https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108736
Bug ID: 108736
Summary: pconcepts] multidimensional subscript operator reports
invalid error in requires test
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: ldalessandro at gmail dot com
Target Milestone: ---
The following code produces an error when evaluating the concept.
auto foo(auto a, auto... i) -> decltype(auto) {
if constexpr (requires { a[i...]; }) {
return a[i...];
}
else {
return a;
}
}
int x = foo(1);
> <source>: In instantiation of 'decltype(auto) foo(auto:1, auto:2 ...) [with
> auto:1 = int; auto:2 = {}]':
> <source>:10:12: required from here
> <source>:2:31: error: built-in subscript operator without expression list
> 2 | if constexpr (requires { a[i...]; }) {
> | ~^
> Compiler returned: 1
Workaround: specialize on sizeof...(i) to avoid this test when i... is empty.
Live example: https://godbolt.org/z/K3oezd1qz
