fix ticket #643: infer the type of C function names as function pointers

Cython/Compiler/ExprNodes.py

@@ -1296,6 +1296,9 @@ class NameNode(AtomicExprNode):
             # Unfortunately the type attribute of type objects
             # is used for the pointer to the type they represent.
             return type_type
+        elif self.entry.type.is_cfunction:
+            # special case: referring to a C function must return it's pointer
+            return PyrexTypes.CPtrType(self.entry.type)
         else:
             return self.entry.type
 

tests/run/type_inference.pyx

@@ -199,6 +199,17 @@ def builtin_type_operations():
     T2 = () * 2
     assert typeof(T2) == "tuple object", typeof(T2)
 
+cdef int func(int x):
+    return x+1
+
+def c_functions():
+    """
+    >>> c_functions()
+    """
+    f = func
+    assert typeof(f) == 'int (*)(int)', typeof(f)
+    assert 2 == f(1)
+
 def cascade():
     """
     >>> cascade()