https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99831
--- Comment #4 from 康桓瑋 <hewillk at gmail dot com> ---
When the array subscript is outside the bounds of array, gcc seems to fall into
infinite recursion due to the default operator==.
Here is the reduced with no header:
struct A {
constexpr A(const char*) {}
char value[1] = {};
};
template <A>
struct B {
constexpr bool operator==(const B&) const = default;
};
constexpr auto foo(auto) {
constexpr auto a = [] {
char value[1];
value[2] = 0; // this line
return A{value};
}();
return B<a>{};
}
constexpr auto b = foo(B<"">{});
<source>: In instantiation of 'struct B<<expression error> >':
<source>:8:18: recursively required from 'struct B<<expression error> >'
<source>:8:18: required from 'struct B<<expression error> >'
<source>:17:15: required from 'constexpr auto foo(auto:1) [with auto:1 =
B<A{""}>]'
<source>:20:23: required from here
<source>:8:18: fatal error: template instantiation depth exceeds maximum of 900
(use '-ftemplate-depth=' to increase the maximum)
8 | constexpr bool operator==(const B&) const = default;
| ^~~~~~~~
compilation terminated.
