Implement spot and don't use keep_script_lines in Ruby 3.2

We want to use error highlight with eval'd code, specifically ERB
templates.

Previously we could only get the information we needed by setting
`keep_script_lines` to true. In Ruby 3.2 and error_highlight we added
the ability to get this information without setting `keep_script_lines`.

This change implements that new behavior for Rails.

I removed the script line changes to support this in 3.1 because it is
not in any released version.

Ruby change: ruby/ruby#6593
Erorr highlight change: ruby/error_highlight#26

Co-authored-by: Aaron Patterson <tenderlove@ruby-lang.org>

actionpack/lib/action_dispatch/middleware/exception_wrapper.rb

@@ -228,7 +228,12 @@ def initialize(location, template)
         end
 
         def spot(exc)
-          location = super
+          if RubyVM::AbstractSyntaxTree.respond_to?(:node_id_for_backtrace_location)
+            location = @template.spot(__getobj__)
+          else
+            location = super
+          end
+
           if location
             @template.translate_location(__getobj__, location)
           end

actionview/lib/action_view/template.rb

@@ -154,11 +154,19 @@ def locals
       end
     end
 
+    def spot(location) # :nodoc:
+      ast = RubyVM::AbstractSyntaxTree.parse(compiled_source, keep_script_lines: true)
+      node_id = RubyVM::AbstractSyntaxTree.node_id_for_backtrace_location(location)
+      node = find_node_by_id(ast, node_id)
+
+      ErrorHighlight.spot(node)
+    end
+
     # Translate an error location returned by ErrorHighlight to the correct
     # source location inside the template.
     def translate_location(backtrace_location, spot)
       if handler.respond_to?(:translate_location)
-        handler.translate_location(spot, backtrace_location, source)
+        handler.translate_location(spot, backtrace_location, encode!)
       else
         spot
       end
@@ -303,6 +311,17 @@ def method_name # :nodoc:
     end
 
     private
+      def find_node_by_id(node, node_id)
+        return node if node.node_id == node_id
+
+        node.children.grep(node.class).each do |child|
+          found = find_node_by_id(child, node_id)
+          return found if found
+        end
+
+        false
+      end
+
       # Compile a template. This method ensures a template is compiled
       # just once and removes the source after it is compiled.
       def compile!(view)

actionview/test/template/render_test.rb

@@ -208,30 +208,20 @@ def test_render_outside_path
     end
   end
 
-  # rubocop:disable Minitest/SkipEnsure
-  def test_render_runtime_error
-    skip unless RubyVM.respond_to?(:keep_script_lines)
-
-    # We need to enable this setting so that when we eval the template
-    # the compiled source is kept around.
-    setting = RubyVM.keep_script_lines
-    RubyVM.keep_script_lines = true
-
-    ex = assert_raises(ActionView::Template::Error) {
-      @view.render(template: "test/runtime_error")
-    }
-    erb_btl = ex.backtrace_locations.first
-
-    # Get the spot information from ErrorHighlight
-    spot = erb_btl.spot(ex.cause)
-    translated_spot = ex.template.translate_location(erb_btl, spot)
-    assert_equal 6, translated_spot[:first_column]
-  ensure
-    if RubyVM.respond_to?(:keep_script_lines)
-      RubyVM.keep_script_lines = setting
+  if RUBY_VERSION >= "3.2"
+    def test_render_runtime_error
+      ex = assert_raises(ActionView::Template::Error) {
+        @view.render(template: "test/runtime_error")
+      }
+      erb_btl = ex.backtrace_locations.first
+
+      # Get the spot information from ErrorHighlight
+      translating_frame = ActionDispatch::ExceptionWrapper::SourceMapLocation.new(erb_btl, ex.template)
+      translated_spot = translating_frame.spot(ex.cause)
+
+      assert_equal 6, translated_spot[:first_column]
     end
   end
-  # rubocop:enable Minitest/SkipEnsure
 
   def test_render_partial
     assert_equal "only partial", @view.render(partial: "test/partial_only")

railties/lib/rails/application/configuration.rb

@@ -34,10 +34,6 @@ def initialize(*)
         @filter_redirect                         = []
         @helpers_paths                           = []
         if Rails.env.development?
-          if defined?(RubyVM) && RubyVM.respond_to?(:keep_script_lines=)
-            RubyVM.keep_script_lines = true
-          end
-
           @hosts = ActionDispatch::HostAuthorization::ALLOWED_HOSTS_IN_DEVELOPMENT +
             ENV["RAILS_DEVELOPMENT_HOSTS"].to_s.split(",").map(&:strip)
         else