Data same_dim_tags_as fix auto_create_placeholders (#1159)

Don't first create a new size placeholder and then later call declare_same_as.

Esp this is required when declare_same_as becomes stricter (#1143).

Fix wrong batch info:

The dim tag could have an old invalid batch info.
E.g. the global batch_dim when it comes from an old run.

If we really need this, we should validate the dim tag first.

But probably it's better to remove it and clean it up.

Engine reset global batch dim.

returnn/tf/engine.py

@@ -1293,6 +1293,8 @@ def _init_network(self, net_desc, epoch=None):
     use_dataset_pipeline = False
     if self.config.is_true("dataset_pipeline"):
       use_dataset_pipeline = True
+    from returnn.tf.util.data import batch_dim
+    batch_dim.batch = None  # make sure it is reset
     extern_data = ExternData()
     extern_data.init_from_config(config=self.config, auto_create_placeholders=not use_dataset_pipeline)
     if use_dataset_pipeline:

returnn/tf/util/data.py

@@ -2823,11 +2823,6 @@ def __init__(self, name,
       if time_dim_axis is NotSpecified:
         time_dim_axis = _default_time_dim_axis_dim_tags(dim_tags)
       dim_tags = tuple(dim_tags)
-      if auto_create_placeholders:
-        _auto_create_size_placeholders_on_dim_tags(name=name, dim_tags=dim_tags)
-      if batch_dim_axis_ is not None:
-        if dim_tags[batch_dim_axis_].batch and not self._batch:
-          self._batch = dim_tags[batch_dim_axis_].batch
       del shape_
       del batch_dim_axis_
     else:
@@ -2846,7 +2841,7 @@ def __init__(self, name,
       dim_tags = _infer_dim_tags_tuple_from_shape(
         shape, batch_dim_axis=batch_dim_axis, time_dim_axis=time_dim_axis, feature_dim_axis=feature_dim_axis,
         size_placeholder=size_placeholder, name=name,
-        auto_create_placeholders=auto_create_placeholders,
+        extern_data=auto_create_placeholders,
         dim_tags=dim_tags, sparse=sparse)
       del batch_dim_axis
       del shape
@@ -2893,8 +2888,10 @@ def __init__(self, name,
         base_tag = self._dim_tags[_axis]
         if base_tag != _dim_tag:
           base_tag.declare_same_as(_dim_tag)
-          if _dim_tag.dyn_size is not None:
-            self.set_dynamic_size(_axis, _dim_tag.dyn_size)
+        self._dim_tags = self._dim_tags[:_axis] + (_dim_tag,) + self._dim_tags[_axis + 1:]
+    if auto_create_placeholders:
+      # Do that after same_dim_tags_as handling.
+      _auto_create_size_placeholders_on_dim_tags(name=name, dim_tags=self._dim_tags)
     self._adapt_batch_consistent_dim_tags()
     self.sanity_check(assume_complete=False)
 
@@ -5780,7 +5777,7 @@ def _infer_dim_tags_tuple_from_shape(
   size_placeholder,
   dim_tags,
   name,
-  auto_create_placeholders
+  extern_data
 ):
   """
   :param tuple[int|None]|list[int|None] shape: this is without batch-dim-axis
@@ -5790,7 +5787,7 @@ def _infer_dim_tags_tuple_from_shape(
   :param bool sparse:
   :param dict[int,tf.Tensor]|None size_placeholder: key is axis without batch-dim
   :param dict[int,Dim]|None dim_tags: some existing explicitly specified dim tags. key is axis with batch-dim
-  :param bool auto_create_placeholders:
+  :param bool extern_data:
   :param str name:
   :return: dim tags tuple
   :rtype: tuple[Dim]
@@ -5808,8 +5805,6 @@ def _infer_dim_tags_tuple_from_shape(
   dim_tags = dim_tags.copy() if dim_tags else {}
   if batch_dim_axis is not None and batch_dim_axis not in dim_tags:
     dim_tags[batch_dim_axis] = Dim(kind=Dim.Types.Batch, description="batch:%s" % name)
-  # noinspection PyShadowingNames
-  batch_dim = dim_tags[batch_dim_axis] if batch_dim_axis is not None else None
   # Note: Consistent to Data.get_dim_tag,
   # prefer interpretation as spatial axis if there is a dynamic size or this is marked as time axis.
   if size_placeholder:
@@ -5833,7 +5828,7 @@ def _infer_dim_tags_tuple_from_shape(
     axis_wo_b = _get_axis_wo_b(axis, batch_dim_axis=batch_dim_axis)
     dyn_size = size_placeholder.get(axis_wo_b) if (size_placeholder and axis_wo_b is not None) else None
     dim = batch_shape[axis]
-    if auto_create_placeholders and dim is None and dyn_size is None and axis != batch_dim_axis:
+    if extern_data and dim is None and dyn_size is None and axis != batch_dim_axis:
       if not tag:
         if axis == time_dim_axis:
           tag_name = "time"
@@ -5845,7 +5840,6 @@ def _infer_dim_tags_tuple_from_shape(
           # This is such that Dim.is_equal behaves as before, e.g. in Data.get_common_data.
           kind=Dim.Types.Spatial)
         dim_tags[axis] = tag
-      _create_size_placeholder(name=name, axis_wo_b=axis_wo_b, tag=tag, batch_dim=batch_dim)
       dyn_size = tag.dyn_size
     if tag:
       # Just some sanity checks.

tests/test_TFNetworkLayer.py

@@ -2223,12 +2223,13 @@ def test_SplitDimsLayer_dim_tags():
     feat_dim = FeatureDim("feat", 3)
     config = Config({
       "extern_data": {"data": {"dim_tags": [batch_dim, time_dim, feat_dim]}}})
-    net = TFNetwork(config=config)
-    net.construct_from_dict({
-      "output": {
-        'class': 'split_dims', 'from': 'data', 'axis': time_dim, 'dims': [rem_dim, window_dim],
-        'out_shape': {batch_dim, rem_dim, window_dim, feat_dim}}
-    })
+    with make_scope():
+      net = TFNetwork(config=config)
+      net.construct_from_dict({
+        "output": {
+          'class': 'split_dims', 'from': 'data', 'axis': time_dim, 'dims': [rem_dim, window_dim],
+          'out_shape': {batch_dim, rem_dim, window_dim, feat_dim}}
+      })
 
 
 def test_SplitDimsLayer_dim_tags_expand():
@@ -2238,12 +2239,13 @@ def test_SplitDimsLayer_dim_tags_expand():
   expand_dim = SpatialDim("expand_dim", 1)
   config = Config({
     "extern_data": {"data": {"dim_tags": [batch_dim, time_dim, feat_dim]}}})
-  net = TFNetwork(config=config)
-  net.construct_from_dict({
-    "output": {
-      'class': 'split_dims', 'from': 'data', 'axis': feat_dim, 'dims': [feat_dim, expand_dim],
-      'out_shape': {batch_dim, time_dim, feat_dim, expand_dim}}
-  })
+  with make_scope():
+    net = TFNetwork(config=config)
+    net.construct_from_dict({
+      "output": {
+        'class': 'split_dims', 'from': 'data', 'axis': feat_dim, 'dims': [feat_dim, expand_dim],
+        'out_shape': {batch_dim, time_dim, feat_dim, expand_dim}}
+    })
 
 
 def test_SplitDimsLayer_dim_tags_split_batch_simple():

tests/test_TFUtil.py

@@ -1243,6 +1243,22 @@ def test_Data_verify_out_shape_optional_implicit_dim():
   x.verify_out_shape({time_dim, feat_dim}, allow_missing_implicit_dims=True)
 
 
+def test_Data_auto_create_placeholders_same_dim_tags_as_existing():
+  # Came up via: https://github.com/rwth-i6/returnn/pull/1143
+  n_out = 3
+  time_tag = SpatialDim("time")
+  with tf.Graph().as_default() as graph, tf_compat.v1.Session(graph=graph) as session:
+    assert isinstance(graph, tf.Graph)
+    data = Data("data", dim=n_out, same_dim_tags_as={"t": time_tag}, auto_create_placeholders=True)
+    classes = Data("classes", dim=n_out, sparse=True, same_dim_tags_as={"t": time_tag}, auto_create_placeholders=True)
+    assert time_tag.dyn_size is not None  # this is not so relevant and might change
+    seq_len = time_tag.dyn_size
+    assert seq_len is data.get_sequence_lengths() is classes.get_sequence_lengths()
+    assert seq_len.op.type == "Placeholder"
+    placeholder_ops = [op for op in graph.get_operations() if op.type == "Placeholder"]
+    assert_equal(set(placeholder_ops), {data.placeholder.op, classes.placeholder.op, time_tag.dyn_size.op})
+
+
 def test_Dim_copy():
   # https://github.com/rwth-i6/returnn/issues/860
   import copy