https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94511
Bug ID: 94511
Summary: User-defined type in non-type template parameter
yields an incorrect value
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: pacoarjonilla at yahoo dot es
Target Milestone: ---
g++ --std=c++2a code.cc && ./a.out
The following snippet misbehaves with GCC9 and GCC10 master
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
#include <cstddef>
#include <iostream>
struct A {
std::byte data [6] {static_cast<std::byte>(0x00)};
constexpr A(char ch) {
data[ch/8] |= static_cast<std::byte>(0x01 << (ch % 8));
}
};
template <A chars> struct B { char ch; };
void print(A a) {
for (int i = 0; i < 6; i++)
std::cout << (unsigned)a.data[i] << ' ';
std::cout << std::endl;
}
using Bn = B<{'\n'}>; // XXX Replacing \n by any other character less than 48
corrects the issue XXX
using Ba = B<{'.'}>;
template <A T> void foo () {
print(T);
}
int main() {
foo<'*'>(); // XXX Replacing the * also corrects the issue XXX
print(A{'*'});
}
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
Expected output
0 0 0 0 0 4
0 0 0 0 0 4
Actual output
0 4 0 0 0 0
0 0 0 0 0 4
