qt GUI: avoid decrementing argc to 0 in main because this seems to prevent setting WM_CLASS during qapp::exec()

src/qtgui/main.cpp

@@ -256,30 +256,38 @@ int main(int argc, char **argv)
     string a_lang;
     string question;
     string urltoview;
-    
-    thisprog = argv[0];
-    argc--; argv++;
 
-    while (argc > 0 && **argv == '-') {
+    // Avoid disturbing argc and argv. Especially, setting argc to 0
-        (*argv)++;
+    // prevents WM_CLASS to be set from argv[0] (it appears that qt
-        if (!(**argv))
+    // keeps a ref to argc, and that it is used at exec() time to set
+    // WM_CLASS from argv[0]). Curiously, it seems that the argv
+    // pointer can be modified without consequences, but we use a copy
+    // to play it safe
+    int myargc = argc;
+    char **myargv = argv;
+    thisprog = myargv[0];
+    myargc--; myargv++;
+    
+    while (myargc > 0 && **myargv == '-') {
+        (*myargv)++;
+        if (!(**myargv))
             Usage();
-        while (**argv)
+        while (**myargv)
-            switch (*(*argv)++) {
+            switch (*(*myargv)++) {
             case 'a': op_flags |= OPT_a; break;
-            case 'c':   op_flags |= OPT_c; if (argc < 2)  Usage();
+            case 'c':   op_flags |= OPT_c; if (myargc < 2)  Usage();
-                a_config = *(++argv);
+                a_config = *(++myargv);
-                argc--; goto b1;
+                myargc--; goto b1;
             case 'f': op_flags |= OPT_f; break;
             case 'h': op_flags |= OPT_h; Usage();break;
-            case 'L':   op_flags |= OPT_L; if (argc < 2)  Usage();
+            case 'L':   op_flags |= OPT_L; if (myargc < 2)  Usage();
-                a_lang = *(++argv);
+                a_lang = *(++myargv);
-                argc--; goto b1;
+                myargc--; goto b1;
             case 'l': op_flags |= OPT_l; break;
             case 'o': op_flags |= OPT_o; break;
-            case 'q':   op_flags |= OPT_q; if (argc < 2)  Usage();
+            case 'q':   op_flags |= OPT_q; if (myargc < 2)  Usage();
-                question = *(++argv);
+                question = *(++myargv);
-                argc--; goto b1;
+                myargc--; goto b1;
             case 't': op_flags |= OPT_t; break;
             case 'v': op_flags |= OPT_v;
                 fprintf(stdout, "%s\n", Rcl::version_string().c_str());
@@ -287,26 +295,26 @@ int main(int argc, char **argv)
             case 'w': op_flags |= OPT_w; break;
             default: Usage();
             }
-    b1: argc--; argv++;
+    b1: myargc--; myargv++;
     }
 
     // If -q was given, all remaining non-option args are concatenated
     // to the query. This is for the common case recoll -q x y z to
     // avoid needing quoting "x y z"
     if (op_flags & OPT_q)
-        while (argc > 0) {
+        while (myargc > 0) {
             question += " ";
-            question += *argv++;
+            question += *myargv++;
-            argc--;
+            myargc--;
         }
 
     // Else the remaining argument should be an URL to be opened
-    if (argc == 1) {
+    if (myargc == 1) {
-        urltoview = *argv++;argc--;
+        urltoview = *myargv++;myargc--;
         if (urltoview.compare(0, 7, cstr_fileu)) {
             Usage();
         }
-    } else if (argc > 0)
+    } else if (myargc > 0)
         Usage();