From 9e4e0682bdb2fd26cf59fc259875e3784aa73757 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 6 Mar 2007 22:45:41 +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 | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index ca1f1623bd0..0725cd92184 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.154.2.5 2007/02/02 00:04:02 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.154.2.6 2007/03/06 22:45:41 tgl Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -31,6 +31,7 @@
 #include "optimizer/var.h"
 #include "parser/analyze.h"
 #include "parser/parse_clause.h"
+#include "parser/parse_coerce.h"
 #include "parser/parse_expr.h"
 #include "tcop/tcopprot.h"
 #include "utils/acl.h"
@@ -1414,6 +1415,7 @@ eval_const_expressions_mutator(Node *node, List *active_fns)
 			newrelabel->arg = (Expr *) arg;
 			newrelabel->resulttype = relabel->resulttype;
 			newrelabel->resulttypmod = relabel->resulttypmod;
+			newrelabel->relabelformat = relabel->relabelformat;
 			return (Node *) newrelabel;
 		}
 	}
@@ -1979,6 +1981,21 @@ 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.