* [Dy2Stat] Add test for ptb model. test=develop

* Simplify code for gast.If in is_control_flow_to_transform. test=develop

* Move IsControlFlowVisitor to file utils. test=develop

* Don't use convert_call for build-in func in CallTransformer. test=develop

* Optimize api is_control_flow_to_transform. test=develop

* Polish the document of IsControlFlowVisitor. test=develop

* Use declarative instead of dygraph_to_static_func. test=develop

* update err msg for dynamic_lstm and dynamic_lstmp, test=develop

test=release/1.8

l1_norm
norm
squared_l2_norm
squared_l2_distance
conv_shift
sample_logits

* API/OP (Some SL API) error message enhancement  (#24441)

* polish some sl api error message, test=develop

* polish python input check of stride slice, test=develop

* fix unittest bugs, test=develop

* fix error info for transpose sequence_conv_pool max_sequence_len sequ… (#24437)

* fix error info for transpose sequence_conv_pool max_sequence_len sequence_erase, test=develop

* fix error info for transpose sequence_conv_pool max_sequence_len sequence_erase, test=develop

* update modify, test=develop

* update modify, test=develop

* fixed some modifications, test=develop
Co-authored-by: NXing Wu <wuxing03@baidu.com>

* add enable_imperative, disable_imperative; test=develop

* add unitest; test=develop

* polish example; test=develop

* enhance rank_loss error message, test=develop

* enhance similarity_focus error message, test=develop

* enhance squeeze error message, test=develop

* fix error log: resahpe, range, reverse.

* test=develop

* test=develop

* Fix error info (#23891)

* fix error info for rnn related api

* passed local test, test=develop

* double check the code

* double check the code, test=develop

* update 'shape' check in RNNCell, test=develop

* add long dtype to RNNCell

* fix long type in python3
Co-authored-by: NXingWu01 <wuxing@iie.ac.cn>

* fix rnn check_type list error (#24346)

* fix rnn check_type list error

* tigger ci, test=release/1.8

* update modify, test=release/1.8
Co-authored-by: NXingWu01 <wuxing@iie.ac.cn>

* API/OP (margin_rank_loss, nce, row_conv, glu, positive_negative_pair) error message enchancement, test=release/1.8

OP(warpctc, add_position_encoding, scaled_dot_product_attention) error message enhancement (#24261) (#24372)

* enhance add_position_encoding error message, test=develop

* enhance warpctc & scaled_dot_product_attention error message, test=develop

* modified error message and ctest of scaled_dot_product_attention, test=develop

* Rename internal gradient variables in multiple backward
* so that they have different names with previous backward
* For example:
*  y = x * x, grad = fluid.gradients(fluid.gradients(y, x) + y * y, x)
* In second-time backward, gradient variable names of partial
* forward network (y * y) may be have same names with first-time
* fluid.gradients(y, x).

test=develop

* fix kron_op: when only one input needs gradient, test=develop
* fix a typo in paddle.complex.matmul, test=release/1.8

* test=develop fix generate_proposals

* delete paddle.nn  api, test=develop

* fix optest, test=develop

* delete paddle.optimizer, paddle.meric, paddle.framework, paddle.io, test=develop

* fix optest, test=develop

* fix test_trace_op.py, test=develop

* fix test_activation_op.py, test=develop

* fix CrossEntropyLoss op en doc, test=develop

* delete unittests,test=release/2.0

* Add meshgrid op (#23736)

* update paddle/tensor, test=develop

* update linalg,py, test=develop

* update nn/functional, test=develop

* delete paddle/tensor/*, test=develop

* merge upstream, test=develop

* update __init__, test=develop

* pass ci, test=develop

* add reshape in paddle.complex, test=develop
* fix typos in paddle.complex.kron's comment, fix unittest, test=release-2.0

* merge latest. test=develop

* move full_like to fluid.layers

* copy api from paddle to paddle.fluid, test=develop

* fix optest, test=develop

* add decorator, test=develop

* add fake_interface_only, test=develop

* remove some dygraph_not_support, test=develop

* change dygraph to imperative, test=develop

* cherrypick: add kron op (#24105)
* add kron op and fluid.layers.kron
* add paddle.complex.kron

* update index sample

* API/OP (affine_channel, group_norm, layer_norm, random_crop, unpool, log_loss) error message enhancement test=develop

* adapt old version pretrain model load, test=develop

* fix infer error & multiple input error, test=develop

* Error message enhancement of 6 op, test=release/2.0
* refine huber loss unittests, test=release/2.0

* fix test_multiprocess_dataloader_base timeout. test=develop.
test=release/2.0

test=release/2.0

* Init complex number neural network, test=release/2.0

* Improve doc writing

* Fix elementwise add & sub

* Fix elementwise mul act

* a) add ut for complex variable; b) remove arg act in elementwise_ops

* Add trainable_statistics in attr for batch_norm
* Unifying behavior of dynamic graph and static graph

* add nll_loss op test=develop