[Bug libstdc++/120235] New: std::fabs(const std::complex&) should not be defined

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120235

            Bug ID: 120235
           Summary: std::fabs(const std::complex<T>&) should not be
                    defined
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Keywords: accepts-invalid
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redi at gcc dot gnu.org
  Target Milestone: ---

TR1 defined std::tr1::fabs (8.1.8 [tr.c99.cmplx.fabs]) but this is not present
in the C++ standard. We should not define it in <complex>:

  template<typename _Tp>
    inline _Tp
    /// fabs(__z) [8.1.8].
    //  Effects:  Behaves the same as C99 function cabs, defined
    //            in subclause 7.3.8.1.
    fabs(const std::complex<_Tp>& __z)
    { return std::abs(__z); }


This should not compile:

#include <complex>
auto x = std::fabs(std::complex<double>{});