From 078aaf796eda274cd6cd241331278d4f089a6d7e Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 7 Oct 2008 01:47:55 +0000
Subject: [PATCH] Improve parser error location for cases where an INSERT or
 UPDATE command supplies an expression that can't be coerced to the target
 column type. The code previously attempted to point at the target column
 name, which doesn't work at all in an INSERT with omitted column name list,
 and is also not remarkably helpful when the problem is buried somewhere in a
 long INSERT-multi-VALUES command.  Make it point at the failed expression
 instead.

---
 src/backend/parser/analyze.c      | 16 ++++++++++------
 src/backend/parser/parse_target.c | 13 ++++++++++---
 2 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c
index 8e762f824c..2a99d099d8 100644
--- a/src/backend/parser/analyze.c
+++ b/src/backend/parser/analyze.c
@@ -17,7 +17,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- *	$PostgreSQL: pgsql/src/backend/parser/analyze.c,v 1.381 2008/10/06 15:15:22 tgl Exp $
+ *	$PostgreSQL: pgsql/src/backend/parser/analyze.c,v 1.382 2008/10/07 01:47:54 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -426,11 +426,15 @@ transformInsertStmt(ParseState *pstate, InsertStmt *stmt)
 				exprType((Node *) tle->expr) == UNKNOWNOID)
 				expr = tle->expr;
 			else
-				expr = (Expr *) makeVar(rtr->rtindex,
-										tle->resno,
-										exprType((Node *) tle->expr),
-										exprTypmod((Node *) tle->expr),
-										0);
+			{
+				Var	   *var = makeVar(rtr->rtindex,
+									  tle->resno,
+									  exprType((Node *) tle->expr),
+									  exprTypmod((Node *) tle->expr),
+									  0);
+				var->location = exprLocation((Node *) tle->expr);
+				expr = (Expr *) var;
+			}
 			exprList = lappend(exprList, expr);
 		}
 
diff --git a/src/backend/parser/parse_target.c b/src/backend/parser/parse_target.c
index d83caab7e8..c12201fff7 100644
--- a/src/backend/parser/parse_target.c
+++ b/src/backend/parser/parse_target.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_target.c,v 1.167 2008/10/06 15:15:22 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_target.c,v 1.168 2008/10/07 01:47:55 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -343,6 +343,11 @@ markTargetListOrigin(ParseState *pstate, TargetEntry *tle,
  * location		error cursor position for the target column, or -1
  *
  * Returns the modified expression.
+ *
+ * Note: location points at the target column name (SET target or INSERT
+ * column name list entry), and must therefore be -1 in an INSERT that
+ * omits the column name list.  So we should usually prefer to use
+ * exprLocation(expr) for errors that can happen in a default INSERT.
  */
 Expr *
 transformAssignedExpr(ParseState *pstate,
@@ -446,9 +451,11 @@ transformAssignedExpr(ParseState *pstate,
 		 * For normal non-qualified target column, do type checking and
 		 * coercion.
 		 */
+		Node   *orig_expr = (Node *) expr;
+
 		expr = (Expr *)
 			coerce_to_target_type(pstate,
-								  (Node *) expr, type_id,
+								  orig_expr, type_id,
 								  attrtype, attrtypmod,
 								  COERCION_ASSIGNMENT,
 								  COERCE_IMPLICIT_CAST,
@@ -462,7 +469,7 @@ transformAssignedExpr(ParseState *pstate,
 							format_type_be(attrtype),
 							format_type_be(type_id)),
 				 errhint("You will need to rewrite or cast the expression."),
-					 parser_errposition(pstate, location)));
+					 parser_errposition(pstate, exprLocation(orig_expr))));
 	}
 
 	return expr;