _Ep>
+_LIBCPP_HIDE_FROM_ABI exception_ptr make_exception_ptr(_Ep __e) _NOEXCEPT {
+ // Objective-C exceptions are thrown via pointer. When throwing an
Objective-C exception,
+ // Clang generates a call to `objc_exception_throw` instead of the usual
`__cxa_throw`.
+ // That function creates an exception with a special Objective-C typeinfo
instead of
+ // the usual C++ typeinfo, since that is needed to implement the behavior
documented
+ // at [1]).
+ //
+ // Because of this special behavior, we can't create an exception via
`__cxa_init_primary_exception`
+ // for Objective-C exceptions, otherwise we'd bypass `objc_exception_throw`.
See https://llvm.org/PR135089.
+ //
+ // [1]:
+ //
https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/Exceptions/Articles/Exceptions64Bit.html
+ if _LIBCPP_CONSTEXPR (is_pointer<_Ep>::value) {
+ return std::__make_exception_ptr_via_throw(__e);
+ }
+
+# if _LIBCPP_AVAILABILITY_HAS_INIT_PRIMARY_EXCEPTION &&
!defined(_LIBCPP_CXX03_LANG)
+ return std::__make_exception_ptr_explicit(__e);
+# else
+ return std::__make_exception_ptr_via_throw(__e);
# endif
-# else
- ((void)__e);
+}
+# else // !_LIBCPP_HAS_EXCEPTIONS
+template <class _Ep>
+_LIBCPP_HIDE_FROM_ABI exception_ptr make_exception_ptr(_Ep) _NOEXCEPT {
std::abort();
-# endif
}
+# endif // _LIBCPP_HAS_EXCEPTIONS
#else // _LIBCPP_ABI_MICROSOFT
diff --git
a/libcxx/test/std/language.support/support.exception/propagation/make_exception_ptr.objc.pass.mm
b/libcxx/test/std/language.support/support.exception/propagation/make_exception_ptr.objc.pass.mm
new file mode 100644
index 0000000000000..05a6698ea1a59
--- /dev/null
+++
b/libcxx/test/std/language.support/support.exception/propagation/make_exception_ptr.objc.pass.mm
@@ -0,0 +1,44 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM
Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// This test ensures that we can catch an Objective-C++ exception by type when
+// throwing an exception created via `std::make_exception_ptr`.
+// See http://llvm.org/PR135089.
+
+// UNSUPPORTED: no-exceptions
+// UNSUPPORTED: c++03
+
+// This test requires the Objective-C ARC, which is (only?) available on Darwin
+// out-of-the-box.
+// REQUIRES: has-fobjc-arc && darwin
+
+// ADDITIONAL_COMPILE_FLAGS: -fobjc-arc
+
+#include <cassert>
+#include <exception>
+
+#import <Foundation/Foundation.h>
+
+NSError* RecoverException(const std::exception_ptr& exc) {
+ try {
+ std::rethrow_exception(exc);
+ } catch (NSError* error) {
+ return error;
+ } catch (...) {
+ }
+ return nullptr;
+}
+
+int main(int, char**) {
+ NSError* error = [NSError errorWithDomain:NSPOSIXErrorDomain
code:EPERM userInfo:nil];
+ std::exception_ptr exc = std::make_exception_ptr(error);
+ NSError* recov = RecoverException(exc);
+ assert(recov != nullptr);
+
+ return 0;
+}
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