Add error message if #14 happens

Add a suitable error messages if sys.modules['__main__'].main is called
This should help to identify the problem

Author: AndreasGocht

scorep/__main__.py

@@ -17,9 +17,8 @@ def _usage(outfile):
 cuda_support = None
 opencl_support = None
 
-
 def _err_exit(msg):
-    sys.stderr.write("%s: %s\n" % (sys.argv[0], msg))
+    sys.stderr.write("%s: %s\n" % ("scorep", msg))
     sys.exit(1)
 
 
@@ -62,7 +61,8 @@ def set_init_environment(mpi):
     os.environ["SCOREP_PYTHON_BINDINGS_INITALISED"] = "true"
 
 
-def main(argv=None):
+def scorep_main(argv=None):
+    global target_code
     if argv is None:
         argv = sys.argv
     try:
@@ -131,22 +131,34 @@ def main(argv=None):
     try:
         with open(progname) as fp:
             code = compile(fp.read(), progname, 'exec')
+            target_code = code
         # try to emulate __main__ namespace as much as possible
         globs = {
             '__file__': progname,
             '__name__': '__main__',
             '__package__': None,
             '__cached__': None,
         }
+        
         global_trace.runctx(code, globs, globs)
     except OSError as err:
         _err_exit("Cannot run file %r because: %s" % (sys.argv[0], err))
     except SystemExit:
         pass
 
+def main(argv=None):
+    import traceback
+    call_stack = traceback.extract_stack()
+    call_stack_array = traceback.format_list(call_stack)
+    call_stack_string = ""
+    for elem in call_stack_array[:-1]:
+        call_stack_string+=elem
+    _err_exit("Someone called scorep.__main__.main(argv).\n"
+              "This is not supposed to happen, but might be triggered, if your application calls \"_sys.modules['__main__'].main\".\n"
+              "This python stacktrace might be helpfull to find the reason:\n%s" % call_stack_string)
 
 if __name__ == '__main__':
-    main()
+    scorep_main()
 
 else:
     '''

test/test.py

@@ -116,6 +116,38 @@ def test_mpi(self):
         #self.assertEqual(out.stderr.decode("utf-8"), expected_std_err)
         #self.assertEqual(out.stdout.decode("utf-8"), "hello world\n")
 
+    def test_call_main(self):
+        env = self.env
+        env["SCOREP_EXPERIMENT_DIRECTORY"] += "/test_call_main"
+        trace_path = env["SCOREP_EXPERIMENT_DIRECTORY"] + "/traces.otf2"
+        out = subprocess.run(["python3",
+                              "-m",
+                              "scorep",
+                              "test_call_main.py"],
+                             stdout=subprocess.PIPE,
+                             stderr=subprocess.PIPE,
+                             env=env)
+        expected_std_err = """scorep: Someone called scorep.__main__.main(argv).
+This is not supposed to happen, but might be triggered, if your application calls "_sys.modules['__main__'].main".
+This python stacktrace might be helpfull to find the reason:
+  File "/usr/lib/python3.6/runpy.py", line 193, in _run_module_as_main
+    "__main__", mod_spec)
+  File "/usr/lib/python3.6/runpy.py", line 85, in _run_code
+    exec(code, run_globals)
+  File "/home/gocht/virtenv/test_scorep_python_3.6/lib/python3.6/site-packages/scorep/__main__.py", line 161, in <module>
+    scorep_main()
+  File "/home/gocht/virtenv/test_scorep_python_3.6/lib/python3.6/site-packages/scorep/__main__.py", line 143, in scorep_main
+    global_trace.runctx(code, globs, globs)
+  File "/home/gocht/virtenv/test_scorep_python_3.6/lib/python3.6/site-packages/scorep/trace.py", line 57, in runctx
+    exec(cmd, globals, locals)
+  File "test_call_main.py", line 6, in <module>
+    sys.modules['__main__'].main(sys.argv)
+
+"""
+        expected_std_out = ""
+        self.assertEqual(out.stderr.decode("utf-8"), expected_std_err)
+        self.assertEqual(out.stdout.decode("utf-8"), expected_std_out)
+
     def tearDown(self):
         shutil.rmtree(
             self.env["SCOREP_EXPERIMENT_DIRECTORY"],

test/test_call_main.py

@@ -0,0 +1,6 @@
+import sys
+
+def main(argv=None):
+    print("successfully called main")
+
+sys.modules['__main__'].main(sys.argv)

test/test_nosleep.py

@@ -2,7 +2,7 @@
 
 
 def pointless_sleep():
-    time.sleep(60)
+    time.sleep(5)
 
 
 def baz():

test/test_sleep.py

@@ -2,7 +2,7 @@
 
 
 def pointless_sleep():
-    time.sleep(60)
+    time.sleep(5)
 
 
 def baz():