feat[next]: Support for local dimension in output

pyproject.toml

@@ -342,6 +342,7 @@ markers = [
   'uses_reduction_with_only_sparse_fields: tests that require backend support for with sparse fields',
   'uses_scan_in_field_operator: tests that require backend support for scan in field operator',
   'uses_sparse_fields: tests that require backend support for sparse fields',
+  'uses_sparse_fields_as_output: tests that require backend support for writing sparse fields',
   'uses_strided_neighbor_offset: tests that require backend support for strided neighbor offset',
   'uses_tuple_args: tests that require backend support for tuple arguments',
   'uses_tuple_returns: tests that require backend support for tuple results',

tests/next_tests/exclusion_matrices.py

@@ -95,6 +95,7 @@ class ProgramFormatterId(_PythonObjectIdMixin, str, enum.Enum):
 USES_REDUCTION_OVER_LIFT_EXPRESSIONS = "uses_reduction_over_lift_expressions"
 USES_SCAN_IN_FIELD_OPERATOR = "uses_scan_in_field_operator"
 USES_SPARSE_FIELDS = "uses_sparse_fields"
+USES_SPARSE_FIELDS_AS_OUTPUT = "uses_sparse_fields_as_output"
 USES_REDUCTION_WITH_ONLY_SPARSE_FIELDS = "uses_reduction_with_only_sparse_fields"
 USES_STRIDED_NEIGHBOR_OFFSET = "uses_strided_neighbor_offset"
 USES_TUPLE_ARGS = "uses_tuple_args"
@@ -119,6 +120,7 @@ class ProgramFormatterId(_PythonObjectIdMixin, str, enum.Enum):
     (USES_NEGATIVE_MODULO, XFAIL, UNSUPPORTED_MESSAGE),
     (USES_REDUCTION_WITH_ONLY_SPARSE_FIELDS, XFAIL, REDUCTION_WITH_ONLY_SPARSE_FIELDS_MESSAGE),
     (USES_SCAN_IN_FIELD_OPERATOR, XFAIL, UNSUPPORTED_MESSAGE),
+    (USES_SPARSE_FIELDS_AS_OUTPUT, XFAIL, UNSUPPORTED_MESSAGE),
 ]
 DACE_SKIP_TEST_LIST = COMMON_SKIP_TEST_LIST + [
     (USES_CONSTANT_FIELDS, XFAIL, UNSUPPORTED_MESSAGE),
@@ -160,4 +162,5 @@ class ProgramFormatterId(_PythonObjectIdMixin, str, enum.Enum):
     ProgramFormatterId.GTFN_CPP_FORMATTER: [
         (USES_REDUCTION_WITH_ONLY_SPARSE_FIELDS, XFAIL, REDUCTION_WITH_ONLY_SPARSE_FIELDS_MESSAGE),
     ],
+    ProgramBackendId.ROUNDTRIP: [(USES_SPARSE_FIELDS_AS_OUTPUT, XFAIL, UNSUPPORTED_MESSAGE)],
 }

tests/next_tests/integration_tests/feature_tests/ffront_tests/test_external_local_field.py

@@ -82,3 +82,22 @@ def testee(inp: gtx.Field[[Vertex, V2EDim], int32]) -> gtx.Field[[Vertex], int32
         out=cases.allocate(unstructured_case, testee, cases.RETURN)(),
         ref=np.sum(unstructured_case.offset_provider["V2E"].table, axis=1),
     )
+
+
+@pytest.mark.uses_sparse_fields_as_output
+def test_write_local_field(unstructured_case):
+    @gtx.field_operator
+    def testee(inp: gtx.Field[[Edge], int32]) -> gtx.Field[[Vertex, V2EDim], int32]:
+        return inp(V2E)
+
+    out = unstructured_case.as_field(
+        [Vertex, V2EDim], np.zeros_like(unstructured_case.offset_provider["V2E"].table)
+    )
+    inp = cases.allocate(unstructured_case, testee, "inp")()
+    cases.verify(
+        unstructured_case,
+        testee,
+        inp,
+        out=out,
+        ref=inp.asnumpy()[unstructured_case.offset_provider["V2E"].table],
+    )