Set "trailing" on the comment node

ext/prism/extension.c

@@ -471,9 +471,12 @@ parser_location(const pm_parser_t *parser, VALUE source, bool freeze, const uint
  */
 static inline VALUE
 parser_comment(const pm_parser_t *parser, VALUE source, bool freeze, const pm_comment_t *comment) {
-    VALUE argv[] = { PARSER_LOCATION_LOC(parser, source, freeze, comment->location) };
+    VALUE argv[] = {
+        comment->trailing ? Qtrue : Qfalse,
+        PARSER_LOCATION_LOC(parser, source, freeze, comment->location)
+    };
     VALUE type = (comment->type == PM_COMMENT_EMBDOC) ? rb_cPrismEmbDocComment : rb_cPrismInlineComment;
-    return rb_class_new_instance_freeze(1, argv, type, freeze);
+    return rb_class_new_instance_freeze(2, argv, type, freeze);
 }
 
 /**

include/prism/parser.h

@@ -467,6 +467,8 @@ typedef struct pm_comment {
 
     /** The type of comment that we've found. */
     pm_comment_type_t type;
+
+    bool trailing;
 } pm_comment_t;
 
 /**

lib/prism/parse_result.rb

@@ -513,8 +513,15 @@ class Comment
     # The location of this comment in the source.
     attr_reader :location
 
+    # Returns true if this comment happens on the same line as other code and
+    # false if the comment is by itself.
+    def trailing?
+      @trailing
+    end
+
     # Create a new comment object with the given location.
-    def initialize(location)
+    def initialize(trailing, location)
+      @trailing = trailing
       @location = location
     end
 
@@ -532,12 +539,6 @@ def slice
   # InlineComment objects are the most common. They correspond to comments in
   # the source file like this one that start with #.
   class InlineComment < Comment
-    # Returns true if this comment happens on the same line as other code and
-    # false if the comment is by itself.
-    def trailing?
-      !location.start_line_slice.strip.empty?
-    end
-
     # Returns a string representation of this comment.
     def inspect
       "#<Prism::InlineComment @location=#{location.inspect}>"
@@ -547,11 +548,6 @@ def inspect
   # EmbDocComment objects correspond to comments that are surrounded by =begin
   # and =end.
   class EmbDocComment < Comment
-    # This can only be true for inline comments.
-    def trailing?
-      false
-    end
-
     # Returns a string representation of this comment.
     def inspect
       "#<Prism::EmbDocComment @location=#{location.inspect}>"

src/prism.c

@@ -9291,12 +9291,13 @@ parser_lex_callback(pm_parser_t *parser) {
  * Return a new comment node of the specified type.
  */
 static inline pm_comment_t *
-parser_comment(pm_parser_t *parser, pm_comment_type_t type) {
+parser_comment(pm_parser_t *parser, pm_comment_type_t type, bool trailing) {
     pm_comment_t *comment = (pm_comment_t *) xcalloc(1, sizeof(pm_comment_t));
     if (comment == NULL) return NULL;
 
     *comment = (pm_comment_t) {
         .type = type,
+        .trailing = trailing,
         .location = { parser->current.start, parser->current.end }
     };
 
@@ -9324,7 +9325,7 @@ lex_embdoc(pm_parser_t *parser) {
     parser_lex_callback(parser);
 
     // Now, create a comment that is going to be attached to the parser.
-    pm_comment_t *comment = parser_comment(parser, PM_COMMENT_EMBDOC);
+    pm_comment_t *comment = parser_comment(parser, PM_COMMENT_EMBDOC, false);
     if (comment == NULL) return PM_TOKEN_EOF;
 
     // Now, loop until we find the end of the embedded documentation or the end
@@ -9831,7 +9832,11 @@ parser_lex(pm_parser_t *parser) {
                     // If we found a comment while lexing, then we're going to
                     // add it to the list of comments in the file and keep
                     // lexing.
-                    pm_comment_t *comment = parser_comment(parser, PM_COMMENT_INLINE);
+                    bool trailing = true;
+                    if (parser->previous.type == PM_TOKEN_EOF || parser->previous.type == PM_TOKEN_NEWLINE) {
+                        trailing = false;
+                    }
+                    pm_comment_t *comment = parser_comment(parser, PM_COMMENT_INLINE, trailing);
                     pm_list_append(&parser->comment_list, (pm_list_node_t *) comment);
 
                     if (ending) parser->current.end++;

templates/lib/prism/serialize.rb.erb

@@ -295,8 +295,8 @@ module Prism
           Array.new(load_varuint) do
             comment =
               case load_varuint
-              when 0 then InlineComment.new(load_location_object(freeze))
-              when 1 then EmbDocComment.new(load_location_object(freeze))
+              when 0 then InlineComment.new(load_boolean, load_location_object(freeze))
+              when 1 then EmbDocComment.new(load_boolean, load_location_object(freeze))
               end
 
             comment.freeze if freeze
@@ -450,6 +450,10 @@ module Prism
         value
       end
 
+      def load_boolean
+        io.getbyte != 0
+      end
+
       def load_double
         io.read(8).unpack1("D")
       end

templates/src/serialize.c.erb

@@ -173,6 +173,9 @@ pm_serialize_comment(pm_parser_t *parser, pm_comment_t *comment, pm_buffer_t *bu
     // serialize type
     pm_buffer_append_byte(buffer, (uint8_t) comment->type);
 
+    // serialize trailing
+    pm_buffer_append_byte(buffer, (uint8_t) comment->trailing);
+
     // serialize location
     pm_serialize_location(parser, &comment->location, buffer);
 }