Cause CHAR(n) to TEXT or VARCHAR conversion to automatically strip trailing

blanks, in hopes of reducing the surprise factor for newbies.  Remove
redundant operators for VARCHAR (it depends wholly on TEXT operations now).
Clean up resolution of ambiguous operators/functions to avoid surprising
choices for domains: domains are treated as equivalent to their base types
and binary-coercibility is no longer considered a preference item when
choosing among multiple operators/functions.  IsBinaryCoercible now correctly
reflects the notion that you need *only* relabel the type to get from type
A to type B: that is, a domain is binary-coercible to its base type, but
not vice versa.  Various marginal cleanup, including merging the essentially
duplicate resolution code in parse_func.c and parse_oper.c.  Improve opr_sanity
regression test to understand about binary compatibility (using pg_cast),
and fix a couple of small errors in the catalogs revealed thereby.
Restructure "special operator" handling to fetch operators via index opclasses
rather than hardwiring assumptions about names (cleans up the pattern_ops
stuff a little).

src/include/parser/parse_func.h

@@ -7,13 +7,14 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: parse_func.h,v 1.45 2003/04/29 22:13:11 tgl Exp $
+ * $Id: parse_func.h,v 1.46 2003/05/26 00:11:28 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
 #ifndef PARSER_FUNC_H
 #define PARSER_FUNC_H
 
+#include "catalog/namespace.h"
 #include "parser/parse_node.h"
 
 
@@ -48,6 +49,15 @@ extern FuncDetailCode func_get_detail(List *funcname, List *fargs,
 				Oid *funcid, Oid *rettype,
 				bool *retset, Oid **true_typeids);
 
+extern int	func_match_argtypes(int nargs,
+								Oid *input_typeids,
+								FuncCandidateList raw_candidates,
+								FuncCandidateList *candidates);
+
+extern FuncCandidateList func_select_candidate(int nargs,
+											   Oid *input_typeids,
+											   FuncCandidateList candidates);
+
 extern bool typeInheritsFrom(Oid subclassTypeId, Oid superclassTypeId);
 
 extern void make_fn_arguments(ParseState *pstate,