From c5a5efa9d20413bdd252746ba72b6d17df893af8 Mon Sep 17 00:00:00 2001
From: "A. Jiang" <de34@live.cn>
Date: Sat, 29 Apr 2023 03:49:41 +0800
Subject: [PATCH] `<optional>`: Fix exception specification for `optional`'s
 transform-construction (#3668)

Co-authored-by: S. B. Tam <cpplearner@outlook.com>
Co-authored-by: Stephan T. Lavavej <stl@nuwen.net>
---
 stl/inc/optional                              |  6 +++---
 .../test.cpp                                  | 21 +++++++++++++++++++
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/stl/inc/optional b/stl/inc/optional
index 093cbb659b..6767863110 100644
--- a/stl/inc/optional
+++ b/stl/inc/optional
@@ -85,7 +85,7 @@ struct _Optional_destruct_base { // either contains a value of _Ty or is empty (
 #if _HAS_CXX23
     template <class _Fn, class _Ux>
     constexpr _Optional_destruct_base(_Construct_from_invoke_result_tag, _Fn&& _Func, _Ux&& _Arg) noexcept(
-        is_nothrow_constructible_v<_Ty, invoke_result_t<_Fn, _Ux>>)
+        noexcept(static_cast<_Ty>(_STD invoke(_STD forward<_Fn>(_Func), _STD forward<_Ux>(_Arg)))))
         : _Value(_STD invoke(_STD forward<_Fn>(_Func), _STD forward<_Ux>(_Arg))), _Has_value{true} {}
 #endif // _HAS_CXX23
 
@@ -118,7 +118,7 @@ struct _Optional_destruct_base<_Ty, false> { // either contains a value of _Ty o
 #if _HAS_CXX23
     template <class _Fn, class _Ux>
     constexpr _Optional_destruct_base(_Construct_from_invoke_result_tag, _Fn&& _Func, _Ux&& _Arg) noexcept(
-        is_nothrow_constructible_v<_Ty, invoke_result_t<_Fn, _Ux>>)
+        noexcept(static_cast<_Ty>(_STD invoke(_STD forward<_Fn>(_Func), _STD forward<_Ux>(_Arg)))))
         : _Value(_STD invoke(_STD forward<_Fn>(_Func), _STD forward<_Ux>(_Arg))), _Has_value{true} {}
 #endif // _HAS_CXX23
 
@@ -277,7 +277,7 @@ public:
 #if _HAS_CXX23
     template <class _Fn, class _Ux>
     constexpr optional(_Construct_from_invoke_result_tag _Tag, _Fn&& _Func, _Ux&& _Arg) noexcept(
-        is_nothrow_constructible_v<_Ty, invoke_result_t<_Fn, _Ux>>)
+        noexcept(static_cast<_Ty>(_STD invoke(_STD forward<_Fn>(_Func), _STD forward<_Ux>(_Arg)))))
         : _Mybase(_Tag, _STD forward<_Fn>(_Func), _STD forward<_Ux>(_Arg)) {}
 #endif // _HAS_CXX23
 
diff --git a/tests/std/tests/P0798R8_monadic_operations_for_std_optional/test.cpp b/tests/std/tests/P0798R8_monadic_operations_for_std_optional/test.cpp
index b19a121e5d..f0d38acfa0 100644
--- a/tests/std/tests/P0798R8_monadic_operations_for_std_optional/test.cpp
+++ b/tests/std/tests/P0798R8_monadic_operations_for_std_optional/test.cpp
@@ -2,7 +2,9 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 #include <cassert>
+#include <exception>
 #include <optional>
+#include <string>
 #include <type_traits>
 #include <utility>
 
@@ -109,7 +111,26 @@ constexpr bool test() {
     return true;
 }
 
+template <class T>
+void test_gh_3667() {
+    // GH-3667 <optional>: Throwing transformers will cause the program to terminate
+    class unique_exception : public exception {};
+
+    try {
+        optional<T> opt(in_place);
+        opt.transform([](const T&) -> T { throw unique_exception{}; });
+    } catch (const unique_exception&) {
+        return;
+    } catch (...) {
+        assert(false); // shouldn't terminate or reach here
+    }
+    assert(false); // shouldn't terminate or reach here
+}
+
 int main() {
     test();
     static_assert(test());
+
+    test_gh_3667<int>(); // trivial destructor
+    test_gh_3667<string>(); // non-trivial destructor
 }