[Bug c++/83802] New: Caller doesn't destroy default argument passed to a constructor

[pdziepak at quarnos dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83802

            Bug ID: 83802
           Summary: Caller doesn't destroy default argument passed to a
                    constructor
           Product: gcc
           Version: 7.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pdziepak at quarnos dot org
  Target Milestone: ---

Godbolt link: https://godbolt.org/g/fBbYgF

When the following code is compiled with -std=c++17:

struct foo {
    ~foo();
};
extern foo f;

struct bar {
    bar(int, foo = f);
};

void fn()
{
    bar b(0);
}

...the destructor of the copy of f passed to the bar's constructor is never
called:

fn():
  pushq %rbp
  movq %rsp, %rbp
  subq $16, %rsp
  leaq -1(%rbp), %rdx
  leaq -2(%rbp), %rax
  movl $0, %esi
  movq %rax, %rdi
  call bar::bar(int, foo)
  nop
  leave
  ret