Merge pull request #1320 from lamblin/set_error_in_fail

theano/gof/cc.py

@@ -124,8 +124,19 @@ class CodeBlock:
 
 
 def failure_code(sub):
-    """WRITEME"""
-    return "{%(failure_var)s = %(id)s; goto __label_%(id)i;}" % sub
+    """Code contained in sub['fail'], usually substituted for %(fail)s.
+
+    It sets information about current error, then goto the code
+    actually handling the failure, which is defined in struct_gen().
+    """
+    return '''{
+        %(failure_var)s = %(id)s;
+        if (!PyErr_Occurred()) {
+            PyErr_SetString(PyExc_RuntimeError,
+                "Unexpected error in an Op's C code. "
+                "No Python exception was set.");
+            }
+        goto __label_%(id)i;}''' % sub
 
 
 def code_gen(blocks):

theano/sandbox/cuda/elemwise.py

@@ -43,7 +43,7 @@ class NaiveAlgo(object):
     def cache_version(self):
         ver = self.scalar_op.c_code_cache_version()
         if ver:
-            return (16, self.verbose, self.sync, ver)
+            return (17, self.verbose, self.sync, ver)
         else:
             return ver
 
@@ -978,6 +978,15 @@ nd_collapse_[i]=0;
         for (int i = 0; (i< %(nd)s) && (%(oname)s); ++i) {
             if (dims[i] != CudaNdarray_HOST_DIMS(%(oname)s)[i])
             {
+                PyErr_Format(PyExc_ValueError,
+                             "GpuElemwise. Output dimension mis-match. Output"
+                             " %(idx)d (indices start at 0), working inplace"
+                             " on input %(input_idx)s, has shape[%%i] == %%i"
+                             ", but the output's size on that axis is %%i.",
+                             i,
+                             CudaNdarray_HOST_DIMS(%(oname)s)[i],
+                             dims[i]
+                            );
                 Py_DECREF(%(oname)s);
                 %(oname)s = NULL;
                 %(fail)s;