[rubygems/rubygems] Fix generic platform gems getting incorrectly removed when locked for a specific platform

If they are already in the lockfile as the most specific variant for a
platform, we shouldn't change that unless explicitly unlocking.

https://github.com/rubygems/rubygems/commit/a901660498

3 files changed, 11 insertions, 2 deletions

diff --git a/lib/bundler/gem_helpers.rb b/lib/bundler/gem_helpers.rb
index c27ceb360a..70ccceb491 100644
--- a/lib/bundler/gem_helpers.rb
+++ b/lib/bundler/gem_helpers.rb
@@ -46,13 +46,18 @@ module Bundler
     end
     module_function :platform_specificity_match
 
-    def select_best_platform_match(specs, platform, force_ruby: false)
+    def select_best_platform_match(specs, platform, force_ruby: false, prefer_locked: false)
       matching = if force_ruby
         specs.select {|spec| spec.match_platform(Gem::Platform::RUBY) && spec.force_ruby_platform! }
       else
         specs.select {|spec| spec.match_platform(platform) }
       end
 
+      if prefer_locked
+        locked_originally = matching.select {|spec| spec.is_a?(LazySpecification) }
+        return locked_originally if locked_originally.any?
+      end
+
       sort_best_platform_match(matching, platform)
     end
     module_function :select_best_platform_match
diff --git a/lib/bundler/resolver.rb b/lib/bundler/resolver.rb
index b640eaf81b..2be7af94a2 100644
--- a/lib/bundler/resolver.rb
+++ b/lib/bundler/resolver.rb
@@ -255,7 +255,7 @@ module Bundler
       results = filter_matching_specs(results, locked_requirement) if locked_requirement
 
       results.group_by(&:version).reduce([]) do |groups, (version, specs)|
-        platform_specs = package.platforms.map {|platform| select_best_platform_match(specs, platform) }
+        platform_specs = package.platform_specs(specs)
 
         # If package is a top-level dependency,
         #   candidate is only valid if there are matching versions for all resolution platforms.
diff --git a/lib/bundler/resolver/package.rb b/lib/bundler/resolver/package.rb
index 0461328683..16c43d05af 100644
--- a/lib/bundler/resolver/package.rb
+++ b/lib/bundler/resolver/package.rb
@@ -25,6 +25,10 @@ module Bundler
         @prerelease = @dependency.prerelease? || @locked_version&.prerelease? || prerelease ? :consider_first : :ignore
       end
 
+      def platform_specs(specs)
+        platforms.map {|platform| GemHelpers.select_best_platform_match(specs, platform, prefer_locked: !unlock?) }
+      end
+
       def to_s
         @name.delete("\0")
       end