add configuration and support for freezing string literals in compile…

…d templates

lib/view_component/base.rb

@@ -67,7 +67,7 @@ def set_original_view_context(view_context)
     #
     # @return [String]
     def render_in(view_context, &block)
-      self.class.compile(raise_errors: true)
+      self.class.compile(raise_errors: true, frozen_string_literal: ViewComponent::Base.config.frozen_string_literal)
 
       @view_context = view_context
       self.__vc_original_view_context ||= view_context
@@ -466,7 +466,7 @@ def inherited(child)
             def render_template_for(variant = nil)
               # Force compilation here so the compiler always redefines render_template_for.
               # This is mostly a safeguard to prevent infinite recursion.
-              self.class.compile(raise_errors: true, force: true)
+              self.class.compile(raise_errors: true, force: true, frozen_string_literal: #{ViewComponent::Base.config.frozen_string_literal})
               # .compile replaces this method; call the new one
               render_template_for(variant)
             end
@@ -519,8 +519,8 @@ def ensure_compiled
       # Do as much work as possible in this step, as doing so reduces the amount
       # of work done each time a component is rendered.
       # @private
-      def compile(raise_errors: false, force: false)
-        compiler.compile(raise_errors: raise_errors, force: force)
+      def compile(raise_errors: false, force: false, frozen_string_literal: false)
+        compiler.compile(raise_errors: raise_errors, force: force, frozen_string_literal: frozen_string_literal)
       end
 
       # @private

lib/view_component/compiler.rb

@@ -26,7 +26,7 @@ def development?
       self.class.mode == DEVELOPMENT_MODE
     end
 
-    def compile(raise_errors: false, force: false)
+    def compile(raise_errors: false, force: false, frozen_string_literal: false)
       return if compiled? && !force
       return if component_class == ViewComponent::Base
 
@@ -48,12 +48,17 @@ def compile(raise_errors: false, force: false)
 
         redefinition_lock.synchronize do
           component_class.silence_redefinition_of_method("call")
-          # rubocop:disable Style/EvalWithLocation
-          component_class.class_eval <<-RUBY, template.path, template.lineno
+          source = <<-SOURCE
           def call
             #{compiled_inline_template(template)}
           end
-          RUBY
+          SOURCE
+          # rubocop:disable Style/EvalWithLocation
+          if frozen_string_literal
+            component_class.class_eval("# frozen_string_literal: true\n#{source}", template.path, template.lineno - 1)
+          else
+            component_class.class_eval(source, template.path, template.lineno)
+          end
           # rubocop:enable Style/EvalWithLocation
 
           component_class.define_method("_call_#{safe_class_name}", component_class.instance_method(:call))
@@ -71,12 +76,17 @@ def render_template_for(variant = nil)
 
           redefinition_lock.synchronize do
             component_class.silence_redefinition_of_method(method_name)
+            source = <<-SOURCE
+              def #{method_name}
+                #{compiled_template(template[:path])}
+              end
+            SOURCE
             # rubocop:disable Style/EvalWithLocation
-            component_class.class_eval <<-RUBY, template[:path], 0
-            def #{method_name}
-              #{compiled_template(template[:path])}
+            if frozen_string_literal
+              component_class.class_eval("# frozen_string_literal: true\n#{source}", template[:path], -1)
+            else
+              component_class.class_eval(source, template[:path], 0)
             end
-            RUBY
             # rubocop:enable Style/EvalWithLocation
           end
         end

lib/view_component/config.rb

@@ -25,7 +25,8 @@ def defaults
           preview_paths: default_preview_paths,
           test_controller: "ApplicationController",
           default_preview_layout: nil,
-          capture_compatibility_patch_enabled: false
+          capture_compatibility_patch_enabled: false,
+          frozen_string_literal: false
         })
       end
 
@@ -154,6 +155,11 @@ def defaults
       # previews.
       # Defaults to `false`.
 
+      # @!attribute frozen_string_literal
+      # @return [Boolean]
+      # Enables compiling templates with frozen_string_literal
+      # Defaults to `false`.
+
       def default_preview_paths
         return [] unless defined?(Rails.root) && Dir.exist?("#{Rails.root}/test/components/previews")
 

test/sandbox/test/config_test.rb

@@ -18,6 +18,7 @@ def test_defaults_are_correct
       assert_equal @config.render_monkey_patch_enabled, true
       assert_equal @config.show_previews, true
       assert_equal @config.preview_paths, ["#{Rails.root}/test/components/previews"]
+      assert_equal @config.frozen_string_literal, false
     end
 
     def test_all_methods_are_documented

test/sandbox/test/rendering_test.rb

@@ -1094,4 +1094,28 @@ def test_content_security_policy_nonce
 
     assert_selector("script", text: "\n//<![CDATA[\n  \"alert('hello')\"\n\n//]]>\n", visible: :hidden)
   end
+
+  def test_frozen_string_literal_disabled
+    old_value = ViewComponent::Base.config.frozen_string_literal
+    ViewComponent::Base.config.frozen_string_literal = false
+
+    with_new_cache do
+      render_inline(MutatedStringComponent.new)
+      assert_includes rendered_content, "ab"
+    end
+  ensure
+    ViewComponent::Base.config.frozen_string_literal = old_value
+  end
+
+  def test_frozen_string_literal_enabled
+    old_value = ViewComponent::Base.config.frozen_string_literal
+    ViewComponent::Base.config.frozen_string_literal = true
+    with_new_cache do
+      assert_raises FrozenError do
+        render_inline(MutatedStringComponent.new)
+      end
+    end
+  ensure
+    ViewComponent::Base.config.frozen_string_literal = old_value
+  end
 end