Auto-pythonization of func returning tuple fails

[Axel-Naumann]

Check duplicate issues.

• Checked for duplicates

Description

python3
Python 3.12.3 (main, Sep 11 2024, 14:17:37) [GCC 13.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import ROOT
>>> ROOT.gInterpreter.ProcessLine('#include "tpl.cxx"')
0
>>> ROOT.fund()
input_line_40:3:14: error: no matching constructor for initialization of 'tuple<vector<int>, vector<string> >' (aka 'tuple<vector<int>,
      vector<basic_string<char> > >')
  self = new tuple<vector<int>,vector<string> >{_1, _0};
             ^                                 ~~~~~~~~
/usr/include/c++/13/tuple:1460:2: note: candidate constructor template not viable: no known conversion from 'const std::vector<string>' (aka
      'const vector<basic_string<char> >') to 'allocator_arg_t' for 1st argument
        tuple(allocator_arg_t __tag, const _Alloc& __a)
        ^     ~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/tuple:1331:2: note: candidate constructor template not viable: no known conversion from 'const vector<string,
      allocator<std::basic_string<char>>>' to 'const vector<int, allocator<int>>' for 1st argument
        tuple(const _T1& __a1, const _T2& __a2)
        ^     ~~~~~~~~~~~~~~~
/usr/include/c++/13/tuple:1338:2: note: candidate template ignored: requirement '_TupleConstraints<true, std::vector<int, std::allocator<int> >,
      std::vector<std::basic_string<char, std::char_traits<char>, std::allocator<char> >,
      std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > >
      >::__is_explicitly_constructible()' was not satisfied [with _Dummy = true]
        tuple(const _T1& __a1, const _T2& __a2)
        ^
/usr/include/c++/13/tuple:1345:2: note: candidate template ignored: requirement '_TupleConstraints<true, std::vector<int, std::allocator<int> >,
      std::vector<std::basic_string<char, std::char_traits<char>, std::allocator<char> >,
      std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > >
      >::__is_implicitly_constructible()' was not satisfied [with _U1 = const std::vector<string> &, _U2 = const
      std::vector<int> &]
        tuple(_U1&& __a1, _U2&& __a2)
        ^
/usr/include/c++/13/tuple:1352:2: note: candidate template ignored: requirement '_TupleConstraints<true, std::vector<int, std::allocator<int> >,
      std::vector<std::basic_string<char, std::char_traits<char>, std::allocator<char> >,
      std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > >
      >::__is_explicitly_constructible()' was not satisfied [with _U1 = const std::vector<string> &, _U2 = const
      std::vector<int> &]
        tuple(_U1&& __a1, _U2&& __a2)
        ^
/usr/include/c++/13/tuple:1467:2: note: candidate template ignored: requirement '_TupleConstraints<true, std::vector<int, std::allocator<int> >,
      std::vector<std::basic_string<char, std::char_traits<char>, std::allocator<char> >,
      std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > >
      >::__is_explicitly_default_constructible()' was not satisfied [with _Alloc = std::vector<int>]
        tuple(allocator_arg_t __tag, const _Alloc& __a)
        ^
/usr/include/c++/13/tuple:1356:17: note: candidate constructor not viable: requires 1 argument, but 2 were provided
      constexpr tuple(const tuple&) = default;
                ^     ~~~~~~~~~~~~
/usr/include/c++/13/tuple:1358:17: note: candidate constructor not viable: requires 1 argument, but 2 were provided
      constexpr tuple(tuple&&) = default;
                ^     ~~~~~~~
/usr/include/c++/13/tuple:1363:2: note: candidate constructor template not viable: requires single argument '__in', but 2 arguments were provided
        tuple(const tuple<_U1, _U2>& __in)
        ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/tuple:1370:2: note: candidate constructor template not viable: requires single argument '__in', but 2 arguments were provided
        tuple(const tuple<_U1, _U2>& __in)
        ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/tuple:1377:2: note: candidate constructor template not viable: requires single argument '__in', but 2 arguments were provided
        tuple(tuple<_U1, _U2>&& __in)
        ^     ~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/tuple:1384:2: note: candidate constructor template not viable: requires single argument '__in', but 2 arguments were provided
        tuple(tuple<_U1, _U2>&& __in)
        ^     ~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/tuple:1409:2: note: candidate constructor template not viable: requires single argument '__in', but 2 arguments were provided
        tuple(const pair<_U1, _U2>& __in)
        ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/tuple:1416:2: note: candidate constructor template not viable: requires single argument '__in', but 2 arguments were provided
        tuple(const pair<_U1, _U2>& __in)
        ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/tuple:1423:2: note: candidate constructor template not viable: requires single argument '__in', but 2 arguments were provided
        tuple(pair<_U1, _U2>&& __in)
        ^     ~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/tuple:1431:2: note: candidate constructor template not viable: requires single argument '__in', but 2 arguments were provided
        tuple(pair<_U1, _U2>&& __in)
        ^     ~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/tuple:1503:2: note: candidate constructor template not viable: requires 3 arguments, but 2 were provided
        tuple(allocator_arg_t __tag, const _Alloc& __a, const tuple& __in)
        ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/tuple:1508:2: note: candidate constructor template not viable: requires 3 arguments, but 2 were provided
        tuple(allocator_arg_t __tag, const _Alloc& __a, tuple&& __in)
        ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/tuple:1514:2: note: candidate constructor template not viable: requires 3 arguments, but 2 were provided
        tuple(allocator_arg_t __tag, const _Alloc& __a,
        ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/tuple:1524:2: note: candidate constructor template not viable: requires 3 arguments, but 2 were provided
        tuple(allocator_arg_t __tag, const _Alloc& __a,
        ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/tuple:1533:2: note: candidate constructor template not viable: requires 3 arguments, but 2 were provided
        tuple(allocator_arg_t __tag, const _Alloc& __a, tuple<_U1, _U2>&& __in)
        ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/tuple:1541:2: note: candidate constructor template not viable: requires 3 arguments, but 2 were provided
        tuple(allocator_arg_t __tag, const _Alloc& __a, tuple<_U1, _U2>&& __in)
        ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/tuple:1570:2: note: candidate constructor template not viable: requires 3 arguments, but 2 were provided
        tuple(allocator_arg_t __tag, const _Alloc& __a,
        ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/tuple:1578:2: note: candidate constructor template not viable: requires 3 arguments, but 2 were provided
        tuple(allocator_arg_t __tag, const _Alloc& __a,
        ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/tuple:1585:2: note: candidate constructor template not viable: requires 3 arguments, but 2 were provided
        tuple(allocator_arg_t __tag, const _Alloc& __a, pair<_U1, _U2>&& __in)
        ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/tuple:1593:2: note: candidate constructor template not viable: requires 3 arguments, but 2 were provided
        tuple(allocator_arg_t __tag, const _Alloc& __a, pair<_U1, _U2>&& __in)
        ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/tuple:1317:2: note: candidate constructor template not viable: requires 0 arguments, but 2 were provided
        tuple()
        ^
/usr/include/c++/13/tuple:1324:2: note: candidate constructor template not viable: requires 0 arguments, but 2 were provided
        tuple()
        ^
/usr/include/c++/13/tuple:1473:2: note: candidate constructor template not viable: requires 4 arguments, but 2 were provided
        tuple(allocator_arg_t __tag, const _Alloc& __a,
        ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/tuple:1481:2: note: candidate constructor template not viable: requires 4 arguments, but 2 were provided
        tuple(allocator_arg_t __tag, const _Alloc& __a,
        ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/tuple:1488:2: note: candidate constructor template not viable: requires 4 arguments, but 2 were provided
        tuple(allocator_arg_t __tag, const _Alloc& __a, _U1&& __a1, _U2&& __a2)
        ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/tuple:1496:2: note: candidate constructor template not viable: requires 4 arguments, but 2 were provided
        tuple(allocator_arg_t __tag, const _Alloc& __a,
        ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<cppyy.gbl.tuple<vector<int>,vector<string> > object at 0x71d97e0>
>>> 

Reproducer

// tpl.cxx
#include <string>
#include <tuple>
#include <vector>

std::tuple<std::vector<int>, std::vector<std::string>>
fund() {
    std::vector<int> a = {1, 2, 3};
    std::vector<std::string> b = {"a", "b", "c"};
    return std::tuple<std::vector<int>, std::vector<std::string>>(std::move(a), std::move(b));
}

ROOT version

master

Installation method

source

Operating system

Ubuntu 24.04

Additional context

No response

[guitargeek]

Thanks for the report! It is fixed by this PR:
#16548

[guitargeek]

Not associating to any ROOT release because this was a temporary error in master

[guitargeek]

In general, std::tuple in very impractical in PyROOT, because it's implicitly replaced by TEmulatedTuple... I'll rewrite our code to not use it.