Fix Prism.parse_comments locations for FFI backend

Offsets are not serialized but the locations require them to work correctly.

Author: Earlopain

include/prism/internal/serialize.h

@@ -14,6 +14,11 @@
  * PRISM_EXCLUDE_SERIALIZATION define. */
 #ifndef PRISM_EXCLUDE_SERIALIZATION
 
+/*
+ * Serialize the given list of offsets to the given buffer.
+ */
+void pm_serialize_line_offset_list(pm_line_offset_list_t *list, pm_buffer_t *buffer);
+
 /*
  * Serialize the given list of comments to the given buffer.
  */

src/prism.c

@@ -23079,6 +23079,7 @@ pm_serialize_parse_comments(pm_buffer_t *buffer, const uint8_t *source, size_t s
     pm_serialize_header(buffer);
     pm_serialize_encoding(parser.encoding, buffer);
     pm_buffer_append_varsint(buffer, parser.start_line);
+    pm_serialize_line_offset_list(&parser.line_offsets, buffer);
     pm_serialize_comment_list(&parser.comment_list, buffer);
 
     pm_parser_cleanup(&parser);

templates/lib/prism/serialize.rb.erb

@@ -135,8 +135,10 @@ module Prism
                    loader.load_header
                    loader.load_encoding
       start_line = loader.load_varsint
+      offsets    = loader.load_line_offsets(freeze)
 
       source.replace_start_line(start_line)
+      source.replace_offsets(offsets)
 
       result =     loader.load_comments(freeze)
       raise unless loader.eof?

templates/src/serialize.c.erb

@@ -156,7 +156,10 @@ pm_serialize_node(pm_parser_t *parser, pm_node_t *node, pm_buffer_t *buffer) {
     }
 }
 
-static void
+/*
+ * Serialize the given list of offsets to the given buffer.
+ */
+void
 pm_serialize_line_offset_list(pm_line_offset_list_t *list, pm_buffer_t *buffer) {
     uint32_t size = pm_sizet_to_u32(list->size);
     pm_buffer_append_varuint(buffer, size);

test/prism/api/parse_comments_test.rb

@@ -9,6 +9,8 @@ def test_parse_comments
 
       assert_kind_of Array, comments
       assert_equal 1, comments.length
+      assert_equal 1, comments[0].location.start_line
+      assert_equal "# foo", comments[0].slice
     end
 
     def test_parse_file_comments