gdb/

	* python/py-breakpoint.c (bppy_set_condition): New comment.
	* python/py-cmd.c (cmdpy_function): Call also gdbpy_print_stack for
	failed PyUnicode_Decode.
	(cmdpy_completer): Skip element for failed
	python_string_to_host_string.
	(cmdpy_init): Return -1 on failed python_string_to_host_string.
	* python/py-frame.c (frapy_read_var): Extend the function comment.
	* python/py-function.c (fnpy_init): Return -1 on failed
	python_string_to_host_string.
	* python/py-inferior.c (infpy_read_memory, infpy_write_memory): Extend
	the function comment.
	(infpy_search_memory): Extend the function comment.  Remove the
	PyErr_SetString call on already set error state.
	* python/py-param.c (set_parameter_value): Extend the function
	comment.  Return -1 on failed python_string_to_host_string, twice.
	(set_attr): Extend the function comment.
	(compute_enum_values): Extend the function comment.  New variable
	back_to.  Protect self->enumeration by BACK_TO cleanups.  Return 0 on
	failed python_string_to_host_string.
	(get_doc_string): Call gdbpy_print_stack on failed
	python_string_to_host_string.
	(parmpy_init): Extend the function comment.
	* python/py-prettyprint.c (pretty_print_one_value): Likewise.
	(gdbpy_get_display_hint, print_children): Call gdbpy_print_stack on
	failed python_string_to_host_string.
	* python/py-value.c (valpy_new, valpy_getitem, valpy_call)
	(valpy_binop, valpy_richcompare): Extend the function comment.
	* python/python.c
	(struct python_env) <error_type, error_value, error_traceback>: New
	fields.
	(restore_python_env): Handle PyErr_Occurred.  Call PyErr_Restore.
	(ensure_python_env): Call PyErr_Fetch.
	* varobj.c (update_dynamic_varobj_children): Call gdbpy_print_stack on
	failed convert_value_from_python.
	(value_get_print_value): Call gdbpy_print_stack on failed
	python_string_to_target_python_string.

gdb/testsuite/
	* gdb.python/py-error.exp: New file.
	* gdb.python/py-error.py: New file.

14 files changed, 241 insertions, 34 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 55bf57a..0f35473 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,42 @@
+2010-10-13  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
+	* python/py-breakpoint.c (bppy_set_condition): New comment.
+	* python/py-cmd.c (cmdpy_function): Call also gdbpy_print_stack for
+	failed PyUnicode_Decode.
+	(cmdpy_completer): Skip element for failed
+	python_string_to_host_string.
+	(cmdpy_init): Return -1 on failed python_string_to_host_string.
+	* python/py-frame.c (frapy_read_var): Extend the function comment.
+	* python/py-function.c (fnpy_init): Return -1 on failed
+	python_string_to_host_string.
+	* python/py-inferior.c (infpy_read_memory, infpy_write_memory): Extend
+	the function comment.
+	(infpy_search_memory): Extend the function comment.  Remove the
+	PyErr_SetString call on already set error state.
+	* python/py-param.c (set_parameter_value): Extend the function
+	comment.  Return -1 on failed python_string_to_host_string, twice.
+	(set_attr): Extend the function comment.
+	(compute_enum_values): Extend the function comment.  New variable
+	back_to.  Protect self->enumeration by BACK_TO cleanups.  Return 0 on
+	failed python_string_to_host_string.
+	(get_doc_string): Call gdbpy_print_stack on failed
+	python_string_to_host_string.
+	(parmpy_init): Extend the function comment.
+	* python/py-prettyprint.c (pretty_print_one_value): Likewise.
+	(gdbpy_get_display_hint, print_children): Call gdbpy_print_stack on
+	failed python_string_to_host_string.
+	* python/py-value.c (valpy_new, valpy_getitem, valpy_call)
+	(valpy_binop, valpy_richcompare): Extend the function comment.
+	* python/python.c
+	(struct python_env) <error_type, error_value, error_traceback>: New
+	fields.
+	(restore_python_env): Handle PyErr_Occurred.  Call PyErr_Restore.
+	(ensure_python_env): Call PyErr_Fetch.
+	* varobj.c (update_dynamic_varobj_children): Call gdbpy_print_stack on
+	failed convert_value_from_python.
+	(value_get_print_value): Call gdbpy_print_stack on failed
+	python_string_to_target_python_string.
+
 2010-10-12  Tom Tromey  <tromey@redhat.com>
 
 	* python/py-prettyprint.c (search_pp_list): Fix error checking.
diff --git a/gdb/python/py-breakpoint.c b/gdb/python/py-breakpoint.c
index 0c70cbf..b18f7f3 100644
--- a/gdb/python/py-breakpoint.c
+++ b/gdb/python/py-breakpoint.c
@@ -420,6 +420,9 @@ bppy_get_condition (PyObject *self, void *closure)
   return PyString_Decode (str, strlen (str), host_charset (), NULL);
 }
 
+/* Returns 0 on success.  Returns -1 on error, with a python exception set.
+   */
+
 static int
 bppy_set_condition (PyObject *self, PyObject *newvalue, void *closure)
 {
diff --git a/gdb/python/py-cmd.c b/gdb/python/py-cmd.c
index 2cff4ba..9f71290 100644
--- a/gdb/python/py-cmd.c
+++ b/gdb/python/py-cmd.c
@@ -139,7 +139,10 @@ cmdpy_function (struct cmd_list_element *command, char *args, int from_tty)
     args = "";
   argobj = PyUnicode_Decode (args, strlen (args), host_charset (), NULL);
   if (! argobj)
-    error (_("Could not convert arguments to Python string."));
+    {
+      gdbpy_print_stack ();
+      error (_("Could not convert arguments to Python string."));
+    }
 
   ttyobj = from_tty ? Py_True : Py_False;
   Py_INCREF (ttyobj);
@@ -256,6 +259,12 @@ cmdpy_completer (struct cmd_list_element *command, char *text, char *word)
 	      continue;
 	    }
 	  result[out] = python_string_to_host_string (elt);
+	  if (result[out] == NULL)
+	    {
+	      /* Skip problem elements.  */
+	      PyErr_Clear ();
+	      continue;
+	    }
 	  ++out;
 	}
       result[out] = NULL;
@@ -466,7 +475,15 @@ cmdpy_init (PyObject *self, PyObject *args, PyObject *kw)
       PyObject *ds_obj = PyObject_GetAttr (self, gdbpy_doc_cst);
 
       if (ds_obj && gdbpy_is_string (ds_obj))
-	docstring = python_string_to_host_string (ds_obj);
+	{
+	  docstring = python_string_to_host_string (ds_obj);
+	  if (docstring == NULL)
+	    {
+	      xfree (cmd_name);
+	      xfree (pfx_name);
+	      return -1;
+	    }
+	}
     }
   if (! docstring)
     docstring = xstrdup (_("This command is not documented."));
diff --git a/gdb/python/py-frame.c b/gdb/python/py-frame.c
index bb82903..1d3152c 100644
--- a/gdb/python/py-frame.c
+++ b/gdb/python/py-frame.c
@@ -385,7 +385,8 @@ frapy_find_sal (PyObject *self, PyObject *args)
    start the search from that block, otherwise search from the frame's
    current block (determined by examining the resume address of the
    frame).  The variable argument must be a string or an instance of a
-   gdb.Symbol.  The block argument must be an instance of gdb.Block.  */
+   gdb.Symbol.  The block argument must be an instance of gdb.Block.  Returns
+   NULL on error, with a python exception set.  */
 static PyObject *
 frapy_read_var (PyObject *self, PyObject *args)
 {
diff --git a/gdb/python/py-function.c b/gdb/python/py-function.c
index f09c6b4..762eb35 100644
--- a/gdb/python/py-function.c
+++ b/gdb/python/py-function.c
@@ -113,7 +113,14 @@ fnpy_init (PyObject *self, PyObject *args, PyObject *kwds)
     {
       PyObject *ds_obj = PyObject_GetAttrString (self, "__doc__");
       if (ds_obj && gdbpy_is_string (ds_obj))
-	docstring = python_string_to_host_string (ds_obj);
+	{
+	  docstring = python_string_to_host_string (ds_obj);
+	  if (docstring == NULL)
+	    {
+	      Py_DECREF (self);
+	      return -1;
+	    }
+	}
     }
   if (! docstring)
     docstring = xstrdup (_("This function is not documented."));
diff --git a/gdb/python/py-inferior.c b/gdb/python/py-inferior.c
index 3a0feab..b1ddb168 100644
--- a/gdb/python/py-inferior.c
+++ b/gdb/python/py-inferior.c
@@ -293,7 +293,8 @@ gdbpy_inferiors (PyObject *unused, PyObject *unused2)
 
 /* Implementation of gdb.read_memory (address, length).
    Returns a Python buffer object with LENGTH bytes of the inferior's
-   memory at ADDRESS.  Both arguments are integers.  */
+   memory at ADDRESS.  Both arguments are integers.  Returns NULL on error,
+   with a python exception set.  */
 static PyObject *
 infpy_read_memory (PyObject *self, PyObject *args, PyObject *kw)
 {
@@ -361,7 +362,8 @@ infpy_read_memory (PyObject *self, PyObject *args, PyObject *kw)
    Writes the contents of BUFFER (a Python object supporting the read
    buffer protocol) at ADDRESS in the inferior's memory.  Write LENGTH
    bytes from BUFFER, or its entire contents if the argument is not
-   provided.  The function returns nothing.  */
+   provided.  The function returns nothing.  Returns NULL on error, with
+   a python exception set.  */
 static PyObject *
 infpy_write_memory (PyObject *self, PyObject *args, PyObject *kw)
 {
@@ -473,7 +475,8 @@ get_char_buffer (PyObject *self, Py_ssize_t segment, char **ptrptr)
    search from ADDRESS.  PATTERN is the pattern to search for (and
    must be a Python object supporting the buffer protocol).
    Returns a Python Long object holding the address where the pattern
-   was located, or if the pattern was not found, returns None.  */
+   was located, or if the pattern was not found, returns None.  Returns NULL
+   on error, with a python exception set.  */
 static PyObject *
 infpy_search_memory (PyObject *self, PyObject *args, PyObject *kw)
 {
@@ -511,12 +514,7 @@ infpy_search_memory (PyObject *self, PyObject *args, PyObject *kw)
 	}
     }
   else
-    {
-      PyErr_SetString (PyExc_RuntimeError,
-		       _("Cannot get search address/range from Python."));
-
-      return NULL;
-    }
+    return NULL;
 
   if (!PyObject_CheckReadBuffer (pattern))
     {
diff --git a/gdb/python/py-param.c b/gdb/python/py-param.c
index 5596eb7..b8eb447 100644
--- a/gdb/python/py-param.c
+++ b/gdb/python/py-param.c
@@ -110,8 +110,8 @@ get_attr (PyObject *obj, PyObject *attr_name)
   return PyObject_GenericGetAttr (obj, attr_name);
 }
 
-/* Set a parameter value from a Python value.  Return 0 on success, -1
-   on failure.  */
+/* Set a parameter value from a Python value.  Return 0 on success.  Returns
+   -1 on error, with a python exception set.  */
 static int
 set_parameter_value (parmpy_object *self, PyObject *value)
 {
@@ -132,17 +132,25 @@ set_parameter_value (parmpy_object *self, PyObject *value)
 
 	  return -1;
 	}
-      if (self->value.stringval)
-	xfree (self->value.stringval);
       if (value == Py_None)
 	{
+	  xfree (self->value.stringval);
 	  if (self->type == var_optional_filename)
 	    self->value.stringval = xstrdup ("");
 	  else
 	    self->value.stringval = NULL;
 	}
       else
-	self->value.stringval = python_string_to_host_string (value);
+	{
+	  char *string;
+
+	  string = python_string_to_host_string (value);
+	  if (string == NULL)
+	    return -1;
+
+	  xfree (self->value.stringval);
+	  self->value.stringval = string;
+	}
       break;
 
     case var_enum:
@@ -158,6 +166,8 @@ set_parameter_value (parmpy_object *self, PyObject *value)
 	  }
 
 	str = python_string_to_host_string (value);
+	if (str == NULL)
+	  return -1;
 	for (i = 0; self->enumeration[i]; ++i)
 	  if (! strcmp (self->enumeration[i], str))
 	    break;
@@ -258,7 +268,7 @@ set_parameter_value (parmpy_object *self, PyObject *value)
   return 0;
 }
 
-/* Set an attribute.  */
+/* Set an attribute.  Returns -1 on error, with a python exception set.  */
 static int
 set_attr (PyObject *obj, PyObject *attr_name, PyObject *val)
 {
@@ -358,12 +368,13 @@ add_setshow_generic (int parmclass, enum command_class cmdclass,
     }
 }
 
-/* A helper which computes enum values.  Returns 1 on success, 0 on
-   error.  */
+/* A helper which computes enum values.  Returns 1 on success.  Returns 0 on
+   error, with a python exception set.  */
 static int
 compute_enum_values (parmpy_object *self, PyObject *enum_values)
 {
   Py_ssize_t size, i;
+  struct cleanup *back_to;
 
   if (! enum_values)
     {
@@ -390,6 +401,7 @@ compute_enum_values (parmpy_object *self, PyObject *enum_values)
     }
 
   self->enumeration = xmalloc ((size + 1) * sizeof (char *));
+  back_to = make_cleanup (free_current_contents, &self->enumeration);
   memset (self->enumeration, 0, (size + 1) * sizeof (char *));
 
   for (i = 0; i < size; ++i)
@@ -397,16 +409,27 @@ compute_enum_values (parmpy_object *self, PyObject *enum_values)
       PyObject *item = PySequence_GetItem (enum_values, i);
 
       if (! item)
-	return 0;
+	{
+	  do_cleanups (back_to);
+	  return 0;
+	}
       if (! gdbpy_is_string (item))
 	{
+	  do_cleanups (back_to);
 	  PyErr_SetString (PyExc_RuntimeError, 
 			   _("The enumeration item not a string."));
 	  return 0;
 	}
       self->enumeration[i] = python_string_to_host_string (item);
+      if (self->enumeration[i] == NULL)
+	{
+	  do_cleanups (back_to);
+	  return 0;
+	}
+      make_cleanup (xfree, (char *) self->enumeration[i]);
     }
 
+  discard_cleanups (back_to);
   return 1;
 }
 
@@ -422,7 +445,11 @@ get_doc_string (PyObject *object, PyObject *attr)
       PyObject *ds_obj = PyObject_GetAttr (object, attr);
 
       if (ds_obj && gdbpy_is_string (ds_obj))
-	result = python_string_to_host_string (ds_obj);
+	{
+	  result = python_string_to_host_string (ds_obj);
+	  if (result == NULL)
+	    gdbpy_print_stack ();
+	}
     }
   if (! result)
     result = xstrdup (_("This command is not documented."));
@@ -449,8 +476,9 @@ get_doc_string (PyObject *object, PyObject *attr)
 
    The documentation for the parameter is taken from the doc string
    for the python class.
-   
-*/
+
+   Returns -1 on error, with a python exception set.  */
+
 static int
 parmpy_init (PyObject *self, PyObject *args, PyObject *kwds)
 {
diff --git a/gdb/python/py-prettyprint.c b/gdb/python/py-prettyprint.c
index 7aa83bc..cc6a346 100644
--- a/gdb/python/py-prettyprint.c
+++ b/gdb/python/py-prettyprint.c
@@ -196,8 +196,8 @@ find_pretty_printer (PyObject *value)
    is returned.  If the function returns Py_NONE that means the pretty
    printer returned the Python None as a value.  Otherwise, if the
    function returns a value,  *OUT_VALUE is set to the value, and NULL
-   is returned.  On error, *OUT_VALUE is set to NULL, and NULL is
-   returned.  */
+   is returned.  On error, *OUT_VALUE is set to NULL, NULL is
+   returned, with a python exception set.  */
 
 static PyObject *
 pretty_print_one_value (PyObject *printer, struct value **out_value)
@@ -243,7 +243,11 @@ gdbpy_get_display_hint (PyObject *printer)
   if (hint)
     {
       if (gdbpy_is_string (hint))
-	result = python_string_to_host_string (hint);
+	{
+	  result = python_string_to_host_string (hint);
+	  if (result == NULL)
+	    gdbpy_print_stack ();
+	}
       Py_DECREF (hint);
     }
   else
@@ -566,7 +570,10 @@ print_children (PyObject *printer, const char *hint,
 	  else
 	    {
 	      output = python_string_to_host_string (py_v);
-	      fputs_filtered (output, stream);
+	      if (!output)
+		gdbpy_print_stack ();
+	      else
+		fputs_filtered (output, stream);
 	      xfree (output);
 	    }
 	}
diff --git a/gdb/python/py-value.c b/gdb/python/py-value.c
index 0aeea7c..4445655 100644
--- a/gdb/python/py-value.c
+++ b/gdb/python/py-value.c
@@ -119,7 +119,8 @@ note_value (value_object *value_obj)
   values_in_python = value_obj;
 }
 
-/* Called when a new gdb.Value object needs to be allocated.  */
+/* Called when a new gdb.Value object needs to be allocated.  Returns NULL on
+   error, with a python exception set.  */
 static PyObject *
 valpy_new (PyTypeObject *subtype, PyObject *args, PyObject *keywords)
 {
@@ -438,7 +439,7 @@ valpy_length (PyObject *self)
 }
 
 /* Given string name of an element inside structure, return its value
-   object.  */
+   object.  Returns NULL on error, with a python exception set.  */
 static PyObject *
 valpy_getitem (PyObject *self, PyObject *key)
 {
@@ -499,7 +500,7 @@ valpy_setitem (PyObject *self, PyObject *key, PyObject *value)
 }
 
 /* Called by the Python interpreter to perform an inferior function
-   call on the value.  */
+   call on the value.  Returns NULL on error, with a python exception set.  */
 static PyObject *
 valpy_call (PyObject *self, PyObject *args, PyObject *keywords)
 {
@@ -619,7 +620,8 @@ enum valpy_opcode
   ((TYPE_CODE (TYPE) == TYPE_CODE_REF) ? (TYPE_TARGET_TYPE (TYPE)) : (TYPE))
 
 /* Returns a value object which is the result of applying the operation
-   specified by OPCODE to the given arguments.  */
+   specified by OPCODE to the given arguments.  Returns NULL on error, with
+   a python exception set.  */
 static PyObject *
 valpy_binop (enum valpy_opcode opcode, PyObject *self, PyObject *other)
 {
@@ -871,7 +873,8 @@ valpy_xor (PyObject *self, PyObject *other)
   return valpy_binop (VALPY_BITXOR, self, other);
 }
 
-/* Implements comparison operations for value objects.  */
+/* Implements comparison operations for value objects.  Returns NULL on error,
+   with a python exception set.  */
 static PyObject *
 valpy_richcompare (PyObject *self, PyObject *other, int op)
 {
diff --git a/gdb/python/python.c b/gdb/python/python.c
index bbff55f..78410c6 100644
--- a/gdb/python/python.c
+++ b/gdb/python/python.c
@@ -79,6 +79,7 @@ struct python_env
   PyGILState_STATE state;
   struct gdbarch *gdbarch;
   const struct language_defn *language;
+  PyObject *error_type, *error_value, *error_traceback;
 };
 
 static void
@@ -86,6 +87,16 @@ restore_python_env (void *p)
 {
   struct python_env *env = (struct python_env *)p;
 
+  /* Leftover Python error is forbidden by Python Exception Handling.  */
+  if (PyErr_Occurred ())
+    {
+      /* This order is similar to the one calling error afterwards. */
+      gdbpy_print_stack ();
+      warning (_("internal error: Unhandled Python exception"));
+    }
+
+  PyErr_Restore (env->error_type, env->error_value, env->error_traceback);
+
   PyGILState_Release (env->state);
   python_gdbarch = env->gdbarch;
   python_language = env->language;
@@ -108,6 +119,9 @@ ensure_python_env (struct gdbarch *gdbarch,
   python_gdbarch = gdbarch;
   python_language = language;
 
+  /* Save it and ensure ! PyErr_Occurred () afterwards.  */
+  PyErr_Fetch (&env->error_type, &env->error_value, &env->error_traceback);
+  
   return make_cleanup (restore_python_env, env);
 }
 
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index f94b56b..bc3b2fc 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2010-10-13  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
+	* gdb.python/py-error.exp: New file.
+	* gdb.python/py-error.py: New file.
+
 2010-10-12  Jan Kratochvil  <jan.kratochvil@redhat.com>
 
 	* gdb.base/break-interp.exp (test_ld): Replace gdb_expect by
diff --git a/gdb/testsuite/gdb.python/py-error.exp b/gdb/testsuite/gdb.python/py-error.exp
new file mode 100644
index 0000000..a366fc3
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-error.exp
@@ -0,0 +1,56 @@
+# Copyright (C) 2010 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Test error while loading *-gdb.py.  IBM1047 is chosen as possibly supported
+# by glibc but unsupported by Python
+
+set testfile "py-error"
+
+load_lib gdb-python.exp
+
+# Start with a fresh gdb.
+gdb_exit
+gdb_start
+
+# Skip all tests if Python scripting is not enabled.
+if { [skip_python_tests] } { continue }
+
+set charset "IBM1047"
+
+set test2 "main reached"
+
+set test "set host-charset $charset"
+set test_regex [string_to_regexp $test]
+gdb_test_multiple $test $test {
+    -re "^$test_regex\r\n$gdb_prompt $" {
+	pass $test
+    }
+    -re "^$test_regex\r\nUndefined item: \"$charset\"\\.\r\n$gdb_prompt $" {
+	xfail $test
+	untested $test2
+	set test2 ""
+    }
+}
+
+if {$test2 == ""} {
+    return 0
+}
+
+set remote_python_file [remote_download host ${srcdir}/${subdir}/${testfile}.py]
+
+# argc=LookupError: unknown encoding: IBM1047
+gdb_test "source $remote_python_file" "Traceback.*ClassName.*\r\nLookupError: unknown encoding: $charset" $test2
+
+gdb_test "p 1" " = 1" "no delayed error"
diff --git a/gdb/testsuite/gdb.python/py-error.py b/gdb/testsuite/gdb.python/py-error.py
new file mode 100644
index 0000000..9182a09
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-error.py
@@ -0,0 +1,25 @@
+# Copyright (C) 2010 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import gdb
+
+class ClassName(gdb.Command):
+    'a'
+    def __init__(self):
+        gdb.Command.__init__ (self, "ClassName", gdb.COMMAND_DATA, prefix=True)
+    def invoke(self, args, from_tty):
+        print
+
+ClassName()
diff --git a/gdb/varobj.c b/gdb/varobj.c
index 56cb8ae..e56bbf7 100644
--- a/gdb/varobj.c
+++ b/gdb/varobj.c
@@ -1052,6 +1052,8 @@ update_dynamic_varobj_children (struct varobj *var,
 	    error (_("Invalid item from the child list"));
 
 	  v = convert_value_from_python (py_v);
+	  if (v == NULL)
+	    gdbpy_print_stack ();
 	  install_dynamic_child (var, can_mention ? changed : NULL,
 				 can_mention ? new : NULL,
 				 can_mention ? unchanged : NULL,
@@ -2540,6 +2542,8 @@ value_get_print_value (struct value *value, enum varobj_display_formats format,
 			type = builtin_type (gdbarch)->builtin_char;
 			Py_DECREF (py_str);
 		      }
+		    else
+		      gdbpy_print_stack ();
 		  }
 		Py_DECREF (output);
 	      }