Preload RubyGems before Bundler standalone setup

Author: ledsun

lib/ruby_wasm/packager/core.rb

@@ -221,49 +221,9 @@ def _build_gem_exts(executor, build, gem_home)
       ]
 
       executor.system(*args, env: env)
-      patch_bundler_standalone_setup(local_path)
       executor.cp_r(local_path, gem_home)
     end
 
-    # Bundler standalone setup.rb assumes that once `Gem` is defined,
-    # Gem.ruby_api_version and Gem.extension_api_version are also available.
-    # In ruby-head packaging this assumption can fail (Gem exists, but these
-    # API-version helpers are missing), so we inject a compatibility shim
-    # before Bundler's load-path setup runs.
-    def patch_bundler_standalone_setup(local_path)
-      setup_rb = File.join(local_path, "bundler", "setup.rb")
-      return unless File.file?(setup_rb)
-
-      content = File.read(setup_rb)
-      marker = "# ruby.wasm compatibility shim for missing Gem API version methods"
-      return if content.include?(marker)
-
-      shim = <<~RUBY
-        #{marker}
-        if defined?(Gem)
-          module Gem
-            def self.ruby_api_version
-              RbConfig::CONFIG["ruby_version"]
-            end unless respond_to?(:ruby_api_version)
-
-            def self.extension_api_version
-              if "no" == RbConfig::CONFIG["ENABLE_SHARED"]
-                "\#{ruby_api_version}-static"
-              else
-                ruby_api_version
-              end
-            end unless respond_to?(:extension_api_version)
-          end
-        end
-      RUBY
-
-      patched = content.sub(/^require 'rbconfig'\n/, "require 'rbconfig'\n#{shim}\n")
-      return if patched == content
-
-      RubyWasm.logger.info("Patching #{setup_rb} for RubyGems API compatibility")
-      File.write(setup_rb, patched)
-    end
-
     def cache_key(digest)
       derive_build.cache_key(digest)
     end

packages/npm-packages/ruby-wasm-wasi/src/vm.ts

@@ -335,6 +335,11 @@ export class RubyVM {
       this.eval(`
         # Require Bundler standalone setup
         if File.exist?("/bundle/bundler/setup.rb")
+          # Some ruby-head + ruby.wasm revisions return from rubyInit with a partial
+          # Gem module: Gem is defined, but RubyGems is not loaded yet and its API
+          # helpers are still missing. Bundler standalone treats defined?(Gem) as
+          # sufficient, so load RubyGems explicitly before requiring its setup file.
+          require "rubygems" if defined?(Gem) && !Gem.respond_to?(:ruby_api_version)
           require "/bundle/bundler/setup.rb"
         elsif File.exist?("/bundle/setup.rb")
           # For non-CM builds, which doesn't use Bundler's standalone mode

sig/ruby_wasm/packager.rbs

@@ -81,7 +81,6 @@ class RubyWasm::Packager
       def name: () -> string
 
       private def _build_gem_exts: (RubyWasm::BuildExecutor, RubyWasm::Build, string gem_home) -> void
-      private def patch_bundler_standalone_setup: (string local_path) -> void
       private def _link_gem_exts: (RubyWasm::BuildExecutor, RubyWasm::Build, string ruby_root, string gem_home, bytes module_bytes) -> bytes
     end