[Bug c++/77375] New: constant object with mutable subobject allocated in read-only memory

["Casey at Carter dot net" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77375

            Bug ID: 77375
           Summary: constant object with mutable subobject allocated in
                    read-only memory
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: Casey at Carter dot net
  Target Milestone: ---

When run, this program results in a segmentation fault:

struct Base {
    mutable int i;
};

struct Derived : Base {};

const Derived foo{};

int main() { foo.i = 42; }

Despite its mutable subobject, the compiler allocates foo in read-only memory.