Extend the parser location infrastructure to include a location field in

most node types used in expression trees (both before and after parse
analysis).  This allows us to place an error cursor in many situations
where we formerly could not, because the information wasn't available
beyond the very first level of parse analysis.  There's a fair amount
of work still to be done to persuade individual ereport() calls to actually
include an error location, but this gets the initdb-forcing part of the
work out of the way; and the situation is already markedly better than
before for complaints about unimplementable implicit casts, such as
CASE and UNION constructs with incompatible alternative data types.
Per my proposal of a few days ago.

1 files changed, 28 insertions, 15 deletions

diff --git a/src/backend/parser/parse_node.c b/src/backend/parser/parse_node.c
index 8cc531b350a..1760e492854 100644
--- a/src/backend/parser/parse_node.c
+++ b/src/backend/parser/parse_node.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_node.c,v 1.101 2008/08/25 22:42:33 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_node.c,v 1.102 2008/08/28 23:09:47 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -117,8 +117,9 @@ parser_errposition(ParseState *pstate, int location)
  *		Build a Var node for an attribute identified by RTE and attrno
  */
 Var *
-make_var(ParseState *pstate, RangeTblEntry *rte, int attrno)
+make_var(ParseState *pstate, RangeTblEntry *rte, int attrno, int location)
 {
+	Var		   *result;
 	int			vnum,
 				sublevels_up;
 	Oid			vartypeid;
@@ -126,7 +127,9 @@ make_var(ParseState *pstate, RangeTblEntry *rte, int attrno)
 
 	vnum = RTERangeTablePosn(pstate, rte, &sublevels_up);
 	get_rte_attribute_type(rte, attrno, &vartypeid, &type_mod);
-	return makeVar(vnum, attrno, vartypeid, type_mod, sublevels_up);
+	result = makeVar(vnum, attrno, vartypeid, type_mod, sublevels_up);
+	result->location = location;
+	return result;
 }
 
 /*
@@ -243,11 +246,13 @@ transformArraySubscripts(ParseState *pstate,
 												subexpr, exprType(subexpr),
 												INT4OID, -1,
 												COERCION_ASSIGNMENT,
-												COERCE_IMPLICIT_CAST);
+												COERCE_IMPLICIT_CAST,
+												-1);
 				if (subexpr == NULL)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
-						  errmsg("array subscript must have type integer")));
+							 errmsg("array subscript must have type integer"),
+							 parser_errposition(pstate, exprLocation(ai->lidx))));
 			}
 			else
 			{
@@ -267,11 +272,13 @@ transformArraySubscripts(ParseState *pstate,
 										subexpr, exprType(subexpr),
 										INT4OID, -1,
 										COERCION_ASSIGNMENT,
-										COERCE_IMPLICIT_CAST);
+										COERCE_IMPLICIT_CAST,
+										-1);
 		if (subexpr == NULL)
 			ereport(ERROR,
 					(errcode(ERRCODE_DATATYPE_MISMATCH),
-					 errmsg("array subscript must have type integer")));
+					 errmsg("array subscript must have type integer"),
+					 parser_errposition(pstate, exprLocation(ai->uidx))));
 		upperIndexpr = lappend(upperIndexpr, subexpr);
 	}
 
@@ -283,20 +290,24 @@ transformArraySubscripts(ParseState *pstate,
 	{
 		Oid			typesource = exprType(assignFrom);
 		Oid			typeneeded = isSlice ? arrayType : elementType;
+		Node	   *newFrom;
 
-		assignFrom = coerce_to_target_type(pstate,
-										   assignFrom, typesource,
-										   typeneeded, elementTypMod,
-										   COERCION_ASSIGNMENT,
-										   COERCE_IMPLICIT_CAST);
-		if (assignFrom == NULL)
+		newFrom = coerce_to_target_type(pstate,
+										assignFrom, typesource,
+										typeneeded, elementTypMod,
+										COERCION_ASSIGNMENT,
+										COERCE_IMPLICIT_CAST,
+										-1);
+		if (newFrom == NULL)
 			ereport(ERROR,
 					(errcode(ERRCODE_DATATYPE_MISMATCH),
 					 errmsg("array assignment requires type %s"
 							" but expression is of type %s",
 							format_type_be(typeneeded),
 							format_type_be(typesource)),
-			   errhint("You will need to rewrite or cast the expression.")));
+			   errhint("You will need to rewrite or cast the expression."),
+					 parser_errposition(pstate, exprLocation(assignFrom))));
+		assignFrom = newFrom;
 	}
 
 	/*
@@ -333,7 +344,7 @@ transformArraySubscripts(ParseState *pstate,
  *	too many examples that fail if we try.
  */
 Const *
-make_const(Value *value)
+make_const(Value *value, int location)
 {
 	Datum		val;
 	int64		val64;
@@ -423,6 +434,7 @@ make_const(Value *value)
 							(Datum) 0,
 							true,
 							false);
+			con->location = location;
 			return con;
 
 		default:
@@ -436,6 +448,7 @@ make_const(Value *value)
 					val,
 					false,
 					typebyval);
+	con->location = location;
 
 	return con;
 }