Issue 8202: when using the -m command line switch, sys.argv[0] is now '-m' instead of '-c' while searching for the module to be executed

Doc/using/cmdline.rst

@@ -95,8 +95,9 @@ source.
       file is not available.
 
    If this option is given, the first element of :data:`sys.argv` will be the
-   full path to the module file. As with the :option:`-c` option, the current
-   directory will be added to the start of :data:`sys.path`.
+   full path to the module file (while the module file is being located, the
+   first element will be set to ``"-m"``). As with the :option:`-c` option,
+   the current directory will be added to the start of :data:`sys.path`.
 
    Many standard library modules contain code that is invoked on their execution
    as a script.  An example is the :mod:`timeit` module::

Misc/NEWS

@@ -12,6 +12,10 @@ What's New in Python 2.7 beta 2?
 Core and Builtins
 -----------------
 
+- Issue #8202: sys.argv[0] is now set to '-m' instead of '-c' when
+  searching for the module file to be executed with the -m command
+  line option
+
 - Issue #7319: When -Q is used, do not silence DeprecationWarning.
 
 - Issue #7332: Remove the 16KB stack-based buffer in

Modules/main.c

@@ -519,10 +519,10 @@ Py_Main(int argc, char **argv)
 	}
 
 	if (module != NULL) {
-		/* Backup _PyOS_optind and force sys.argv[0] = '-c'
+		/* Backup _PyOS_optind and force sys.argv[0] = '-m'
 		   so that PySys_SetArgv correctly sets sys.path[0] to ''*/
 		_PyOS_optind--;
-		argv[_PyOS_optind] = "-c";
+		argv[_PyOS_optind] = "-m";
 	}
 
 	PySys_SetArgv(argc-_PyOS_optind, argv+_PyOS_optind);