instant appears to incorrectly identify a function signature

[Patrick Farrell]

I have a function

void snes_execute_linesearch(SNES snes, Vec X, Vec F, PetscReal *fnorm, Vec Y)

that I'd like to wrap with instant. I've had good success in using instant for similar tasks of wrapping PETSc before.

The code compiles successfully. But when I try to call it, it gives me

snes_execute_linesearch(snes, x, f, fnorm, y)

Traceback (most recent call last):
  File "x.py", line 51, in <module>
    snes_execute_linesearch(snes, x, f, fnorm, y)
TypeError: snes_execute_linesearch expected 4 arguments, got 5

Even though the function actually takes 5 arguments, instant seems to think that it should only take 4.

Full code to reproduce:

import instant
import petsc4py
from petsc4py import PETSc
import os

include_dirs = [os.path.join(os.getenv('PETSC_DIR'), 'include'),
                os.path.join(os.getenv('PETSC_DIR'), os.getenv('PETSC_ARCH'), 'include'),
                petsc4py.get_include(),
                # May need to add extras here depending on your environment
                '/usr/lib/openmpi/include', '/usr/lib/openmpi/include/openmpi',
                ]
swig_include_dirs = [petsc4py.get_include()]
library_dirs = [os.path.join(os.getenv('PETSC_DIR'), os.getenv('PETSC_ARCH'), 'lib')]
libraries = ['petsc']

snes_execute_linesearch_cpp_code = r"""
#ifdef SWIG
%include "petsc4py/petsc4py.i"
#endif

#include <petsc.h>

int snes_execute_linesearch(SNES snes, Vec X, Vec F, PetscReal *fnorm, Vec Y)
{
    SNESLineSearch linesearch;
    PetscErrorCode ierr;

    ierr = SNESGetLineSearch(snes, &linesearch);CHKERRQ(ierr);
    ierr = SNESLineSearchSetType(linesearch, SNESLINESEARCHBASIC);CHKERRQ(ierr);
    ierr = SNESLineSearchSetFromOptions(linesearch);CHKERRQ(ierr);
    ierr = SNESLineSearchSetUp(linesearch);CHKERRQ(ierr);

    ierr = SNESLineSearchApply(linesearch, X, F, fnorm, Y);CHKERRQ(ierr);
    return 0;
}
"""

snes_execute_linesearch =  instant.build_module(code=snes_execute_linesearch_cpp_code,
                                              include_dirs=include_dirs,
                                              library_dirs=library_dirs,
                                              libraries=libraries,
                                              swig_include_dirs=swig_include_dirs).snes_execute_linesearch
del snes_execute_linesearch_cpp_code

snes = PETSc.SNES().create()
x = PETSc.Vec().createSeq(10)
y = x.duplicate()
f = x.duplicate()
fnorm = 0.0

snes_execute_linesearch(snes, x, f, fnorm, y)

[Johan Hake]

This is not instant per se. Most probably does petsc4py.i provide an argout typemap for PetscReal*, which means it think it is a return argument. Try changing the interface to:

int snes_execute_linesearch(SNES snes, Vec X, Vec F, PetscReal fnorm, Vec Y)
..
ierr = SNESLineSearchApply(linesearch, X, F, &fnorm, Y);CHKERRQ(ierr);

This will result in a segfault when run, but that happens inside SNESLineSearchSetUp and instant should not be blamed.

[Johan Hake]

Not an instant bug