Fill generated Erlang data-flow source labels

Author: dannote

lib/reach/visualize.ex

@@ -278,15 +278,16 @@ defmodule Reach.Visualize do
       module = function_module(function)
       file = node.source_span[:file] || source_file(function)
       line = node.source_span[:start_line]
+      node_label = ir_node_label(node)
 
       %{
         id: to_string(node.id),
         function_id: if(function_id, do: to_string(function_id)),
-        label: "#{function_prefix}L#{line}: #{ir_node_label(node)}",
+        label: "#{function_prefix}L#{line}: #{node_label}",
         module: if(module, do: display_module(module)),
         file: file,
         start_line: line,
-        source_html: Source.highlight_line(file, line)
+        source_html: Source.highlight_line(file, line, node_label)
       }
     end
   end

lib/reach/visualize/source.ex

@@ -69,6 +69,18 @@ defmodule Reach.Visualize.Source do
 
   def highlight_line(_, _), do: nil
 
+  def highlight_line(file, line, fallback) when is_binary(fallback) do
+    case highlight_line(file, line) do
+      source when is_binary(source) ->
+        if String.trim(source) == "", do: highlight_fallback(fallback, file), else: source
+
+      _missing_source ->
+        highlight_fallback(fallback, file)
+    end
+  end
+
+  def highlight_line(file, line, _fallback), do: highlight_line(file, line)
+
   def highlight_lines(file, from, to) when is_binary(file) do
     case cached_file_lines(file) do
       nil ->
@@ -168,6 +180,10 @@ defmodule Reach.Visualize.Source do
   def source_file?(nil), do: false
   def source_file?(file), do: Path.extname(file) in @source_extensions
 
+  defp highlight_fallback(fallback, file) do
+    highlight_source(fallback, lang_for_file(file)) || escape_html(fallback)
+  end
+
   defp escape_html(source) do
     source
     |> String.replace("&", "&")

test/reach/visualize_test.exs

@@ -188,6 +188,32 @@ defmodule Reach.VisualizeTest do
       assert Enum.all?(data_nodes, &(is_binary(&1.function_id) and &1.function_id != ""))
       refute Enum.any?(data_nodes, &(&1.label =~ "export(...)" or &1.label =~ "spec(...)"))
     end
+
+    test "data flow falls back to labels for generated Erlang source locations" do
+      dir =
+        Path.join(
+          System.tmp_dir!(),
+          "reach-generated-erlang-data-flow-#{System.unique_integer([:positive])}"
+        )
+
+      path = Path.join(dir, "generated_parser.erl")
+      File.mkdir_p!(dir)
+
+      File.write!(path, """
+      -file("grammar.yrl", 42).
+      -module(generated_parser).
+      -export([normalize/1]).
+      normalize(Input) -> Normalized = Input, Normalized.
+      """)
+
+      on_exit(fn -> File.rm_rf!(dir) end)
+
+      project = Reach.Project.from_sources([path], plugins: [])
+      data_nodes = Reach.Visualize.to_graph_json(project).data_flow.functions
+
+      assert data_nodes != []
+      assert Enum.all?(data_nodes, &(is_binary(&1.source_html) and &1.source_html != ""))
+    end
   end
 
   describe "to_json/2" do