TAxis constructor from bin edges silently accepts the same edges in the list

[VanyaBelyaev]

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Description

TAxis constructor from the bin-edges "allows" the same edges in the list:

import ROOT
axis1 = ROOT.TAxis ( [1,2] )  ## OK 
axis2 = ROOT.TAxis ( [2,1] ) ## properly fails: it is OK   
axis3 = ROOT.TAxis ( [1,1] ) ## silently acceptd, but  it is *NOT* OK  

The issue comes from TAxis::Set method, that must checks that edges
are in increasing order, but indeed it checks that the order is non-decreasing:

from TAxis.cxx , see line 803

  795void TAxis::Set(Int_t nbins, const Float_t *xbins)
  796{
  797   Int_t bin;
  798   fNbins  = nbins;
  799   fXbins.Set(fNbins+1);
  800   for (bin=0; bin<= fNbins; bin++)
  801      fXbins.fArray[bin] = xbins[bin];
  802   for (bin=1; bin<= fNbins; bin++)
  803      if (fXbins.fArray[bin] < fXbins.fArray[bin-1])
  804         Error("TAxis::Set", "bins must be in increasing order");
  805   fXmin      = fXbins.fArray[0];
  806   fXmax      = fXbins.fArray[fNbins];
  807   if (!fParent) SetDefaults();
  808}
  809 

There should be <= instead of < at line 803
And the same for TAXis::Set method with const Double_t* argument

Reproducer

Reproducer is trivial:

import ROOT
axis1 = ROOT.TAxis ( [1,2] )  ## OK 
axis2 = ROOT.TAxis ( [2,1] ) ## properly fails, it is OK  
axis3 = ROOT.TAxis ( [1,1] ) ## silently accepts, but it is not OK  

ROOT version

I think it is a very ancient code and the problem should be there for all versions of ROOT...

I am working with LCG cvmfs nightlies dev3 slot

Installation method

LCG cvmfs nightlies dev3

Operating system

Linux, el9, lxplus

Additional context

I think it is a very ancient code and the problem should be there for all versions of ROOT...