[petsc-dev] C++ and hypre long long int vs PETSc int64_t for 64 bit integer builds

[Stefano Zampini]

This is what we currently have in PETSc, we check for sizeof and cast

Il giorno mer 13 apr 2022 alle ore 17:13 Jed Brown <jed at jedbrown.org> ha
scritto:

> C/C++ integer hierarchy was a mistake, with the language-specified types
> overlapping and the size-specific (int64_t) being typedefs. So long is
> "different" from long long even if they're both 64-bit signed integers.
>
> I think they should test that sizeof(HYPRE_Int) == sizeof(PetscInt), but
> not that they're "the same". They might still need some casts depending on
> usage.
>
> Barry Smith <bsmith at petsc.dev> writes:
>
> > For 64 bit integer builds  AMReX has this test in their code
> >
> > CMakeFiles/amrex.dir/F_Interfaces/Base/AMReX_multifab_mod.F90.o
> >
> /lcrc/project/PhloughToolz/petsc/petsc-3.17.0_oneAPI_2021.4.0.3422/externalpackages/git.amrex/Src/Extern/PETSc/AMReX_PETSc.cpp(44):
> error: static assertion failed with "HYPRE_Int != PetscInt"
> >       static_assert(std::is_same<HYPRE_Int, PetscInt>::value, "HYPRE_Int
> != PetscInt");
> >
> >  Currently, hypre uses long lont int for 64 bit integers, PETSc
> depending on what MPI and integer types are available uses int64_t but may
> fall back to long long int.
> >
> >   This means depending on configuration information the PETSc built
> hypre and PETSc may or may not be compatible by the AMReX tests for C++
> code.
> >
> >  What is the correct general fix for this three-body problem?
> >
> >    Will the C++ code in AMReX, which presumably is
> template-and-polymorphic-method-city, fail if the long long int and int64_t
> are mixed and treated as the same (that is one just removes the is_same()
> check)? Clearly, the easiest fix
> >
> >    Do HYPRE and PETSc configure need to have command-line options to
> allow controlling exactly the type used to ensure matching?
> >
> >    Something else?
> >
> >   Barry
>


-- 
Stefano
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