[analyzer] SATest: Make main script Python2 compatible

[vsavchenko]

Summary

If the user has only python2 installed and wants to use
the dockerized testing system, it is now totally OK.

[NoQ]

Woohoo!

clang/utils/analyzer/SATest.py

 #!/usr/bin/env python
 
-import SATestAdd
-import SATestBuild
-import SATestUpdateDiffs
-import CmpRuns
-
-from ProjectMap import ProjectInfo, ProjectMap
-
 import argparse
 import sys
 import os
 
 from subprocess import call
 
 SCRIPTS_DIR = os.path.dirname(os.path.realpath(__file__))
 PROJECTS_DIR = os.path.join(SCRIPTS_DIR, "projects")
 DEFAULT_LLVM_DIR = os.path.realpath(os.path.join(SCRIPTS_DIR,
                                                  os.path.pardir,
                                                  os.path.pardir,
                                                  os.path.pardir))
 
 
 def add(parser, args):
+    import SATestAdd
+    from ProjectMap import ProjectInfo
+
     if args.source == "git" and (args.origin == "" or args.commit == ""):
         parser.error(
             "Please provide both --origin and --commit if source is 'git'")
 
     if args.source != "git" and (args.origin != "" or args.commit != ""):
         parser.error("Options --origin and --commit don't make sense when "
                      "source is not 'git'")
 
     project = ProjectInfo(args.name[0], args.mode, args.source, args.origin,
                           args.commit)
 
     SATestAdd.add_new_project(project)
 
 
 def build(parser, args):
+    import SATestBuild
+    from ProjectMap import ProjectMap
+
     SATestBuild.VERBOSE = args.verbose
 
     project_map = ProjectMap()
     projects = project_map.projects
 
     if args.projects:
         projects_arg = args.projects.split(",")
         available_projects = [project.name
def build(parser, args):
     tests_passed = tester.test_all()
 
     if not tests_passed:
         sys.stderr.write("ERROR: Tests failed.\n")
         sys.exit(42)
 
 
 def compare(parser, args):
+    import CmpRuns
+
+    choices = [CmpRuns.HistogramType.RELATIVE.value,
+               CmpRuns.HistogramType.LOG_RELATIVE.value,
+               CmpRuns.HistogramType.ABSOLUTE.value]
+
+    if args.histogram is not None and args.histogram not in choices:
+        parser.error("Incorrect histogram type, available choices are {}"
+                     .format(choices))
+
     dir_old = CmpRuns.ResultsDirectory(args.old[0], args.root_old)
     dir_new = CmpRuns.ResultsDirectory(args.new[0], args.root_new)
 
     CmpRuns.dump_scan_build_results_diff(dir_old, dir_new,
                                          show_stats=args.show_stats,
                                          stats_only=args.stats_only,
                                          histogram=args.histogram,
                                          verbose_log=args.verbose_log)
 
 
 def update(parser, args):
+    import SATestUpdateDiffs
+    from ProjectMap import ProjectMap
+
     project_map = ProjectMap()
     for project in project_map.projects:
         SATestUpdateDiffs.update_reference_results(project)
 
 
 def docker(parser, args):
     if len(args.rest) > 0:
         if args.rest[0] != "--":
add_parser.add_argument("--mode", action="store", default=1, type=int,
                             "2 for single file c++11 project")
     add_parser.add_argument("--source", action="store", default="script",
                             choices=["script", "git", "zip"],
                             help="Source type of the new project: "
                             "'git' for getting from git "
                             "(please provide --origin and --commit), "
                             "'zip' for unpacking source from a zip file, "
                             "'script' for downloading source by running "
-                            "a custom script {}"
-                            .format(SATestBuild.DOWNLOAD_SCRIPT))
+                            "a custom script")
     add_parser.add_argument("--origin", action="store", default="",
                             help="Origin link for a git repository")
     add_parser.add_argument("--commit", action="store", default="",
                             help="Git hash for a commit to checkout")
     add_parser.set_defaults(func=add)
 
     # build subcommand
     build_parser = subparsers.add_parser(
cmp_parser.add_argument("--verbose-log", dest="verbose_log",
                             metavar="LOG")
     cmp_parser.add_argument("--stats-only", action="store_true",
                             dest="stats_only", default=False,
                             help="Only show statistics on reports")
     cmp_parser.add_argument("--show-stats", action="store_true",
                             dest="show_stats", default=False,
                             help="Show change in statistics")
     cmp_parser.add_argument("--histogram", action="store", default=None,
-                            choices=[CmpRuns.HistogramType.RELATIVE.value,
-                                     CmpRuns.HistogramType.LOG_RELATIVE.value,
-                                     CmpRuns.HistogramType.ABSOLUTE.value],
                             help="Show histogram of paths differences. "
                             "Requires matplotlib")
     cmp_parser.add_argument("old", nargs=1, help="Directory with old results")
     cmp_parser.add_argument("new", nargs=1, help="Directory with new results")
     cmp_parser.set_defaults(func=compare)
 
     # update subcommand
     upd_parser = subparsers.add_parser(
         "update",
         help="Update static analyzer reference results based on the previous "
         "run of SATest build. Assumes that SATest build was just run.")
     # TODO: add option to decide whether we should use git
     upd_parser.set_defaults(func=update)
 
     # docker subcommand
     dock_parser = subparsers.add_parser(
         "docker",
         help="Run regression system in the docker.")
 
     dock_parser.add_argument("--build-image", action="store_true",
                              help="Build docker image for running tests.")
+    dock_parser.add_argument("--shell", action="store_true",
+                             help="Start a shell on docker.")
     dock_parser.add_argument("--llvm-project-dir", action="store",
                              default=DEFAULT_LLVM_DIR,
                              help="Path to LLVM source code. Defaults "
                              "to the repo where this script is located. ")
     dock_parser.add_argument("--build-dir", action="store", default="",
                              help="Path to a directory where docker should "
                              "build LLVM code.")
     dock_parser.add_argument("--clang-dir", action="store", default="",