Avoid an assertion when compiling in debug mode with MSVC 2015

Seemingly, when removing an argument from argv, and thus inserting
a null pointer to shorten the array, causes an assertion because
the null pointer is not a valid heap pointer (sic!)

Fixes bug #10440

src/main.cpp

@@ -35,7 +35,7 @@ int main(int argc, char * argv[])
 	// early as possible.
 	lyx::lyxerr.setStream(cerr);
 
-	lyx::support::os::init(argc, argv);
+	lyx::support::os::init(argc, &argv);
 
 	lyx::LyX the_lyx_instance;
 

src/support/os.h

@@ -38,7 +38,7 @@ enum file_access {
 };
 
 /// Do some work just once.
-void init(int argc, char * argv[]);
+void init(int argc, char ** argv[]);
 
 /// Returns the i-th program argument in utf8 encoding.
 std::string utf8_argv(int i);

src/support/os_cygwin.cpp

@@ -210,10 +210,10 @@ BOOL terminate_handler(DWORD event)
 
 } // namespace anon
 
-void init(int argc, char * argv[])
+void init(int argc, char ** argv[])
 {
 	argc_ = argc;
-	argv_ = argv;
+	argv_ = *argv;
 
 	// Set environment's default locale
 	setlocale(LC_ALL, "");

src/support/os_unix.cpp

@@ -45,10 +45,10 @@ char ** argv_ = 0;
 
 } // namespace anon
 
-void init(int argc, char * argv[])
+void init(int argc, char ** argv[])
 {
 	argc_ = argc;
-	argv_ = argv;
+	argv_ = *argv;
 
 	// Set environment's default locale
 	setlocale(LC_ALL, "");

src/support/os_win32.cpp

@@ -99,7 +99,7 @@ BOOL terminate_handler(DWORD event)
 
 } // namespace anon
 
-void init(int argc, char * argv[])
+void init(int argc, char ** argv[])
 {
 	/* Note from Angus, 17 Jan 2005:
 	 *
@@ -158,6 +158,22 @@ void init(int argc, char * argv[])
 	 */
 
 
+#if defined(_MSC_VER) && (_MSC_VER >= 1900)
+	// Removing an argument from argv leads to an assertion on Windows
+	// when compiling with MSVC 2015 in debug mode (see bug #10440).
+	// To avoid this we make a copy of the array of pointers.
+	char ** newargv = (char **) malloc((argc + 1) * sizeof(char *));
+	if (newargv) {
+		memcpy(newargv, *argv, (argc + 1) * sizeof(char *));
+		*argv = newargv;
+	} else {
+		lyxerr << "LyX warning: Cannot make a copy of "
+		          "command line arguments!"
+		       << endl;
+	}
+#endif
+
+
 	// Get the wide program arguments array
 #if defined(_MSC_VER) && (_MSC_VER >= 1900)
 	argv_ = CommandLineToArgvW(GetCommandLineW(), &argc_);

src/tex2lyx/tex2lyx.cpp

@@ -1179,7 +1179,7 @@ int main(int argc, char * argv[])
 
 	lyx::lyxerr.setStream(cerr);
 
-	os::init(argc, argv);
+	os::init(argc, &argv);
 
 	lyx::TeX2LyXApp app(argc, argv);
 	return app.exec();