Fix bug in map_fusion transformation

dace/transformation/dataflow/map_fusion.py

@@ -480,6 +480,10 @@
             else:
                 local_node = edge.src
                 src_connector = edge.src_conn
+                if isinstance(edge.src, nodes.AccessNode):
+                    edge.data.data = edge.src.data
+                elif isinstance(edge.dst, nodes.AccessNode):
+                    edge.data.data = edge.dst.data
 
             # If destination of edge leads to multiple destinations, redirect all through an access node.
             if other_edges:

tests/transformations/mapfusion_test.py

@@ -163,6 +163,43 @@ def test_fusion_with_transient():
     assert np.allclose(A, expected)
 
 
+def test_fusion_with_transient_scalar():
+    N = 10
+    K = 4
+
+    def build_sdfg():
+        sdfg = dace.SDFG("map_fusion_with_transient_scalar")
+        state = sdfg.add_state()
+        sdfg.add_array("A",  (N,K), dace.float64)
+        sdfg.add_array("B",  (N,), dace.float64)
+        sdfg.add_array("T",  (N,), dace.float64, transient=True)
+        t_node = state.add_access("T")
+        sdfg.add_scalar("V",  dace.float64, transient=True)
+        v_node = state.add_access("V")
+
+        me1, mx1 = state.add_map("map1", dict(i=f"0:{N}"))
+        tlet1 = state.add_tasklet("select", {"_v"}, {"_out"}, f"_out = _v[i, {K-1}]")
+        state.add_memlet_path(state.add_access("A"), me1, tlet1, dst_conn="_v", memlet=dace.Memlet.from_array("A", sdfg.arrays["A"]))
+        state.add_edge(tlet1, "_out", v_node, None, dace.Memlet("V[0]"))
+        state.add_memlet_path(v_node, mx1, t_node, memlet=dace.Memlet("T[i]"))
+
+        me2, mx2 = state.add_map("map2", dict(j=f"0:{N}"))
+        tlet2 = state.add_tasklet("numeric", {"_inp"}, {"_out"}, f"_out = _inp + 1")
+        state.add_memlet_path(t_node, me2, tlet2, dst_conn="_inp", memlet=dace.Memlet("T[j]"))
+        state.add_memlet_path(tlet2, mx2, state.add_access("B"), src_conn="_out", memlet=dace.Memlet("B[j]"))
+
+        return sdfg
+
+    sdfg = build_sdfg()
+    sdfg.apply_transformations(MapFusion)
+
+    A = np.random.rand(N, K)
+    B = np.repeat(np.nan, N)
+    sdfg(A=A, B=B)
+
+    assert np.allclose(B, (A[:, K-1] + 1))
+
+
 def test_fusion_with_inverted_indices():
 
     @dace.program
@@ -278,6 +315,7 @@ def fusion_with_nested_sdfg_1(A: dace.int32[10], B: dace.int32[10], C: dace.int3
     test_multiple_fusions()
     test_fusion_chain()
     test_fusion_with_transient()
+    test_fusion_with_transient_scalar()
     test_fusion_with_inverted_indices()
     test_fusion_with_empty_memlet()
     test_fusion_with_nested_sdfg_0()