[analyzer] scan-build-py: Remove relative path hack for SATestsBuild.py

[dcoughlin]

Summary

Remove the relative path hack in scan-build-py that converts a fully qualified directory name and a fully qualified file path to a relative path before running the analyzer on a file.

This hack is not needed: the bad interaction with SATestsBuild.py it was intended to address is actually the same underlying problem that D24163 fixed. Further, because the hack would always relativize paths, it caused SATestBuild.py to be unable to properly line up issues when the build system changed directory and then built a source file in a child directory but used a fully-qualified path for the source file.

Laszlo: Are you OK with me removing this hack? This is the last outstanding issue in scan-build-py preventing us in using it for our regression suite.

Note: I still think the approach used here (and especially in intercept-build) is not ideal. I really think we should be storing both the working directory and the actual path argument (even if it is relative) in the compilation database. Storing the fully-qualified paths loses information (i.e., which of the many possible paths for that file was actually used) and makes replaying the build with fidelity impossible. That said, after D24163 I don't have any examples where is actually an issue in practice.

[rizsotto.mailinglist]

thanks Devin, i like smaller code, have no problem with this change. :)

about the file/directory paths: i agree that the situation is not ideal. but there are/were strict constrains on how a compilation database shall look like. once a year i ask the question on the mailing list about it. the situation might have been improved since... besides, using absolute path is actually the safest bet we can make. (other tools doing the same (CMake is a good example)) would not invest time into this until i see it got broken.

tools/scan-build-py/libscanbuild/runner.py

def filter_debug_flags(opts, continuation=run_analyzer):
 
     if opts.pop('force_debug'):
         # lazy implementation just append an undefine macro at the end
         opts.update({'flags': opts['flags'] + ['-UNDEBUG']})
 
     return continuation(opts)
 
 
-@require(['file', 'directory'])
-def set_file_path_relative(opts, continuation=filter_debug_flags):
-    """ Set source file path to relative to the working directory.
-
-    The only purpose of this function is to pass the SATestBuild.py tests. """
-
-    opts.update({'file': os.path.relpath(opts['file'], opts['directory'])})
-
-    return continuation(opts)
-
-
 @require(['language', 'compiler', 'file', 'flags'])
-def language_check(opts, continuation=set_file_path_relative):
+def language_check(opts, continuation=filter_debug_flags):
     """ Find out the language from command line parameters or file name
     extension. The decision also influenced by the compiler invocation. """
 
     accepted = frozenset({
         'c', 'c++', 'objective-c', 'objective-c++', 'c-cpp-output',
         'c++-cpp-output', 'objective-c-cpp-output'
     })
 

tools/scan-build-py/tests/unit/test_runner.py

def test_nodebug_macros_appended(self):
             self.assertEqual(spy.success,
                              sut.filter_debug_flags(opts, spy.call))
             return spy.arg['flags']
 
         self.assertEqual(['-UNDEBUG'], test([]))
         self.assertEqual(['-DNDEBUG', '-UNDEBUG'], test(['-DNDEBUG']))
         self.assertEqual(['-DSomething', '-UNDEBUG'], test(['-DSomething']))
 
-    def test_set_file_relative_path(self):
-        def test(expected, input):
-            spy = Spy()
-            self.assertEqual(spy.success,
-                             sut.set_file_path_relative(input, spy.call))
-            self.assertEqual(expected, spy.arg['file'])
-
-        test('source.c',
-             {'file': '/home/me/source.c', 'directory': '/home/me'})
-        test('me/source.c',
-             {'file': '/home/me/source.c', 'directory': '/home'})
-        test('../home/me/source.c',
-             {'file': '/home/me/source.c', 'directory': '/tmp'})
-
     def test_set_language_fall_through(self):
         def language(expected, input):
             spy = Spy()
             input.update({'compiler': 'c', 'file': 'test.c'})
             self.assertEqual(spy.success, sut.language_check(input, spy.call))
             self.assertEqual(expected, spy.arg['language'])
 
         language('c',   {'language': 'c', 'flags': []})