Some crash fix and skip some tests when g++ isn't available.

theano/compile/tests/test_function_module.py

@@ -371,7 +371,12 @@ class T_function(unittest.TestCase):
         four = f(o)
         assert numpy.all(four==4)
         f(o+.1) #should clobber the memory used to store four
-        assert not numpy.all(four==4)
+        if theano.config.cxx:
+            assert not numpy.all(four==4)
+        else:
+            # The Elemwise.perform method don't reuse memory
+            # as some numpy version don't support that correctly.
+            assert numpy.all(four==4)
 
     def test_disconnected_input(self):
         a = T.scalar('a')

theano/configdefaults.py

@@ -160,7 +160,7 @@ else:
     AddConfigVar('linker',
                  ("Default linker used if the theano flags mode is Mode "
                   "or ProfileMode(deprecated)"),
-                 EnumStr('py', 'vm', 'vm_nogc'),
+                 EnumStr('vm', 'py', 'vm_nogc'),
                  in_c_key=False)
     _logger.warning('g++ not detected ! Theano will be unable to execute '
             'optimized C-implementations (for both CPU and GPU) and will '

theano/gof/tests/test_op.py

 import unittest
 
+from nose.plugins.skip import SkipTest
 import numpy
 
 import theano
-
 import theano.gof.op as op
 from theano.gof.type import Type, Generic
 from theano.gof.graph import Apply, Variable
@@ -130,6 +130,8 @@ class TestOp:
         assert rval == 'test Op no input'
 
     def test_op_struct(self):
+        if not theano.config.cxx:
+            raise SkipTest("G++ not available, so we need to skip this test.")
         sop = StructOp()
         c = sop(theano.tensor.constant(0))
         mode = None

theano/gof/tests/test_types.py

 import numpy
-import theano
 
+import theano
 from theano import Op, Apply
 from theano.tensor import TensorType
-
 from theano.gof.type import CDataType
 
+from nose.plugins.skip import SkipTest
+
 # todo: test generic
 
+
 class ProdOp(Op):
     __props__ = ()
 
@@ -57,6 +59,8 @@ Py_INCREF(%(out)s);
 
 
 def test_cdata():
+    if not theano.config.cxx:
+        raise SkipTest("G++ not available, so we need to skip this test.")
     i = TensorType('float32', (False,))()
     c = ProdOp()(i)
     i2 = GetOp()(c)