dist_object<T>.fetch isn't a constant function

[Alexander Ding]

Shouldn’t the fetch function be a constant function given that it is only reading?

int get(dist_object<int> v, int rank) const {
  return v.fetch(rank).wait();
}

doesn’t actually work as fetch isn’t constant.

[Dan Bonachea]

Thanks for the report - you've correctly identified a bug. This function is specified as const, but the implementation is non-conforming.

Note your example program is ill-formed for two reasons - the const qualifier cannot appear on a free function, and dist_object is not CopyConstructible, so it cannot be passed to a function by value (only by reference or pointer).

Here is a complete reproducer:

#include <upcxx/upcxx.hpp>
#include <iostream>

struct foo {
  upcxx::dist_object<int> v;
  int get(int rank) const {
    return v.fetch(rank).wait();
  }
};


int main() {
  upcxx::init();

  const foo f{4};
  int x = f.get(0);

  upcxx::finalize();
  return 0;
}

[Dan Bonachea]

Proposed fix in pull request #90, which can also be used to patch your copy of UPC++.

[Dan Bonachea]

Fix issue 224: missing const qualifier on dist_object<T>.fetch()

→ <<cset ea7b3efeabe0>>

[Dan Bonachea]

Merge pull request #90 into develop

• fetch-const: issue 224: Add test and update ChangeLog Fix issue 224: missing const qualifier on dist_object<T>.fetch()

→ <<cset 2ef844170b93>>