[Windows] Run native unit tests in CI

[GregoryComer]

Summary

Build and run C++ tests in the unit test CI job on Windows. Fix a few lingering issues on Windows that surfaced.

Changes:

• Add CMake build + CTest execution the Windows unit test job.
• Gate Core ML export recipe tests (and coremltools imports) to non-Windows platforms.
• Add some explicit cases for size_t 0 literals to make MSVC overload resolution happy.
• Remove 2> /dev/null from some CMake PTE export custom commands. I'm not entirely sure why this is there in the first place (keep the log a little cleaner?), but it doesn't work on Windows. Easiest to just remove it.
• Update the temp file utility code (in extension/testing_util/temp_file.h) to use standard library file IO (as opposed to posix).
• (Critical): Replace long with int64_t in a few portable kernels that deal with indices. It should be int64_t, as this is the correct type for long tensors. On Windows, for example, long is actually 32-bit for historical reasons, and it causes memory corruption / crashes when trying to read/write ScalarType::Long tensors with long* pointers.
• Update a bunch of custom commands to use platform-specific syntax or replace with a cross-platform approach.
• Use non-strict export for test models. We can support strict export on Windows, but it take a bit of env setup. This is covered in CI in places, but non-strict is the default so it makes it a bit easier to build tests this way.

I've also excluded method_test and tensor_parser_test for now, due to the env issues with some of the PTE test models. The tests pass locally - but I need to debug the build-time PTE creation for these tests. I'm disabling to get the remaining 98% of the tests up first, and will fix these shortly. Tracking in #13883.

Test plan

CI - the tests are covered by the unittest jobs (debug, release, and editable).

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/13923

• 📄 Preview Python docs built from this PR

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❌ 1 New Failure, 42 Pending

As of commit 04826a7 with merge base 9af908d ():

NEW FAILURE - The following job has failed:

• pull / android / run-emulator (gh)
  The process '/usr/bin/sh' failed with exit code 255

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[JacobSzwejbka]

This seems like evidence that we shouldnt have a mono recipe test with real backends.

[GregoryComer]

Yeah, might make sense to refactor it as a follow up. CC @abhinaykukkadapu Do you have any preferences on handling of platform-specific recipes?

[abhinaykukkadapu]

I was under the impression that lowering works across all platforms, although i haven't thought about windows tbf.

This seems like evidence that we shouldnt have a mono recipe test with real backends.

these tests only call forward if those specific et backends are available, check here: https://github.com/pytorch/executorch/blob/main/export/tests/test_target_recipes.py#L103, otherwise these tests just lowers the model.

@metascroy do you know if coreml tools work on a windows platform?

[GregoryComer]

Thanks. From what I read, coremltools AOT flow is not available on Windows.

[GregoryComer]

@JacobSzwejbka I've made a few small updates to address comments. Do you have any blocking concerns?

[GregoryComer]

After rebase and minor cleanup, I'm seeing one (flaky) test failure relating to etdump generation due to being unable to access a temp file because there's another open handle to it. Tracking this in #13883. I've updated and am re-running CI now. If no additional objections, I hope to land this shortly, pending final approval from reviewers.