https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124600
Bug ID: 124600
Summary: [rejects-valid] pack expansion of function types with
conditional noexcept clauses
Product: gcc
Version: 16.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: eric.niebler at gmail dot com
Target Milestone: ---
clang accepts the following code, gcc rejects it:
template <class... Fns>
struct var_fun_test;
template <class... Ret, class... Arg, bool... Noexcept>
struct var_fun_test<Ret(Arg) noexcept(Noexcept)...>
{};
int main()
{
auto c = var_fun_test<void(int), void(int) noexcept>();
}
error:
<source>:6:43: error: parameter packs not expanded with '...':
6 | struct test<Ret(Arg) noexcept(Noexcept)...>
| ^
<source>:6:43: note: 'Noexcept'
<source>:6:12: error: template parameters not deducible in partial
specialization:
6 | struct test<Ret(Arg) noexcept(Noexcept)...>
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:6:12: note: 'Noexcept'
i think the error about 'Noexcept' not being deducible is a red herring because
gcc gladly accepts the following:
template <class Fn>
struct fun_test;
template <class Ret, class Arg, bool Noexcept>
struct fun_test<Ret(Arg) noexcept(Noexcept)>
{};
int main()
{
auto a = fun_test<void(int)>();
auto b = fun_test<void(int) noexcept>();
}
See: https://godbolt.org/z/czWT9jnPx
