"Changes of default constructor" build failure(s) — clang 12.0.1

This code is a defect of the C++ standard:
http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1344
class foo {
    int a;
    foo(int);
};

foo::foo(int c = 5) : a(c) {

}

PackageVersionSupposed error messageFull log Bug report
gtkguitune 0.8-6lcdview.cc:26:31: error: addition of default argument on redeclaration makes this constructor a default constructor Log

1 errors