[ruby/prism] Fix incompatibilities for `on_word_sep` in ripper

It was mostly good, just a few edgecases:
* word_sep always only contains a single line. if there are multiple lines, it is also multiple word_sep
* Handle trailing whitespace

The excluded testcase is interpolation mixed with heredoc.
That is not currently handled properly and word_sep contains
the content of the heredoc

I also switched start/end_offset names in the method, they seem to be backwards

https://github.com/ruby/prism/commit/2e151ad41b

2 files changed, 24 insertions, 9 deletions

diff --git a/lib/prism/translation/ripper.rb b/lib/prism/translation/ripper.rb
index b066f3e3ac..00506d650e 100644
--- a/lib/prism/translation/ripper.rb
+++ b/lib/prism/translation/ripper.rb
@@ -704,6 +704,8 @@ module Prism
             previous = element
           end
 
+          visit_words_sep(opening_loc, node.elements.last, node.closing_loc)
+
           bounds(node.closing_loc)
           on_tstring_end(node.closing)
         when /^%i/
@@ -723,6 +725,8 @@ module Prism
             previous = element
           end
 
+          visit_words_sep(opening_loc, node.elements.last, node.closing_loc)
+
           bounds(node.closing_loc)
           on_tstring_end(node.closing)
         when /^%W/
@@ -760,6 +764,8 @@ module Prism
             previous = element
           end
 
+          visit_words_sep(opening_loc, node.elements.last, node.closing_loc)
+
           bounds(node.closing_loc)
           on_tstring_end(node.closing)
         when /^%I/
@@ -797,6 +803,8 @@ module Prism
             previous = element
           end
 
+          visit_words_sep(opening_loc, node.elements.last, node.closing_loc)
+
           bounds(node.closing_loc)
           on_tstring_end(node.closing)
         else
@@ -813,15 +821,21 @@ module Prism
         on_array(elements)
       end
 
-      # Dispatch a words_sep event that contains the space between the elements
+      # Dispatch words_sep events that contains the whitespace between the elements
       # of list literals.
       private def visit_words_sep(opening_loc, previous, current)
-        end_offset = (previous.nil? ? opening_loc : previous.location).end_offset
-        start_offset = current.location.start_offset
-
-        if end_offset != start_offset
-          bounds(current.location.copy(start_offset: end_offset))
-          on_words_sep(source.byteslice(end_offset...start_offset))
+        start_offset = (previous.nil? ? opening_loc : previous.location).end_offset
+        end_offset = current.start_offset
+        length = end_offset - start_offset
+
+        if length > 0
+          whitespace = source.byteslice(start_offset, length)
+          current_offset = start_offset
+          whitespace.each_line do |part|
+            bounds(opening_loc.copy(start_offset: current_offset, length: part.bytesize))
+            on_words_sep(part)
+            current_offset += part.bytesize
+          end
         end
       end
 
diff --git a/test/prism/ruby/ripper_test.rb b/test/prism/ruby/ripper_test.rb
index 61065e3ffc..cdb8375f96 100644
--- a/test/prism/ruby/ripper_test.rb
+++ b/test/prism/ruby/ripper_test.rb
@@ -101,6 +101,7 @@ module Prism
       "seattlerb/messy_op_asgn_lineno.txt",
       "seattlerb/op_asgn_primary_colon_const_command_call.txt",
       "seattlerb/parse_pattern_076.txt",
+      "seattlerb/pct_w_heredoc_interp_nested.txt",
       "tilde_heredocs.txt",
       "unparser/corpus/literal/assignment.txt",
       "unparser/corpus/literal/pattern.txt",
@@ -138,11 +139,11 @@ module Prism
       end
     end
 
-    UNSUPPORTED_EVENTS = %i[comma ignored_nl label_end nl semicolon sp words_sep ignored_sp]
+    UNSUPPORTED_EVENTS = %i[comma ignored_nl label_end nl semicolon sp ignored_sp]
     # Events that are currently not emitted
     SUPPORTED_EVENTS = Translation::Ripper::EVENTS - UNSUPPORTED_EVENTS
     # Events that assert against their line/column
-    CHECK_LOCATION_EVENTS = %i[kw op lbrace rbrace lbracket rbracket lparen rparen]
+    CHECK_LOCATION_EVENTS = %i[kw op lbrace rbrace lbracket rbracket lparen rparen words_sep]
 
     module Events
       attr_reader :events