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).

1 files changed, 18 insertions, 403 deletions

diff --git a/src/backend/parser/parse_oper.c b/src/backend/parser/parse_oper.c
index 6238258ed2f..21f73994c42 100644
--- a/src/backend/parser/parse_oper.c
+++ b/src/backend/parser/parse_oper.c
@@ -8,18 +8,13 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_oper.c,v 1.63 2003/04/29 22:13:10 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_oper.c,v 1.64 2003/05/26 00:11:27 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
 
 #include "postgres.h"
 
-#include "access/genam.h"
-#include "access/heapam.h"
-#include "catalog/catname.h"
-#include "catalog/indexing.h"
-#include "catalog/namespace.h"
 #include "catalog/pg_operator.h"
 #include "parser/parse_coerce.h"
 #include "parser/parse_expr.h"
@@ -289,107 +284,29 @@ binary_oper_exact(Oid arg1, Oid arg2,
 
 
 /* oper_select_candidate()
- * Given the input argtype array and one or more candidates
- * for the function argtype array, attempt to resolve the conflict.
- * Returns the selected argtype array if the conflict can be resolved,
- * otherwise returns NULL.
+ *		Given the input argtype array and one or more candidates
+ *		for the operator, attempt to resolve the conflict.
  *
- * By design, this is pretty similar to func_select_candidate in parse_func.c.
- * However, we can do a couple of extra things here because we know we can
- * have no more than two args to deal with.  Also, the calling convention
- * is a little different: we must prune away "candidates" that aren't actually
- * coercion-compatible with the input types, whereas in parse_func.c that
- * gets done by match_argtypes before func_select_candidate is called.
+ * Returns the OID of the selected operator if the conflict can be resolved,
+ * otherwise returns InvalidOid.
  *
- * This routine is new code, replacing binary_oper_select_candidate()
- * which dates from v4.2/v1.0.x days. It tries very hard to match up
- * operators with types, including allowing type coercions if necessary.
- * The important thing is that the code do as much as possible,
- * while _never_ doing the wrong thing, where "the wrong thing" would
- * be returning an operator when other better choices are available,
- * or returning an operator which is a non-intuitive possibility.
- * - thomas 1998-05-21
- *
- * The comments below came from binary_oper_select_candidate(), and
- * illustrate the issues and choices which are possible:
- * - thomas 1998-05-20
- *
- * current wisdom holds that the default operator should be one in which
- * both operands have the same type (there will only be one such
- * operator)
- *
- * 7.27.93 - I have decided not to do this; it's too hard to justify, and
- * it's easy enough to typecast explicitly - avi
- * [the rest of this routine was commented out since then - ay]
- *
- * 6/23/95 - I don't complete agree with avi. In particular, casting
- * floats is a pain for users. Whatever the rationale behind not doing
- * this is, I need the following special case to work.
- *
- * In the WHERE clause of a query, if a float is specified without
- * quotes, we treat it as float8. I added the float48* operators so
- * that we can operate on float4 and float8. But now we have more than
- * one matching operator if the right arg is unknown (eg. float
- * specified with quotes). This break some stuff in the regression
- * test where there are floats in quotes not properly casted. Below is
- * the solution. In addition to requiring the operator operates on the
- * same type for both operands [as in the code Avi originally
- * commented out], we also require that the operators be equivalent in
- * some sense. (see equivalentOpersAfterPromotion for details.)
- * - ay 6/95
+ * Note that the caller has already determined that there is no candidate
+ * exactly matching the input argtype(s).  Incompatible candidates are not yet
+ * pruned away, however.
  */
 static Oid
 oper_select_candidate(int nargs,
 					  Oid *input_typeids,
 					  FuncCandidateList candidates)
 {
-	FuncCandidateList current_candidate;
-	FuncCandidateList last_candidate;
-	Oid		   *current_typeids;
-	Oid			current_type;
-	int			unknownOids;
-	int			i;
 	int			ncandidates;
-	int			nbestMatch,
-				nmatch;
-	CATEGORY	slot_category[FUNC_MAX_ARGS],
-				current_category;
-	bool		slot_has_preferred_type[FUNC_MAX_ARGS];
-	bool		resolved_unknowns;
 
 	/*
-	 * First, delete any candidates that cannot actually accept the given
-	 * input types, whether directly or by coercion.  (Note that
-	 * can_coerce_type will assume that UNKNOWN inputs are coercible to
-	 * anything, so candidates will not be eliminated on that basis.)
+	 * Delete any candidates that cannot actually accept the given
+	 * input types, whether directly or by coercion.
 	 */
-	ncandidates = 0;
-	last_candidate = NULL;
-	for (current_candidate = candidates;
-		 current_candidate != NULL;
-		 current_candidate = current_candidate->next)
-	{
-		if (can_coerce_type(nargs, input_typeids, current_candidate->args,
-							COERCION_IMPLICIT))
-		{
-			if (last_candidate == NULL)
-			{
-				candidates = current_candidate;
-				last_candidate = current_candidate;
-				ncandidates = 1;
-			}
-			else
-			{
-				last_candidate->next = current_candidate;
-				last_candidate = current_candidate;
-				ncandidates++;
-			}
-		}
-		/* otherwise, don't bother keeping this one... */
-	}
-
-	if (last_candidate)			/* terminate rebuilt list */
-		last_candidate->next = NULL;
+	ncandidates = func_match_argtypes(nargs, input_typeids,
+									  candidates, &candidates);
 
 	/* Done if no candidate or only one candidate survives */
 	if (ncandidates == 0)
@@ -398,317 +315,15 @@ oper_select_candidate(int nargs,
 		return candidates->oid;
 
 	/*
-	 * Run through all candidates and keep those with the most matches on
-	 * exact types. Keep all candidates if none match.
-	 */
-	ncandidates = 0;
-	nbestMatch = 0;
-	last_candidate = NULL;
-	for (current_candidate = candidates;
-		 current_candidate != NULL;
-		 current_candidate = current_candidate->next)
-	{
-		current_typeids = current_candidate->args;
-		nmatch = 0;
-		for (i = 0; i < nargs; i++)
-		{
-			if (input_typeids[i] != UNKNOWNOID &&
-				current_typeids[i] == input_typeids[i])
-				nmatch++;
-		}
-
-		/* take this one as the best choice so far? */
-		if ((nmatch > nbestMatch) || (last_candidate == NULL))
-		{
-			nbestMatch = nmatch;
-			candidates = current_candidate;
-			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++;
-		}
-		/* otherwise, don't bother keeping this one... */
-	}
-
-	if (last_candidate)			/* terminate rebuilt list */
-		last_candidate->next = NULL;
-
-	if (ncandidates == 1)
-		return candidates->oid;
-
-	/*
-	 * Still too many candidates? Run through all candidates and keep
-	 * those with the most matches on exact types + binary-compatible
-	 * types. Keep all candidates if none match.
-	 */
-	ncandidates = 0;
-	nbestMatch = 0;
-	last_candidate = NULL;
-	for (current_candidate = candidates;
-		 current_candidate != NULL;
-		 current_candidate = current_candidate->next)
-	{
-		current_typeids = current_candidate->args;
-		nmatch = 0;
-		for (i = 0; i < nargs; i++)
-		{
-			if (input_typeids[i] != UNKNOWNOID)
-			{
-				if (IsBinaryCoercible(input_typeids[i], current_typeids[i]))
-					nmatch++;
-			}
-		}
-
-		/* take this one as the best choice so far? */
-		if ((nmatch > nbestMatch) || (last_candidate == NULL))
-		{
-			nbestMatch = nmatch;
-			candidates = current_candidate;
-			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++;
-		}
-		/* otherwise, don't bother keeping this one... */
-	}
-
-	if (last_candidate)			/* terminate rebuilt list */
-		last_candidate->next = NULL;
-
-	if (ncandidates == 1)
-		return candidates->oid;
-
-	/*
-	 * Still too many candidates? Now look for candidates which are
-	 * preferred types at the args that will require coercion. Keep all
-	 * candidates if none match.
-	 */
-	ncandidates = 0;
-	nbestMatch = 0;
-	last_candidate = NULL;
-	for (current_candidate = candidates;
-		 current_candidate != NULL;
-		 current_candidate = current_candidate->next)
-	{
-		current_typeids = current_candidate->args;
-		nmatch = 0;
-		for (i = 0; i < nargs; i++)
-		{
-			if (input_typeids[i] != UNKNOWNOID)
-			{
-				current_category = TypeCategory(current_typeids[i]);
-				if (current_typeids[i] == input_typeids[i] ||
-					IsPreferredType(current_category, current_typeids[i]))
-					nmatch++;
-			}
-		}
-
-		if ((nmatch > nbestMatch) || (last_candidate == NULL))
-		{
-			nbestMatch = nmatch;
-			candidates = current_candidate;
-			last_candidate = current_candidate;
-			ncandidates = 1;
-		}
-		else if (nmatch == nbestMatch)
-		{
-			last_candidate->next = current_candidate;
-			last_candidate = current_candidate;
-			ncandidates++;
-		}
-	}
-
-	if (last_candidate)			/* terminate rebuilt list */
-		last_candidate->next = NULL;
-
-	if (ncandidates == 1)
-		return candidates->oid;
-
-	/*
-	 * Still too many candidates? Try assigning types for the unknown
-	 * columns.
-	 *
-	 * First try: if we have an unknown and a non-unknown input, see whether
-	 * there is a candidate all of whose input types are the same as the
-	 * known input type (there can be at most one such candidate).	If so,
-	 * use that candidate.	NOTE that this is cool only because operators
-	 * can't have more than 2 args, so taking the last non-unknown as
-	 * current_type can yield only one possibility if there is also an
-	 * unknown.
-	 */
-	unknownOids = FALSE;
-	current_type = UNKNOWNOID;
-	for (i = 0; i < nargs; i++)
-	{
-		if ((input_typeids[i] != UNKNOWNOID)
-			&& (input_typeids[i] != InvalidOid))
-			current_type = input_typeids[i];
-		else
-			unknownOids = TRUE;
-	}
-
-	if (unknownOids && (current_type != UNKNOWNOID))
-	{
-		for (current_candidate = candidates;
-			 current_candidate != NULL;
-			 current_candidate = current_candidate->next)
-		{
-			current_typeids = current_candidate->args;
-			nmatch = 0;
-			for (i = 0; i < nargs; i++)
-			{
-				if (current_type == current_typeids[i])
-					nmatch++;
-			}
-			if (nmatch == nargs)
-				return current_candidate->oid;
-		}
-	}
-
-	/*
-	 * Second try: same algorithm as for unknown resolution in
-	 * parse_func.c.
-	 *
-	 * We do this by examining each unknown argument position to see if we
-	 * can determine a "type category" for it.	If any candidate has an
-	 * input datatype of STRING category, use STRING category (this bias
-	 * towards STRING is appropriate since unknown-type literals look like
-	 * strings).  Otherwise, if all the candidates agree on the type
-	 * category of this argument position, use that category.  Otherwise,
-	 * fail because we cannot determine a category.
-	 *
-	 * If we are able to determine a type category, also notice whether any
-	 * of the candidates takes a preferred datatype within the category.
-	 *
-	 * Having completed this examination, remove candidates that accept the
-	 * wrong category at any unknown position.	Also, if at least one
-	 * candidate accepted a preferred type at a position, remove
-	 * candidates that accept non-preferred types.
-	 *
-	 * If we are down to one candidate at the end, we win.
+	 * Use the same heuristics as for ambiguous functions to resolve
+	 * the conflict.
 	 */
-	resolved_unknowns = false;
-	for (i = 0; i < nargs; i++)
-	{
-		bool		have_conflict;
-
-		if (input_typeids[i] != UNKNOWNOID)
-			continue;
-		resolved_unknowns = true;		/* assume we can do it */
-		slot_category[i] = INVALID_TYPE;
-		slot_has_preferred_type[i] = false;
-		have_conflict = false;
-		for (current_candidate = candidates;
-			 current_candidate != NULL;
-			 current_candidate = current_candidate->next)
-		{
-			current_typeids = current_candidate->args;
-			current_type = current_typeids[i];
-			current_category = TypeCategory(current_type);
-			if (slot_category[i] == INVALID_TYPE)
-			{
-				/* first candidate */
-				slot_category[i] = current_category;
-				slot_has_preferred_type[i] =
-					IsPreferredType(current_category, current_type);
-			}
-			else if (current_category == slot_category[i])
-			{
-				/* more candidates in same category */
-				slot_has_preferred_type[i] |=
-					IsPreferredType(current_category, current_type);
-			}
-			else
-			{
-				/* category conflict! */
-				if (current_category == STRING_TYPE)
-				{
-					/* STRING always wins if available */
-					slot_category[i] = current_category;
-					slot_has_preferred_type[i] =
-						IsPreferredType(current_category, current_type);
-				}
-				else
-				{
-					/*
-					 * Remember conflict, but keep going (might find
-					 * STRING)
-					 */
-					have_conflict = true;
-				}
-			}
-		}
-		if (have_conflict && slot_category[i] != STRING_TYPE)
-		{
-			/* Failed to resolve category conflict at this position */
-			resolved_unknowns = false;
-			break;
-		}
-	}
+	candidates = func_select_candidate(nargs, input_typeids, candidates);
 
-	if (resolved_unknowns)
-	{
-		/* Strip non-matching candidates */
-		ncandidates = 0;
-		last_candidate = NULL;
-		for (current_candidate = candidates;
-			 current_candidate != NULL;
-			 current_candidate = current_candidate->next)
-		{
-			bool		keepit = true;
-
-			current_typeids = current_candidate->args;
-			for (i = 0; i < nargs; i++)
-			{
-				if (input_typeids[i] != UNKNOWNOID)
-					continue;
-				current_type = current_typeids[i];
-				current_category = TypeCategory(current_type);
-				if (current_category != slot_category[i])
-				{
-					keepit = false;
-					break;
-				}
-				if (slot_has_preferred_type[i] &&
-					!IsPreferredType(current_category, current_type))
-				{
-					keepit = false;
-					break;
-				}
-			}
-			if (keepit)
-			{
-				/* keep this candidate */
-				last_candidate = current_candidate;
-				ncandidates++;
-			}
-			else
-			{
-				/* forget this candidate */
-				if (last_candidate)
-					last_candidate->next = current_candidate->next;
-				else
-					candidates = current_candidate->next;
-			}
-		}
-		if (last_candidate)		/* terminate rebuilt list */
-			last_candidate->next = NULL;
-	}
-
-	if (ncandidates == 1)
+	if (candidates)
 		return candidates->oid;
 
-	return InvalidOid;			/* failed to determine a unique candidate */
+	return InvalidOid;			/* failed to select a best candidate */
 }	/* oper_select_candidate() */
 
 
@@ -751,7 +366,7 @@ oper(List *opname, Oid ltypeId, Oid rtypeId, bool noError)
 
 			/*
 			 * Unspecified type for one of the arguments? then use the
-			 * other
+			 * other (XXX this is probably dead code?)
 			 */
 			if (rtypeId == InvalidOid)
 				rtypeId = ltypeId;