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.

4 files changed, 49 insertions, 0 deletions

diff --git a/src/backend/executor/functions.c b/src/backend/executor/functions.c
index 502edc7d97f..c6f6451466e 100644
--- a/src/backend/executor/functions.c
+++ b/src/backend/executor/functions.c
@@ -1168,6 +1168,11 @@ 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 composite 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 d23578455cb..1b07d572c1f 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -3493,6 +3493,10 @@ evaluate_function(Oid funcid, Oid result_type, int32 result_typmod, 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.
  */
@@ -3525,6 +3529,7 @@ inline_function(Oid funcid, Oid result_type, List *args,
 	if (funcform->prolang != SQLlanguageId ||
 		funcform->prosecdef ||
 		funcform->proretset ||
+		funcform->prorettype == RECORDOID ||
 		!heap_attisnull(func_tuple, Anum_pg_proc_proconfig) ||
 		funcform->pronargs != list_length(args))
 		return NULL;
diff --git a/src/test/regress/expected/rangefuncs.out b/src/test/regress/expected/rangefuncs.out
index e8bdc42b9b6..0769fa66f9d 100644
--- a/src/test/regress/expected/rangefuncs.out
+++ b/src/test/regress/expected/rangefuncs.out
@@ -891,3 +891,23 @@ select * from foobar();
 (2 rows)
 
 drop function foobar();
+-- 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 d780c6cd3eb..c813a306436 100644
--- a/src/test/regress/sql/rangefuncs.sql
+++ b/src/test/regress/sql/rangefuncs.sql
@@ -423,3 +423,22 @@ select foobar();
 select * from foobar();
 
 drop function foobar();
+
+-- 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();