[rubygems/rubygems] Fix truffleruby failing to install sorbet-static when there's no lockfile

The generic Ruby platform was getting unconditionally added in
truffleruby, preventing resolution in situations where there's no
generic ruby version (sorbet-static). Instead, the generic platform
should be considered per dependency, not globally.

a96afc5351

lib/bundler/definition.rb

@@ -740,7 +740,6 @@ module Bundler
     def start_resolution
       local_platform_needed_for_resolvability = @most_specific_non_local_locked_platform && !@platforms.include?(Bundler.local_platform)
       @platforms << Bundler.local_platform if local_platform_needed_for_resolvability
-      add_platform(Gem::Platform::RUBY) if RUBY_ENGINE == "truffleruby"
 
       result = SpecSet.new(resolver.start)
 

lib/bundler/resolver/package.rb

@@ -21,6 +21,7 @@ module Bundler
         @locked_version = locked_specs.version_for(name)
         @unlock = unlock
         @dependency = dependency || Dependency.new(name, @locked_version)
+        @platforms |= [Gem::Platform::RUBY] if @dependency.default_force_ruby_platform
         @top_level = !dependency.nil?
         @prerelease = @dependency.prerelease? || @locked_version&.prerelease? || prerelease ? :consider_first : :ignore
         @prefer_local = prefer_local

spec/bundler/commands/lock_spec.rb

@@ -2237,7 +2237,6 @@ RSpec.describe "bundle lock" do
               nokogiri (1.14.2-x86_64-linux)
 
           PLATFORMS
-            ruby
             x86_64-linux
 
           DEPENDENCIES

spec/bundler/install/gemfile/specific_platform_spec.rb

@@ -392,7 +392,23 @@ RSpec.describe "bundle install with specific platforms" do
     end
   end
 
-  it "installs sorbet-static, which does not provide a pure ruby variant, just fine", :truffleruby do
+  it "installs sorbet-static, which does not provide a pure ruby variant, in absence of a lockfile, just fine", :truffleruby do
+    skip "does not apply to Windows" if Gem.win_platform?
+
+    build_repo2 do
+      build_gem("sorbet-static", "0.5.6403") {|s| s.platform = Bundler.local_platform }
+    end
+
+    gemfile <<~G
+      source "https://gem.repo2"
+
+      gem "sorbet-static", "0.5.6403"
+    G
+
+    bundle "install --verbose"
+  end
+
+  it "installs sorbet-static, which does not provide a pure ruby variant, in presence of a lockfile, just fine", :truffleruby do
     skip "does not apply to Windows" if Gem.win_platform?
 
     build_repo2 do