fix cascaded assignments to buffer indices: forgot to reassign the analysed...

fix cascaded assignments to buffer indices: forgot to reassign the analysed (and potentially replaced) node in the tree

Cython/Compiler/Nodes.py

@@ -5126,8 +5126,8 @@ class CascadedAssignmentNode(AssignmentNode):
 
         # collect distinct types used on the LHS
         lhs_types = set()
-        for lhs in self.lhs_list:
-            lhs.analyse_target_types(env)
+        for i, lhs in enumerate(self.lhs_list):
+            lhs = self.lhs_list[i] = lhs.analyse_target_types(env)
             lhs.gil_assignment_check(env)
             lhs_types.add(lhs.type)
 

tests/buffers/bufaccess.pyx

@@ -483,6 +483,63 @@ def set_int_2d(object[int, ndim=2] buf, int i, int j, int value):
     """
     buf[i, j] = value
 
+@testcase
+def set_int_2d_cascaded(object[int, ndim=2] buf, int i, int j, int value):
+    """
+    Uses get_int_2d to read back the value afterwards. For pure
+    unit test, one should support reading in MockBuffer instead.
+
+    >>> C = IntMockBuffer("C", range(6), (2,3))
+    >>> set_int_2d_cascaded(C, 1, 1, 10)
+    acquired C
+    released C
+    10
+    >>> get_int_2d(C, 1, 1)
+    acquired C
+    released C
+    10
+
+    Check negative indexing:
+    >>> set_int_2d_cascaded(C, -1, 0, 3)
+    acquired C
+    released C
+    3
+    >>> get_int_2d(C, -1, 0)
+    acquired C
+    released C
+    3
+
+    >>> set_int_2d_cascaded(C, -1, -2, 8)
+    acquired C
+    released C
+    8
+    >>> get_int_2d(C, -1, -2)
+    acquired C
+    released C
+    8
+
+    >>> set_int_2d_cascaded(C, -2, -3, 9)
+    acquired C
+    released C
+    9
+    >>> get_int_2d(C, -2, -3)
+    acquired C
+    released C
+    9
+
+    Out-of-bounds errors:
+    >>> set_int_2d_cascaded(C, 2, 0, 19)
+    Traceback (most recent call last):
+    IndexError: Out of bounds on buffer access (axis 0)
+    >>> set_int_2d_cascaded(C, 0, -4, 19)
+    Traceback (most recent call last):
+    IndexError: Out of bounds on buffer access (axis 1)
+
+    """
+    cdef int casc_value
+    buf[i, j] = casc_value = value
+    return casc_value
+
 @testcase
 def list_comprehension(object[int] buf, len):
     """