From b485e50fde3be08d796a2dac66cb822da1226bb3 Mon Sep 17 00:00:00 2001
From: Raymond Hettinger <rhettinger@users.noreply.github.com>
Date: Wed, 17 Sep 2025 16:50:15 -0500
Subject: [PATCH] gh-139074: Fix missing high precision case in sumprod()
 (gh-139075)

---
 Lib/test/test_math.py                         |  4 ++-
 ...-09-17-13-21-26.gh-issue-139074.dVZO5F.rst |  2 ++
 Modules/mathmodule.c                          | 33 +++++++++----------
 3 files changed, 21 insertions(+), 18 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Core_and_Builtins/2025-09-17-13-21-26.gh-issue-139074.dVZO5F.rst

diff --git a/Lib/test/test_math.py b/Lib/test/test_math.py
index e3b0d4fa9ee..92326a46c33 100644
--- a/Lib/test/test_math.py
+++ b/Lib/test/test_math.py
@@ -1485,7 +1485,9 @@ def __rmul__(self, other):
 
         # Error cases that arose during development
         args = ((-5, -5, 10), (1.5, 4611686018427387904, 2305843009213693952))
-        self.assertEqual(sumprod(*args), 0.0)
+        self.assertEqual(sumprod(*args), -7.5)
+        self.assertEqual(sumprod([-0.01, 1, -1, 0.01], [1, 1, 1, 1]), 0.0)
+        self.assertEqual(sumprod([1, 1, 1, 1], [-0.01, 1, -1, 0.01], ), 0.0)
 
     @requires_IEEE_754
     @unittest.skipIf(HAVE_DOUBLE_ROUNDING,
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-09-17-13-21-26.gh-issue-139074.dVZO5F.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-09-17-13-21-26.gh-issue-139074.dVZO5F.rst
new file mode 100644
index 00000000000..56c9f21296d
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2025-09-17-13-21-26.gh-issue-139074.dVZO5F.rst
@@ -0,0 +1,2 @@
+Fixed a missing case in :func:`math.sumprod` where a low precision path was
+taken when an int/int input pair followed a float input.
diff --git a/Modules/mathmodule.c b/Modules/mathmodule.c
index c631beb9ce5..d8bf9e76cdd 100644
--- a/Modules/mathmodule.c
+++ b/Modules/mathmodule.c
@@ -2937,24 +2937,10 @@ math_sumprod_impl(PyObject *module, PyObject *p, PyObject *q)
 
             if (!finished) {
                 double flt_p, flt_q;
-                bool p_type_float = PyFloat_CheckExact(p_i);
-                bool q_type_float = PyFloat_CheckExact(q_i);
-                if (p_type_float && q_type_float) {
+
+                if (PyFloat_CheckExact(p_i)) {
                     flt_p = PyFloat_AS_DOUBLE(p_i);
-                    flt_q = PyFloat_AS_DOUBLE(q_i);
-                } else if (p_type_float && (PyLong_CheckExact(q_i) || PyBool_Check(q_i))) {
-                    /* We care about float/int pairs and int/float pairs because
-                       they arise naturally in several use cases such as price
-                       times quantity, measurements with integer weights, or
-                       data selected by a vector of bools. */
-                    flt_p = PyFloat_AS_DOUBLE(p_i);
-                    flt_q = PyLong_AsDouble(q_i);
-                    if (flt_q == -1.0 && PyErr_Occurred()) {
-                        PyErr_Clear();
-                        goto finalize_flt_path;
-                    }
-                } else if (q_type_float && (PyLong_CheckExact(p_i) || PyBool_Check(p_i))) {
-                    flt_q = PyFloat_AS_DOUBLE(q_i);
+                } else if (PyLong_CheckExact(p_i) || PyBool_Check(p_i)) {
                     flt_p = PyLong_AsDouble(p_i);
                     if (flt_p == -1.0 && PyErr_Occurred()) {
                         PyErr_Clear();
@@ -2963,6 +2949,19 @@ math_sumprod_impl(PyObject *module, PyObject *p, PyObject *q)
                 } else {
                     goto finalize_flt_path;
                 }
+
+                if (PyFloat_CheckExact(q_i)) {
+                    flt_q = PyFloat_AS_DOUBLE(q_i);
+                } else if (PyLong_CheckExact(q_i) || PyBool_Check(q_i)) {
+                    flt_q = PyLong_AsDouble(q_i);
+                    if (flt_q == -1.0 && PyErr_Occurred()) {
+                        PyErr_Clear();
+                        goto finalize_flt_path;
+                    }
+                } else {
+                    goto finalize_flt_path;
+                }
+
                 TripleLength new_flt_total = tl_fma(flt_p, flt_q, flt_total);
                 if (isfinite(new_flt_total.hi)) {
                     flt_total = new_flt_total;