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From: "nickhuang99 at hotmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/104255] parsing trailing return type fails with parameter
 pack expansion when two parameter packs at present
Date: Thu, 27 Jan 2022 20:49:31 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104255

--- Comment #1 from qingzhe huang <nickhuang99 at hotmail dot com> ---
Just a FYI, this version is a bit simplified from this original code.
(https://www.godbolt.org/z/n7ajzr46f) because this is an actual meaningful
function to reverse a given index_sequence. You can see if trailing return =
type
works, it doesn't need to define the function body so that the template
function works exactly like a meta function.


template<size_t...Indexes, size_t...Numbers>
auto get_reverse_sequence_helper(index_sequence<Indexes...>indexes,=20
            index_sequence<Numbers...>numbers)
// If this trailing return type is OK, we don't need actually define=20
// function body.
->index_sequence< (getSeqByIndex<Indexes, Numbers...>(numbers))... >
{
    return index_sequence< (getSeqByIndex<Indexes, Numbers...>(numbers))...
>{};
}=