Ban redundant then keyword via RuboCop

[st0012]

This has bothered me for quite a while. I was thinking about dropping them gradually, but with agents reading other code they constantly add then too. So let's ban this.

Cops enabled

.rubocop.yml uses DisabledByDefault: true, so each cop is opted in explicitly:

• Style/MultilineIfThen — if cond then with the body on the next line
• Style/MultilineWhenThen — same for when
• Style/MultilineInPatternThen — same for in pattern matching

There is no single "redundant then" cop; these three are RuboCop's coverage for it.

They intentionally leave single-line forms alone, where then is required and not redundant:

when Hash then (name[:rdoc] || "rdoc").to_s

[matzbot]

🚀 Preview deployment available at: https://259c1d9f.rdoc-6cd.pages.dev (commit: 88c8b73)

[Copilot]

Pull request overview

Bans redundant multiline then keywords through RuboCop and updates existing Ruby code accordingly without changing behavior.

Changes:

• Enables three multiline then style cops.
• Removes existing violations across source and test files.
• Preserves required single-line then forms.

Reviewed changes

Copilot reviewed 50 out of 50 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
.rubocop.yml	Enables multiline then cops.
exe/rdoc	Removes redundant then.
lib/rdoc/code_object.rb	Removes redundant then.
lib/rdoc/code_object/any_method.rb	Removes redundant then.
lib/rdoc/code_object/attr.rb	Removes redundant then.
lib/rdoc/code_object/class_module.rb	Removes redundant then.
lib/rdoc/code_object/constant.rb	Removes redundant then.
lib/rdoc/code_object/context.rb	Removes redundant then.
lib/rdoc/code_object/method_attr.rb	Removes redundant then.
lib/rdoc/code_object/require.rb	Removes redundant then.
lib/rdoc/cross_reference.rb	Removes redundant then.
lib/rdoc/encoding.rb	Removes redundant then.
lib/rdoc/generator/darkfish.rb	Removes redundant then.
lib/rdoc/generator/markup.rb	Removes redundant then.
lib/rdoc/markup.rb	Removes redundant then.
lib/rdoc/markup/document.rb	Removes redundant then.
lib/rdoc/markup/formatter.rb	Removes redundant then.
lib/rdoc/markup/indented_paragraph.rb	Removes redundant then.
lib/rdoc/markup/paragraph.rb	Removes redundant then.
lib/rdoc/markup/parser.rb	Removes redundant then.
lib/rdoc/markup/pre_process.rb	Removes redundant then.
lib/rdoc/markup/to_ansi.rb	Removes redundant then.
lib/rdoc/markup/to_bs.rb	Removes redundant then.
lib/rdoc/markup/to_html.rb	Removes redundant then.
lib/rdoc/markup/to_html_crossref.rb	Removes redundant then.
lib/rdoc/markup/to_html_snippet.rb	Removes redundant then.
lib/rdoc/markup/to_markdown.rb	Removes redundant then.
lib/rdoc/markup/to_rdoc.rb	Removes redundant then.
lib/rdoc/markup/to_test.rb	Removes redundant then.
lib/rdoc/markup/to_tt_only.rb	Removes redundant then.
lib/rdoc/markup/verbatim.rb	Removes redundant then.
lib/rdoc/options.rb	Removes redundant then.
lib/rdoc/parser.rb	Removes redundant then.
lib/rdoc/parser/c.rb	Removes redundant then.
lib/rdoc/parser/changelog.rb	Removes redundant then.
lib/rdoc/parser/ruby.rb	Removes redundant then.
lib/rdoc/rd.rb	Removes redundant then.
lib/rdoc/rd/inline.rb	Removes redundant then.
lib/rdoc/rdoc.rb	Removes redundant then.
lib/rdoc/ri/driver.rb	Removes redundant then.
lib/rdoc/ri/paths.rb	Removes redundant then.
lib/rdoc/ri/servlet.rb	Removes redundant then.
lib/rdoc/rubygems_hook.rb	Removes redundant then.
lib/rdoc/stats.rb	Removes redundant then.
lib/rdoc/stats/normal.rb	Removes redundant then.
lib/rdoc/store.rb	Removes redundant then.
lib/rdoc/task.rb	Removes redundant then.
lib/rdoc/token_stream.rb	Removes redundant then.
lib/rdoc/tom_doc.rb	Removes redundant then.
test/rdoc/code_object/class_module_test.rb	Updates test code to comply.

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