From 7da324aa04fa3a4637e3094343878257a8d85121 Mon Sep 17 00:00:00 2001
From: MuhammadTahaNaveed <mnaveed.bese20seecs@seecs.edu.pk>
Date: Wed, 1 Mar 2023 02:13:48 +0500
Subject: [PATCH] Fix Issue #693 - server termination from return exists(path)

- Updated assert to pass EXPR_KIND_SELECT_TARGET.
- Added regression tests.
---
 regress/expected/cypher_match.out  | 96 ++++++++++++++++++++++++++++++
 regress/sql/cypher_match.sql       | 23 +++++++
 src/backend/parser/cypher_clause.c |  1 +
 3 files changed, 120 insertions(+)

diff --git a/regress/expected/cypher_match.out b/regress/expected/cypher_match.out
index 9ec4112d6..8f325cbe6 100644
--- a/regress/expected/cypher_match.out
+++ b/regress/expected/cypher_match.out
@@ -720,6 +720,57 @@ AS (u agtype, e agtype, v agtype);
  {"id": 2814749767106561, "label": "loop", "properties": {"id": "initial"}}::vertex | {"id": 3096224743817217, "label": "self", "end_id": 2814749767106561, "start_id": 2814749767106561, "properties": {}}::edge | {"id": 2814749767106561, "label": "loop", "properties": {"id": "initial"}}::vertex
 (1 row)
 
+-- Return exists(pattern)
+SELECT * FROM cypher('cypher_match',
+ $$MATCH (u) RETURN EXISTS((u)-[]->()) $$)
+AS (exists agtype);
+ exists 
+--------
+ false
+ false
+ false
+ false
+ false
+ true
+ true
+ false
+ false
+ true
+ false
+ true
+ false
+ true
+ true
+(15 rows)
+
+SELECT * FROM cypher('cypher_match',
+ $$MATCH p=(u)-[e]->(v) RETURN EXISTS((p)) $$)
+AS (exists agtype);
+ exists 
+--------
+ true
+ true
+ true
+ true
+ true
+ true
+ true
+(7 rows)
+
+SELECT * FROM cypher('cypher_match',
+ $$MATCH (u)-[e]->(v) RETURN EXISTS((u)-[e]->(v)-[e]->(u))$$)
+AS (exists agtype);
+ exists 
+--------
+ false
+ false
+ false
+ false
+ false
+ false
+ false
+(7 rows)
+
 -- These should error
 -- Bad pattern
 SELECT * FROM cypher('cypher_match',
@@ -809,6 +860,51 @@ AS (u agtype);
  {"id": 2814749767106561, "label": "loop", "properties": {"id": "initial"}}::vertex
 (1 row)
 
+-- Return exists(property)
+SELECT * FROM cypher('cypher_match',
+ $$MATCH (u) RETURN EXISTS(u.id), properties(u) $$)
+AS (exists agtype, properties agtype);
+ exists |                                                 properties                                                  
+--------+-------------------------------------------------------------------------------------------------------------
+ false  | {"int_key": 1, "map_key": {"key": "value"}, "list_key": [1, 2, 3], "float_key": 3.14, "string_key": "test"}
+ false  | {"lst": [1, null, 3.14, "string", {"key": "value"}, []]}
+ false  | {}
+ false  | {"i": 0}
+ false  | {"i": 1}
+ true   | {"id": "initial"}
+ true   | {"id": "middle"}
+ true   | {"id": "end"}
+ true   | {"id": "initial"}
+ true   | {"id": "middle"}
+ true   | {"id": "end"}
+ true   | {"id": "initial"}
+ true   | {"id": "middle"}
+ true   | {"id": "end"}
+ true   | {"id": "initial"}
+(15 rows)
+
+SELECT * FROM cypher('cypher_match',
+ $$MATCH (u) RETURN EXISTS(u.name), properties(u) $$)
+AS (exists agtype, properties agtype);
+ exists |                                                 properties                                                  
+--------+-------------------------------------------------------------------------------------------------------------
+ false  | {"int_key": 1, "map_key": {"key": "value"}, "list_key": [1, 2, 3], "float_key": 3.14, "string_key": "test"}
+ false  | {"lst": [1, null, 3.14, "string", {"key": "value"}, []]}
+ false  | {}
+ false  | {"i": 0}
+ false  | {"i": 1}
+ false  | {"id": "initial"}
+ false  | {"id": "middle"}
+ false  | {"id": "end"}
+ false  | {"id": "initial"}
+ false  | {"id": "middle"}
+ false  | {"id": "end"}
+ false  | {"id": "initial"}
+ false  | {"id": "middle"}
+ false  | {"id": "end"}
+ false  | {"id": "initial"}
+(15 rows)
+
 -- should give an error
 SELECT * FROM cypher('cypher_match',
  $$MATCH (u) WHERE EXISTS(u) RETURN u$$)
diff --git a/regress/sql/cypher_match.sql b/regress/sql/cypher_match.sql
index aeed9f386..70f638df2 100644
--- a/regress/sql/cypher_match.sql
+++ b/regress/sql/cypher_match.sql
@@ -372,6 +372,20 @@ SELECT * FROM cypher('cypher_match',
  $$MATCH (u)-[e]->(v) WHERE EXISTS((u)-[e]->(u)) AND EXISTS((v)-[e]->(v)) RETURN u, e, v $$)
 AS (u agtype, e agtype, v agtype);
 
+-- Return exists(pattern)
+
+SELECT * FROM cypher('cypher_match',
+ $$MATCH (u) RETURN EXISTS((u)-[]->()) $$)
+AS (exists agtype);
+
+SELECT * FROM cypher('cypher_match',
+ $$MATCH p=(u)-[e]->(v) RETURN EXISTS((p)) $$)
+AS (exists agtype);
+
+SELECT * FROM cypher('cypher_match',
+ $$MATCH (u)-[e]->(v) RETURN EXISTS((u)-[e]->(v)-[e]->(u))$$)
+AS (exists agtype);
+
 -- These should error
 -- Bad pattern
 SELECT * FROM cypher('cypher_match',
@@ -410,6 +424,15 @@ SELECT * FROM cypher('cypher_match',
  $$MATCH (u) WHERE EXISTS(u.id) AND EXISTS((u)-[]->(u)) RETURN u$$)
 AS (u agtype);
 
+-- Return exists(property)
+SELECT * FROM cypher('cypher_match',
+ $$MATCH (u) RETURN EXISTS(u.id), properties(u) $$)
+AS (exists agtype, properties agtype);
+
+SELECT * FROM cypher('cypher_match',
+ $$MATCH (u) RETURN EXISTS(u.name), properties(u) $$)
+AS (exists agtype, properties agtype);
+
 -- should give an error
 SELECT * FROM cypher('cypher_match',
  $$MATCH (u) WHERE EXISTS(u) RETURN u$$)
diff --git a/src/backend/parser/cypher_clause.c b/src/backend/parser/cypher_clause.c
index 380eef92b..e1e6c94be 100644
--- a/src/backend/parser/cypher_clause.c
+++ b/src/backend/parser/cypher_clause.c
@@ -5142,6 +5142,7 @@ transform_cypher_clause_as_subquery(cypher_parsestate *cpstate,
     Assert(pstate->p_expr_kind == EXPR_KIND_NONE ||
            pstate->p_expr_kind == EXPR_KIND_OTHER ||
            pstate->p_expr_kind == EXPR_KIND_WHERE ||
+           pstate->p_expr_kind == EXPR_KIND_SELECT_TARGET ||
            pstate->p_expr_kind == EXPR_KIND_FROM_SUBSELECT);
 
     /*