From 85456a22f41a8a51703650f2853fb6d8c9711fc7 Mon Sep 17 00:00:00 2001
From: Erik Wienhold <ewie@ewie.name>
Date: Sat, 6 Apr 2024 22:36:54 +0200
Subject: [PATCH v1] plpgsql: create valid IN expression for CASE WHEN clause

The expression in CASE x WHEN <expr> THEN may end with a line comment.
This results in a syntax error when the WHEN clause is rewritten to
x IN (<expr>).  Cope with that by appending \n after <expr> to terminate
the line comment.
---
 src/pl/plpgsql/src/expected/plpgsql_control.out | 17 +++++++++++++++++
 src/pl/plpgsql/src/pl_gram.y                    |  6 +++++-
 src/pl/plpgsql/src/sql/plpgsql_control.sql      | 14 ++++++++++++++
 3 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/src/pl/plpgsql/src/expected/plpgsql_control.out b/src/pl/plpgsql/src/expected/plpgsql_control.out
index 328bd48586..ccd4f54704 100644
--- a/src/pl/plpgsql/src/expected/plpgsql_control.out
+++ b/src/pl/plpgsql/src/expected/plpgsql_control.out
@@ -681,3 +681,20 @@ select case_test(13);
  other
 (1 row)
 
+-- test line comment between WHEN and THEN
+create or replace function case_comment(int) returns text as $$
+begin
+  case $1
+    when 1 -- comment before THEN
+      then return 'one';
+    else
+      return 'other';
+  end case;
+end;
+$$ language plpgsql immutable;
+select case_comment(1);
+ case_comment 
+--------------
+ one
+(1 row)
+
diff --git a/src/pl/plpgsql/src/pl_gram.y b/src/pl/plpgsql/src/pl_gram.y
index bef33d58a2..98339589ba 100644
--- a/src/pl/plpgsql/src/pl_gram.y
+++ b/src/pl/plpgsql/src/pl_gram.y
@@ -4161,7 +4161,11 @@ make_case(int location, PLpgSQL_expr *t_expr,
 			/* Do the string hacking */
 			initStringInfo(&ds);
 
-			appendStringInfo(&ds, "\"%s\" IN (%s)",
+			/*
+			 * The read expression may end in a line comment, so
+			 * append \n after it to create a valid expression.
+			 */
+			appendStringInfo(&ds, "\"%s\" IN (%s\n)",
 							 varname, expr->query);
 
 			pfree(expr->query);
diff --git a/src/pl/plpgsql/src/sql/plpgsql_control.sql b/src/pl/plpgsql/src/sql/plpgsql_control.sql
index ed7231134f..8e007c51dc 100644
--- a/src/pl/plpgsql/src/sql/plpgsql_control.sql
+++ b/src/pl/plpgsql/src/sql/plpgsql_control.sql
@@ -486,3 +486,17 @@ select case_test(1);
 select case_test(2);
 select case_test(12);
 select case_test(13);
+
+-- test line comment between WHEN and THEN
+create or replace function case_comment(int) returns text as $$
+begin
+  case $1
+    when 1 -- comment before THEN
+      then return 'one';
+    else
+      return 'other';
+  end case;
+end;
+$$ language plpgsql immutable;
+
+select case_comment(1);
-- 
2.44.0