--- /dev/null
+cimport cython
+
+cdef object two = 2
+cdef int size_in_bits = sizeof(INT) * 8
+
+cdef bint is_signed_ = (<INT>-1 < 0)
+cdef INT max_value_ = <INT>(two ** (size_in_bits - is_signed_) - 1)
+cdef INT min_value_ = ~max_value_
+cdef INT half_ = max_value_ // 2
+
+# Python visible.
+is_signed = is_signed_
+max_value = max_value_
+min_value = min_value_
+half = half_
+
+
+import operator
+from libc.math cimport sqrt
+
+cpdef check(func, op, a, b):
+ cdef INT res, op_res
+ cdef bint func_overflow = False
+ cdef bint assign_overflow = False
+ try:
+ res = func(a, b)
+ except OverflowError:
+ func_overflow = True
+ try:
+ op_res = op(a, b)
+ except OverflowError:
+ assign_overflow = True
+ assert func_overflow == assign_overflow, "Inconsistant overflow: %s(%s, %s)" % (func, a, b)
+ if not func_overflow:
+ assert res == op_res, "Inconsistant values: %s(%s, %s) == %s != %s" % (func, a, b, res, op_res)
+
+medium_values = (max_value_ / 2, max_value_ / 3, min_value_ / 2, <INT>sqrt(max_value_) - 1, <INT>sqrt(max_value_) + 1)
+def run_test(func, op):
+ cdef INT offset, b
+ check(func, op, 300, 200)
+ check(func, op, max_value_, max_value_)
+ check(func, op, max_value_, min_value_)
+ if not is_signed_ or not func is test_sub:
+ check(func, op, min_value_, min_value_)
+
+ for offset in range(5):
+ check(func, op, max_value_ - 1, offset)
+ check(func, op, min_value_ + 1, offset)
+ if is_signed_:
+ check(func, op, max_value_ - 1, 2 - offset)
+ check(func, op, min_value_ + 1, 2 - offset)
+
+ for offset in range(9):
+ check(func, op, max_value_ / 2, offset)
+ check(func, op, min_value_ / 3, offset)
+ check(func, op, max_value_ / 4, offset)
+ check(func, op, min_value_ / 5, offset)
+ if is_signed_:
+ check(func, op, max_value_ / 2, 4 - offset)
+ check(func, op, min_value_ / 3, 4 - offset)
+ check(func, op, max_value_ / -4, 3 - offset)
+ check(func, op, min_value_ / -5, 3 - offset)
+
+ for offset in range(-3, 4):
+ for a in medium_values:
+ for b in medium_values:
+ check(func, op, a, b + offset)
+
+@cython.overflowcheck(True)
+def test_add(INT a, INT b):
+ """
+ >>> test_add(1, 2)
+ 3
+ >>> test_add(max_value, max_value) #doctest: +ELLIPSIS
+ Traceback (most recent call last):
+ ...
+ OverflowError: value too large
+ >>> run_test(test_add, operator.add)
+ """
+ return int(a + b)
+
+@cython.overflowcheck(True)
+def test_sub(INT a, INT b):
+ """
+ >>> test_sub(10, 1)
+ 9
+ >>> test_sub(min_value, 1) #doctest: +ELLIPSIS
+ Traceback (most recent call last):
+ ...
+ OverflowError: value too large
+ >>> run_test(test_sub, operator.sub)
+ """
+ return int(a - b)
+
+@cython.overflowcheck(True)
+def test_mul(INT a, INT b):
+ """
+ >>> test_mul(11, 13)
+ 143
+ >>> test_mul(max_value / 2, max_value / 2) #doctest: +ELLIPSIS
+ Traceback (most recent call last):
+ ...
+ OverflowError: value too large
+ >>> run_test(test_mul, operator.mul)
+ """
+ return int(a * b)
+
+@cython.overflowcheck(True)
+def test_nested(INT a, INT b, INT c):
+ """
+ >>> test_nested(1, 2, 3)
+ 6
+ >>> expect_overflow(test_nested, half + 1, half + 1, half + 1)
+ >>> expect_overflow(test_nested, half - 1, half - 1, half - 1)
+ """
+ return int(a + b + c)
+
+def expect_overflow(func, *args):
+ try:
+ res = func(*args)
+ except OverflowError:
+ return
+ assert False, "Expected OverflowError, got %s" % res
+
+cpdef format(INT value):
+ """
+ >>> format(1)
+ '1'
+ >>> format(half - 1)
+ 'half - 1'
+ >>> format(half)
+ 'half'
+ >>> format(half + 2)
+ 'half + 2'
+ >>> format(half + half - 3)
+ 'half + half - 3'
+ >>> format(max_value)
+ 'max_value'
+ """
+ if value == max_value_:
+ return "max_value"
+ elif value == half_:
+ return "half"
+ elif max_value_ - value <= max_value_ // 4:
+ return "half + half - %s" % (half_ + half_ - value)
+ elif max_value_ - value <= half_:
+ return "half + %s" % (value - half_)
+ elif max_value_ - value <= half_ + max_value_ // 4:
+ return "half - %s" % (half_ - value)
+ else:
+ return "%s" % value
+
+cdef INT called(INT value):
+ print("called(%s)" % format(value))
+ return value
+
+@cython.overflowcheck(True)
+def test_nested_func(INT a, INT b, INT c):
+ """
+ >>> test_nested_func(1, 2, 3)
+ called(5)
+ 6
+ >>> expect_overflow(test_nested_func, half + 1, half + 1, half + 1)
+ >>> expect_overflow(test_nested_func, half - 1, half - 1, half - 1)
+ called(half + half - 2)
+ >>> print(format(test_nested_func(1, half - 1, half - 1)))
+ called(half + half - 2)
+ half + half - 1
+ >>>
+ """
+ return int(a + called(b + c))
+
+
+@cython.overflowcheck(True)
+def test_add_const(INT a):
+ """
+ >>> test_add_const(1)
+ 101
+ >>> expect_overflow(test_add_const, max_value)
+ >>> expect_overflow(test_add_const , max_value - 99)
+ >>> test_add_const(max_value - 100) == max_value
+ True
+ """
+ return int(a + <INT>100)
+
+@cython.overflowcheck(True)
+def test_sub_const(INT a):
+ """
+ >>> test_sub_const(101)
+ 1
+ >>> expect_overflow(test_sub_const, min_value)
+ >>> expect_overflow(test_sub_const, min_value + 99)
+ >>> test_sub_const(min_value + 100) == min_value
+ True
+ """
+ return int(a - <INT>100)
+
+@cython.overflowcheck(True)
+def test_mul_const(INT a):
+ """
+ >>> test_mul_const(2)
+ 200
+ >>> expect_overflow(test_mul_const, max_value)
+ >>> expect_overflow(test_mul_const, max_value // 99)
+ >>> test_mul_const(max_value // 100) == max_value - max_value % 100
+ True
+ """
+ return int(a * <INT>100)