From 2ec1aa4cb8cb053d197480eaa74dac07857585f2 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Wed, 12 Jan 2005 17:32:36 +0000
Subject: [PATCH] =?UTF-8?q?Re-allow=20an=20untyped=20literal=20as=20the=20?=
 =?UTF-8?q?test=20expression=20of=20a=20CASE,=20ie=20CASE=20'a'=20WHEN=20'?=
 =?UTF-8?q?a'=20THEN=201=20ELSE=202=20END.=20=20This=20worked=20in=207.4?=
 =?UTF-8?q?=20and=20before=20but=20had=20been=20broken=20due=20to=20premat?=
 =?UTF-8?q?ure=20freezing=20of=20the=20type=20of=20the=20test=20expression?=
 =?UTF-8?q?.=20=20Per=20gripe=20from=20G=C3=84bor=20Sz=C3=83cs.?=
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---
 src/backend/parser/parse_expr.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c
index c00dc72ac3..6676ae0a4b 100644
--- a/src/backend/parser/parse_expr.c
+++ b/src/backend/parser/parse_expr.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_expr.c,v 1.178 2004/12/31 22:00:27 pgsql Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_expr.c,v 1.179 2005/01/12 17:32:36 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -646,10 +646,21 @@ transformExpr(ParseState *pstate, Node *expr)
 
 				/* transform the test expression, if any */
 				arg = transformExpr(pstate, (Node *) c->arg);
-				newc->arg = (Expr *) arg;
+
 				/* generate placeholder for test expression */
 				if (arg)
 				{
+					/*
+					 * If test expression is an untyped literal, force it to
+					 * text.  We have to do something now because we won't be
+					 * able to do this coercion on the placeholder.  This is
+					 * not as flexible as what was done in 7.4 and before,
+					 * but it's good enough to handle the sort of silly
+					 * coding commonly seen.
+					 */
+					if (exprType(arg) == UNKNOWNOID)
+						arg = coerce_to_common_type(pstate, arg,
+													TEXTOID, "CASE");
 					placeholder = makeNode(CaseTestExpr);
 					placeholder->typeId = exprType(arg);
 					placeholder->typeMod = exprTypmod(arg);
@@ -657,6 +668,8 @@ transformExpr(ParseState *pstate, Node *expr)
 				else
 					placeholder = NULL;
 
+				newc->arg = (Expr *) arg;
+
 				/* transform the list of arguments */
 				newargs = NIL;
 				typeids = NIL;
-- 
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