From 392f16ccb8a96b4cc6eb74465fdbe61ea0e00041 Mon Sep 17 00:00:00 2001
From: Ivan Smirnov <i.s.smirnov@gmail.com>
Date: Sun, 28 Aug 2016 21:25:25 +0100
Subject: [PATCH 1/2] Properly format type name in error_already_set()

---
 include/pybind11/cast.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/pybind11/cast.h b/include/pybind11/cast.h
index b4698d81..5783c1a6 100644
--- a/include/pybind11/cast.h
+++ b/include/pybind11/cast.h
@@ -111,7 +111,7 @@ PYBIND11_NOINLINE inline std::string error_string() {
 
    std::string errorString;
     if (type) {
-        errorString += (std::string) handle(type).str();
+        errorString += handle(type).attr("__name__").cast<std::string>();
         errorString += ": ";
     }
     if (value)

From 67b54894b2e590279493270af7e859e3d0107e93 Mon Sep 17 00:00:00 2001
From: Ivan Smirnov <i.s.smirnov@gmail.com>
Date: Wed, 7 Sep 2016 21:10:16 +0100
Subject: [PATCH 2/2] Set error if it's not set in error_already_set()

---
 include/pybind11/cast.h   | 11 ++++++++---
 tests/test_exceptions.cpp | 20 +++++++++++++++++++-
 tests/test_exceptions.py  | 12 ++++++++++++
 3 files changed, 39 insertions(+), 4 deletions(-)

diff --git a/include/pybind11/cast.h b/include/pybind11/cast.h
index 5783c1a6..080b2e09 100644
--- a/include/pybind11/cast.h
+++ b/include/pybind11/cast.h
@@ -106,10 +106,15 @@ PYBIND11_NOINLINE inline handle get_type_handle(const std::type_info &tp) {
 }
 
 PYBIND11_NOINLINE inline std::string error_string() {
-   PyObject *type, *value, *traceback;
-   PyErr_Fetch(&type, &value, &traceback);
+    if (!PyErr_Occurred()) {
+        PyErr_SetString(PyExc_RuntimeError, "Unknown internal error occurred");
+        return "Unknown internal error occurred";
+    }
 
-   std::string errorString;
+    PyObject *type, *value, *traceback;
+    PyErr_Fetch(&type, &value, &traceback);
+
+    std::string errorString;
     if (type) {
         errorString += handle(type).attr("__name__").cast<std::string>();
         errorString += ": ";
diff --git a/tests/test_exceptions.cpp b/tests/test_exceptions.cpp
index 534f23bf..67133a63 100644
--- a/tests/test_exceptions.cpp
+++ b/tests/test_exceptions.cpp
@@ -104,5 +104,23 @@ test_initializer custom_exceptions([](py::module &m) {
     m.def("throws3", &throws3);
     m.def("throws4", &throws4);
     m.def("throws_logic_error", &throws_logic_error);
-});
 
+    m.def("throw_already_set", [](bool err) {
+        if (err)
+            PyErr_SetString(PyExc_ValueError, "foo");
+        try {
+            throw py::error_already_set();
+        } catch (const std::runtime_error& e) {
+            if ((err && e.what() != std::string("ValueError: foo")) ||
+                (!err && e.what() != std::string("Unknown internal error occurred")))
+            {
+                PyErr_Clear();
+                throw std::runtime_error("error message mismatch");
+            }
+        }
+        PyErr_Clear();
+        if (err)
+            PyErr_SetString(PyExc_ValueError, "foo");
+        throw py::error_already_set();
+    });
+});
diff --git a/tests/test_exceptions.py b/tests/test_exceptions.py
index 24f9769b..a92300c3 100644
--- a/tests/test_exceptions.py
+++ b/tests/test_exceptions.py
@@ -1,6 +1,18 @@
 import pytest
 
 
+def test_error_already_set(msg):
+    from pybind11_tests import throw_already_set
+
+    with pytest.raises(RuntimeError) as excinfo:
+        throw_already_set(False)
+    assert msg(excinfo.value) == "Unknown internal error occurred"
+
+    with pytest.raises(ValueError) as excinfo:
+        throw_already_set(True)
+    assert msg(excinfo.value) == "foo"
+
+
 def test_custom(msg):
     from pybind11_tests import (MyException, throws1, throws2, throws3, throws4,
                                 throws_logic_error)