fix #H4144 - rejecting named monster's own name

Some monsters can't be named, but if the user tried to assign them a
name that matched what they were already called, the rejection message
could be silly.  Reported case was "I'm Izchak, not Izchak!".  The fix
is more general than just for shopkeepers, although their reject
message was silliest when complaining about the name already in use.
For the cited case, feedback will now be 'He is already called Izchak.'

doc/fixes36.1

@@ -65,6 +65,8 @@ Warn_of_mon wouldn't have been able to sense giant ants if any creature were
 	to have that ability, caused by using 0 instead of NON_PM for 'none'
 tone down energy vortex's drain energy attack
 fix message typo if tame mind flayer dies trying to eat Medusa's brains
+use alternate rejection message if attempting to name an unnameable monster
+	with the name it already has
 
 
 Platform- and/or Interface-Specific Fixes

src/do_name.c

@@ -7,6 +7,7 @@
 STATIC_DCL char *NDECL(nextmbuf);
 STATIC_DCL void FDECL(getpos_help, (BOOLEAN_P, const char *));
 STATIC_DCL void NDECL(do_mname);
+STATIC_DCL boolean FDECL(alreadynamed, (struct monst *, char *, char *));
 STATIC_DCL void FDECL(do_oname, (struct obj *));
 STATIC_DCL void NDECL(namefloorobj);
 STATIC_DCL char *FDECL(bogusmon, (char *,char *));
@@ -409,15 +410,45 @@ const char *name;
     return mtmp;
 }
 
+/* check whether user-supplied name matches or nearly matches an unnameable
+   monster's name; if so, give an alternate reject message for do_mname() */
+STATIC_OVL boolean
+alreadynamed(mtmp, monnambuf, usrbuf)
+struct monst *mtmp;
+char *monnambuf, *usrbuf;
+{
+    char pronounbuf[10], *p;
+
+    if (fuzzymatch(usrbuf, monnambuf, " -_", TRUE)
+        /* catch trying to name "the Oracle" as "Oracle" */
+        || (!strncmpi(monnambuf, "the ", 4)
+            && fuzzymatch(usrbuf, monnambuf + 4, " -_", TRUE))
+        /* catch trying to name "invisible Orcus" as "Orcus" */
+        || ((p = strstri(monnambuf, "invisible ")) != 0
+            && fuzzymatch(usrbuf, p + 10, " -_", TRUE))
+        /* catch trying to name "the {priest,Angel} of Crom" as "Crom" */
+        || ((p = strstri(monnambuf, " of ")) != 0
+            && fuzzymatch(usrbuf, p + 4, " -_", TRUE))) {
+        pline("%s is already called %s.",
+              upstart(strcpy(pronounbuf, mhe(mtmp))), monnambuf);
+        return TRUE;
+    } else if (mtmp->data == &mons[PM_JUIBLEX]
+               && strstri(monnambuf, "Juiblex")
+               && !strcmpi(usrbuf, "Jubilex")) {
+        pline("%s doesn't like being called %s.", upstart(monnambuf), usrbuf);
+        return TRUE;
+    }
+    return FALSE;
+}
+
 /* allow player to assign a name to some chosen monster */
 STATIC_OVL void
 do_mname()
 {
-    char buf[BUFSZ], monnambuf[BUFSZ];
+    char buf[BUFSZ], monnambuf[BUFSZ], qbuf[QBUFSZ];
     coord cc;
-    register int cx, cy;
-    register struct monst *mtmp;
-    char qbuf[QBUFSZ];
+    int cx, cy;
+    struct monst *mtmp = 0;
 
     if (Hallucination) {
         You("would never recognize it anyway.");
@@ -431,9 +462,9 @@ do_mname()
     cy = cc.y;
 
     if (cx == u.ux && cy == u.uy) {
-        if (u.usteed && canspotmon(u.usteed))
+        if (u.usteed && canspotmon(u.usteed)) {
             mtmp = u.usteed;
-        else {
+        } else {
             pline("This %s creature is called %s and cannot be renamed.",
                   beautiful(), plname);
             return;
@@ -459,18 +490,25 @@ do_mname()
     /* strip leading and trailing spaces; unnames monster if all spaces */
     (void) mungspaces(buf);
 
-    /* unique monsters have their own specific names or titles;
-       shopkeepers, temple priests and other minions use alternate
-       name formatting routines which ignore any user-supplied name */
-    if ((mtmp->data->geno & G_UNIQ) && !mtmp->ispriest)
-        pline("%s doesn't like being called names!", upstart(monnambuf));
-    else if (mtmp->isshk
-             && !(Deaf || mtmp->msleeping || !mtmp->mcanmove
-                  || mtmp->data->msound <= MS_ANIMAL))
-        verbalize("I'm %s, not %s.", shkname(mtmp), buf);
-    else if (mtmp->ispriest || mtmp->isminion || mtmp->isshk)
-        pline("%s will not accept the name %s.", upstart(monnambuf), buf);
-    else
+    /* Unique monsters have their own specific names or titles.
+     * Shopkeepers, temple priests and other minions use alternate
+     * name formatting routines which ignore any user-supplied name.
+     *
+     * Don't say the name is being rejected if it happens to match
+     * the existing name.
+     */
+    if ((mtmp->data->geno & G_UNIQ) && !mtmp->ispriest) {
+        if (!alreadynamed(mtmp, monnambuf, buf))
+            pline("%s doesn't like being called names!", upstart(monnambuf));
+    } else if (mtmp->isshk
+               && !(Deaf || mtmp->msleeping || !mtmp->mcanmove
+                    || mtmp->data->msound <= MS_ANIMAL)) {
+        if (!alreadynamed(mtmp, monnambuf, buf))
+            verbalize("I'm %s, not %s.", shkname(mtmp), buf);
+    } else if (mtmp->ispriest || mtmp->isminion || mtmp->isshk) {
+        if (!alreadynamed(mtmp, monnambuf, buf))
+            pline("%s will not accept the name %s.", upstart(monnambuf), buf);
+    } else
         (void) christen_monst(mtmp, buf);
 }