Reject cases where a query in WITH rewrites to just NOTIFY.

Since the executor can't cope with a utility statement appearing
as a node of a plan tree, we can't support cases where a rewrite
rule inserts a NOTIFY into an INSERT/UPDATE/DELETE command appearing
in a WITH clause of a larger query.  (One can imagine ways around
that, but it'd be a new feature not a bug fix, and so far there's
been no demand for it.)  RewriteQuery checked for this, but it
missed the case where the DML command rewrites to *only* a NOTIFY.
That'd lead to crashes later on in planning.  Add the missed check,
and improve the level of testing of this area.

Per bug #17094 from Yaoguang Chen.  It's been busted since WITH
was introduced, so back-patch to all supported branches.

Discussion: https://postgr.es/m/17094-bf15dff55eaf2e28@postgresql.org

2 files changed, 46 insertions, 0 deletions

diff --git a/src/test/regress/expected/with.out b/src/test/regress/expected/with.out
index 0d506348e1c..9a99bd64194 100644
--- a/src/test/regress/expected/with.out
+++ b/src/test/regress/expected/with.out
@@ -2315,6 +2315,31 @@ WITH t AS (
 )
 VALUES(FALSE);
 ERROR:  conditional DO INSTEAD rules are not supported for data-modifying statements in WITH
+CREATE OR REPLACE RULE y_rule AS ON INSERT TO y DO INSTEAD NOTHING;
+WITH t AS (
+	INSERT INTO y VALUES(0)
+)
+VALUES(FALSE);
+ERROR:  DO INSTEAD NOTHING rules are not supported for data-modifying statements in WITH
+CREATE OR REPLACE RULE y_rule AS ON INSERT TO y DO INSTEAD NOTIFY foo;
+WITH t AS (
+	INSERT INTO y VALUES(0)
+)
+VALUES(FALSE);
+ERROR:  DO INSTEAD NOTIFY rules are not supported for data-modifying statements in WITH
+CREATE OR REPLACE RULE y_rule AS ON INSERT TO y DO ALSO NOTIFY foo;
+WITH t AS (
+	INSERT INTO y VALUES(0)
+)
+VALUES(FALSE);
+ERROR:  DO ALSO rules are not supported for data-modifying statements in WITH
+CREATE OR REPLACE RULE y_rule AS ON INSERT TO y
+  DO INSTEAD (NOTIFY foo; NOTIFY bar);
+WITH t AS (
+	INSERT INTO y VALUES(0)
+)
+VALUES(FALSE);
+ERROR:  multi-statement DO INSTEAD rules are not supported for data-modifying statements in WITH
 DROP RULE y_rule ON y;
 -- check that parser lookahead for WITH doesn't cause any odd behavior
 create table foo (with baz);  -- fail, WITH is a reserved word
diff --git a/src/test/regress/sql/with.sql b/src/test/regress/sql/with.sql
index 43cd2e10af3..4869de4067d 100644
--- a/src/test/regress/sql/with.sql
+++ b/src/test/regress/sql/with.sql
@@ -1066,6 +1066,27 @@ WITH t AS (
 	INSERT INTO y VALUES(0)
 )
 VALUES(FALSE);
+CREATE OR REPLACE RULE y_rule AS ON INSERT TO y DO INSTEAD NOTHING;
+WITH t AS (
+	INSERT INTO y VALUES(0)
+)
+VALUES(FALSE);
+CREATE OR REPLACE RULE y_rule AS ON INSERT TO y DO INSTEAD NOTIFY foo;
+WITH t AS (
+	INSERT INTO y VALUES(0)
+)
+VALUES(FALSE);
+CREATE OR REPLACE RULE y_rule AS ON INSERT TO y DO ALSO NOTIFY foo;
+WITH t AS (
+	INSERT INTO y VALUES(0)
+)
+VALUES(FALSE);
+CREATE OR REPLACE RULE y_rule AS ON INSERT TO y
+  DO INSTEAD (NOTIFY foo; NOTIFY bar);
+WITH t AS (
+	INSERT INTO y VALUES(0)
+)
+VALUES(FALSE);
 DROP RULE y_rule ON y;
 
 -- check that parser lookahead for WITH doesn't cause any odd behavior