[PR,18438] PyExc_MemoryError != gdbpy_gdb_memory_error

diff --git a/gdb/python/py-lazy-string.c b/gdb/python/py-lazy-string.c
index c9774ab..97bc9cb 100644
--- a/gdb/python/py-lazy-string.c
+++ b/gdb/python/py-lazy-string.c
@@ -99,7 +99,7 @@  stpy_convert_to_value  (PyObject *self, PyObject *args)

    if (self_string->address == 0)
      {
-      PyErr_SetString (PyExc_MemoryError,
+      PyErr_SetString (gdbpy_gdb_memory_error,
  		       _("Cannot create a value from NULL."));
        return NULL;
      }
@@ -133,7 +133,7 @@  gdbpy_create_lazy_string_object (CORE_ADDR address,  
long length,

    if (address == 0 && length != 0)
      {
-      PyErr_SetString (PyExc_MemoryError,
+      PyErr_SetString (gdbpy_gdb_memory_error,
  		       _("Cannot create a lazy string with address 0x0, " \
  			 "and a non-zero length."));
        return NULL;
diff --git a/gdb/testsuite/gdb.python/py-lazy-string.c  
b/gdb/testsuite/gdb.python/py-lazy-string.c
new file mode 100644
index 0000000..c72e1fa
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-lazy-string.c
@@ -0,0 +1,24 @@ 
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2015 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/>.   
*/
+
+int
+main ()
+{
+  const char *null = 0;
+
+  return 0; /* break here */
+}
diff --git a/gdb/testsuite/gdb.python/py-lazy-string.exp  
b/gdb/testsuite/gdb.python/py-lazy-string.exp
new file mode 100644
index 0000000..55e903e
--- /dev/null
+++ b/gdb/testsuite/gdb.python/py-lazy-string.exp
@@ -0,0 +1,42 @@ 
+# Copyright (C) 2015 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/>.
+
+# This file is part of the GDB testsuite.  It tests lazy string support
+# not tested by py-prettyprinter.exp.
+
+load_lib gdb-python.exp
+
+standard_testfile
+
+if {[prepare_for_testing $testfile.exp $testfile $srcfile {debug c++}]} {
+    return -1
+}
+
+# Skip all tests if Python scripting is not enabled.
+if { [skip_python_tests] } { continue }
+
+if ![runto_main ] {
+    return -1
+}
+
+gdb_breakpoint [gdb_get_line_number "break here"]
+gdb_continue_to_breakpoint "break here"
+
+gdb_test_no_output "python null = gdb.parse_and_eval(\"null\")"
+
+gdb_test "python print null.lazy_string(length=0).value()" \
+    "gdb.MemoryError: Cannot create a value from NULL.*Error while  
executing Python code."
+gdb_test "python print null.lazy_string(length=3).value()" \
+    "gdb.MemoryError: Cannot create a lazy string with address 0x0, and a  
non-zero length.*Error while executing Python code."
diff --git a/gdb/testsuite/gdb.python/py-prettyprint.c  
b/gdb/testsuite/gdb.python/py-prettyprint.c
index 60163d6..b6e111d 100644
--- a/gdb/testsuite/gdb.python/py-prettyprint.c
+++ b/gdb/testsuite/gdb.python/py-prettyprint.c
@@ -42,6 +42,8 @@  struct ns {

  struct lazystring {
    const char *lazy_str;
+  /* If -1, don't pass length to gdb.lazy_string().  */
+  int len;
  };

  struct hint_error {
@@ -270,7 +272,7 @@  main ()
    nostring_type nstype, nstype2;
    struct memory_error me;
    struct ns ns, ns2;
-  struct lazystring estring, estring2;
+  struct lazystring estring, estring2, estring3;
    struct hint_error hint_error;
    struct children_as_list children_as_list;

@@ -295,10 +297,15 @@  main ()
    ns2.null_str = NULL;
    ns2.length = 20;

-  estring.lazy_str = "embedded x\201\202\203\204" ;
+  estring.lazy_str = "embedded x\201\202\203\204";
+  estring.len = -1;

    /* Incomplete UTF-8, but ok Latin-1.  */
    estring2.lazy_str = "embedded x\302";
+  estring2.len = -1;
+
+  estring3.lazy_str = NULL;
+  estring3.len = 42;

  #ifdef __cplusplus
    S cps;
diff --git a/gdb/testsuite/gdb.python/py-prettyprint.exp  
b/gdb/testsuite/gdb.python/py-prettyprint.exp
index 094f956..399f041 100644
--- a/gdb/testsuite/gdb.python/py-prettyprint.exp
+++ b/gdb/testsuite/gdb.python/py-prettyprint.exp
@@ -92,6 +92,8 @@  proc run_lang_tests {exefile lang} {
      gdb_test "print cstring" " = \"const string\""

      gdb_test "print estring" " = \"embedded  
x\\\\201\\\\202\\\\203\\\\204\""
+    gdb_test "print estring3" \
+	" = <error reading variable: Cannot create a lazy string with address  
0x0, and a non-zero length.>"

      gdb_test_no_output "python pp_ls_encoding = 'UTF-8'"
      gdb_test "print estring2" "\"embedded \", <incomplete sequence  
\\\\302>"
diff --git a/gdb/testsuite/gdb.python/py-prettyprint.py  
b/gdb/testsuite/gdb.python/py-prettyprint.py
index c350bfe..442813b 100644
--- a/gdb/testsuite/gdb.python/py-prettyprint.py
+++ b/gdb/testsuite/gdb.python/py-prettyprint.py
@@ -152,10 +152,20 @@  class pp_ls (object):
          self.val = val

      def to_string(self):
+        length = self.val['len']
          if pp_ls_encoding is not None:
-            return self.val['lazy_str'].lazy_string(encoding =  
pp_ls_encoding)
+            if length >= 0:
+                return self.val['lazy_str'].lazy_string(
+                        encoding = pp_ls_encoding,
+                        length = length)
+            else:
+                return self.val['lazy_str'].lazy_string(
+                        encoding = pp_ls_encoding)
          else:
-            return self.val['lazy_str'].lazy_string()
+            if length >= 0:
+                return self.val['lazy_str'].lazy_string(length = length)
+            else:
+                return self.val['lazy_str'].lazy_string()

      def display_hint (self):