"Changes of default constructor" build failure(s) — clang 11.0.0

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
canu 2.0+dfsg-1overlapAlign/clearRangeFile.C:29:38: error: addition of default argument on redeclaration makes this constructor a default constructor Log
gtkguitune 0.8-6lcdview.cc:26:31: error: addition of default argument on redeclaration makes this constructor a default constructor Log
libgdf 0.1.3-4TagHeader.cpp:188:31: error: addition of default argument on redeclaration makes this constructor a default constructor Log 751540

3 errors