https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87372
--- Comment #2 from eric-bugs at omnifarious dot org ---
Also, this works in clang 6.0 (with --std=c++17), but not gcc 8.2:
--------
#include <array>
constexpr int ce_strlen(char const *s)
{
int i = 0;
while (s[i]) ++i;
return i;
}
template <int len>
constexpr auto as_array(char const *s)
{
::std::array<char, len + 1> output{};
for (int i = 0; i < len; ++i) {
output[i] = s[i];
}
output[output.size() - 1] = '\0';
return output;
}
template <unsigned long s1, unsigned long s2>
constexpr auto paste_array(::std::array<char, s1> a, ::std::array<char, s2> b)
{
constexpr unsigned long tlen = s1 + s2 - 1;
::std::array<char, tlen> output{};
int o = 0;
for (unsigned long i = 0; i < s1; ++i, ++o) {
output[o] = a[i];
}
--o;
for (unsigned long i = 0; i < s2; ++i, ++o) {
output[o] = b[i];
}
return output;
}
#define stringify(x) #x
#define evstringify(x) stringify(x)
char const * joe()
{
constexpr static auto mystr =
paste_array(paste_array(as_array<ce_strlen(__PRETTY_FUNCTION__)>(__PRETTY_FUNCTION__),
as_array<sizeof(" at line ") - 1>(" at line ")),
as_array<ce_strlen(evstringify(__LINE__))>(evstringify(__LINE__)));
return mystr.data();
}
