Keep trailing comments after nodes without closing metadata

[rubas-agent]

Since elixir-lang/elixir#15893, Code.quoted_to_algebra/2 moves a comment into the node before it when that node has no :closing or :end metadata. ASTs built by hand or with quote often have no such metadata. On main, this breaks the Igniter tests of Phoenix LiveView (test/phoenix_live_view/igniter/upgrade_to_1_1_test.exs).

Here a list holds a call without metadata, and a comment follows the call:

comments = [%{line: 2, column: 3, previous_eol_count: 1, next_eol_count: 1, text: "# comment"}]

{:__block__, [line: 1, closing: [line: 3]], [[{:foo, [], [1]}]]}
|> Code.quoted_to_algebra(comments: comments)
|> Inspect.Algebra.format(98)
|> IO.puts()

v1.20 and this branch:

[
  foo(1)
  # comment
]

main:

[
  foo(
    1
    # comment
  )
]

SteffenDE reported the same bug with a 3-tuple in a comment on elixir-lang/elixir#15893. Operators, 2-tuples, maps, lists and keyword lists without metadata break the same way.

The cause is comments_boundaries/3 in code.ex. A node without :closing or :end gives its children the boundary of its parent, or its own :end_of_expression line. The last child then takes every comment up to that line as its trailing comments.

With this change, such a node gives its children no boundary, so a comment stays with the nearest node that has :closing or :end. :-> passes the boundary on to its body, as :. already does. In Code.Formatter.map_to_algebra/4, the | of a map update now prints its trailing comments, because comments can attach to it now.

Tests: quoted_ast_test.exs has the 3-tuple, call and operator cases without metadata. comments_test.exs has parsed cases with a comment after an operator, an attribute, a list tail, a map update, and a single expression in parens. All of them fail on main.

[rubas-agent]

Upstream merged the fix in elixir-lang#15961.