Fix broken list-slinging logic in func_select_candidate and

agg_select_candidate, which could cause them to keep more candidates
than they should and thus fail to select a single match.  I had
previously fixed the identical bug in oper_select_candidate, but
didn't realize that the same error was repeated over here.
Also, repair func_select_candidate's curious notion that it could
scribble on the input type-OID vector.  That was causing failure to
apply necessary type coercion later on, leading to malfunction of
examples such as select date('now').

diff --git a/src/backend/parser/parse_func.c b/src/backend/parser/parse_func.c
index 06afc867903a051822d2e6903ef90f43f68c803a..939d7a91ec3c220d0aa04b00ed02ce50e0285bae 100644 (file)
--- a/src/backend/parser/parse_func.c
+++ b/src/backend/parser/parse_func.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *   $Header: /cvsroot/pgsql/src/backend/parser/parse_func.c,v 1.69 2000/02/15 03:37:47 thomas Exp $
+ *   $Header: /cvsroot/pgsql/src/backend/parser/parse_func.c,v 1.70 2000/02/20 06:35:08 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -45,14 +45,13 @@ static Oid **argtype_inherit(int nargs, Oid *oid_array);
 
 static int find_inheritors(Oid relid, Oid **supervec);
 static CandidateList func_get_candidates(char *funcname, int nargs);
-static bool
-func_get_detail(char *funcname,
-               int nargs,
-               Oid *oid_array,
-               Oid *funcid,    /* return value */
-               Oid *rettype,   /* return value */
-               bool *retset,   /* return value */
-               Oid **true_typeids);
+static bool func_get_detail(char *funcname,
+                           int nargs,
+                           Oid *oid_array,
+                           Oid *funcid,    /* return value */
+                           Oid *rettype,   /* return value */
+                           bool *retset,   /* return value */
+                           Oid **true_typeids);
 static Oid **gen_cross_product(InhPaths *arginh, int nargs);
 static void make_arguments(ParseState *pstate,
               int nargs,
@@ -228,10 +227,11 @@ agg_select_candidate(Oid typeid, CandidateList candidates)
            }
        }
        /* otherwise, don't bother keeping this one around... */
-       else if (last_candidate != NULL)
-           last_candidate->next = NULL;
    }
 
+   if (last_candidate)         /* terminate rebuilt list */
+       last_candidate->next = NULL;
+
    return ((ncandidates == 1) ? candidates->args[0] : 0);
 }  /* agg_select_candidate() */
 
@@ -559,8 +559,8 @@ ParseFuncOrColumn(ParseState *pstate, char *funcname, List *fargs,
        }
 
        /* Most of the rest of the parser just assumes that functions do not
-        * have more than FUNC_MAX_ARGS parameters.  We have to test here to protect
-        * against array overruns, etc.
+        * have more than FUNC_MAX_ARGS parameters.  We have to test here
+        * to protect against array overruns, etc.
         */
        if (nargs >= FUNC_MAX_ARGS)
            elog(ERROR, "Cannot pass more than %d arguments to a function",
@@ -892,6 +892,7 @@ func_select_candidate(int nargs,
        if ((nmatch + nident) == nargs)
            return current_candidate->args;
 
+       /* take this one as the best choice so far? */
        if ((nmatch > nbestMatch) || (last_candidate == NULL))
        {
            nbestMatch = nmatch;
@@ -899,16 +900,19 @@ func_select_candidate(int nargs,
            last_candidate = current_candidate;
            ncandidates = 1;
        }
+       /* no worse than the last choice, so keep this one too? */
        else if (nmatch == nbestMatch)
        {
            last_candidate->next = current_candidate;
            last_candidate = current_candidate;
            ncandidates++;
        }
-       else
-           last_candidate->next = NULL;
+       /* otherwise, don't bother keeping this one... */
    }
 
+   if (last_candidate)         /* terminate rebuilt list */
+       last_candidate->next = NULL;
+
    if (ncandidates == 1)
        return candidates->args;
 
@@ -922,6 +926,7 @@ func_select_candidate(int nargs,
        {
            slot_category = INVALID_TYPE;
            slot_type = InvalidOid;
+           last_candidate = NULL;
            for (current_candidate = candidates;
                 current_candidate != NULL;
                 current_candidate = current_candidate->next)
@@ -935,26 +940,39 @@ func_select_candidate(int nargs,
                    slot_category = current_category;
                    slot_type = current_type;
                }
-               else if ((current_category != slot_category)
-                        && IS_BUILTIN_TYPE(current_type))
+               else if (current_category != slot_category)
+               {
+                   /* punt if more than one category for this slot */
                    return NULL;
+               }
                else if (current_type != slot_type)
                {
                    if (IsPreferredType(slot_category, current_type))
                    {
                        slot_type = current_type;
+                       /* forget all previous candidates */
                        candidates = current_candidate;
+                       last_candidate = current_candidate;
                    }
                    else if (IsPreferredType(slot_category, slot_type))
-                       candidates->next = current_candidate->next;
+                   {
+                       /* forget this candidate */
+                       if (last_candidate)
+                           last_candidate->next = current_candidate->next;
+                       else
+                           candidates = current_candidate->next;
+                   }
+                   else
+                       last_candidate = current_candidate;
+               }
+               else
+               {
+                   /* keep this candidate */
+                   last_candidate = current_candidate;
                }
            }
-
-           if (slot_type != InvalidOid)
-               input_typeids[i] = slot_type;
-       }
-       else
-       {
+           if (last_candidate)         /* terminate rebuilt list */
+               last_candidate->next = NULL;
        }
    }