From cafbf1e1cca910a663485f4a9b4189edee0dd259 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 6 Mar 2007 22:45:23 +0000
Subject: [PATCH] Fix oversight in original coding of inline_function(): since
 check_sql_fn_retval allows binary-compatibility cases, the expression
 extracted from an inline-able SQL function might have a type that is only
 binary-compatible with the declared function result type.  To avoid possibly
 changing the semantics of the expression, we should insert a RelabelType node
 in such cases.  This has only been shown to have bad consequences in recent
 8.1 and up releases, but I suspect there may be failure cases in the older
 branches too, so patch it all the way back.  Per bug #3116 from Greg Mullane.

Along the way, fix an omission in eval_const_expressions_mutator: it failed
to copy the relabelformat field when processing a RelabelType.  No known
observable failures from this, but it definitely isn't intended behavior.
---
 src/backend/optimizer/util/clauses.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index 5a3fe8f378..fa55e15b26 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.223.2.1 2007/02/02 00:03:17 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.223.2.2 2007/03/06 22:45:23 tgl Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -1842,6 +1842,7 @@ eval_const_expressions_mutator(Node *node,
 			newrelabel->arg = (Expr *) arg;
 			newrelabel->resulttype = relabel->resulttype;
 			newrelabel->resulttypmod = relabel->resulttypmod;
+			newrelabel->relabelformat = relabel->relabelformat;
 			return (Node *) newrelabel;
 		}
 	}
@@ -2795,7 +2796,8 @@ inline_function(Oid funcid, Oid result_type, List *args,
 	 * no rewriting was needed; that's probably not important, but let's be
 	 * careful.
 	 */
-	(void) check_sql_fn_retval(funcid, result_type, querytree_list, NULL);
+	if (check_sql_fn_retval(funcid, result_type, querytree_list, NULL))
+		goto fail;				/* reject whole-tuple-result cases */
 
 	/*
 	 * Additional validity checks on the expression.  It mustn't return a set,
@@ -2880,6 +2882,21 @@ inline_function(Oid funcid, Oid result_type, List *args,
 
 	MemoryContextDelete(mycxt);
 
+	/*
+	 * Since check_sql_fn_retval allows binary-compatibility cases, the
+	 * expression we now have might return some type that's only binary
+	 * compatible with the original expression result type.  To avoid
+	 * confusing matters, insert a RelabelType in such cases.
+	 */
+	if (exprType(newexpr) != funcform->prorettype)
+	{
+		Assert(IsBinaryCoercible(exprType(newexpr), funcform->prorettype));
+		newexpr = (Node *) makeRelabelType((Expr *) newexpr,
+										   funcform->prorettype,
+										   -1,
+										   COERCE_IMPLICIT_CAST);
+	}
+
 	/*
 	 * Recursively try to simplify the modified expression.  Here we must add
 	 * the current function to the context list of active functions.