From 8a6eb2ee9895b88311d01fd0d54fb380304d3df6 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Wed, 1 Dec 2010 00:53:44 -0500
Subject: [PATCH] Prevent inlining a SQL function with multiple OUT parameters.

There were corner cases in which the planner would attempt to inline such
a function, which would result in a failure at runtime due to loss of
information about exactly what the result record type is.  Fix by disabling
inlining when the function's recorded result type is RECORD.  There might
be some sub-cases where inlining could still be allowed, but this is a
simple and backpatchable fix, so leave refinements for another day.
Per bug #5777 from Nate Carson.

Back-patch to all supported branches.  8.1 happens to avoid a core-dump
here, but it still does the wrong thing.
---
 src/backend/executor/functions.c         |  5 +++++
 src/backend/optimizer/util/clauses.c     |  5 +++++
 src/test/regress/expected/rangefuncs.out | 20 ++++++++++++++++++++
 src/test/regress/sql/rangefuncs.sql      | 19 +++++++++++++++++++
 4 files changed, 49 insertions(+)

diff --git a/src/backend/executor/functions.c b/src/backend/executor/functions.c
index 84398e8a960..f974febeee5 100644
--- a/src/backend/executor/functions.c
+++ b/src/backend/executor/functions.c
@@ -949,6 +949,11 @@ check_sql_fn_retval(Oid func_id, Oid rettype, List *queryTreeList,
 		 * This can happen, for example, where the body of the function is
 		 * 'SELECT func2()', where func2 has the same return type as the
 		 * function that's calling it.
+		 *
+		 * XXX Note that if rettype is RECORD, the IsBinaryCoercible check
+		 * will succeed for any composite restype.  For the moment we rely on
+		 * runtime type checking to catch any discrepancy, but it'd be nice to
+		 * do better at parse time.
 		 */
 		if (tlistlen == 1)
 		{
diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index 7029ee1738d..bc5df1f6f97 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -2289,6 +2289,10 @@ evaluate_function(Oid funcid, Oid result_type, List *args,
  * We must also beware of changing the volatility or strictness status of
  * functions by inlining them.
  *
+ * Also, at the moment we can't inline functions returning RECORD.  This
+ * doesn't work in the general case because it discards information such
+ * as OUT-parameter declarations.
+ *
  * Returns a simplified expression if successful, or NULL if cannot
  * simplify the function.
  */
@@ -2320,6 +2324,7 @@ inline_function(Oid funcid, Oid result_type, List *args,
 	if (funcform->prolang != SQLlanguageId ||
 		funcform->prosecdef ||
 		funcform->proretset ||
+		funcform->prorettype == RECORDOID ||
 		funcform->pronargs != list_length(args))
 		return NULL;
 
diff --git a/src/test/regress/expected/rangefuncs.out b/src/test/regress/expected/rangefuncs.out
index 49fc121f04f..a043bc1d338 100644
--- a/src/test/regress/expected/rangefuncs.out
+++ b/src/test/regress/expected/rangefuncs.out
@@ -528,3 +528,23 @@ CREATE FUNCTION bad (f1 int, out f2 anyelement, out f3 anyarray)
 AS 'select $1, array[$1,$1]' LANGUAGE sql;
 ERROR:  cannot determine result data type
 DETAIL:  A function returning "anyarray" or "anyelement" must have at least one argument of either type.
+-- check handling of a SQL function with multiple OUT params (bug #5777)
+create or replace function foobar(out integer, out numeric) as
+$$ select (1, 2.1) $$ language sql;
+select * from foobar();
+ column1 | column2 
+---------+---------
+       1 |     2.1
+(1 row)
+
+create or replace function foobar(out integer, out numeric) as
+$$ select (1, 2) $$ language sql;
+select * from foobar();  -- fail
+ERROR:  function return row and query-specified return row do not match
+DETAIL:  Returned type integer at ordinal position 2, but query expects numeric.
+create or replace function foobar(out integer, out numeric) as
+$$ select (1, 2.1, 3) $$ language sql;
+select * from foobar();  -- fail
+ERROR:  function return row and query-specified return row do not match
+DETAIL:  Returned row contains 3 attributes, but query expects 2.
+drop function foobar();
diff --git a/src/test/regress/sql/rangefuncs.sql b/src/test/regress/sql/rangefuncs.sql
index 50495897acd..06bbd1b537d 100644
--- a/src/test/regress/sql/rangefuncs.sql
+++ b/src/test/regress/sql/rangefuncs.sql
@@ -261,3 +261,22 @@ DROP FUNCTION dup(anyelement);
 -- fails, no way to deduce outputs
 CREATE FUNCTION bad (f1 int, out f2 anyelement, out f3 anyarray)
 AS 'select $1, array[$1,$1]' LANGUAGE sql;
+
+-- check handling of a SQL function with multiple OUT params (bug #5777)
+
+create or replace function foobar(out integer, out numeric) as
+$$ select (1, 2.1) $$ language sql;
+
+select * from foobar();
+
+create or replace function foobar(out integer, out numeric) as
+$$ select (1, 2) $$ language sql;
+
+select * from foobar();  -- fail
+
+create or replace function foobar(out integer, out numeric) as
+$$ select (1, 2.1, 3) $$ language sql;
+
+select * from foobar();  -- fail
+
+drop function foobar();