Re: CASE control block broken by a single line comment

On 2024-04-06 20:14 +0200, Michal Bartak wrote:
> The issue described bellow exists in postgresql ver 16.2 (found in some
> previous major versions)

Can confirm also on master.

> The documentation defines a comment as:
>
> > A comment is a sequence of characters beginning with double dashes and
> > extending to the end of the line
>
>
> When using such a comment within CASE control block, it ends up with an
> error:
>
> DO LANGUAGE plpgsql $$
> DECLARE
> t TEXT = 'a';
> BEGIN
> CASE t
> WHEN 'a' -- my comment
> THEN RAISE NOTICE 'a';
> WHEN 'b'
> THEN RAISE NOTICE 'b';
> ELSE NULL;
> END CASE;
> END;$$;
>
> ERROR: syntax error at end of input
> LINE 1: "__Case__Variable_2__" IN ('a' -- my comment)
> ^
> QUERY: "__Case__Variable_2__" IN ('a' -- my comment)
> CONTEXT: PL/pgSQL function inline_code_block line 5 at CASE

I'm surprised that the comment is not skipped by the scanner at this
point. Maybe because the parser just reads the raw expression between
WHEN and THEN with plpgsql_append_source_text via read_sql_construct.

How about the attached patch? It's a workaround by simply adding a line
feed character between the raw expression and the closing parenthesis.

--
Erik