The following patch makes std::exception_ptr_cast constexpr.
The paper suggests using dynamic_cast, but that does only work for
polymorphic exceptions, doesn't work if they are scalar or non-polymorphic
classes.
Furthermore, the patch adds some static_asserts for
"Mandates: E is a cv-unqualified complete object type. E is not an array type.
E is not a pointer or pointer-to-member type."
2025-07-11 Jakub Jelinek <jakub@redhat.com>
* libsupc++/exception_ptr.h: Implement C++26 P3748R0 - Inspecting
exception_ptr should be constexpr.
(std::exception_ptr_cast): Make constexpr, remove inline keyword. Add
static_asserts for Mandates. For if consteval use std::rethrow_exception,
catch it and return its address or nullptr.
* testsuite/18_support/exception_ptr/exception_ptr_cast.cc (E::~E): Add
constexpr.
(G::G): Likewise.
(test01): Likewise. Return bool and take bool argument, throw if the
argument is true. Add static_assert(test01(false)).
(main): Call test01(true) in try.
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