From c08c89addfe30a3e0e70c3200e7d5c2a56373dc8 Mon Sep 17 00:00:00 2001
From: Sergey B Kirpichev <skirpichev@gmail.com>
Date: Sun, 19 Jul 2026 03:24:16 +0300
Subject: [PATCH] Use Py_complex_protected AC converter for cmath.rect()
 (GH-154034)

---
 Modules/clinic/cmathmodule.c.h | 18 +++++++++++++++---
 Modules/cmathmodule.c          | 12 ++++--------
 2 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/Modules/clinic/cmathmodule.c.h b/Modules/clinic/cmathmodule.c.h
index ecb5257cf6b240..fe40ece030116b 100644
--- a/Modules/clinic/cmathmodule.c.h
+++ b/Modules/clinic/cmathmodule.c.h
@@ -745,7 +745,7 @@ PyDoc_STRVAR(cmath_rect__doc__,
 #define CMATH_RECT_METHODDEF    \
     {"rect", _PyCFunction_CAST(cmath_rect), METH_FASTCALL, cmath_rect__doc__},
 
-static PyObject *
+static Py_complex
 cmath_rect_impl(PyObject *module, double r, double phi);
 
 static PyObject *
@@ -754,6 +754,7 @@ cmath_rect(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
     PyObject *return_value = NULL;
     double r;
     double phi;
+    Py_complex _return_value;
 
     if (!_PyArg_CheckPositional("rect", nargs, 2, 2)) {
         goto exit;
@@ -778,7 +779,18 @@ cmath_rect(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
             goto exit;
         }
     }
-    return_value = cmath_rect_impl(module, r, phi);
+    _return_value = cmath_rect_impl(module, r, phi);
+    if (errno == EDOM) {
+        PyErr_SetString(PyExc_ValueError, "math domain error");
+        goto exit;
+    }
+    else if (errno == ERANGE) {
+        PyErr_SetString(PyExc_OverflowError, "math range error");
+        goto exit;
+    }
+    else {
+        return_value = PyComplex_FromCComplex(_return_value);
+    }
 
 exit:
     return return_value;
@@ -987,4 +999,4 @@ cmath_isclose(PyObject *module, PyObject *const *args, Py_ssize_t nargs, PyObjec
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=7d5ad4cf258526cd input=a9049054013a1b77]*/
+/*[clinic end generated code: output=89513888cb105a65 input=a9049054013a1b77]*/
diff --git a/Modules/cmathmodule.c b/Modules/cmathmodule.c
index 7c736f4610bb98..f6e1475b00ecfb 100644
--- a/Modules/cmathmodule.c
+++ b/Modules/cmathmodule.c
@@ -1060,7 +1060,7 @@ static Py_complex rect_special_values[7][7] = {
 };
 
 /*[clinic input]
-cmath.rect
+cmath.rect -> Py_complex_protected
 
     r: double
     phi: double
@@ -1069,9 +1069,9 @@ cmath.rect
 Convert from polar coordinates to rectangular coordinates.
 [clinic start generated code]*/
 
-static PyObject *
+static Py_complex
 cmath_rect_impl(PyObject *module, double r, double phi)
-/*[clinic end generated code: output=385a0690925df2d5 input=24c5646d147efd69]*/
+/*[clinic end generated code: output=74ff3d17585f3388 input=50e60c5d28c834e6]*/
 {
     Py_complex z;
     errno = 0;
@@ -1115,11 +1115,7 @@ cmath_rect_impl(PyObject *module, double r, double phi)
         z.imag = r * sin(phi);
         errno = 0;
     }
-
-    if (errno != 0)
-        return math_error();
-    else
-        return PyComplex_FromCComplex(z);
+    return z;
 }
 
 /*[clinic input]