Compile errors in giac with c++ 17

[tobiasdiez]

Steps To Reproduce

Remove the line # distutils: extra_compile_args = -std=c++11 in src\sage\libs\giac\giac.pyx. Then compile (which now uses c++17)

Expected Behavior

Compiles fine

Actual Behavior

``̀
In file included from /Users/runner/miniconda3/envs/sage/include/giac/giac.h:5:
In file included from /Users/runner/miniconda3/envs/sage/include/giac/poly.h:26:
/Users/runner/miniconda3/envs/sage/include/giac/monomial.h:341:10: error: no template named 'pointer_to_binary_function' in namespace 'std'
std::pointer_to_binary_function < const monomial &, const monomial &, bool> strictly_greater ;
~~~~~^
/Users/runner/miniconda3/envs/sage/include/giac/monomial.h:342:28: error: no template named 'pointer_to_binary_function' in namespace 'std'
sort_helper(const std::pointer_to_binary_function < const monomial &, const monomial &, bool> is_strictly_greater):strictly_greater(is_strictly_greater) {};
~~~~~^
/Users/runner/miniconda3/envs/sage/include/giac/monomial.h:343:41: error: no member named 'ptr_fun' in namespace 'std'
sort_helper():strictly_greater(std::ptr_fun<const monomial &, const monomial &, bool>(m_lex_is_strictly_greater)) {};
~~~~~^
/Users/runner/miniconda3/envs/sage/include/giac/monomial.h:343:49: error: expected expression
sort_helper():strictly_greater(std::ptr_fun<const monomial &, const monomial &, bool>(m_lex_is_strictly_greater)) {};
^
/Users/runner/miniconda3/envs/sage/include/giac/monomial.h:343:70: error: expected expression
sort_helper():strictly_greater(std::ptr_fun<const monomial &, const monomial &, bool>(m_lex_is_strictly_greater)) {};
^
/Users/runner/miniconda3/envs/sage/include/giac/monomial.h:343:95: error: expected '(' for function-style cast or type construction
sort_helper():strictly_greater(std::ptr_fun<const monomial &, const monomial &, bool>(m_lex_is_strictly_greater)) {};
~~~~^
/Users/runner/miniconda3/envs/sage/include/giac/monomial.h:680:18: error: no template named 'pointer_to_binary_function' in namespace 'std'
const std::pointer_to_binary_function < const monomial &, const monomial &, bool> m_is_strictly_greater
~~~~~^
/Users/runner/miniconda3/envs/sage/include/giac/monomial.h:729:44: error: no template named 'pointer_to_binary_function' in namespace 'std'
typedef std::map< index_t,T,const std::pointer_to_binary_function < const index_m &, const index_m &, bool> > application;
~~~~~^
/Users/runner/miniconda3/envs/sage/include/giac/monomial.h:730:30: error: no type named 'ptr_fun' in namespace 'std'
application produit(std::ptr_fun(is_strictly_greater));
~~~~~^
/Users/runner/miniconda3/envs/sage/include/giac/monomial.h:737:14: error: 'application' (aka 'int') is not a class, namespace, or enumeration
typename application::iterator prod_it,prod_itend;
^
/Users/runner/miniconda3/envs/sage/include/giac/monomial.h:754:29: error: use of undeclared identifier 'prod_itend'; did you mean 'prod_it'?
prod_it=produit.begin(),prod_itend=produit.end();

### Additional Information

_No response_

### Environment

- **OS**: 
- **Sage Version**: 


### Checklist

- [X] I have searched the existing issues for a bug report that matches the one I want to file, without success.
- [X] I have read the documentation and troubleshoot guide

[user202729]

giac/first.h:

#if __cplusplus >= 201103L
// post-c++11 functional headers changes, thanks to George Huebner
#define CPP11
#endif

giac/monomial.h:

#ifdef CPP11
    std::function<bool(const monomial<T> &, const monomial<T> &)> strictly_greater ;
    sort_helper(const std::function<bool(const monomial<T> &, const monomial<T> &)> is_strictly_greater):strictly_greater(is_strictly_greater) {};
    sort_helper():strictly_greater(m_lex_is_strictly_greater<T>) {};
#else
    std::pointer_to_binary_function < const monomial<T> &, const monomial<T> &, bool> strictly_greater ;
    sort_helper(const std::pointer_to_binary_function < const monomial<T> &, const monomial<T> &, bool> is_strictly_greater):strictly_greater(is_strictly_greater) {};
    sort_helper():strictly_greater(std::ptr_fun<const monomial<T> &, const monomial<T> &, bool>(m_lex_is_strictly_greater<T>)) {};
#endif

In principle, the error cannot happen if everything are configured correctly.

I cannot reproduce the error on my machine (either replacing 11 with 17, or delete the line entirely as you suggested).

(I'm compiling with meson however, which if I recalled correctly might not parse the # distutils file headers, but by enabling --verbose I see it is compiling with C++17 by default.)

Which compiler are you using? Could be MSVC issue ?

Or maybe your version of Giac is too old? (judging by your line number, 342, this seems likely. But where is the header pulled from? Sage's spkg?)