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Fix Python dtpye -> mlx conversion narrowing #4656

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Merged
zcbenz merged 1 commit into from
Oct 9, 2026
Merged

Fix Python dtpye -> mlx conversion narrowing #4656

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8 changes: 6 additions & 2 deletions python/src/convert.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -641,6 +641,10 @@ mx::array array_from_list_impl(
std::vector<uint32_t> vals;
fill_vector(pl, vals);
return mx::array(vals.begin(), shape, dtype);
} else if (dtype == mx::float64) {
std::vector<double> vals;
fill_vector(pl, vals);
return mx::array(vals.begin(), shape, dtype);
} else if (mx::issubdtype(dtype, mx::inexact)) {
std::vector<float> vals;
fill_vector(pl, vals);
Expand All @@ -653,7 +657,7 @@ mx::array array_from_list_impl(
}
case pyfloat: {
auto out_type = specified_type.value_or(mx::float32);
if (out_type == mx::float64) {
if (out_type == mx::float64 || !mx::issubdtype(out_type, mx::inexact)) {
std::vector<double> vals;
fill_vector(pl, vals);
return mx::array(vals.begin(), shape, out_type);
Expand Down Expand Up @@ -748,7 +752,7 @@ mx::array create_array(
return mx::array(val, t.value_or(default_type));
} else if (nb::isinstance<nb::float_>(v)) {
auto out_type = t.value_or(mx::float32);
if (out_type == mx::float64) {
if (out_type == mx::float64 || !mx::issubdtype(out_type, mx::inexact)) {
return mx::array(nb::cast<double>(v), out_type);
} else {
return mx::array(nb::cast<float>(v), out_type);
Expand Down
12 changes: 12 additions & 0 deletions python/tests/test_array.py
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Original file line number Diff line number Diff line change
Expand Up @@ -598,6 +598,18 @@ def test_double_keeps_precision(self):
out = mx.array([x], dtype=mx.float64).item()
self.assertEqual(out, x)

# Integer and bool targets
v = 2**24 + 1
self.assertEqual(mx.array(float(v), dtype=mx.int32).item(), v)
self.assertEqual(mx.array([float(v)], dtype=mx.int64).tolist(), [v])
# Small non-zero values are still True
self.assertTrue(mx.array(1e-50, dtype=mx.bool_).item())
self.assertEqual(mx.array([1e-50], dtype=mx.bool_).tolist(), [True])

# Python ints to float64
out = mx.array([v], dtype=mx.float64).tolist()
self.assertEqual(out, [float(v)])

def test_construction_from_lists_wide_ints(self):
# A python int that does not fit in int32 widens to int64, the same
# rule the scalar path already uses. It used to raise std::bad_cast.
Expand Down
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