Check heredoc state for escaped newlines

When escaped newlines are encountered, they are added to the newline
list. We need to check that we aren't backing up to read the rest of
the line because of a heredoc, in which case the newline would have
already have been added to the list.

Author: kddnewton

src/prism.c

@@ -9064,7 +9064,7 @@ escape_write_escape_encoded(pm_parser_t *parser, pm_buffer_t *buffer, pm_buffer_
     }
 
     if (width == 1) {
-        if (*parser->current.end == '\n') pm_line_offset_list_append(&parser->metadata_arena, &parser->line_offsets, PM_TOKEN_END(parser, &parser->current) + 1);
+        if (parser->heredoc_end == NULL && *parser->current.end == '\n') pm_line_offset_list_append(&parser->metadata_arena, &parser->line_offsets, PM_TOKEN_END(parser, &parser->current) + 1);
         escape_write_byte(parser, buffer, regular_expression_buffer, flags, escape_byte(*parser->current.end++, flags));
     } else if (width > 1) {
         // Valid multibyte character.  Just ignore escape.
@@ -9381,7 +9381,7 @@ escape_read(pm_parser_t *parser, pm_buffer_t *buffer, pm_buffer_t *regular_expre
                         return;
                     }
 
-                    if (peeked == '\n') pm_line_offset_list_append(&parser->metadata_arena, &parser->line_offsets, PM_TOKEN_END(parser, &parser->current) + 1);
+                    if (parser->heredoc_end == NULL && peeked == '\n') pm_line_offset_list_append(&parser->metadata_arena, &parser->line_offsets, PM_TOKEN_END(parser, &parser->current) + 1);
                     parser->current.end++;
                     escape_write_byte(parser, buffer, regular_expression_buffer, flags, escape_byte(peeked, flags | PM_ESCAPE_FLAG_CONTROL));
                     return;
@@ -9440,7 +9440,7 @@ escape_read(pm_parser_t *parser, pm_buffer_t *buffer, pm_buffer_t *regular_expre
                         return;
                     }
 
-                    if (peeked == '\n') pm_line_offset_list_append(&parser->metadata_arena, &parser->line_offsets, PM_TOKEN_END(parser, &parser->current) + 1);
+                    if (parser->heredoc_end == NULL && peeked == '\n') pm_line_offset_list_append(&parser->metadata_arena, &parser->line_offsets, PM_TOKEN_END(parser, &parser->current) + 1);
                     parser->current.end++;
                     escape_write_byte(parser, buffer, regular_expression_buffer, flags, escape_byte(peeked, flags | PM_ESCAPE_FLAG_CONTROL));
                     return;
@@ -9494,15 +9494,15 @@ escape_read(pm_parser_t *parser, pm_buffer_t *buffer, pm_buffer_t *regular_expre
                         return;
                     }
 
-                    if (peeked == '\n') pm_line_offset_list_append(&parser->metadata_arena, &parser->line_offsets, PM_TOKEN_END(parser, &parser->current) + 1);
+                    if (parser->heredoc_end == NULL && peeked == '\n') pm_line_offset_list_append(&parser->metadata_arena, &parser->line_offsets, PM_TOKEN_END(parser, &parser->current) + 1);
                     parser->current.end++;
                     escape_write_byte(parser, buffer, regular_expression_buffer, flags, escape_byte(peeked, flags | PM_ESCAPE_FLAG_META));
                     return;
             }
         }
         case '\r': {
             if (peek_offset(parser, 1) == '\n') {
-                pm_line_offset_list_append(&parser->metadata_arena, &parser->line_offsets, PM_TOKEN_END(parser, &parser->current) + 2);
+                if (parser->heredoc_end == NULL) pm_line_offset_list_append(&parser->metadata_arena, &parser->line_offsets, PM_TOKEN_END(parser, &parser->current) + 2);
                 parser->current.end += 2;
                 escape_write_byte_encoded(parser, buffer, flags, escape_byte('\n', flags));
                 return;

test/prism/fuzzer_test.rb

@@ -63,5 +63,9 @@ def self.snippet(name, source)
       a
       /{/, ''\\
     RUBY
+
+    snippet "escaped newline in char literal after heredoc opener", "<<i=?\\\n\n\n"
+    snippet "escaped newline in char literal after heredoc opener with operator", "<<T^?\\\n\n\n"
+    snippet "control escape consuming newline after heredoc in interpolation", "%\n\#{<<e}\\c\n\n"
   end
 end