[Bug c++/80045] New: [cilkplus] The destruction of the temporary variable is not in the child

[ryxi at stu dot xidian.edu.cn]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80045

            Bug ID: 80045
           Summary: [cilkplus] The destruction of the temporary variable
                    is not in the child
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ryxi at stu dot xidian.edu.cn
  Target Milestone: ---

The cilkplus spec
<https://www.cilkplus.org/sites/default/files/open_specifications/Intel_Cilk_plus_lang_spec_1.2.htm>
said:

[3.6] bullet [4]:
> Any unnamed temporary variables created prior to the spawn point are
> not destroyed until after the spawn point (i.e., their destructors are
> invoked in the child).

However currently GCC produces code that destroy the temporary in the
parent. Then following code fails with random SIGSEGVs:

~~~
#include <vector>
#include <cilk/cilk.h>

void walk(std::vector<int> v, unsigned size) {
  if (v.size() < size)
    for (int i=0; i<8; i++) {
      std::vector<int> vnew(v);
      vnew.push_back(i);
      cilk_spawn walk(vnew, size);
    }
}

int main(int argc, char **argv) {
  std::vector<int> v{};
  walk(v, 5);
}
~~~

While the thread sanitizer reports many data races about destroying
temporaries.