From 03b60609ec63d00f0c5630daac92b3cd460c2b69 Mon Sep 17 00:00:00 2001
From: William Zijie Zhang <willizz@Williams-MacBook-Pro.local>
Date: Mon, 24 Jun 2024 14:07:32 -0700
Subject: [PATCH] fixing issues with difference in backends, will need to make
 changes to solving chain as well

---
 cvxpy/atoms/affine/sum.py          | 11 ++++-------
 cvxpy/cvxcore/python/cppbackend.py |  2 +-
 cvxpy/lin_ops/lin_utils.py         |  4 +---
 3 files changed, 6 insertions(+), 11 deletions(-)

diff --git a/cvxpy/atoms/affine/sum.py b/cvxpy/atoms/affine/sum.py
index e7f2599dd9..fe46653b63 100644
--- a/cvxpy/atoms/affine/sum.py
+++ b/cvxpy/atoms/affine/sum.py
@@ -22,7 +22,6 @@
 import cvxpy.interface as intf
 import cvxpy.lin_ops.lin_op as lo
 import cvxpy.lin_ops.lin_utils as lu
-import cvxpy.settings as s
 from cvxpy.atoms.affine.affine_atom import AffAtom
 from cvxpy.atoms.axis_atom import AxisAtom
 from cvxpy.constraints.constraint import Constraint
@@ -84,9 +83,10 @@ def graph_implementation(
         tuple
             (LinOp for objective, list of constraints)
         """
-        if s.DEFAULT_CANON_BACKEND == 'CPP':
-            axis = data[0]
-            keepdims = data[1]
+        axis, keepdims = data
+        if len(arg_objs[0].shape) > 2 or axis not in {None, 0, 1}:
+            obj = lu.sum_entries(arg_objs[0], shape=shape, axis=axis, keepdims=keepdims)
+        else:
             if axis is None:
                 obj = lu.sum_entries(arg_objs[0], shape=shape)
             elif axis == 1:
@@ -103,9 +103,6 @@ def graph_implementation(
                     const_shape = (arg_objs[0].shape[0],)
                 ones = lu.create_const(np.ones(const_shape), const_shape)
                 obj = lu.mul_expr(ones, arg_objs[0], shape)
-        else:
-            axis, keepdims = data
-            obj = lu.sum_entries(arg_objs[0], shape=shape, axis=axis, keepdims=keepdims)
         return (obj, [])
 
 
diff --git a/cvxpy/cvxcore/python/cppbackend.py b/cvxpy/cvxcore/python/cppbackend.py
index 2f4648afb3..52141ecfb6 100644
--- a/cvxpy/cvxcore/python/cppbackend.py
+++ b/cvxpy/cvxcore/python/cppbackend.py
@@ -175,7 +175,7 @@ def make_linC_from_linPy(linPy, linPy_to_linC) -> None:
     linC = cvxcore.LinOp(typ, shape, lin_args_vec)
     linPy_to_linC[linPy] = linC
 
-    if linPy.data is not None:
+    if linPy.data is not None and linPy.type != "sum_entries":
         if isinstance(linPy.data, lo.LinOp):
             linC_data = linPy_to_linC[linPy.data]
             linC.set_linOp_data(linC_data)
diff --git a/cvxpy/lin_ops/lin_utils.py b/cvxpy/lin_ops/lin_utils.py
index 5217335ba7..35ce351065 100644
--- a/cvxpy/lin_ops/lin_utils.py
+++ b/cvxpy/lin_ops/lin_utils.py
@@ -21,7 +21,6 @@
 import numpy as np
 
 import cvxpy.lin_ops.lin_op as lo
-import cvxpy.settings as s
 import cvxpy.utilities as u
 from cvxpy.lin_ops.lin_constraints import LinEqConstr, LinLeqConstr
 
@@ -384,8 +383,7 @@ def sum_entries(operator, shape: Tuple[int, ...], axis=None, keepdims=None):
     LinOp
         An operator representing the sum.
     """
-    data = None if s.DEFAULT_CANON_BACKEND == "CPP" else [axis, keepdims]
-    return lo.LinOp(lo.SUM_ENTRIES, shape, [operator], data=data)
+    return lo.LinOp(lo.SUM_ENTRIES, shape, [operator], data=[axis, keepdims])
 
 
 def trace(operator):