Remove useless argtype_inherit() code, and make consequent simplifications.

As I pointed out a few days ago, this code has failed to do anything useful
for some time ... and if we did want to revive the capability to select
functions by nearness of inheritance ancestry, this is the wrong place
and way to do it anyway.  The knowledge would need to go into
func_select_candidate() instead.  Perhaps someday someone will be motivated
to do that, but I am not today.

Author: tglsfdc

src/backend/parser/parse_func.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_func.c,v 1.178 2005/04/14 20:03:25 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_func.c,v 1.179 2005/04/23 22:09:58 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -34,10 +34,6 @@
 
 static Node *ParseComplexProjection(ParseState *pstate, char *funcname,
 					   Node *first_arg);
-static Oid **argtype_inherit(int nargs, Oid *argtypes);
-
-static int	find_inheritors(Oid relid, Oid **supervec);
-static Oid **gen_cross_product(InhPaths *arginh, int nargs);
 static void unknown_attribute(ParseState *pstate, Node *relref, char *attname);
 
 
@@ -754,63 +750,34 @@ func_get_detail(List *funcname,
 		 */
 		if (raw_candidates != NULL)
 		{
-			Oid		  **input_typeid_vector = NULL;
-			Oid		   *current_input_typeids;
+			FuncCandidateList current_candidates;
+			int			ncandidates;
+
+			ncandidates = func_match_argtypes(nargs,
+											  argtypes,
+											  raw_candidates,
+											  &current_candidates);
+
+			/* one match only? then run with it... */
+			if (ncandidates == 1)
+				best_candidate = current_candidates;
 
 			/*
-			 * First we will search with the given argtypes, then with
-			 * variants based on replacing complex types with their
-			 * inheritance ancestors.  Stop as soon as any match is found.
+			 * multiple candidates? then better decide or throw an error...
 			 */
-			current_input_typeids = argtypes;
-
-			do
+			else if (ncandidates > 1)
 			{
-				FuncCandidateList current_candidates;
-				int			ncandidates;
-
-				ncandidates = func_match_argtypes(nargs,
-												  current_input_typeids,
-												  raw_candidates,
-												  &current_candidates);
-
-				/* one match only? then run with it... */
-				if (ncandidates == 1)
-				{
-					best_candidate = current_candidates;
-					break;
-				}
+				best_candidate = func_select_candidate(nargs,
+													   argtypes,
+													   current_candidates);
 
 				/*
-				 * multiple candidates? then better decide or throw an
-				 * error...
+				 * If we were able to choose a best candidate, we're
+				 * done.  Otherwise, ambiguous function call.
 				 */
-				if (ncandidates > 1)
-				{
-					best_candidate = func_select_candidate(nargs,
-												   current_input_typeids,
-													 current_candidates);
-
-					/*
-					 * If we were able to choose a best candidate, we're
-					 * done.  Otherwise, ambiguous function call.
-					 */
-					if (best_candidate)
-						break;
+				if (!best_candidate)
 					return FUNCDETAIL_MULTIPLE;
-				}
-
-				/*
-				 * No match here, so try the next inherited type vector.
-				 * First time through, we need to compute the list of
-				 * vectors.
-				 */
-				if (input_typeid_vector == NULL)
-					input_typeid_vector = argtype_inherit(nargs, argtypes);
-
-				current_input_typeids = *input_typeid_vector++;
 			}
-			while (current_input_typeids != NULL);
 		}
 	}
 
@@ -840,81 +807,27 @@ func_get_detail(List *funcname,
 	return FUNCDETAIL_NOTFOUND;
 }
 
-/*
- *	argtype_inherit() -- Construct an argtype vector reflecting the
- *						 inheritance properties of the supplied argv.
- *
- *		This function is used to handle resolution of function calls when
- *		there is no match to the given argument types, but there might be
- *		matches based on considering complex types as members of their
- *		superclass types (parent classes).
- *
- *		It takes an array of input type ids.  For each type id in the array
- *		that's a complex type (a class), it walks up the inheritance tree,
- *		finding all superclasses of that type. A vector of new Oid type
- *		arrays is returned to the caller, listing possible alternative
- *		interpretations of the input typeids as members of their superclasses
- *		rather than the actually given argument types.	The vector is
- *		terminated by a NULL pointer.
- *
- *		The order of this vector is as follows:  all superclasses of the
- *		rightmost complex class are explored first.  The exploration
- *		continues from right to left.  This policy means that we favor
- *		keeping the leftmost argument type as low in the inheritance tree
- *		as possible.  This is intentional; it is exactly what we need to
- *		do for method dispatch.
- *
- *		The vector does not include the case where no complex classes have
- *		been promoted, since that was already tried before this routine
- *		got called.
- */
-static Oid **
-argtype_inherit(int nargs, Oid *argtypes)
-{
-	Oid		  **result;
-	Oid			relid;
-	int			i;
-	InhPaths   *arginh;
-
-	/* Set up the vector of superclass information */
-	arginh = (InhPaths *) palloc(nargs * sizeof(InhPaths));
-
-	for (i = 0; i < nargs; i++)
-	{
-		arginh[i].self = argtypes[i];
-		if ((relid = typeidTypeRelid(argtypes[i])) != InvalidOid)
-			arginh[i].nsupers = find_inheritors(relid, &(arginh[i].supervec));
-		else
-		{
-			arginh[i].nsupers = 0;
-			arginh[i].supervec = NULL;
-		}
-	}
-
-	/* Compute an ordered cross-product of the classes involved */
-	result = gen_cross_product(arginh, nargs);
-
-	pfree(arginh);
-
-	return result;
-}
 
 /*
- * Look up the parent superclass(es) of the given relation.
- *
- * *supervec is set to an array of the type OIDs (not the relation OIDs)
- * of the parents, with nearest ancestors listed first.  It's set to NULL
- * if there are no parents.  The return value is the number of parents.
+ * Given two type OIDs, determine whether the first is a complex type
+ * (class type) that inherits from the second.
  */
-static int
-find_inheritors(Oid relid, Oid **supervec)
+bool
+typeInheritsFrom(Oid subclassTypeId, Oid superclassTypeId)
 {
+	bool		result = false;
+	Oid			relid;
 	Relation	inhrel;
-	int			nvisited;
 	List	   *visited,
 			   *queue;
 	ListCell   *queue_item;
 
+	if (!ISCOMPLEX(subclassTypeId) || !ISCOMPLEX(superclassTypeId))
+		return false;
+	relid = typeidTypeRelid(subclassTypeId);
+	if (relid == InvalidOid)
+		return false;
+
 	/*
 	 * Begin the search at the relation itself, so add relid to the queue.
 	 */
@@ -960,149 +873,30 @@ find_inheritors(Oid relid, Oid **supervec)
 		while ((inhtup = heap_getnext(inhscan, ForwardScanDirection)) != NULL)
 		{
 			Form_pg_inherits inh = (Form_pg_inherits) GETSTRUCT(inhtup);
+			Oid		inhparent = inh->inhparent;
+
+			/* If this is the target superclass, we're done */
+			if (get_rel_type_id(inhparent) == superclassTypeId)
+			{
+				result = true;
+				break;
+			}
 
-			queue = lappend_oid(queue, inh->inhparent);
+			/* Else add to queue */
+			queue = lappend_oid(queue, inhparent);
 		}
 
 		heap_endscan(inhscan);
+
+		if (result)
+			break;
 	}
 
 	heap_close(inhrel, AccessShareLock);
 
-	nvisited = list_length(visited);
-	if (nvisited > 0)
-	{
-		Oid		   *relidvec;
-		ListCell   *l;
-
-		relidvec = (Oid *) palloc(nvisited * sizeof(*relidvec));
-		*supervec = relidvec;
-
-		foreach(l, visited)
-		{
-			/* return the type id, rather than the relation id */
-			*relidvec++ = get_rel_type_id(lfirst_oid(l));
-		}
-	}
-	else
-		*supervec = NULL;
-
 	list_free(visited);
 	list_free(queue);
 
-	return nvisited;
-}
-
-/*
- * Generate the ordered list of substitute argtype vectors to try.
- *
- * See comments for argtype_inherit.
- */
-static Oid **
-gen_cross_product(InhPaths *arginh, int nargs)
-{
-	int			nanswers;
-	Oid		  **result;
-	Oid		   *oneres;
-	int			i,
-				j;
-	int		   *cur;
-
-	/*
-	 * At each position we want to try the original datatype, plus each
-	 * supertype.  So the number of possible combinations is this:
-	 */
-	nanswers = 1;
-	for (i = 0; i < nargs; i++)
-		nanswers *= (arginh[i].nsupers + 1);
-
-	/*
-	 * We also need an extra slot for the terminating NULL in the result
-	 * array, but that cancels out with the fact that we don't want to
-	 * generate the zero-changes case.	So we need exactly nanswers slots.
-	 */
-	result = (Oid **) palloc(sizeof(Oid *) * nanswers);
-	j = 0;
-
-	/*
-	 * Compute the cross product from right to left.  When cur[i] == 0,
-	 * generate the original input type at position i.	When cur[i] == k
-	 * for k > 0, generate its k'th supertype.
-	 */
-	cur = (int *) palloc0(nargs * sizeof(int));
-
-	for (;;)
-	{
-		/*
-		 * Find a column we can increment.	All the columns after it get
-		 * reset to zero.  (Essentially, we're adding one to the multi-
-		 * digit number represented by cur[].)
-		 */
-		for (i = nargs - 1; i >= 0 && cur[i] >= arginh[i].nsupers; i--)
-			cur[i] = 0;
-
-		/* if none, we're done */
-		if (i < 0)
-			break;
-
-		/* increment this column */
-		cur[i] += 1;
-
-		/* Generate the proper output type-OID vector */
-		oneres = (Oid *) palloc(nargs * sizeof(Oid));
-
-		for (i = 0; i < nargs; i++)
-		{
-			if (cur[i] == 0)
-				oneres[i] = arginh[i].self;
-			else
-				oneres[i] = arginh[i].supervec[cur[i] - 1];
-		}
-
-		result[j++] = oneres;
-	}
-
-	/* terminate result vector with NULL pointer */
-	result[j++] = NULL;
-
-	Assert(j == nanswers);
-
-	pfree(cur);
-
-	return result;
-}
-
-
-/*
- * Given two type OIDs, determine whether the first is a complex type
- * (class type) that inherits from the second.
- */
-bool
-typeInheritsFrom(Oid subclassTypeId, Oid superclassTypeId)
-{
-	Oid			relid;
-	Oid		   *supervec;
-	int			nsupers,
-				i;
-	bool		result;
-
-	if (!ISCOMPLEX(subclassTypeId) || !ISCOMPLEX(superclassTypeId))
-		return false;
-	relid = typeidTypeRelid(subclassTypeId);
-	if (relid == InvalidOid)
-		return false;
-	nsupers = find_inheritors(relid, &supervec);
-	result = false;
-	for (i = 0; i < nsupers; i++)
-	{
-		if (supervec[i] == superclassTypeId)
-		{
-			result = true;
-			break;
-		}
-	}
-	if (supervec)
-		pfree(supervec);
 	return result;
 }