Parse RBS files as RDoc input

[st0012]

Problem

RDoc already supports parser classes that register handled file names through parse_files_matching, but .rbs documentation parsing currently comes from the rbs gem's rdoc/discover hook, which defines RDoc::Parser::RBS and delegates to RBS::RDocPlugin::Parser at runtime (discovery hook, plugin parser). That leaves RBS documentation generation coupled to a separately released plugin even though RDoc already uses RBS for type-signature display (ruby/rdoc#1665), and internal RDoc API changes can break the plugin independently of RDoc releases (ruby/rdoc#1711).

Solution

• Add RDoc::Parser::RBS inside RDoc, adapted from the existing RBS plugin parser, so .rbs files are registered as RDoc input and common RBS declarations/members become RDoc code objects (RBS plugin parser, PR diff).
• Extend existing Ruby-source documentation when matching RBS declarations are parsed, while still generating documentation for classes, modules, methods, attributes, and constants that only appear in RBS (PR diff).
• Keep RDoc's existing sig/**/*.rbs type-signature loading path and skip the released rbs discovery hook when RDoc's parser is available, so RubyGems discovery does not replace the in-tree parser (ruby/rdoc#1665, discovery hook, PR diff).

[Copilot]

Pull request overview

This PR adds a built-in RDoc::Parser::RBS so .rbs files can be parsed as first-class RDoc inputs (instead of relying on the rbs gem’s runtime rdoc/discover hook), while also refining how sig/**/*.rbs files are auto-discovered and reloaded for type-signature merging and live preview.

Changes:

• Introduces lib/rdoc/parser/rbs.rb and registers it so .rbs files are parsed directly by RDoc.
• Separates “auto-discovered signature files” (sig/**/*.rbs) from explicitly selected .rbs documentation inputs for signature loading + live-reload bookkeeping.
• Refactors live server change detection/reload flow and extends RDoc::Context to support qualified module/constant paths.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
test/rdoc/rdoc_server_test.rb	Extends live-reload tests to cover parsing/reloading .rbs docs + signatures.
test/rdoc/rdoc_rdoc_test.rb	Adds integration tests for explicit .rbs inputs, auto-discovery rules, and skipping released rbs discovery hook.
test/rdoc/rdoc_context_test.rb	Adds coverage for qualified/absolute module additions and constant owner resolution helpers.
test/rdoc/parser/rbs_test.rb	New unit tests for the built-in RBS parser mapping into RDoc code objects.
lib/rdoc/server.rb	Refactors watcher change tracking and adds dedicated RBS signature reload path.
lib/rdoc/rdoc.rb	Renames/refines auto-discovered signature loading APIs and skips released rbs discovery hook.
lib/rdoc/parser/rbs.rb	New built-in .rbs parser implementation.
lib/rdoc/parser.rb	Requires the new RBS parser so it registers with RDoc::Parser.
lib/rdoc/code_object/context.rb	Adds helpers to build module paths + support qualified names in add_module.

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[matzbot]

🚀 Preview deployment available at: https://1553d19f.rdoc-6cd.pages.dev (commit: 13804b7)

[Copilot]

Pull request overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated 2 comments.

[soutaro]

Thanks Stan! 🎉
I haven't reviewed all of the implementation line by line (I cannot!), but looks great to replace existing RDoc plugin in rbs-gem!

[Copilot]

Pull request overview

Copilot reviewed 12 out of 12 changed files in this pull request and generated 2 comments.