[rubygems/rubygems] Fix another case of bundle lock --add-platform doing nothing

https://github.com/rubygems/rubygems/commit/0629e27dda

lib/bundler/definition.rb

@@ -81,7 +81,7 @@ module Bundler
       @resolved_bundler_version = nil
 
       @locked_ruby_version = nil
-      @new_platform = nil
+      @new_platforms = []
       @removed_platform = nil
 
       if lockfile_exists?
@@ -457,8 +457,10 @@ module Bundler
     end
 
     def add_platform(platform)
-      @new_platform ||= !@platforms.include?(platform)
+      return if @platforms.include?(platform)
-      @platforms |= [platform]
+
+      @new_platforms << platform
+      @platforms << platform
     end
 
     def remove_platform(platform)
@@ -482,7 +484,7 @@ module Bundler
 
       !@source_changes &&
         !@dependency_changes &&
-        !@new_platform &&
+        @new_platforms.empty? &&
         !@path_changes &&
         !@local_changes &&
         !@missing_lockfile_dep &&
@@ -703,7 +705,7 @@ module Bundler
       [
         [@source_changes, "the list of sources changed"],
         [@dependency_changes, "the dependencies in your gemfile changed"],
-        [@new_platform, "you added a new platform to your gemfile"],
+        [@new_platforms.any?, "you added a new platform to your gemfile"],
         [@path_changes, "the gemspecs for path gems changed"],
         [@local_changes, "the gemspecs for git local gems changed"],
         [@missing_lockfile_dep, "your lock file is missing \"#{@missing_lockfile_dep}\""],
@@ -1061,7 +1063,7 @@ module Bundler
 
       platforms.reverse_each do |platform|
         next if local_platform == platform ||
-                (@new_platform && platforms.last == platform) ||
+                @new_platforms.include?(platform) ||
                 @path_changes ||
                 @dependency_changes ||
                 @locked_spec_with_invalid_deps ||

spec/bundler/commands/lock_spec.rb

@@ -629,6 +629,62 @@ RSpec.describe "bundle lock" do
     expect(lockfile.platforms).to match_array(default_platform_list(java, x86_mingw32))
   end
 
+  it "supports adding new platforms, when most specific locked platform is not the current platform, and current resolve is not compatible with the target platform" do
+    simulate_platform "arm64-darwin-23" do
+      build_repo4 do
+        build_gem "foo" do |s|
+          s.platform = "arm64-darwin"
+        end
+
+        build_gem "foo" do |s|
+          s.platform = "java"
+        end
+      end
+
+      gemfile <<-G
+        source "https://gem.repo4"
+
+        gem "foo"
+      G
+
+      lockfile <<-L
+        GEM
+          remote: https://gem.repo4/
+          specs:
+            foo (1.0-arm64-darwin)
+
+        PLATFORMS
+          arm64-darwin
+
+        DEPENDENCIES
+          foo
+
+        BUNDLED WITH
+           #{Bundler::VERSION}
+      L
+
+      bundle "lock --add-platform java"
+
+      expect(lockfile).to eq <<~L
+        GEM
+          remote: https://gem.repo4/
+          specs:
+            foo (1.0-arm64-darwin)
+            foo (1.0-java)
+
+        PLATFORMS
+          arm64-darwin
+          java
+
+        DEPENDENCIES
+          foo
+
+        BUNDLED WITH
+           #{Bundler::VERSION}
+      L
+    end
+  end
+
   it "supports adding new platforms with force_ruby_platform = true" do
     lockfile <<-L
       GEM