Definitions of "l_copyOffsets" and "l_ghostOffsets" in LtsLayout.cpp

[Aangniu]

Describe the bug
In collecting the offsets to the beginning of the array of lts->cellLocalInformation, the ghost cluster sizes seem to be mixed up with copy cluster sizes. They are located here:
https://github.com/SeisSol/SeisSol/blob/master/src/Initializer/time_stepping/LtsLayout.cpp#L1255
https://github.com/SeisSol/SeisSol/blob/master/src/Initializer/time_stepping/LtsLayout.cpp#L1251

Expected behavior
The suggested changes are following

// ghost region offsets offsets relative to the absolute start of the lts setup
std::vector< std::vector< unsigned int > > l_ghostOffsets;
l_ghostOffsets.resize( m_clusteredGhost.size() );

// copy region offsets offsets relative to the absolute start of the lts setup
std::vector< std::vector< unsigned int > > l_copyOffsets;
l_copyOffsets.resize( m_clusteredCopy.size() );

Additional context
This change may not influence the behavior of the code very much, if any.

[davschneller]

The two layers should have the same size: for each copy cell, we have a ghost cell and vice-versa, since the facet between them is shared between (exactly) two ranks.

Cf. also here: https://github.com/SeisSol/SeisSol/blob/master/src/Initializer/time_stepping/LtsLayout.cpp#L1044

That line is called before the getCellInformation.

[krenzland]

Yup, should - it's still pretty unclear code IMO