For "w*" the original error is always overwritten.

Author: serhiy-storchaka

Modules/_io/clinic/bufferedio.c.h

@@ -20,6 +20,8 @@ _io__BufferedIOBase_readinto(PyObject *self, PyObject *arg)
     Py_buffer buffer = {NULL, NULL};
 
     if (PyObject_GetBuffer(arg, &buffer, PyBUF_WRITABLE) < 0) {
+        PyErr_Clear();
+        _PyErr_BadArgument("readinto", "read-write bytes-like object", arg);
         goto exit;
     }
     if (!PyBuffer_IsContiguous(&buffer, 'C')) {
@@ -55,6 +57,8 @@ _io__BufferedIOBase_readinto1(PyObject *self, PyObject *arg)
     Py_buffer buffer = {NULL, NULL};
 
     if (PyObject_GetBuffer(arg, &buffer, PyBUF_WRITABLE) < 0) {
+        PyErr_Clear();
+        _PyErr_BadArgument("readinto1", "read-write bytes-like object", arg);
         goto exit;
     }
     if (!PyBuffer_IsContiguous(&buffer, 'C')) {
@@ -192,6 +196,8 @@ _io__Buffered_readinto(buffered *self, PyObject *arg)
     Py_buffer buffer = {NULL, NULL};
 
     if (PyObject_GetBuffer(arg, &buffer, PyBUF_WRITABLE) < 0) {
+        PyErr_Clear();
+        _PyErr_BadArgument("readinto", "read-write bytes-like object", arg);
         goto exit;
     }
     if (!PyBuffer_IsContiguous(&buffer, 'C')) {
@@ -227,6 +233,8 @@ _io__Buffered_readinto1(buffered *self, PyObject *arg)
     Py_buffer buffer = {NULL, NULL};
 
     if (PyObject_GetBuffer(arg, &buffer, PyBUF_WRITABLE) < 0) {
+        PyErr_Clear();
+        _PyErr_BadArgument("readinto1", "read-write bytes-like object", arg);
         goto exit;
     }
     if (!PyBuffer_IsContiguous(&buffer, 'C')) {
@@ -496,4 +504,4 @@ _io_BufferedRandom___init__(PyObject *self, PyObject *args, PyObject *kwargs)
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=ecce6d4ca9143a15 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=7ecda6e1be89950a input=a9049054013a1b77]*/

Modules/_io/clinic/bytesio.c.h

@@ -297,6 +297,8 @@ _io_BytesIO_readinto(bytesio *self, PyObject *arg)
     Py_buffer buffer = {NULL, NULL};
 
     if (PyObject_GetBuffer(arg, &buffer, PyBUF_WRITABLE) < 0) {
+        PyErr_Clear();
+        _PyErr_BadArgument("readinto", "read-write bytes-like object", arg);
         goto exit;
     }
     if (!PyBuffer_IsContiguous(&buffer, 'C')) {
@@ -448,4 +450,4 @@ _io_BytesIO___init__(PyObject *self, PyObject *args, PyObject *kwargs)
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=319d5f4852532292 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=dac44db36ab1c27b input=a9049054013a1b77]*/

Modules/_io/clinic/fileio.c.h

@@ -157,6 +157,8 @@ _io_FileIO_readinto(fileio *self, PyObject *arg)
     Py_buffer buffer = {NULL, NULL};
 
     if (PyObject_GetBuffer(arg, &buffer, PyBUF_WRITABLE) < 0) {
+        PyErr_Clear();
+        _PyErr_BadArgument("readinto", "read-write bytes-like object", arg);
         goto exit;
     }
     if (!PyBuffer_IsContiguous(&buffer, 'C')) {
@@ -381,4 +383,4 @@ _io_FileIO_isatty(fileio *self, PyObject *Py_UNUSED(ignored))
 #ifndef _IO_FILEIO_TRUNCATE_METHODDEF
     #define _IO_FILEIO_TRUNCATE_METHODDEF
 #endif /* !defined(_IO_FILEIO_TRUNCATE_METHODDEF) */
-/*[clinic end generated code: output=13ff9ef76ca044d0 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=5dc247fcd8d03ac0 input=a9049054013a1b77]*/

Modules/_io/clinic/winconsoleio.c.h

@@ -157,6 +157,8 @@ _io__WindowsConsoleIO_readinto(winconsoleio *self, PyObject *arg)
     Py_buffer buffer = {NULL, NULL};
 
     if (PyObject_GetBuffer(arg, &buffer, PyBUF_WRITABLE) < 0) {
+        PyErr_Clear();
+        _PyErr_BadArgument("readinto", "read-write bytes-like object", arg);
         goto exit;
     }
     if (!PyBuffer_IsContiguous(&buffer, 'C')) {
@@ -336,4 +338,4 @@ _io__WindowsConsoleIO_isatty(winconsoleio *self, PyObject *Py_UNUSED(ignored))
 #ifndef _IO__WINDOWSCONSOLEIO_ISATTY_METHODDEF
     #define _IO__WINDOWSCONSOLEIO_ISATTY_METHODDEF
 #endif /* !defined(_IO__WINDOWSCONSOLEIO_ISATTY_METHODDEF) */
-/*[clinic end generated code: output=21005cb3b728c616 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=dafe6e700927e4c0 input=a9049054013a1b77]*/

Tools/clinic/clinic.py

@@ -3282,6 +3282,8 @@ def parse_arg(self, argname):
         elif self.format_unit == 'w*':
             return """
                 if (PyObject_GetBuffer({argname}, &{paramname}, PyBUF_WRITABLE) < 0) {{{{
+                    PyErr_Clear();
+                    _PyErr_BadArgument("{{name}}", "read-write bytes-like object", {argname});
                     goto exit;
                 }}}}
                 if (!PyBuffer_IsContiguous(&{paramname}, 'C')) {{{{