patch 9.0.1593: MS-Windows: assert error when compiled with debug mode

Problem:    MS-Windows: assert error when compiled with debug mode.
Solution:   Adjust arguments to setvbuf(). (Ken Takata, closes #12467)

src/alloc.c

@@ -580,6 +580,7 @@ free_all_mem(void)
 # ifdef FEAT_EVAL
     free_resub_eval_result();
 # endif
+    free_vbuf();
 }
 #endif
 

src/main.c

@@ -76,6 +76,10 @@ static char *(main_errors[]) =
 // Various parameters passed between main() and other functions.
 static mparm_T	params;
 
+#ifdef _IOLBF
+static void *s_vbuf = NULL;		// buffer for setvbuf()
+#endif
+
 #ifndef NO_VIM_MAIN	// skip this for unittests
 
 static char_u *start_dir = NULL;	// current working dir on startup
@@ -353,10 +357,14 @@ main
     check_tty(&params);
 
 #ifdef _IOLBF
+    if (silent_mode)
+    {
 	// Ensure output works usefully without a tty: buffer lines instead of
 	// fully buffered.
-    if (silent_mode)
+	s_vbuf = malloc(BUFSIZ);
-	setvbuf(stdout, NULL, _IOLBF, 0);
+	if (s_vbuf != NULL)
+	    setvbuf(stdout, s_vbuf, _IOLBF, BUFSIZ);
+    }
 #endif
 
     // This message comes before term inits, but after setting "silent_mode"
@@ -1027,6 +1035,21 @@ is_not_a_term_or_gui(void)
 	;
 }
 
+#if defined(EXITFREE) || defined(PROTO)
+    void
+free_vbuf(void)
+{
+# ifdef _IOLBF
+    if (s_vbuf != NULL)
+    {
+	setvbuf(stdout, NULL, _IONBF, 0);
+	free(s_vbuf);
+	s_vbuf = NULL;
+    }
+# endif
+}
+#endif
+
 #if defined(FEAT_GUI) || defined(PROTO)
 /*
  * If a --gui-dialog-file argument was given return the file name.

src/proto/main.pro

@@ -3,6 +3,7 @@ int vim_main2(void);
 void common_init(mparm_T *paramp);
 int is_not_a_term(void);
 int is_not_a_term_or_gui(void);
+void free_vbuf(void);
 char_u *get_gui_dialog_file(void);
 int op_pending(void);
 void may_trigger_safestate(int safe);

src/version.c

@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1593,
 /**/
     1592,
 /**/