Error for non-monster spells in monster specs

Give an error when parsing a monster spec if it lists a spell a monster
can't cast, rather than causing an assertion when the monster tries to
cast it.

4 files changed, 54 insertions, 2 deletions

diff --git a/crawl-ref/source/acr.cc b/crawl-ref/source/acr.cc
index 2a7ef4c6ee..4a020a2183 100644
--- a/crawl-ref/source/acr.cc
+++ b/crawl-ref/source/acr.cc
@@ -85,6 +85,7 @@
 #include "message.h"
 #include "misc.h"
 #include "mon-act.h"
+#include "mon-cast.h"
 #include "monplace.h"
 #include "monstuff.h"
 #include "mon-util.h"
@@ -3533,6 +3534,7 @@ static bool _initialise(void)
     init_monster_symbols();
     init_spell_descs();        // This needs to be way up top. {dlb}
     init_mon_name_cache();
+    init_mons_spells();
 
     // init_item_name_cache() needs to be redone after init_char_table()
     // and init_show_table() have been called, so that the glyphs will
diff --git a/crawl-ref/source/mapdef.cc b/crawl-ref/source/mapdef.cc
index a9e0ee0412..402652713e 100644
--- a/crawl-ref/source/mapdef.cc
+++ b/crawl-ref/source/mapdef.cc
@@ -30,6 +30,7 @@
 #include "mapmark.h"
 #include "maps.h"
 #include "misc.h"
+#include "mon-cast.h"
 #include "monplace.h"
 #include "mon-util.h"
 #include "place.h"
@@ -2368,6 +2369,12 @@ void mons_list::parse_mons_spells(mons_spec &spec, const std::string &spells)
                                      spname.c_str(), spells.c_str());
                 return;
             }
+            if (!is_valid_mon_spell(sp))
+            {
+                error = make_stringf("Not a monster spell: '%s'",
+                                     spname.c_str());
+                return;
+             }
             spec.spells[i] = sp;
         }
     }
diff --git a/crawl-ref/source/mon-cast.cc b/crawl-ref/source/mon-cast.cc
index 1a7e53ee76..cc51dc36aa 100644
--- a/crawl-ref/source/mon-cast.cc
+++ b/crawl-ref/source/mon-cast.cc
@@ -34,6 +34,38 @@
 #include "view.h"
 #include "viewchar.h"
 
+static bool _valid_mon_spells[NUM_SPELLS];
+
+void init_mons_spells()
+{
+    monsters fake_mon;
+    fake_mon.type       = MONS_BLACK_DRACONIAN;
+    fake_mon.hit_points = 1;
+
+    for (int i = 0; i < NUM_SPELLS; i++)
+    {
+        spell_type spell = (spell_type) i;
+
+        _valid_mon_spells[i] = false;
+
+        if (!is_valid_spell(spell))
+            continue;
+
+        bolt beam = mons_spells(&fake_mon, spell, 1, true);
+
+        if (beam.flavour != NUM_BEAMS)
+            _valid_mon_spells[i] = true;
+    }
+}
+
+bool is_valid_mon_spell(spell_type spell)
+{
+    if (spell < 0 || spell >= NUM_SPELLS)
+        return (false);
+
+    return (_valid_mon_spells[spell]);
+}
+
 static void _scale_draconian_breath(bolt& beam, int drac_type)
 {
     int scaling = 100;
@@ -126,7 +158,8 @@ static bool _set_allied_target(monsters * caster, bolt & pbolt)
     return (false);
 }
 
-bolt mons_spells( monsters *mons, spell_type spell_cast, int power )
+bolt mons_spells( monsters *mons, spell_type spell_cast, int power,
+                  bool check_validity )
 {
     ASSERT(power > 0);
 
@@ -606,6 +639,12 @@ bolt mons_spells( monsters *mons, spell_type spell_cast, int power )
         break;
 
     default:
+        if (check_validity)
+        {
+            beam.flavour = NUM_BEAMS;
+            return (beam);
+        }
+
         if (!is_valid_spell(real_spell))
             DEBUGSTR("Invalid spell #%d cast by %s", (int) real_spell,
                      mons->name(DESC_PLAIN, true).c_str());
diff --git a/crawl-ref/source/mon-cast.h b/crawl-ref/source/mon-cast.h
index 5d10125d98..6d7d023abc 100644
--- a/crawl-ref/source/mon-cast.h
+++ b/crawl-ref/source/mon-cast.h
@@ -12,9 +12,13 @@
 class monsters;
 class bolt;
 
+void init_mons_spells();
+bool is_valid_mon_spell(spell_type spell);
+
 bool handle_mon_spell(monsters *monster, bolt &beem);
 
-bolt mons_spells(monsters *mons, spell_type spell_cast, int power);
+bolt mons_spells(monsters *mons, spell_type spell_cast, int power,
+                 bool check_validity = false);
 void mons_cast(monsters *monster, bolt &pbolt, spell_type spell_cast,
                bool do_noise = true);
 void mons_cast_noise(monsters *monster, bolt &pbolt, spell_type spell_cast);