[Freeciv-Dev] (PR#11806) bug in required_tech_helper

["Mateusz Stefek" <mstefek@xxxxxxxxx>]

<URL: http://bugs.freeciv.org/Ticket/Display.html?id=11806 >

Since it's no longer true that player(pplayer, A_NONE)==TECH_KNOWN ( I don't 
known why)

the following if statement from build_required_techs_helper() not always 
returns for A_NONE

  if (!tech_is_available(pplayer, tech)
      || get_invention(pplayer, tech) == TECH_KNOWN
      || is_tech_a_req_for_goal(pplayer, tech, goal)) {
    return;
  }

This bug triggers following assertion, because A_NONE requires A_NONE
  if (advances[tech].req[0] == goal || advances[tech].req[1] == goal) {
    /* TRANS: Obscure ruleset error */
    freelog(LOG_FATAL, _("tech \"%s\": requires itself"),
            get_tech_name(pplayer, goal));
    assert(0);
    exit(EXIT_FAILURE);
  }


Index: common/tech.c
===================================================================
RCS file: /home/freeciv/CVS/freeciv/common/tech.c,v
retrieving revision 1.76.2.2
diff -u -r1.76.2.2 tech.c
--- common/tech.c       9 Dec 2004 02:09:51 -0000       1.76.2.2
+++ common/tech.c       5 Jan 2005 19:21:46 -0000
@@ -101,7 +101,8 @@
    * already marked */
   if (!tech_is_available(pplayer, tech)
       || get_invention(pplayer, tech) == TECH_KNOWN
-      || is_tech_a_req_for_goal(pplayer, tech, goal)) {
+      || is_tech_a_req_for_goal(pplayer, tech, goal)
+      || tech == A_NONE) {
     return;
   }