1 files changed, 42 insertions, 7 deletions
diff --git a/lib/bundler/ruby_dsl.rb b/lib/bundler/ruby_dsl.rb
index f6ba220cd5..fb4b79c4df 100644
--- a/lib/bundler/ruby_dsl.rb
+++ b/lib/bundler/ruby_dsl.rb
@@ -3,16 +3,51 @@
 module Bundler
   module RubyDsl
     def ruby(*ruby_version)
-      options = ruby_version.last.is_a?(Hash) ? ruby_version.pop : {}
+      options = ruby_version.pop if ruby_version.last.is_a?(Hash)
       ruby_version.flatten!
-      raise GemfileError, "Please define :engine_version" if options[:engine] && options[:engine_version].nil?
-      raise GemfileError, "Please define :engine" if options[:engine_version] && options[:engine].nil?
 
-      if options[:engine] == "ruby" && options[:engine_version] &&
-          ruby_version != Array(options[:engine_version])
-        raise GemfileEvalError, "ruby_version must match the :engine_version for MRI"
+      if options
+        patchlevel = options[:patchlevel]
+        engine = options[:engine]
+        engine_version = options[:engine_version]
+
+        raise GemfileError, "Please define :engine_version" if engine && engine_version.nil?
+        raise GemfileError, "Please define :engine" if engine_version && engine.nil?
+
+        if options[:file]
+          raise GemfileError, "Do not pass version argument when using :file option" unless ruby_version.empty?
+          ruby_version << normalize_ruby_file(options[:file])
+        end
+
+        if engine == "ruby" && engine_version && ruby_version != Array(engine_version)
+          raise GemfileEvalError, "ruby_version must match the :engine_version for MRI"
+        end
+      end
+
+      @ruby_version = RubyVersion.new(ruby_version, patchlevel, engine, engine_version)
+    end
+
+    # Support the various file formats found in .ruby-version files.
+    #
+    #     3.2.2
+    #     ruby-3.2.2
+    #
+    # Also supports .tool-versions files for asdf. Lines not starting with "ruby" are ignored.
+    #
+    #     ruby 2.5.1 # comment is ignored
+    #     ruby   2.5.1# close comment and extra spaces doesn't confuse
+    #
+    # Intentionally does not support `3.2.1@gemset` since rvm recommends using .ruby-gemset instead
+    #
+    # Loads the file relative to the dirname of the Gemfile itself.
+    def normalize_ruby_file(filename)
+      file_content = Bundler.read_file(gemfile.dirname.join(filename))
+      # match "ruby-3.2.2" or "ruby   3.2.2" capturing version string up to the first space or comment
+      if /^ruby(-|\s+)([^\s#]+)/.match(file_content)
+        $2
+      else
+        file_content.strip
       end
-      @ruby_version = RubyVersion.new(ruby_version, options[:patchlevel], options[:engine], options[:engine_version])
     end
   end
 end