From: Chapman Flack <chap@anastigmatix.net>
Date: Mon, 21 Feb 2022 20:56:28 -0500
Subject: [PATCH 1/4] Warmup: add a get_call_trftypes function

The existing get_func_trftypes function produces an Oid[], where
both existing get_transform_{from,to}sql functions that depend
on the result expect a List*.

Rather than writing documentation awkwardly describing functions
that won't play together, add a get_call_trftypes function that
returns List*. (The name get_call_... to distinguish from
get_func_... follows the naming used in funcapi.h for a function
returning information about either a function or a procedure.)
---
 src/backend/utils/cache/lsyscache.c | 18 ++++++++++++++++++
 src/include/funcapi.h               |  5 +++++
 src/include/utils/lsyscache.h       |  1 +
 3 files changed, 24 insertions(+)

diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index feef999..a49ccad 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -2107,6 +2107,24 @@ get_transform_tosql(Oid typid, Oid langid, List *trftypes)
 		return InvalidOid;
 }
 
+/*
+ * get_call_trftypes
+ *
+ *		A helper function that does not itself query the transform cache, but
+ *		constructs the transform-type List expected by the functions above.
+ */
+List *
+get_call_trftypes(HeapTuple procTup)
+{
+	Datum		protrftypes;
+	bool		isNull;
+
+	protrftypes = SysCacheGetAttr(PROCOID, procTup,
+								  Anum_pg_proc_protrftypes,
+								  &isNull);
+	return isNull ?  NIL : oid_array_to_list(protrftypes);
+}
+
 
 /*				---------- TYPE CACHE ----------						 */
 
diff --git a/src/include/funcapi.h b/src/include/funcapi.h
index ba927c2..7c61560 100644
--- a/src/include/funcapi.h
+++ b/src/include/funcapi.h
@@ -175,7 +175,12 @@ extern int	get_func_arg_info(HeapTuple procTup,
 extern int	get_func_input_arg_names(Datum proargnames, Datum proargmodes,
 									 char ***arg_names);
 
+/*
+ * A deprecated earlier version of get_call_trftypes (in lsyscache.h).
+ * That version produces a List, which is the form downstream functions expect.
+ */
 extern int	get_func_trftypes(HeapTuple procTup, Oid **p_trftypes);
+
 extern char *get_func_result_name(Oid functionId);
 
 extern TupleDesc build_function_result_tupdesc_d(char prokind,
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index b8dd27d..93b19e7 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -139,6 +139,7 @@ extern char get_rel_relkind(Oid relid);
 extern bool get_rel_relispartition(Oid relid);
 extern Oid	get_rel_tablespace(Oid relid);
 extern char get_rel_persistence(Oid relid);
+extern List *get_call_trftypes(HeapTuple procTup);
 extern Oid	get_transform_fromsql(Oid typid, Oid langid, List *trftypes);
 extern Oid	get_transform_tosql(Oid typid, Oid langid, List *trftypes);
 extern bool get_typisdefined(Oid typid);
-- 
2.7.3


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