Index: src/backend/commands/tablecmds.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/commands/tablecmds.c,v
retrieving revision 1.332
diff -u -3 -p -r1.332 tablecmds.c
--- src/backend/commands/tablecmds.c	6 Jul 2010 19:18:56 -0000	1.332
+++ src/backend/commands/tablecmds.c	21 Jul 2010 14:34:41 -0000
@@ -5788,6 +5788,11 @@ ATPrepAlterColumnType(List **wqueue,
 	NewColumnValue *newval;
 	ParseState *pstate = make_parsestate(NULL);
 
+	if (rel->rd_rel->reloftype)
+		ereport(ERROR,
+				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				 errmsg("cannot alter column type of typed table")));
+
 	/* lookup the attribute so we can check inheritance status */
 	tuple = SearchSysCacheAttName(RelationGetRelid(rel), colName);
 	if (!HeapTupleIsValid(tuple))
@@ -7126,6 +7131,11 @@ ATExecAddInherit(Relation child_rel, Ran
 	int32		inhseqno;
 	List	   *children;
 
+	if (child_rel->rd_rel->reloftype)
+		ereport(ERROR,
+				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				 errmsg("cannot change inheritance of typed table")));
+
 	/*
 	 * AccessShareLock on the parent is what's obtained during normal CREATE
 	 * TABLE ... INHERITS ..., so should be enough here.