numpy · seberg · Jun 28, 2023 · Jun 28, 2023 · Jun 28, 2023
diff --git a/doc/release/upcoming_changes/24071.compatibility.rst b/doc/release/upcoming_changes/24071.compatibility.rst
@@ -0,0 +1,16 @@
+``NPY_MAXARGS`` and ``NPY_MAXDIMS`` increased
+---------------------------------------------
+``NPY_MAXDIMS`` is now 64 and ``NPY_MAXARGS`` is 128, downstream should
+not run into issues due to this, as these are typically only used for stack
+allocations, such as::
+
+    npy_intp shape[NPY_MAXDIMS];
+
+so that an increase is safe.  It will increase the stack usage a little.
+
+There is however a possible bigger complication if a downstream library uses
+one of these in its public headers.
+The library user and library might compile against different versions of
+NumPy and thus break ABI compatibility.
+In this event the downstream library will have to hard-code the old value or
+itself force downstream to recompile (if viable).
diff --git a/doc/release/upcoming_changes/24071.improvement.rst b/doc/release/upcoming_changes/24071.improvement.rst
@@ -0,0 +1,3 @@
+* Maximu number of dimensions increased to 64
+* The maximum number of operands for some operations such as
+  ``einsum`` was increased to 128 (or close to it).
diff --git a/numpy/core/include/numpy/ndarraytypes.h b/numpy/core/include/numpy/ndarraytypes.h
@@ -36,9 +36,8 @@
  * the places where static allocation is used would need to be changed
  * to dynamic (including inside of several structures)
  */
-
-#define NPY_MAXDIMS 32
-#define NPY_MAXARGS 32
+#define NPY_MAXDIMS 64
+#define NPY_MAXARGS 128
 
 /* Used for Converter Functions "O&" code in ParseTuple */
 #define NPY_FAIL 0

diff --git a/numpy/core/multiarray.pyi b/numpy/core/multiarray.pyi
@@ -120,7 +120,7 @@ BUFSIZE: L[8192]
 CLIP: L[0]
 WRAP: L[1]
 RAISE: L[2]
-MAXDIMS: L[32]
+MAXDIMS: L[64]
 MAY_SHARE_BOUNDS: L[0]
 MAY_SHARE_EXACT: L[-1]
 tracemalloc_domain: L[389047]

diff --git a/numpy/core/tests/test_conversion_utils.py b/numpy/core/tests/test_conversion_utils.py
@@ -203,6 +203,6 @@ def test_too_large(self):
             self.conv(2**64)
 
     def test_too_many_dims(self):
-        assert self.conv([1]*32) == (1,)*32
+        assert self.conv([1]*34) == (1,)*34
         with pytest.raises(ValueError):
-            self.conv([1]*33)
+            self.conv([1]*65)
diff --git a/numpy/core/tests/test_einsum.py b/numpy/core/tests/test_einsum.py
@@ -1,6 +1,7 @@
 import itertools
 import sys
 import platform
+import string
 
 import pytest
 
@@ -1062,6 +1063,28 @@ def test_output_order(self):
             tmp = np.einsum('...ft,mf->...mt', d, c, order='a', optimize=opt)
             assert_(tmp.flags.c_contiguous)
 
+    def test_huge_number_of_arguments(self):
+        # einsum limits the number of arguments to the function already,
+        # so the limit is a bit lower than that of the iterator (currently)
+        chars = ",".join(string.ascii_letters)
+        # With an index:
+        res = np.einsum(chars + "->", *[np.array([2.])] * 26*2)
+        assert res == 2.**(26*2)
+        # And without:
+        res = np.einsum("," * 100 + "->", *[np.array(2.)] * 101)
+        assert res == 2.**101
+
+        with pytest.raises(ValueError):
+            res = np.einsum("," * 130 + "->", *[np.array(2.)] * 130)
+
+        # Using the alternative call syntax:
+        res = np.einsum(*[np.array(2.), ()] * 127)
+        assert res == 2.**127
+
+        with pytest.raises(ValueError, match="too many operands"):
+            np.einsum(*[np.array(2.), ()] * 128)
+
+
 class TestEinsumPath:
     def build_operands(self, string, size_dict=global_size_dict):
 

diff --git a/numpy/core/tests/test_indexing.py b/numpy/core/tests/test_indexing.py
@@ -296,8 +296,8 @@ def test_uncontiguous_subspace_assignment(self):
 
     def test_too_many_fancy_indices_special_case(self):
         # Just documents behaviour, this is a small limitation.
-        a = np.ones((1,) * 32)  # 32 is NPY_MAXDIMS
-        assert_raises(IndexError, a.__getitem__, (np.array([0]),) * 32)
+        a = np.ones((1,) * 64)  # 64 is NPY_MAXDIMS
+        assert_raises(IndexError, a.__getitem__, (np.array([0]),) * 64)
 
     def test_scalar_array_bool(self):
         # NumPy bools can be used as boolean index (python ones as of yet not)
@@ -551,11 +551,11 @@ def test_character_assignment(self):
 
     @pytest.mark.parametrize("index",
             [True, False, np.array([0])])
-    @pytest.mark.parametrize("num", [32, 40])
-    @pytest.mark.parametrize("original_ndim", [1, 32])
+    @pytest.mark.parametrize("num", [64, 70])
+    @pytest.mark.parametrize("original_ndim", [1, 64])
     def test_too_many_advanced_indices(self, index, num, original_ndim):
         # These are limitations based on the number of arguments we can process.
-        # For `num=32` (and all boolean cases), the result is actually define;
+        # For `num=64` (and all boolean cases), the result is actually define;
         # but the use of NpyIter (NPY_MAXARGS) limits it for technical reasons.
         arr = np.ones((1,) * original_ndim)
         with pytest.raises(IndexError):

diff --git a/numpy/core/tests/test_multiarray.py b/numpy/core/tests/test_multiarray.py
@@ -733,7 +733,7 @@ def subscript(x, i):
             x[i]
 
         assert_raises(IndexError, subscript, a, (np.newaxis, 0))
-        assert_raises(IndexError, subscript, a, (np.newaxis,)*50)
+        assert_raises(IndexError, subscript, a, (np.newaxis,)*65)
 
     def test_constructor(self):
         x = np.ndarray(())
@@ -815,7 +815,7 @@ def subscript(x, i):
             x[i]
 
         assert_raises(IndexError, subscript, a, (np.newaxis, 0))
-        assert_raises(IndexError, subscript, a, (np.newaxis,)*50)
+        assert_raises(IndexError, subscript, a, (np.newaxis,)*65)
 
     def test_overlapping_assignment(self):
         # With positive strides

diff --git a/numpy/core/tests/test_nditer.py b/numpy/core/tests/test_nditer.py
@@ -718,7 +718,7 @@ def test_iter_flags_errors():
     # Not enough operands
    assert_raises(ValueError, nditer, [], [], [])
     # Too many operands
-    assert_raises(ValueError, nditer, [a]*100, [], [['readonly']]*100)
+    assert_raises(ValueError, nditer, [a]*129, [], [['readonly']]*129)
     # Bad global flag
     assert_raises(ValueError, nditer, [a], ['bad flag'], [['readonly']])
     # Bad op flag

diff --git a/numpy/core/tests/test_numeric.py b/numpy/core/tests/test_numeric.py
@@ -3488,9 +3488,9 @@ def test_broadcast_single_arg(self):
 
     def test_number_of_arguments(self):
         arr = np.empty((5,))
-        for j in range(35):
+        for j in range(140):
             arrs = [arr] * j
-            if j > 32:
+            if j > 128:
                 assert_raises(ValueError, np.broadcast, *arrs)
             else:
                 mit = np.broadcast(*arrs)

diff --git a/numpy/core/tests/test_ove 8076 rrides.py b/numpy/core/tests/test_ove 8076 rrides.py
@@ -134,11 +134,11 @@ class D:
 
     def test_too_many_duck_arrays(self):
         namespace = dict(__array_function__=_return_not_implemented)
-        types = [type('A' + str(i), (object,), namespace) for i in range(33)]
+        types = [type('A' + str(i), (object,), namespace) for i in range(129)]
         relevant_args = [t() for t in types]
 
-        actual = _get_implementing_args(relevant_args[:32])
-        assert_equal(actual, relevant_args[:32])
+        actual = _get_implementing_args(relevant_args[:128])
+        assert_equal(actual, relevant_args[:128])
 
         with assert_raises_regex(TypeError, 'distinct argument types'):
             _get_implementing_args(relevant_args)
@@ -448,7 +448,7 @@ def func(*, like=None):
     def test_too_many_args(self):
         # Mainly a unit-test to increase coverage
         objs = []
-        for i in range(40):
+        for i in range(140):
             class MyArr:
                 def __array_function__(self, *args, **kwargs):
                     return NotImplemented

diff --git a/numpy/core/tests/test_regression.py b/numpy/core/tests/test_regression.py
@@ -1250,7 +1250,7 @@ def test_for_zero_length_in_choose(self):
 
     def test_array_ndmin_overflow(self):
         "Ticket #947."
-        assert_raises(ValueError, lambda: np.array([1], ndmin=33))
+        assert_raises(ValueError, lambda: np.array([1], ndmin=65))
 
     def test_void_scalar_with_titles(self):
         # No ticket
@@ -2238,7 +2238,7 @@ def test_frompyfunc_many_args(self):
         def passer(*args):
             pass
 
-        assert_raises(ValueError, np.frompyfunc, passer, 32, 1)
+        assert_raises(ValueError, np.frompyfunc, passer, 128, 1)
 
     def test_repeat_broadcasting(self):
         # gh-5743

diff --git a/numpy/core/tests/test_umath.py b/numpy/core/tests/test_umath.py
@@ -4676,7 +4676,7 @@ def __array_prepare__(self, obj, context=None):
         assert type(np.add.outer([1, 2], arr)) is cls
 
 def test_outer_exceeds_maxdims():
-    deep = np.ones((1,) * 17)
+    deep = np.ones((1,) * 33)
     with assert_raises(ValueError):
         np.add.outer(deep, deep)