[Bug c++/103827] function which takes an argument via (hidden) reference should assume the argument does not escape or is only read from

[hubicka at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103827

--- Comment #11 from Jan Hubicka <hubicka at gcc dot gnu.org> ---
I see, I misread Jonathan's answer.  If const is relevant only on definition,
what about this one:

#include <cstdio>
struct foo
{
  int a;
  void bar() const;
  ~foo()
  {
    if (a != 42)
      printf ("optimize me away");
  }
};
__attribute__ ((noinline))
void test(const struct foo a)
{
        a.bar();
}
int main()
{
        test({42});
        return 0;
}

Here we assume that call to bar may modify the object (since const is
irrelevant) but it is declared const inside test definition, which may be
relevant?