Merge pull request #2570 from oneandonlydean/fix/libc-future-result-exception-2540

fix(libc): release future results' exceptions through libc on Windows

core/libs/prx/libc/src/exception/ExceptionPointer.cpp

@@ -1,12 +1,23 @@
 #include <exception>
 
 #ifndef _LIBCPP_VERSION
+#include <future>
+
 extern "C" {
 void ExceptionPointerAddref(std::exception_ptr* self) noexcept asm("_ZNSt15__exception_ptr13exception_ptr9_M_addrefEv");
 void ExceptionPointerRelease(std::exception_ptr* self) noexcept asm("_ZNSt15__exception_ptr13exception_ptr10_M_releaseEv");
 void* ExceptionPointerGet(const std::exception_ptr* self) noexcept asm("_ZNKSt15__exception_ptr13exception_ptr6_M_getEv");
 void ExceptionPointerConstruct(std::exception_ptr* self, void* exception) noexcept asm("_ZNSt15__exception_ptr13exception_ptrC1EPv");
 const std::type_info* ExceptionPointerType(const std::exception_ptr* self) noexcept asm("_ZNKSt15__exception_ptr13exception_ptr20__cxa_exception_typeEv");
+void FutureResultDestroy(std::__future_base::_Result_base* self) noexcept asm("_ZNSt13__future_base12_Result_baseD2Ev");
+
+void FutureResultDestroy(std::__future_base::_Result_base* self) noexcept {
+    self->_M_error.~exception_ptr();
+}
+
+void APS5_VABI _ZNSt13__future_base12_Result_baseD2Ev_nid_postfix(std::__future_base::_Result_base* self) noexcept {
+    FutureResultDestroy(self);
+}
 
 void APS5_VABI _ZNSt15__exception_ptr13exception_ptr9_M_addrefEv_nid_postfix(std::exception_ptr* self) noexcept {
     ExceptionPointerAddref(self);

core/libs/tests/WindowsExceptions.cpp

@@ -4,6 +4,7 @@
 #include <atomic>
 #include <array>
 #include <exception>
+#include <future>
 #include <thread>
 #include <cstddef>
 #include <typeinfo>
@@ -105,9 +106,30 @@ static void testExceptionPointer() {
     if (std::current_exception()) throw std::runtime_error("stale current exception");
 }
 
+static void testFutureException() {
+    std::atomic<int> count{0};
+    {
+        std::promise<void> promise;
+        auto future = promise.get_future();
+        try {
+            throw TrackedError(&count);
+        } catch (const TrackedError&) {
+            promise.set_exception(std::current_exception());
+        }
+        try {
+            future.get();
+            throw std::runtime_error("future did not rethrow");
+        } catch (const TrackedError& error) {
+            if (std::strcmp(error.what(), "retained error")) throw std::runtime_error("future rethrew another error");
+        }
+    }
+    if (count != 1) throw std::runtime_error("future result destroyed its exception an incorrect number of times");
+}
+
 int main() {
     TestTypeInfoVtables();
     testExceptionPointer();
+    testFutureException();
     try {
         Rethrow();
         return 1;