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.

2 files changed, 18 insertions, 7 deletions

diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c
index e55eec0b8f..ac2c7ba84c 100644
--- a/src/backend/parser/analyze.c
+++ b/src/backend/parser/analyze.c
@@ -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 4fedc6299a..1f19131ae2 100644
--- a/src/backend/parser/parse_target.c
+++ b/src/backend/parser/parse_target.c
@@ -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;