Nogil transpose

Cython/Compiler/ExprNodes.py

@@ -4196,10 +4196,6 @@ class AttributeNode(ExprNode):
         elif self.type.is_memoryviewslice:
             if self.is_memslice_transpose:
                 # transpose the slice
-                if self.in_nogil_context:
-                    error(self.pos, "Cannot transpose slice in nogil mode")
-                    return
-
                 for access, packing in self.type.axes:
                     if access == 'ptr':
                         error(self.pos, "Transposing not supported for slices "
@@ -4207,7 +4203,7 @@ class AttributeNode(ExprNode):
                         return
 
                 code.putln("%s = %s;" % (self.result(), self.obj.result()))
-                if self.obj.is_name:
+                if self.obj.is_name or self.obj.is_attribute and self.obj.is_memslice_transpose:
                     code.put_incref_memoryviewslice(self.result(), have_gil=True)
 
                 T = "__pyx_memslice_transpose(&%s) == 0"
@@ -4259,7 +4255,8 @@ class AttributeNode(ExprNode):
             elif self.type.is_memoryviewslice:
                 import MemoryView
                 MemoryView.put_assign_to_memviewslice(
-                        select_code, rhs.result(), self.type, code)
+                        select_code, rhs.result(), self.type, code,
+                        incref_rhs=rhs.is_name)
 
             if not self.type.is_memoryviewslice:
                 code.putln(

Cython/Utility/MemoryView.pyx

@@ -723,7 +723,7 @@ cdef char *pybuffer_index(Py_buffer *view, char *bufp, Py_ssize_t index,
 ### Transposing a memoryviewslice
 #
 @cname('__pyx_memslice_transpose')
-cdef int transpose_memslice({{memviewslice_name}} *memslice) except 0:
+cdef int transpose_memslice({{memviewslice_name}} *memslice) nogil except 0:
     cdef int ndim = memslice.memview.view.ndim
 
     cdef Py_ssize_t *shape = memslice.shape
@@ -737,9 +737,8 @@ cdef int transpose_memslice({{memviewslice_name}} *memslice) except 0:
         shape[i], shape[j] = shape[j], shape[i]
 
         if memslice.suboffsets[i] >= 0 or memslice.suboffsets[j] >= 0:
-            dim = i if memslice.suboffsets[i] >= 0 else j
-            raise ValueError("Cannot transpose view with indirect dimension "
-                             "(axis %d)" % dim)
+            with gil:
+                raise ValueError("Cannot transpose memoryview with indirect dimensions")
 
     return 1
 

tests/run/numpy_memoryview.pyx

@@ -163,6 +163,13 @@ def test_transpose():
     print a_obj.T.shape
     print numpy_obj.T.shape
 
+    cdef dtype_t[:, :] c
+    with nogil:
+        c = a.T.T
+
+    assert (<object> a).shape == (<object> c).shape
+    assert (<object> a).strides == (<object> c).strides
+
     print a[3, 2], a.T[2, 3], a_obj[3, 2], a_obj.T[2, 3], numpy_obj[3, 2], numpy_obj.T[2, 3]
 
 def test_coerce_to_numpy():