[psteinroe]

Stacked on #934.

In expanded layout, a CASE nested in the THEN of another CASE moved right by then plus two indent levels per level of nesting. #884 aligns each CASE's branches with the column it starts at, and a nested CASE starts after then . With the default indent, twenty levels reached 184 columns at width 100. Finding P16 of the release review.

What changed

A CASE written as the result of a THEN or ELSE no longer aligns with its own column. It is indented from the line of its keyword: its branches one level in, and END under THEN or ELSE. Each level now costs two indents, the minimum for a WHEN and its THEN:

-- layout: expanded, indentSize: 4
-- before
case status
    when 'A'
        then case
                 when enabled
                     then 'active'
                 else 'paused'
             end
    else 'closed'
end
-- after
case status
    when 'A'
        then case
            when enabled
                then 'active'
            else 'paused'
        end
    else 'closed'
end

else case when ... else case ... chains read the same way. A CASE anywhere else, after select or a leading comma for instance, still aligns with the column it starts at, which is what #884 was about. Fit layout doesn't align, so it is unchanged.

This changes the nested layout that #884's expanded_nested_case_keeps_each_branch_at_its_own_indent test asserted, and the test now expects the new layout. I preferred this over breaking after then for every nested CASE: that would add a line and a level for every nested CASE, also the shallow ones that fit today. The docs section on expanded CASE describes the nested layout.

Tests and snapshot changes

• case_layout.rs: the updated nested test, a CASE nested in ELSE, and twenty levels nested in THEN staying within width 100.
• The only snapshot change is the nested CASE in expanded_case_alignment (added in test(pretty_print): fuzz the option matrix in CI #912), whose inner branches move left to the new indent.
• The option matrix passes over the fixtures and the regression suite.