L026 rule (ansi) cannot find table/view aliases in the FROM clause with JOINS in subquery

[tkachenkomaria244]

Rule L026 finds violations in the code below, but actually all aliases exists in FROM statement.

select
	cc.c1
from
(
	select c.c1
	from
		table1 as c
	join
		table2 as ci
		on c.x_id = ci.x_id
	join
		table3 as pci
		on ci.y_id = pci.y_id
) as cc

Expected Behaviour

no violations of L026

Observed Behaviour

PS D:\py_code\sqlfluff> sqlfluff lint D:\py_code\sqlfluff\real_tests\v_v.sql --rules L026
== [D:\py_code\sqlfluff\real_tests\v_v.sql] FAIL
L:  10 | P:   6 | L026 | Reference 'c.x_id' refers to table/view not found in the
                       | FROM clause or found in parent subquery.
L:  10 | P:  15 | L026 | Reference 'ci.x_id' refers to table/view not found in
                       | the FROM clause or found in parent subquery.
L:  13 | P:   6 | L026 | Reference 'ci.y_id' refers to table/view not found in
                       | the FROM clause or found in parent subquery.
L:  13 | P:  16 | L026 | Reference 'pci.y_id' refers to table/view not found in
                       | the FROM clause or found in parent subquery.

Following scripts dosn't give these errors:

select c.c1
from
	table1 as c
join
	table2 as ci
	on c.x_id = ci.x_id
join
	table3 as pci
	on ci.y_id = pci.y_id

select
	cc.c1
from
(
	select c.c1
	from
		table1 as c,
		table2 as ci,
		table3 as pci
	where c.x_id = ci.x_id
		and ci.y_id = pci.y_id
) as cc

Dialect

Dialects = ansi, tsql

Version

Python 3.9.6
SQLFluff 0.8.1 and earlier.

Configuration

[sqlfluff]
exclude_rules = L007,L015,L017,L020,L021,L022,L023,L024,L029,L031,L032,L033,L034,L035,L037,L038,L041,L042,L043,L044,L045,L046,L047
sql_file_exts = .sql
dialect = tsql

[sqlfluff:indentation]
indented_joins = False
template_blocks_indent = True

[sqlfluff:rules]
tab_space_size = 4
max_line_length = 250
indent_unit = tab
comma_style = leading
single_table_references = qualified
allow_scalar = False

[sqlfluff:rules:L010] # Keywords
capitalisation_policy = lower

[sqlfluff:rules:L014]  # Unquoted identifiers
extended_capitalisation_policy = lower

[sqlfluff:rules:L016]
ignore_comment_lines = False

[sqlfluff:rules:L030] # Function names
capitalisation_policy = lower
[sqlfluff:rules:L040] # Null & Boolean Literals
capitalisation_policy = lower

[sqlfluff:rules:L019]
comma_style = leading

[sqlfluff:rules:L028]
single_table_references = qualified

[jpy-git]

looking into this 👀