add copy_ support for float4 dtype

[vkuzo]

Stack from ghstack (oldest at bottom):

• -> add copy_ support for float4 dtype #169595
• make the float4 dtype support equality comparisons #169575

Summary:

Enables copy_ support for the torch.float4_e2m1fn_x2 dtype. This is
useful when slicing a tensor across dim1 and then calling contiguous,
which can happen in vllm and therefore should be supported.

Test Plan:

pytest test/quantization/core/experimental/test_floatx.py -s -k test_float4_e2m1fn_x2

Reviewers:

Subscribers:

Tasks:

Tags:

cc @jgong5 @mingfeima @XiaobingSuper @sanchitintel @ashokei @jingxu10 @jerryzh168 @aditew01

[pytorch-bot]

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✅ You can merge normally! (7 Unrelated Failures)

As of commit 257cef6 with merge base 685ba6b ():

UNSTABLE - The following jobs are marked as unstable, possibly due to flakiness on trunk:

• pull / linux-jammy-py3.14-clang12 / test (default, 1, 5, lf.linux.4xlarge, unstable) (gh)
  The runner has received a shutdown signal. This can happen when the runner service is stopped, or a manually started runner is canceled.
• pull / linux-jammy-py3.14-clang12 / test (default, 2, 5, lf.linux.4xlarge, unstable) (gh)
  The runner has received a shutdown signal. This can happen when the runner service is stopped, or a manually started runner is canceled.
• pull / linux-jammy-py3.14-clang12 / test (default, 3, 5, lf.linux.4xlarge, unstable) (gh)
  The runner has received a shutdown signal. This can happen when the runner service is stopped, or a manually started runner is canceled.
• pull / linux-jammy-py3.14-clang12 / test (default, 4, 5, lf.linux.4xlarge, unstable) (gh)
  The runner has received a shutdown signal. This can happen when the runner service is stopped, or a manually started runner is canceled.
• pull / linux-jammy-py3.14-clang12 / test (default, 5, 5, lf.linux.4xlarge, unstable) (gh)
  The runner has received a shutdown signal. This can happen when the runner service is stopped, or a manually started runner is canceled.
• pull / linux-jammy-py3.14-clang12 / test (dynamo_wrapped, 2, 3, lf.linux.2xlarge, unstable) (gh)
  The runner has received a shutdown signal. This can happen when the runner service is stopped, or a manually started runner is canceled.
• pull / linux-jammy-py3.14-clang12 / test (dynamo_wrapped, 3, 3, lf.linux.2xlarge, unstable) (gh)
  The runner has received a shutdown signal. This can happen when the runner service is stopped, or a manually started runner is canceled.

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[vkuzo]

@pytorchbot merge -f

[pytorch-bot]

❌ 🤖 pytorchbot command failed:

@pytorchbot merge: error: argument -f/--force: expected one argument

usage: @pytorchbot merge [-f MESSAGE | -i] [-ic] [-r [{viable/strict,main}]]

Try @pytorchbot --help for more info.

[vkuzo]

@pytorchbot merge -f "failures unrelated"

[pytorchmergebot]

Merge started

Your change will be merged immediately since you used the force (-f) flag, bypassing any CI checks (ETA: 1-5 minutes). Please use -f as last resort and instead consider -i/--ignore-current to continue the merge ignoring current failures. This will allow currently pending tests to finish and report signal before the merge.

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