[MERGE PG15] ysql: add yb_make_greater_string

Summary:
When migrating from PG 11.2 to PG 15, we come across commit
49fa99e54ec0ded180b52a4a14e543702d53e8c9 that makes make_greater_string
private:

    Move pattern selectivity code from selfuncs.c to like_support.c.
    ...
    This change localizes the use of pattern_fixed_prefix() and
    make_greater_string() so that they no longer need be exported.
    (We might get pushback from extensions about that, perhaps,
    in which case I'd be inclined to re-export them in a new header
    file like_support.h.)
    ...

ybgin uses make_greater_string for tsvector prefix logic.  Since it is
not trivial to indirectly get the benefit of make_greater_string through
the publicly exposed support functions (they take complex Node
argument), lean towards re-exposing the function through new header
yb_like_support.h and new function yb_make_greater_string.  If, in the
future, upstream postgres decides to expose make_greater_string, these
changes can be scrapped in favor of using make_greater_string again.

Test Plan: Jenkins: compile only, rebase: pg15

Reviewers: neil, amartsinchyk

Reviewed By: amartsinchyk

Subscribers: yql

Differential Revision: https://phabricator.dev.yugabyte.com/D23110

src/postgres/src/backend/access/ybgin/ybginget.c

@@ -42,6 +42,7 @@
 #include "utils/memutils.h"
 #include "utils/rel.h"
 #include "utils/selfuncs.h"
+#include "utils/yb_like_support.h"
 
 #include "pg_yb_utils.h"
 #include "yb/yql/pggate/ybc_pggate.h"
@@ -261,7 +262,7 @@ get_greaterstr(Datum prefix, Oid datatype, Oid colloid)
 	Oid			opfamily;
 	Oid			oproid;
 
-	/* make_greater_string cannot accurately handle non-C collations. */
+	/* yb_make_greater_string cannot accurately handle non-C collations. */
 	if (!lc_collate_is_c(colloid))
 		ereport(ERROR,
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
@@ -287,16 +288,7 @@ get_greaterstr(Datum prefix, Oid datatype, Oid colloid)
 		elog(ERROR, "no < operator for opfamily %u", opfamily);
 	fmgr_info(get_opcode(oproid), &ltproc);
 	prefix_const = text_to_const(prefix, colloid);
-#ifdef YB_TODO
-	/* YB_TODO(jasonk@yugabyte)
-	 * Postgres has stopped calling make_greater_string() in all backend executions. Need to
-	 * investigate if this call is the right thing to do.
-	 */
-	return make_greater_string(prefix_const, &ltproc, colloid);
-#else
-	/* This code is only for the compilation to proceed without errors */
-	return prefix_const;
-#endif
+	return yb_make_greater_string(prefix_const, &ltproc, colloid);
 }
 
 static void

src/postgres/src/backend/utils/adt/like_support.c

@@ -1770,3 +1770,12 @@ string_to_bytea_const(const char *str, size_t str_len)
 
 	return makeConst(BYTEAOID, -1, InvalidOid, -1, conval, false, false);
 }
+
+/*
+ * Externally exposed make_greater_string used by YB.
+ */
+Const *
+yb_make_greater_string(const Const *str_const, FmgrInfo *ltproc, Oid collation)
+{
+	return make_greater_string(str_const, ltproc, collation);
+}

src/postgres/src/include/utils/yb_like_support.h

@@ -0,0 +1,37 @@
+/*--------------------------------------------------------------------------
+ *
+ * yb_like_support.h
+ *	  External like support functions.
+ *
+ * Copyright (c) Yugabyte, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License.  You may obtain a copy
+ * of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ * IDENTIFICATION
+ *			src/include/utils/yb_like_support.h
+ *--------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "fmgr.h"
+#include "nodes/primnodes.h"
+#include "postgres_ext.h"
+
+/*
+ * Postgres 11 -> 15 changed make_greater_string to static, so reexpose as
+ * yb_make_greater_string.  If, in the future, postgres decides to expose
+ * make_greater_string via a like_support.h, this can be replaced by that.
+ */
+Const *yb_make_greater_string(const Const *str_const, FmgrInfo *ltproc,
+							  Oid collation);