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Check for error from cellsToLinkedMultiPolygon; add test #477

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Merged
ajfriend merged 1 commit into from
Jan 29, 2026
Merged

Check for error from cellsToLinkedMultiPolygon; add test #477

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5 changes: 4 additions & 1 deletion src/h3/_cy/to_multipoly.pyx
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
cimport h3lib
from h3lib cimport H3int
from .util cimport check_cell, coord2deg
from .error_system cimport check_for_error


# todo: it's driving me crazy that these three functions are all essentially the same linked list walker...
Expand Down Expand Up @@ -39,7 +40,9 @@ def _to_multi_polygon(const H3int[:] cells):
for h in cells:
check_cell(h)

h3lib.cellsToLinkedMultiPolygon(&cells[0], len(cells), &polygon)
check_for_error(
h3lib.cellsToLinkedMultiPolygon(&cells[0], len(cells), &polygon)
)

out = walk_polys(&polygon)

Expand Down
56 changes: 55 additions & 1 deletion tests/test_lib/polyfill/test_to_multipoly.py
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Original file line number Diff line number Diff line change
@@ -1,5 +1,7 @@
import h3
import pytest

import h3
from h3._cy.error_system import H3FailedError

from .. import util as u

Expand Down Expand Up @@ -47,3 +49,55 @@ def test_2_polys():
cells
)
assert set(map(len, out)) == {1, 12}


def test_cells_to_h3shape_transmeridian_error():
"""
Test for https://github.com/uber/h3-py/issues/476

Cells along the equator and meridian trigger an error in the C library's
normalizeMultiPolygon. Previously this caused a segfault because the error
code wasn't checked. Now it should raise H3FailedError.
"""
cells = [
'81007ffffffffff', '81017ffffffffff', '81033ffffffffff',
'81047ffffffffff', '81057ffffffffff', '81093ffffffffff',
'81097ffffffffff', '8109bffffffffff', '810cbffffffffff',
'810dbffffffffff', '81167ffffffffff', '81177ffffffffff',
'81187ffffffffff', '81197ffffffffff', '81227ffffffffff',
'8132bffffffffff', '8133bffffffffff', '81383ffffffffff',
'8138bffffffffff', '81397ffffffffff', '8147bffffffffff',
'8158bffffffffff', '81593ffffffffff', '8159bffffffffff',
'815abffffffffff', '815bbffffffffff', '815f3ffffffffff',
'81617ffffffffff', '81657ffffffffff', '8166fffffffffff',
'8168bffffffffff', '8168fffffffffff', '816abffffffffff',
'816afffffffffff', '816c7ffffffffff', '816cfffffffffff',
'816f3ffffffffff', '816f7ffffffffff', '816fbffffffffff',
'81707ffffffffff', '8170bffffffffff', '8170fffffffffff',
'8171bffffffffff', '8172bffffffffff', '8172fffffffffff',
'8173bffffffffff', '81743ffffffffff', '8174bffffffffff',
'81753ffffffffff', '81757ffffffffff', '81763ffffffffff',
'81767ffffffffff', '8177bffffffffff', '81783ffffffffff',
'81787ffffffffff', '8179bffffffffff', '817a3ffffffffff',
'817a7ffffffffff', '817bbffffffffff', '817c3ffffffffff',
'817c7ffffffffff', '817cbffffffffff', '817e3ffffffffff',
'817ebffffffffff', '817efffffffffff', '817f7ffffffffff',
'817fbffffffffff', '81807ffffffffff', '8180bffffffffff',
'8180fffffffffff', '81827ffffffffff', '8182bffffffffff',
'8182fffffffffff', '81853ffffffffff', '81857ffffffffff',
'8186bffffffffff', '8186fffffffffff', '8188bffffffffff',
'8188fffffffffff', '818a7ffffffffff', '818afffffffffff',
'818cbffffffffff', '818cfffffffffff', '818f3ffffffffff',
'81933ffffffffff', '81987ffffffffff', '81997ffffffffff',
'819a7ffffffffff', '819b7ffffffffff', '81ac7ffffffffff',
'81ba3ffffffffff', '81bafffffffffff', '81bb3ffffffffff',
'81c07ffffffffff', '81c17ffffffffff', '81d0bffffffffff',
'81d1bffffffffff', '81db3ffffffffff', '81dbbffffffffff',
'81dcbffffffffff', '81ddbffffffffff', '81e67ffffffffff',
'81eabffffffffff', '81eafffffffffff', '81ed7ffffffffff',
'81eebffffffffff', '81efbffffffffff', '81f17ffffffffff',
'81f2bffffffffff', '81f33ffffffffff', '81f3bffffffffff',
]

with pytest.raises(H3FailedError):
h3.cells_to_h3shape(cells)
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