Lock around error info decrefs in nogil try/finally

Cython/Compiler/Nodes.py

@@ -5488,10 +5488,16 @@ class TryFinallyStatNode(StatNode):
                 over_label = code.new_label()
                 code.put_goto(over_label)
                 code.put_label(finally_error_label)
+
                 code.putln("if (__pyx_why == %d) {" % (error_label_case + 1))
+                if self.is_try_finally_in_nogil:
+                    code.put_ensure_gil(declare_gilstate=False)
                 for var in Naming.exc_vars:
                     code.putln("Py_XDECREF(%s);" % var)
+                if self.is_try_finally_in_nogil:
+                    code.put_release_ensured_gil()
                 code.putln("}")
+
                 code.put_goto(old_error_label)
                 code.put_label(over_label)
 
@@ -5543,7 +5549,8 @@ class TryFinallyStatNode(StatNode):
 
     def put_error_uncatcher(self, code, i, error_label):
         code.globalstate.use_utility_code(restore_exception_utility_code)
-        code.putln("case %s: {" % i)
+        code.putln(
+            "case %s: {" % i)
 
         if self.is_try_finally_in_nogil:
             code.put_ensure_gil(declare_gilstate=False)
@@ -5555,10 +5562,12 @@ class TryFinallyStatNode(StatNode):
             code.put_release_ensured_gil()
 
         for var in Naming.exc_vars:
-            code.putln("%s = 0;" % var)
+            code.putln(
+                   "%s = 0;" % var)
 
         code.put_goto(error_label)
-        code.putln("}")
+        code.putln(
+            "}")
 
     def annotate(self, code):
         self.body.annotate(code)

tests/errors/nogil.pyx

@@ -157,6 +157,6 @@ _ERRORS = u"""
 59:17: Truth-testing Python object not allowed without gil
 61:8: For-loop using object bounds or target not allowed without gil
 63:8: Try-except statement not allowed without gil
-67:8: Try-finally statement not allowed without gil
+67:8: Cannot use try/finally in nogil sections unless it contains a 'with gil' statement.
 84:8: For-loop using object bounds or target not allowed without gil
 """

tests/run/with_gil.pyx

@@ -387,3 +387,48 @@ def test_nogil_try_finally_propagate_exception():
                 puts("Execute finally clause")
     except Exception, e:
         print e
+
+def test_nogil_try_finally_return_in_with_gil(x):
+    """
+    >>> test_nogil_try_finally_return_in_with_gil(10)
+    (None, None, None)
+    10
+    """
+    # For some reason, this exception is set, clear it first
+    # (<type 'exceptions.ImportError'>,
+    #  ImportError('cannot import name _TextTestResult',),
+    #  <traceback object at 0x10073c4d0>)
+    sys.exc_clear()
+
+    with nogil:
+        try:
+            with gil:
+                raise Exception("Swallow me!")
+        finally:
+            with gil:
+                print sys.exc_info()
+                return x
+
+    print "I am not executed", sys.exc_info()
+
+cdef void nogil_try_finally_return() nogil:
+    try:
+        with gil:
+            raise Exception("I am swallowed in nogil code... right?")
+    finally:
+        with gil:
+            print sys.exc_info()
+
+        return
+
+    with gil:
+        print "I am not executed", sys.exc_info()
+
+def test_nogil_try_finally_return():
+    """
+    >>> test_nogil_try_finally_return()
+    (None, None, None)
+    """
+    sys.exc_clear()
+    with nogil:
+        nogil_try_finally_return()