From cd9d2b2a3611f23f4c044c3e2a1f852583e078f7 Mon Sep 17 00:00:00 2001
From: Stefan Behnel <scoder@users.berlios.de>
Date: Sun, 26 Dec 2010 22:34:22 +0100
Subject: [PATCH] fix bug 633: make sure we own references to Python arguments
 passed into C functions

---
 Cython/Compiler/ExprNodes.py |  9 ++++++++-
 tests/run/owned_arg_refs.pyx | 28 ++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 1 deletion(-)
 create mode 100644 tests/run/owned_arg_refs.pyx

diff --git a/Cython/Compiler/ExprNodes.py b/Cython/Compiler/ExprNodes.py
index c0440641..8aead92c 100755
--- a/Cython/Compiler/ExprNodes.py
+++ b/Cython/Compiler/ExprNodes.py
@@ -2953,7 +2953,14 @@ class SimpleCallNode(CallNode):
         # Coerce arguments
         for i in range(min(max_nargs, actual_nargs)):
             formal_type = func_type.args[i].type
-            self.args[i] = self.args[i].coerce_to(formal_type, env)
+            arg = self.args[i].coerce_to(formal_type, env)
+            if arg.is_attribute or not arg.is_simple:
+                # we do not own the argument's reference, but we must
+                # make sure it cannot be collected before we return
+                # from the function, so we create an owned temp
+                # reference to it
+                arg = arg.coerce_to_temp(env)
+            self.args[i] = arg
         for i in range(max_nargs, actual_nargs):
             if self.args[i].type.is_pyobject:
                 error(self.args[i].pos,
diff --git a/tests/run/owned_arg_refs.pyx b/tests/run/owned_arg_refs.pyx
new file mode 100644
index 00000000..5bf84d76
--- /dev/null
+++ b/tests/run/owned_arg_refs.pyx
@@ -0,0 +1,28 @@
+
+cdef class Owner:
+    cdef object x
+
+cdef call_me_with_owner(Owner owner, x):
+    owner.x = "def" # overwrite external reference
+    return x        # crashes if x is not owned by function or caller
+
+def test_ext_type_attr():
+    """
+    >>> test_ext_type_attr()
+    'abc5'
+    """
+    owner = Owner()
+    owner.x = ''.join("abc%d" % 5) # non-interned object
+    return call_me_with_owner(owner, owner.x)
+
+cdef call_me_with_list(list l, x):
+    l[:] = [(1,2), (3,4)] # overwrite external reference
+    return x              # crashes if x is not owned by function or caller
+
+def test_index():
+    """
+    >>> test_index()
+    [3, 4]
+    """
+    l = [[1,2],[3,4]]
+    return call_me_with_list(l, l[1])
-- 
2.26.2