Create a new expression node type RelabelType, which exists solely to

represent the result of a binary-compatible type coercion.  At runtime
it just evaluates its argument --- but during type resolution, exprType
will pick up the output type of the RelabelType node instead of the type
of the argument.  This solves some longstanding problems with dropped
type coercions, an example being 'select now()::abstime::int4' which
used to produce date-formatted output, not an integer, because the
coercion to int4 was dropped on the floor.

1 files changed, 41 insertions, 19 deletions

diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index d18cff2789c..0267fc2c576 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -3,7 +3,7 @@
  *			  out of its tuple
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/ruleutils.c,v 1.41 2000/02/15 08:24:12 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/ruleutils.c,v 1.42 2000/02/20 21:32:12 tgl Exp $
  *
  *	  This software is copyrighted by Jan Wieck - Hamburg.
  *
@@ -1006,7 +1006,7 @@ get_select_query_def(Query *query, deparse_context *context)
 						appendStringInfo(buf, "%s",
 										 quote_identifier(strVal(lfirst(col))));
 					}
-					appendStringInfo(buf, ")");
+					appendStringInfoChar(buf, ')');
 				}
 			}
 		}
@@ -1127,7 +1127,7 @@ get_insert_query_def(Query *query, deparse_context *context)
 			sep = ", ";
 			get_tle_expr(tle, context);
 		}
-		appendStringInfo(buf, ")");
+		appendStringInfoChar(buf, ')');
 	}
 	else
 		get_select_query_def(query, context);
@@ -1281,7 +1281,7 @@ get_rule_expr(Node *node, deparse_context *context)
 				switch (expr->opType)
 				{
 					case OP_EXPR:
-						appendStringInfo(buf, "(");
+						appendStringInfoChar(buf, '(');
 						if (length(args) == 2)
 						{
 							/* binary operator */
@@ -1320,35 +1320,35 @@ get_rule_expr(Node *node, deparse_context *context)
 									elog(ERROR, "get_rule_expr: bogus oprkind");
 							}
 						}
-						appendStringInfo(buf, ")");
+						appendStringInfoChar(buf, ')');
 						break;
 
 					case OR_EXPR:
-						appendStringInfo(buf, "(");
+						appendStringInfoChar(buf, '(');
 						get_rule_expr((Node *) lfirst(args), context);
 						while ((args = lnext(args)) != NIL)
 						{
 							appendStringInfo(buf, " OR ");
 							get_rule_expr((Node *) lfirst(args), context);
 						}
-						appendStringInfo(buf, ")");
+						appendStringInfoChar(buf, ')');
 						break;
 
 					case AND_EXPR:
-						appendStringInfo(buf, "(");
+						appendStringInfoChar(buf, '(');
 						get_rule_expr((Node *) lfirst(args), context);
 						while ((args = lnext(args)) != NIL)
 						{
 							appendStringInfo(buf, " AND ");
 							get_rule_expr((Node *) lfirst(args), context);
 						}
-						appendStringInfo(buf, ")");
+						appendStringInfoChar(buf, ')');
 						break;
 
 					case NOT_EXPR:
 						appendStringInfo(buf, "(NOT ");
 						get_rule_expr((Node *) lfirst(args), context);
-						appendStringInfo(buf, ")");
+						appendStringInfoChar(buf, ')');
 						break;
 
 					case FUNC_EXPR:
@@ -1373,7 +1373,7 @@ get_rule_expr(Node *node, deparse_context *context)
 					appendStringInfo(buf, "*");
 				else
 					get_rule_expr(aggref->target, context);
-				appendStringInfo(buf, ")");
+				appendStringInfoChar(buf, ')');
 			}
 			break;
 
@@ -1405,6 +1405,28 @@ get_rule_expr(Node *node, deparse_context *context)
 			}
 			break;
 
+		case T_RelabelType:
+			{
+				RelabelType *relabel = (RelabelType *) node;
+				HeapTuple	typetup;
+				Form_pg_type typeStruct;
+				char	   *extval;
+
+				appendStringInfoChar(buf, '(');
+				get_rule_expr(relabel->arg, context);
+				typetup = SearchSysCacheTuple(TYPEOID,
+									ObjectIdGetDatum(relabel->resulttype),
+											  0, 0, 0);
+				if (!HeapTupleIsValid(typetup))
+					elog(ERROR, "cache lookup of type %u failed",
+						 relabel->resulttype);
+				typeStruct = (Form_pg_type) GETSTRUCT(typetup);
+				extval = pstrdup(NameStr(typeStruct->typname));
+				appendStringInfo(buf, ")::%s", quote_identifier(extval));
+				pfree(extval);
+			}
+			break;
+
 		case T_CaseExpr:
 			{
 				CaseExpr   *caseexpr = (CaseExpr *) node;
@@ -1474,14 +1496,14 @@ get_func_expr(Expr *expr, deparse_context *context)
 	{
 		if (!strcmp(proname, "nullvalue"))
 		{
-			appendStringInfo(buf, "(");
+			appendStringInfoChar(buf, '(');
 			get_rule_expr((Node *) lfirst(expr->args), context);
 			appendStringInfo(buf, " ISNULL)");
 			return;
 		}
 		if (!strcmp(proname, "nonnullvalue"))
 		{
-			appendStringInfo(buf, "(");
+			appendStringInfoChar(buf, '(');
 			get_rule_expr((Node *) lfirst(expr->args), context);
 			appendStringInfo(buf, " NOTNULL)");
 			return;
@@ -1500,7 +1522,7 @@ get_func_expr(Expr *expr, deparse_context *context)
 		sep = ", ";
 		get_rule_expr((Node *) lfirst(l), context);
 	}
-	appendStringInfo(buf, ")");
+	appendStringInfoChar(buf, ')');
 }
 
 
@@ -1712,13 +1734,13 @@ get_sublink_expr(Node *node, deparse_context *context)
 	Oper	   *oper;
 	bool		need_paren;
 
-	appendStringInfo(buf, "(");
+	appendStringInfoChar(buf, '(');
 
 	if (sublink->lefthand != NIL)
 	{
 		need_paren = (length(sublink->lefthand) > 1);
 		if (need_paren)
-			appendStringInfo(buf, "(");
+			appendStringInfoChar(buf, '(');
 
 		sep = "";
 		foreach(l, sublink->lefthand)
@@ -1731,7 +1753,7 @@ get_sublink_expr(Node *node, deparse_context *context)
 		if (need_paren)
 			appendStringInfo(buf, ") ");
 		else
-			appendStringInfo(buf, " ");
+			appendStringInfoChar(buf, ' ');
 	}
 
 	need_paren = true;
@@ -1768,14 +1790,14 @@ get_sublink_expr(Node *node, deparse_context *context)
 	}
 
 	if (need_paren)
-		appendStringInfo(buf, "(");
+		appendStringInfoChar(buf, '(');
 
 	get_query_def(query, buf, context->rangetables);
 
 	if (need_paren)
 		appendStringInfo(buf, "))");
 	else
-		appendStringInfo(buf, ")");
+		appendStringInfoChar(buf, ')');
 }
 
 /* ----------