Files
pytorch/cmake/Modules
Sam Estep 5bcbbf5373 Lint trailing newlines (#54737)
Summary:
*Context:* https://github.com/pytorch/pytorch/issues/53406 added a lint for trailing whitespace at the ends of lines. However, in order to pass FB-internal lints, that PR also had to normalize the trailing newlines in four of the files it touched. This PR adds an OSS lint to normalize trailing newlines.

The changes to the following files (made in 54847d0adb9be71be4979cead3d9d4c02160e4cd) are the only manually-written parts of this PR:

- `.github/workflows/lint.yml`
- `mypy-strict.ini`
- `tools/README.md`
- `tools/test/test_trailing_newlines.py`
- `tools/trailing_newlines.py`

I would have liked to make this just a shell one-liner like the other three similar lints, but nothing I could find quite fit the bill. Specifically, all the answers I tried from the following Stack Overflow questions were far too slow (at least a minute and a half to run on this entire repository):

- [How to detect file ends in newline?](https://stackoverflow.com/q/38746)
- [How do I find files that do not end with a newline/linefeed?](https://stackoverflow.com/q/4631068)
- [How to list all files in the Git index without newline at end of file](https://stackoverflow.com/q/27624800)
- [Linux - check if there is an empty line at the end of a file [duplicate]](https://stackoverflow.com/q/34943632)
- [git ensure newline at end of each file](https://stackoverflow.com/q/57770972)

To avoid giving false positives during the few days after this PR is merged, we should probably only merge it after https://github.com/pytorch/pytorch/issues/54967.

Pull Request resolved: https://github.com/pytorch/pytorch/pull/54737

Test Plan:
Running the shell script from the "Ensure correct trailing newlines" step in the `quick-checks` job of `.github/workflows/lint.yml` should print no output and exit in a fraction of a second with a status of 0. That was not the case prior to this PR, as shown by this failing GHA workflow run on an earlier draft of this PR:

- https://github.com/pytorch/pytorch/runs/2197446987?check_suite_focus=true

In contrast, this run (after correcting the trailing newlines in this PR) succeeded:

- https://github.com/pytorch/pytorch/pull/54737/checks?check_run_id=2197553241

To unit-test `tools/trailing_newlines.py` itself (this is run as part of our "Test tools" GitHub Actions workflow):
```
python tools/test/test_trailing_newlines.py
```

Reviewed By: malfet

Differential Revision: D27409736

Pulled By: samestep

fbshipit-source-id: 46f565227046b39f68349bbd5633105b2d2e9b19
2021-03-30 13:09:52 -07:00
..
2019-04-07 08:27:00 -07:00
2021-03-03 08:23:02 -08:00
2016-12-13 09:29:01 -05:00
2016-12-13 09:29:01 -05:00
2021-03-30 13:09:52 -07:00
2021-03-30 13:09:52 -07:00

This folder contains various custom cmake modules for finding libraries and packages. Details about some of them are listed below.

FindOpenMP.cmake

This is modified from the file included in CMake 3.13 release, with the following changes:

  • Replace VERSION_GREATER_EQUAL with NOT ... VERSION_LESS as VERSION_GREATER_EQUAL is not supported in CMake 3.5 (our min supported version).

  • Update the separate_arguments commands to not use NATIVE_COMMAND which is not supported in CMake 3.5 (our min supported version).

  • Make it respect the QUIET flag so that, when it is set, try_compile failures are not reported.

  • For AppleClang compilers, use -Xpreprocessor instead of -Xclang as the later is not documented.

  • For AppleClang compilers, an extra flag option is tried, which is -Xpreprocessor -openmp -I${DIR_OF_omp_h}, where ${DIR_OF_omp_h} is a obtained using find_path on omp.h with brew's default include directory as a hint. Without this, the compiler will complain about missing headers as they are not natively included in Apple's LLVM.

  • For non-GNU compilers, whenever we try a candidate OpenMP flag, first try it with directly linking MKL's libomp if it has one. Otherwise, we may end up linking two libomps and end up with this nasty error:

    OMP: Error #15: Initializing libomp.dylib, but found libiomp5.dylib already
    initialized.
    
    OMP: Hint This means that multiple copies of the OpenMP runtime have been
    linked into the program. That is dangerous, since it can degrade performance
    or cause incorrect results. The best thing to do is to ensure that only a
    single OpenMP runtime is linked into the process, e.g. by avoiding static
    linking of the OpenMP runtime in any library. As an unsafe, unsupported,
    undocumented workaround you can set the environment variable
    KMP_DUPLICATE_LIB_OK=TRUE to allow the program to continue to execute, but
    that may cause crashes or silently produce incorrect results. For more
    information, please see http://openmp.llvm.org/
    

    See NOTE [ Linking both MKL and OpenMP ] for details.