From aeb4907ed658ad5538f8cd569facae5beaab2940 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Storsj=C3=B6?= <martin@martin.st>
Date: Wed, 4 May 2022 15:50:24 +0300
Subject: [PATCH] [libcxxabi] Use the right calling convention for exception
 destructors on i386 Windows

On Windows on i386, C++ member functions use a different calling
convention (`__thiscall`) than the default one for regular functions
(`__cdecl`). (On Windows on architectures other than i386, both calling
convention attributes are no-ops.)

This matches how libstdc++ declares these types.

This fixes the std/thread/futures/futures.{shared,unique}_future/dtor.pass.cpp
tests on i386 mingw.

Differential Revision: https://reviews.llvm.org/D124990
---
 libcxxabi/include/__cxxabi_config.h | 6 ++++++
 libcxxabi/include/cxxabi.h          | 2 +-
 libcxxabi/src/cxa_exception.cpp     | 2 +-
 libcxxabi/src/cxa_exception.h       | 4 ++--
 4 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/libcxxabi/include/__cxxabi_config.h b/libcxxabi/include/__cxxabi_config.h
index 7bc39ada8dda..11a74db2ef97 100644
--- a/libcxxabi/include/__cxxabi_config.h
+++ b/libcxxabi/include/__cxxabi_config.h
@@ -97,4 +97,10 @@
 #  define _LIBCXXABI_NO_EXCEPTIONS
 #endif
 
+#if defined(_WIN32)
+#define _LIBCXXABI_DTOR_FUNC __thiscall
+#else
+#define _LIBCXXABI_DTOR_FUNC
+#endif
+
 #endif // ____CXXABI_CONFIG_H
diff --git a/libcxxabi/include/cxxabi.h b/libcxxabi/include/cxxabi.h
index 770a8cbc441c..85cb4b36b811 100644
--- a/libcxxabi/include/cxxabi.h
+++ b/libcxxabi/include/cxxabi.h
@@ -47,7 +47,7 @@ __cxa_free_exception(void *thrown_exception) throw();
 // 2.4.3 Throwing the Exception Object
 extern _LIBCXXABI_FUNC_VIS _LIBCXXABI_NORETURN void
 __cxa_throw(void *thrown_exception, std::type_info *tinfo,
-            void (*dest)(void *));
+            void (_LIBCXXABI_DTOR_FUNC *dest)(void *));
 
 // 2.5.3 Exception Handlers
 extern _LIBCXXABI_FUNC_VIS void *
diff --git a/libcxxabi/src/cxa_exception.cpp b/libcxxabi/src/cxa_exception.cpp
index 059d75ca2ab4..b17c79eea303 100644
--- a/libcxxabi/src/cxa_exception.cpp
+++ b/libcxxabi/src/cxa_exception.cpp
@@ -254,7 +254,7 @@ will call terminate, assuming that there was no handler for the
 exception.
 */
 void
-__cxa_throw(void *thrown_object, std::type_info *tinfo, void (*dest)(void *)) {
+__cxa_throw(void *thrown_object, std::type_info *tinfo, void (_LIBCXXABI_DTOR_FUNC *dest)(void *)) {
     __cxa_eh_globals *globals = __cxa_get_globals();
     __cxa_exception* exception_header = cxa_exception_from_thrown_object(thrown_object);
 
diff --git a/libcxxabi/src/cxa_exception.h b/libcxxabi/src/cxa_exception.h
index 7a32fb653b07..64123d443a9b 100644
--- a/libcxxabi/src/cxa_exception.h
+++ b/libcxxabi/src/cxa_exception.h
@@ -43,7 +43,7 @@ struct _LIBCXXABI_HIDDEN __cxa_exception {
 
     //  Manage the exception object itself.
     std::type_info *exceptionType;
-    void (*exceptionDestructor)(void *);
+    void (_LIBCXXABI_DTOR_FUNC *exceptionDestructor)(void *);
     std::unexpected_handler unexpectedHandler;
     std::terminate_handler  terminateHandler;
 
@@ -81,7 +81,7 @@ struct _LIBCXXABI_HIDDEN __cxa_dependent_exception {
 #endif
 
     std::type_info *exceptionType;
-    void (*exceptionDestructor)(void *);
+    void (_LIBCXXABI_DTOR_FUNC *exceptionDestructor)(void *);
     std::unexpected_handler unexpectedHandler;
     std::terminate_handler terminateHandler;