[Dy2st]Fix while to static bug

[zhangbo9674]

PR Category

Execute Infrastructure

PR Types

Bug fixes

Description

Fix to static bug of while op in this case：

import paddle
from paddle.jit import to_static

@to_static(full_graph=True)
def test():
    x = paddle.to_tensor(1, dtype='float32')
    y = paddle.to_tensor(False, dtype='bool')
    while y:
        x = 2
test()

Origin error is：

File "./paddle/static/nn/control_flow.py", line 952, in while_loop
        cf_yield([next_cond, *(var.next_var for var in variable_loop_vars)])
RuntimeError: Unable to cast Python instance of type <class 'int'> to C++ type '?' (#define PYBIND11_DETAILED_ERROR_MESSAGES or compile in debug mode for details) 

Pcard-67164

[paddle-bot]

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