no match for ‘operator==’

[thiagotps]

Hi everyone. The following code

#include <bits/stdc++.h>
#include <symengine/expression.h>
#include <symengine/functions.h>
#include <symengine/symbol.h>
#include <symengine/add.h>
#include <symengine/mul.h>

using namespace SymEngine;
using namespace std;




int main() {
  const RCP<const Basic> i1 = integer(10);
  const RCP<const Basic> i2 = i1;

  assert(i1 == i2);
  return 0;
}

results in the error:

/home/thiago/research/lmscpp/sym.cpp:18:13: error: no match for ‘operator==’ (operand types are ‘const SymEngine::RCP<const SymEngine::Basic>’ and ‘const SymEngine::RCP<const SymEngine::Basic>’)

The following code compiles fine:

#include <bits/stdc++.h>
#include <symengine/expression.h>
#include <symengine/functions.h>
#include <symengine/symbol.h>
#include <symengine/add.h>
#include <symengine/mul.h>

using namespace SymEngine;
using namespace std;

int main() {
  RCP<const Basic> i1 = integer(10);
  RCP<const Basic> i2 = i1;

  assert(i1 == i2);
  return 0;
}

I think the cause for this is the lack of a const in the end of bool operator==(const RCP<T2> &p2) in line 172, file symengine_rcp.h:

    template <class T2>
    bool operator==(const RCP<T2> &p2)
    {
        return ptr_ == p2.ptr_;
    }

That is, i think it should be:

    template <class T2>
    bool operator==(const RCP<T2> &p2) const
    {
        return ptr_ == p2.ptr_;
    }

Is this a bug ? Or its me using RCP wrongly ? Thanks in advance.

[isuruf]

Yes, it should be marked const. Btw, == will compare pointer equality and not that the two objects are equal. i.e. i1 == integer(10) will return False as they are two different Integer objects with the same value 10. You should use eq(*i1, *i2) if you want to check that the objects are equal.

[naveensaigit]

Yes, it should be marked const.

Is this change required? I can add it

[lkeegan]

fixed in #1756