check that cython does not automatically convert from native type to an object...

check that cython does not automatically convert from native type to an object whenn calling cpp funtions. added file  tests/errors/cpp_no_auto_conversion.pyx

tests/errors/cpp_no_auto_conversion.pyx

+# mode: error
+# tag: cpp
+
+# cpp will convert function arguments to a type if it has suitable constructor
+# we do not want that when calling from cython
+
+cdef extern from "no_such_file.cpp" nogil:
+    cppclass wrapped_int:
+        long long val
+        wrapped_int()
+        wrapped_int(long long val)
+        wrapped_int& operator=(const wrapped_int &other)
+        wrapped_int& operator=(const long long other)
+
+    long long constructor_overload(const wrapped_int& x)
+    long long constructor_overload(const wrapped_int x)
+
+cdef long long e = constructor_overload(17)
+ 
+
+_ERRORS = u"""
+18:40: Cannot assign type 'long' to 'const wrapped_int'
+"""