Make skipping of unknown option smarter

To make XBoard better resistant to the presence of disbanded or future
options in its settings file, encountering those is no longer a fatal error.
But the error recovery only consisted of skipping the rest of the line.
This fails badly on string options with a multi-line value, which is
enclosed by {braces}. We now detect that case, to skip to } instead.

diff --git a/args.h b/args.h
index 9533406..76b2452 100644 (file)
--- a/args.h
+++ b/args.h
@@ -919,8 +919,9 @@ ParseArgs(GetFunc get, void *cl)
       for (ad = argDescriptors; ad->argName != NULL; ad++)
        if (strcmp(ad->argName, argName + 1) == 0) break;
       if (ad->argName == NULL) {
+       char endChar = (ch && ch != '\n' && (ch = get(cl)) == '{' ? '}' : '\n');
        ExitArgError(_("Unrecognized argument %s"), argName, get != &FileGet); // [HGM] make unknown argument non-fatal
-       while (ch != '\n' && ch != NULLCHAR) ch = get(cl); // but skip rest of line it is on
+       while (ch != endChar && ch != NULLCHAR) ch = get(cl); // but skip rest of line it is on (or until closing '}' )
        continue; // so that when it is in a settings file, it is the only setting that will be purged from it
       }
     } else if (ch == '@') {