import torch

from torch._export.db.case import export_case


@export_case(
    example_inputs=(torch.ones(3, 2, 2),),
    tags={"torch.dynamic-shape", "python.control-flow"},
)
class DynamicShapeIfGuard(torch.nn.Module):
    """
    `if` statement with backed dynamic shape predicate will be specialized into
    one particular branch and generate a guard. However, export will fail if the
    the dimension is marked as dynamic shape from higher level API.
    """

    def forward(self, x):
        if x.shape[0] == 3:
            return x.cos()

        return x.sin()