pytorch - 💡(How to fix) Fix `import functorch.dim` silently breaks `torch.Tensor.expand(size=...)` [1 comments, 2 participants]

torch.Tensor.expand = _C._instancemethod(_C.expand)

---

import torch


def test_expand(input: torch.Tensor, size: tuple[int, ...]) -> None:
    output_args = input.expand(*size)
    output_kwargs = input.expand(size=size)
    assert output_args.shape == size, (
        f"The shape of the output of `torch.Tensor.expand(self, *size)` "
        f"should be `{size}` but it is different: `{output_args.shape}`."
    )
    assert output_kwargs.shape == size, (
        f"The shape of the output of `torch.Tensor.expand(self, size=size)` "
        f"should be `{size}` but it is different: `{output_kwargs.shape}`."
    )


input = torch.zeros(1)
size = (10, 1)

test_expand(input, size)

print("Before importing `functorch.dim`: OK")


import functorch.dim

test_expand(input, size)

print("After importing `functorch.dim`: OK")

---

Before importing `functorch.dim`: OK
Traceback (most recent call last):
  File "/home/8/ue06348/projects/SSDP/test.py", line 27, in <module>
    test_expand(input, size)
  File "/home/8/ue06348/projects/SSDP/test.py", line 11, in test_expand
    assert output_kwargs.shape == size, (
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: The shape of the output of `torch.Tensor.expand(self, size=size)` should be `(10, 1)` but it is different: `torch.Size([1])`.

---

$ curl -sL https://raw.githubusercontent.com/pytorch/pytorch/main/torch/utils/collect_env.py | uv run python
Collecting environment information...
PyTorch version: 2.8.0+cu129
Is debug build: False
CUDA used to build PyTorch: 12.9
ROCM used to build PyTorch: N/A

OS: Red Hat Enterprise Linux 9.4 (Plow) (x86_64)
GCC version: (GCC) 11.4.1 20231218 (Red Hat 11.4.1-3)
Clang version: 17.0.6 (Red Hat, Inc. 17.0.6-5.el9)
CMake version: version 3.26.5
Libc version: glibc-2.34

Python version: 3.11.13 (main, Sep 18 2025, 19:46:39) [Clang 20.1.4 ] (64-bit runtime)
Python platform: Linux-5.14.0-503.40.1.el9_5.x86_64-x86_64-with-glibc2.34
Is CUDA available: True
CUDA runtime version: Could not collect
CUDA_MODULE_LOADING set to: LAZY
GPU models and configuration: 
GPU 0: NVIDIA H100
  MIG 4g.47gb     Device  0:

Nvidia driver version: 575.57.08
cuDNN version: Could not collect
Is XPU available: False
HIP runtime version: N/A
MIOpen runtime version: N/A
Is XNNPACK available: True
Caching allocator config: N/A

CPU:
Architecture:                         x86_64
CPU op-mode(s):                       32-bit, 64-bit
Address sizes:                        52 bits physical, 57 bits virtual
Byte Order:                           Little Endian
CPU(s):                               384
On-line CPU(s) list:                  0-383
Vendor ID:                            AuthenticAMD
Model name:                           AMD EPYC 9654 96-Core Processor
CPU family:                           25
Model:                                17
Thread(s) per core:                   2
Core(s) per socket:                   96
Socket(s):                            2
Stepping:                             1
Frequency boost:                      enabled
CPU(s) scaling MHz:                   68%
CPU max MHz:                          3707.8120
CPU min MHz:                          1500.0000
BogoMIPS:                             4792.45
Flags:                                fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good amd_lbr_v2 nopl nonstop_tsc cpuid extd_apicid aperfmperf rapl pni pclmulqdq monitor ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt aes xsave avx f16c rdrand lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs skinit wdt tce topoext perfctr_core perfctr_nb bpext perfctr_llc mwaitx cpb cat_l3 cdp_l3 hw_pstate ssbd mba perfmon_v2 ibrs ibpb stibp ibrs_enhanced vmmcall fsgsbase bmi1 avx2 smep bmi2 erms invpcid cqm rdt_a avx512f avx512dq rdseed adx smap avx512ifma clflushopt clwb avx512cd sha_ni avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local avx512_bf16 clzero irperf xsaveerptr rdpru wbnoinvd amd_ppin cppc arat npt lbrv svm_lock nrip_save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold avic v_vmsave_vmload vgif x2avic v_spec_ctrl vnmi avx512vbmi umip pku ospke avx512_vbmi2 gfni vaes vpclmulqdq avx512_vnni avx512_bitalg avx512_vpopcntdq la57 rdpid overflow_recov succor smca fsrm flush_l1d debug_swap
Virtualization:                       AMD-V
L1d cache:                            6 MiB (192 instances)
L1i cache:                            6 MiB (192 instances)
L2 cache:                             192 MiB (192 instances)
L3 cache:                             768 MiB (24 instances)
NUMA node(s):                         2
NUMA node0 CPU(s):                    0-95,192-287
NUMA node1 CPU(s):                    96-191,288-383
Vulnerability Gather data sampling:   Not affected
Vulnerability Itlb multihit:          Not affected
Vulnerability L1tf:                   Not affected
Vulnerability Mds:                    Not affected
Vulnerability Meltdown:               Not affected
Vulnerability Mmio stale data:        Not affected
Vulnerability Reg file data sampling: Not affected
Vulnerability Retbleed:               Not affected
Vulnerability Spec rstack overflow:   Mitigation; Safe RET
Vulnerability Spec store bypass:      Mitigation; Speculative Store Bypass disabled via prctl
Vulnerability Spectre v1:             Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2:             Mitigation; Enhanced / Automatic IBRS; IBPB conditional; STIBP always-on; RSB filling; PBRSB-eIBRS Not affected; BHI Not affected
Vulnerability Srbds:                  Not affected
Vulnerability Tsx async abort:        Not affected

Versions of relevant libraries:
[pip3] Could not collect
[conda] Could not collect