Issue #9041: raised exception is misleading

An issue in ctypes.c_longdouble, ctypes.c_double, and ctypes.c_float that
caused an incorrect exception to be returned in the case of overflow has been
fixed.

Lib/ctypes/test/test_numbers.py

@@ -217,6 +217,16 @@ class NumberTestCase(unittest.TestCase):
         # probably be changed:
         self.assertRaises(TypeError, c_int, c_long(42))
 
+    def test_float_overflow(self):
+        import sys
+        big_int = int(sys.float_info.max) * 2
+        for t in float_types + [c_longdouble]:
+            self.assertRaises(OverflowError, t, big_int)
+            if (hasattr(t, "__ctype_be__")):
+                self.assertRaises(OverflowError, t.__ctype_be__, big_int)
+            if (hasattr(t, "__ctype_le__")):
+                self.assertRaises(OverflowError, t.__ctype_le__, big_int)
+
 ##    def test_perf(self):
 ##        check_perf()
 

Misc/NEWS

@@ -714,6 +714,10 @@ Documentation
 Extension Modules
 -----------------
 
+- Issue #9041: An issue in ctypes.c_longdouble, ctypes.c_double, and
+  ctypes.c_float that caused an incorrect exception to be returned in the
+  case of overflow has been fixed.
+
 - Issue #14212: The re module didn't retain a reference to buffers it was
   scanning, resulting in segfaults.
 

Modules/_ctypes/cfield.c

@@ -999,12 +999,8 @@ g_set(void *ptr, PyObject *value, Py_ssize_t size)
     long double x;
 
     x = PyFloat_AsDouble(value);
-    if (x == -1 && PyErr_Occurred()) {
-        PyErr_Format(PyExc_TypeError,
-                     " float expected instead of %s instance",
-                     value->ob_type->tp_name);
+    if (x == -1 && PyErr_Occurred())
         return NULL;
-    }
     memcpy(ptr, &x, sizeof(long double));
     _RET(value);
 }
@@ -1023,12 +1019,8 @@ d_set(void *ptr, PyObject *value, Py_ssize_t size)
     double x;
 
     x = PyFloat_AsDouble(value);
-    if (x == -1 && PyErr_Occurred()) {
-        PyErr_Format(PyExc_TypeError,
-                     " float expected instead of %s instance",
-                     value->ob_type->tp_name);
+    if (x == -1 && PyErr_Occurred())
         return NULL;
-    }
     memcpy(ptr, &x, sizeof(double));
     _RET(value);
 }
@@ -1047,12 +1039,8 @@ d_set_sw(void *ptr, PyObject *value, Py_ssize_t size)
     double x;
 
     x = PyFloat_AsDouble(value);
-    if (x == -1 && PyErr_Occurred()) {
-        PyErr_Format(PyExc_TypeError,
-                     " float expected instead of %s instance",
-                     value->ob_type->tp_name);
+    if (x == -1 && PyErr_Occurred())
         return NULL;
-    }
 #ifdef WORDS_BIGENDIAN
     if (_PyFloat_Pack8(x, (unsigned char *)ptr, 1))
         return NULL;
@@ -1079,12 +1067,8 @@ f_set(void *ptr, PyObject *value, Py_ssize_t size)
     float x;
 
     x = (float)PyFloat_AsDouble(value);
-    if (x == -1 && PyErr_Occurred()) {
-        PyErr_Format(PyExc_TypeError,
-                     " float expected instead of %s instance",
-                     value->ob_type->tp_name);
+    if (x == -1 && PyErr_Occurred())
         return NULL;
-    }
     memcpy(ptr, &x, sizeof(x));
     _RET(value);
 }
@@ -1103,12 +1087,8 @@ f_set_sw(void *ptr, PyObject *value, Py_ssize_t size)
     float x;
 
     x = (float)PyFloat_AsDouble(value);
-    if (x == -1 && PyErr_Occurred()) {
-        PyErr_Format(PyExc_TypeError,
-                     " float expected instead of %s instance",
-                     value->ob_type->tp_name);
+    if (x == -1 && PyErr_Occurred())
         return NULL;
-    }
 #ifdef WORDS_BIGENDIAN
     if (_PyFloat_Pack4(x, (unsigned char *)ptr, 1))
         return NULL;