Damage control for yesterday's CheckIndexCompatible changes.

Rip out a regression test that doesn't play well with settings put in
place by the build farm, and rewrite the code in CheckIndexCompatible
in a hopefully more transparent style.

src/backend/commands/indexcmds.c

@@ -214,11 +214,20 @@ CheckIndexCompatible(Oid oldId,
 
 	ReleaseSysCache(tuple);
 
+	if (!ret)
+		return false;
+
 	/* For polymorphic opcintype, column type changes break compatibility. */
 	irel = index_open(oldId, AccessShareLock); /* caller probably has a lock */
-	for (i = 0; i < old_natts && ret; i++)
-		ret = (!IsPolymorphicType(get_opclass_input_type(classObjectId[i])) ||
-			   irel->rd_att->attrs[i]->atttypid == typeObjectId[i]);
+	for (i = 0; i < old_natts; i++)
+	{
+		if (IsPolymorphicType(get_opclass_input_type(classObjectId[i])) &&
+		    irel->rd_att->attrs[i]->atttypid != typeObjectId[i])
+		{
+			ret = false;
+			break;
+		}
+	}
 
 	/* Any change in exclusion operator selections breaks compatibility. */
 	if (ret && indexInfo->ii_ExclusionOps != NULL)
@@ -231,14 +240,21 @@ CheckIndexCompatible(Oid oldId,
 					 old_natts * sizeof(Oid)) == 0;
 
 		/* Require an exact input type match for polymorphic operators. */
-		for (i = 0; i < old_natts && ret; i++)
+		if (ret)
 		{
-			Oid			left,
-						right;
+			for (i = 0; i < old_natts && ret; i++)
+			{
+				Oid			left,
+							right;
 
-			op_input_types(indexInfo->ii_ExclusionOps[i], &left, &right);
-			ret = (!(IsPolymorphicType(left) || IsPolymorphicType(right)) ||
-				   irel->rd_att->attrs[i]->atttypid == typeObjectId[i]);
+				op_input_types(indexInfo->ii_ExclusionOps[i], &left, &right);
+				if ((IsPolymorphicType(left) || IsPolymorphicType(right)) &&
+					   irel->rd_att->attrs[i]->atttypid != typeObjectId[i])
+				{
+					ret = false;
+					break;
+				}
+			}
 		}
 	}
 

src/test/regress/expected/alter_table.out

@@ -1665,15 +1665,6 @@ where oid = 'test_storage'::regclass;
  t
 (1 row)
 
--- SET DATA TYPE without a rewrite
-CREATE DOMAIN other_textarr AS text[];
-CREATE TABLE norewrite_array(c text[] PRIMARY KEY);
-NOTICE:  CREATE TABLE / PRIMARY KEY will create implicit index "norewrite_array_pkey" for table "norewrite_array"
-SET client_min_messages = debug1;
-ALTER TABLE norewrite_array ALTER c TYPE text[]; -- no work
-ALTER TABLE norewrite_array ALTER c TYPE other_textarr; -- rebuild index
-DEBUG:  building index "norewrite_array_pkey" on table "norewrite_array"
-RESET client_min_messages;
 --
 -- lock levels
 --

src/test/regress/sql/alter_table.sql

@@ -1197,14 +1197,6 @@ select reltoastrelid <> 0 as has_toast_table
 from pg_class
 where oid = 'test_storage'::regclass;
 
--- SET DATA TYPE without a rewrite
-CREATE DOMAIN other_textarr AS text[];
-CREATE TABLE norewrite_array(c text[] PRIMARY KEY);
-SET client_min_messages = debug1;
-ALTER TABLE norewrite_array ALTER c TYPE text[]; -- no work
-ALTER TABLE norewrite_array ALTER c TYPE other_textarr; -- rebuild index
-RESET client_min_messages;
-
 --
 -- lock levels
 --