[bug][nn.Graph] stft with registered window and pad_mode='reflect' crashes in Graph mode ("This is a oneflow bug")

[tinywisdom]

Summary

Calling oneflow.stft inside nn.Graph with a registered window buffer and pad_mode='reflect' fails during graph build with a generic:

RuntimeError: This is a oneflow bug, please submit an issue...

In eager mode this call works, but in Graph mode it crashes with the generic internal error, offering no actionable message.

Code to reproduce bug

import oneflow as flow
import oneflow.nn as nn

class M(nn.Module):
    def __init__(self):
        super().__init__()
        self.n_fft = 256
        self.hop_length = 128
        self.register_buffer("window", flow.hann_window(self.n_fft, dtype=flow.float32))
        self.pad_mode = "reflect"  # <- triggers the failing path in Graph

    def forward(self, x):
        return flow.stft(
            x,
            n_fft=self.n_fft,
            hop_length=self.hop_length,
            window=self.window,
            return_complex=False,
            pad_mode=self.pad_mode,
        )

class G(nn.Graph):
    def __init__(self, m): super().__init__(); self.m = m
    def build(self, x): return self.m(x)

x = flow.randn(1, 1024)
g = G(M())
g(x)  # -> RuntimeError: "This is a oneflow bug..."

Output

...
result = unbound_forward_of_module_instance(self, *args, **kwargs)
return flow.stft(...)
RuntimeError: Error: RuntimeError : This is a oneflow bug, please submit an issue at 'https://github.com/Oneflow-Inc/oneflow/issues' ...

System Information

• OS: Ubuntu 22.04.4 LTS (x86_64)
• OneFlow version : 1.0.0.dev20250921+cpu
• Python version: 3.10.16