[lit] Remove (or allow specific) unused imports

[modocache]

Summary

Using Python linter flake8 on the utils/lit reveals several linter
warnings designated "F401: Unused import". Fix or silence these
warnings.

Some of these unused imports are legitimate, while some are part of lit's API.
For example, users of lit expect to be able to access lit.formats.ShTest in
their lit.cfg, despite the module hierarchy for that symbol actually being
lit.formats.shtest.ShTest. To silence linter errors for these lines,
include a "noqa" directive.

[grimar]

Hi Brian, I have a error after that change on windows (when reverting r283710, it is works fine again):

C:\c_make_build_dir\Debug\bin\llvm-lit.py -v C:\llvm\test\Object\invalid.test
Traceback (most recent call last):

  File "C:\c_make_build_dir\Debug\bin\llvm-lit.py", line 44, in <module>
    lit.main(builtin_parameters)
AttributeError: 'module' object has no attribute 'main'

[asb]

In D25407#566074, @grimar wrote:

Hi Brian, I have a error after that change on windows (when reverting r283710, it is works fine again):

C:\c_make_build_dir\Debug\bin\llvm-lit.py -v C:\llvm\test\Object\invalid.test
Traceback (most recent call last):

  File "C:\c_make_build_dir\Debug\bin\llvm-lit.py", line 44, in <module>
    lit.main(builtin_parameters)
AttributeError: 'module' object has no attribute 'main'

Same issue on Arch:

./bin/llvm-lit test
Traceback (most recent call last):
  File "./bin/llvm-lit", line 44, in <module>
    lit.main(builtin_parameters)
AttributeError: module 'lit' has no attribute 'main'

[chapuni]

Brian, could you check bin/llvm-lit with py3?
See, http://bb.pgr.jp/builders/cmake-llvm-x86_64-linux/builds/43951

[modocache]

@chapuni Apologies again! I'm testing llvm-lit with Python 3 now. I assume it's been fixed by the other patches (thanks again), but I'm double-checking now.

[modocache]

I'm at r283822 and have confirmed that the following work:

python3 /path/to/llvm/build/bin/llvm-lit /path/to/llvm/utils/lit/tests
python3 /path/to/llvm/build/bin/llvm-lit /path/to/llvm/build/test

utils/lit/lit.py

 #!/usr/bin/env python
 
+from lit.main import main
+
 if __name__=='__main__':
-    import lit
-    lit.main()
+    main()

utils/lit/lit/LitConfig.py

def maxIndividualTestTime(self, value):
             a single test
         """
         self._maxIndividualTestTime = value
         if self.maxIndividualTestTime > 0:
             # The current implementation needs psutil to set
             # a timeout per test. Check it's available.
             # See lit.util.killProcessAndChildren()
             try:
-                import psutil
+                import psutil  # noqa: F401
             except ImportError:
                 self.fatal("Setting a timeout per test requires the"
                            " Python psutil module but it could not be"
                            " found. Try installing it via pip or via"
                            " your operating system's package manager.")
         elif self.maxIndividualTestTime < 0:
             self.fatal('The timeout per test must be >= 0 seconds')
 

utils/lit/lit/__init__.py

 """'lit' Testing Tool"""
 
-from __future__ import absolute_import
-from .main import main
-
 __author__ = 'Daniel Dunbar'
 __email__ = '[e-mail]'
 __versioninfo__ = (0, 6, 0)
 __version__ = '.'.join(str(v) for v in __versioninfo__) + 'dev'
 
 __all__ = []

utils/lit/lit/formats/__init__.py

-from __future__ import absolute_import
-from lit.formats.base import TestFormat, FileBasedTest, OneCommandPerFileTest
-from lit.formats.googletest import GoogleTest
-from lit.formats.shtest import ShTest
+from lit.formats.base import (  # noqa: F401
+    TestFormat,
+    FileBasedTest,
+    OneCommandPerFileTest
+)
+
+from lit.formats.googletest import GoogleTest  # noqa: F401
+from lit.formats.shtest import ShTest  # noqa: F401