Return error messages as 'const char *', not 'char *'.

They're never dynamically allocated, and are almost always string
literals, so const is more appropriate.

1 files changed, 12 insertions, 7 deletions

diff --git a/windows.c b/windows.c
index 5b70285..84cf5ec 100644
--- a/windows.c
+++ b/windows.c
@@ -1002,7 +1002,7 @@ void print(frontend *fe)
     document *doc;
     midend *nme = NULL;  /* non-interactive midend for bulk puzzle generation */
     int i;
-    char *err = NULL;
+    const char *err = NULL;
 
     /*
      * Create our document structure and fill it up with puzzles.
@@ -1586,7 +1586,7 @@ static midend *midend_for_new_game(frontend *fe, const game *cgame,
         midend_new_game(me);
     } else {
         FILE *fp;
-        char *err_param, *err_load;
+        const char *err_param, *err_load;
 
         /*
          * See if arg is a valid filename of a save game file.
@@ -2103,7 +2103,8 @@ static config_item *frontend_get_config(frontend *fe, int which,
     }
 }
 
-static char *frontend_set_config(frontend *fe, int which, config_item *cfg)
+static const char *frontend_set_config(
+    frontend *fe, int which, config_item *cfg)
 {
     if (which < CFG_FRONTEND_SPECIFIC) {
 	return midend_set_config(fe->me, which, cfg);
@@ -2276,7 +2277,8 @@ static int CALLBACK ConfigDlgProc(HWND hwnd, UINT msg,
 	 */
 	if ((LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL)) {
 	    if (LOWORD(wParam) == IDOK) {
-		char *err = frontend_set_config(fe, fe->cfg_which, fe->cfg);
+		const char *err = frontend_set_config(
+                    fe, fe->cfg_which, fe->cfg);
 
 		if (err) {
 		    MessageBox(hwnd, err, "Validation error",
@@ -3015,7 +3017,7 @@ static LRESULT CALLBACK WndProc(HWND hwnd, UINT message,
 	    break;
 	  case IDM_SOLVE:
 	    {
-		char *msg = midend_solve(fe->me);
+		const char *msg = midend_solve(fe->me);
 		if (msg)
 		    MessageBox(hwnd, msg, "Unable to solve",
 			       MB_ICONERROR | MB_OK);
@@ -3107,7 +3109,8 @@ static LRESULT CALLBACK WndProc(HWND hwnd, UINT message,
 			fclose(fp);
 		    } else {
 			FILE *fp = fopen(filename, "r");
-			char *err = NULL;
+			const char *err = NULL;
+                        char *err_w = NULL;
                         midend *me = fe->me;
 #ifdef COMBINED
                         char *id_name;
@@ -3135,7 +3138,8 @@ static LRESULT CALLBACK WndProc(HWND hwnd, UINT message,
                                     "supported by this program";
                             } else {
                                 me = midend_for_new_game(fe, gamelist[i], NULL,
-                                                         FALSE, FALSE, &err);
+                                                         FALSE, FALSE, &err_w);
+                                err = err_w;
                                 rewind(fp); /* for the actual load */
                             }
                             sfree(id_name);
@@ -3148,6 +3152,7 @@ static LRESULT CALLBACK WndProc(HWND hwnd, UINT message,
 
 			if (err) {
 			    MessageBox(hwnd, err, "Error", MB_ICONERROR|MB_OK);
+                            sfree(err_w);
 			    break;
 			}