Fix a thinko in my patch of a couple months ago for bug #3116: it did the

wrong thing when inlining polymorphic SQL functions, because it was using the
function's declared return type where it should have used the actual result
type of the current call.  In 8.1 and 8.2 this causes obvious failures even if
you don't have assertions turned on; in 8.0 and 7.4 it would only be a problem
if the inlined expression were used as an input to a function that did
run-time type determination on its inputs.  Add a regression test, since this
is evidently an under-tested area.

src/backend/optimizer/util/clauses.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.243 2007/04/30 00:14:54 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.244 2007/05/01 18:53:51 tgl Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -3063,11 +3063,11 @@ inline_function(Oid funcid, Oid result_type, List *args,
 	 * compatible with the original expression result type.  To avoid
 	 * confusing matters, insert a RelabelType in such cases.
 	 */
-	if (exprType(newexpr) != funcform->prorettype)
+	if (exprType(newexpr) != result_type)
 	{
-		Assert(IsBinaryCoercible(exprType(newexpr), funcform->prorettype));
+		Assert(IsBinaryCoercible(exprType(newexpr), result_type));
 		newexpr = (Node *) makeRelabelType((Expr *) newexpr,
-										   funcform->prorettype,
+										   result_type,
 										   -1,
 										   COERCE_IMPLICIT_CAST);
 	}

src/test/regress/expected/polymorphism.out

@@ -542,3 +542,38 @@ select mysum2(f1, f1 + 1) from t;
      38
 (1 row)
 
+-- test inlining of polymorphic SQL functions
+create function bleat(int) returns int as $$
+begin
+  raise notice 'bleat %', $1;
+  return $1;
+end$$ language plpgsql;
+create function sql_if(bool, anyelement, anyelement) returns anyelement as $$
+select case when $1 then $2 else $3 end $$ language sql;
+-- Note this would fail with integer overflow, never mind wrong bleat() output,
+-- if the CASE expression were not successfully inlined
+select f1, sql_if(f1 > 0, bleat(f1), bleat(f1 + 1)) from int4_tbl;
+NOTICE:  bleat 1
+NOTICE:  bleat 123456
+NOTICE:  bleat -123455
+NOTICE:  bleat 2147483647
+NOTICE:  bleat -2147483646
+     f1      |   sql_if    
+-------------+-------------
+           0 |           1
+      123456 |      123456
+     -123456 |     -123455
+  2147483647 |  2147483647
+ -2147483647 | -2147483646
+(5 rows)
+
+select q2, sql_if(q2 > 0, q2, q2 + 1) from int8_tbl;
+        q2         |      sql_if       
+-------------------+-------------------
+               456 |               456
+  4567890123456789 |  4567890123456789
+               123 |               123
+  4567890123456789 |  4567890123456789
+ -4567890123456789 | -4567890123456788
+(5 rows)
+

src/test/regress/sql/polymorphism.sql

@@ -374,3 +374,19 @@ select f3, myaggn08b(f1) from t group by f3;
 select f3, myaggn09a(f1) from t group by f3;
 select f3, myaggn10a(f1) from t group by f3;
 select mysum2(f1, f1 + 1) from t;
+
+-- test inlining of polymorphic SQL functions
+create function bleat(int) returns int as $$
+begin
+  raise notice 'bleat %', $1;
+  return $1;
+end$$ language plpgsql;
+
+create function sql_if(bool, anyelement, anyelement) returns anyelement as $$
+select case when $1 then $2 else $3 end $$ language sql;
+
+-- Note this would fail with integer overflow, never mind wrong bleat() output,
+-- if the CASE expression were not successfully inlined
+select f1, sql_if(f1 > 0, bleat(f1), bleat(f1 + 1)) from int4_tbl;
+
+select q2, sql_if(q2 > 0, q2, q2 + 1) from int8_tbl;