Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

PR #15822 fixed the warning for direct hyphenated gem requires like
`benchmark/ips` → `benchmark-ips`. However, hyphenated gems often
provide multiple files under their namespace.

For example, `benchmark-ips` provides:
- benchmark/ips.rb
- benchmark/timing.rb
- benchmark/compare.rb

When requiring `benchmark/timing`, the previous fix only checked for
`benchmark-timing` gem (doesn't exist), not `benchmark-ips` which
actually provides the file.

This fix checks if ANY gem matching `{prefix}-*` is in the bundle
specs, which covers all subfeatures provided by hyphenated gems.

Reported in https://github.com/ruby/ruby/pull/15822#issuecomment-123456

This patch silences the "this won't work in the next version of Ruby"
warning displayed when irb is autoloaded via `binding.irb`.

    main.rb:1: warning: irb used to be loaded from the standard library, but is not part of the default gems since Ruby 4.0.0.
    You can add irb to your Gemfile or gemspec to fix this error.
    /.../irb.rb:9: warning: reline used to be loaded from the standard library, but is not part of the default gems since Ruby 4.0.0.
    You can add reline to your Gemfile or gemspec to fix this error.

    From: main.rb @ line 1 :

     => 1: binding.irb

    /.../input-method.rb:284: warning: rdoc used to be loaded from the standard library, but is not part of the default gems since Ruby 4.0.0.
    You can add rdoc to your Gemfile or gemspec to fix this error.

This warning is incorrect and misleading: users should not need to
include irb (and its dependencies) to their Gemfiles to use
`binding.irb`, even in future versions of Ruby. It is agreed that the
runtime takes care of that.

Bundler::Runtime#setup requires a real existing lockfile (see
Bundler::SharedHelpers#default_lockfile).

This patch fixes a problem where `binding.irb` (= force_activate('irb'))
fails under `bundle exec` when the Gemfile does not contain `irb` and
does contain a gem which is (1) not installed in GEM_HOME (2) sourced
using `path:`/`git:`.

The original approach constructing a temporary definition fails since
it does not set the equalivent of `path:`/`git:`.

Always reconstructing a definition from a Gemfile and applying lockfile
constraints should be a more robust approach.

[Bug #21723]

When requiring a file like "benchmark/ips", the warning system would
incorrectly warn about the "benchmark" gem not being a default gem,
even when the user has "benchmark-ips" (a separate third-party gem)
in their Gemfile.

The fix checks if a hyphenated version of the require path exists in
the bundle specs before issuing a warning. For example, requiring
"benchmark/ips" now checks for both "benchmark" and "benchmark-ips"
in the Gemfile.

[Bug #21828]