[ruby/prism] Expose main_script in serialization API

https://github.com/ruby/prism/commit/0b527ca93f

lib/prism/ffi.rb

@@ -448,6 +448,9 @@ module Prism
       template << "C"
       values << (options[:encoding] == false ? 1 : 0)
 
+      template << "C"
+      values << (options.fetch(:main_script, false) ? 1 : 0)
+
       template << "L"
       if (scopes = options[:scopes])
         values << scopes.length

prism/extension.c

@@ -756,6 +756,11 @@ parse_input(pm_string_t *input, const pm_options_t *options) {
  *       has been set. This should be a boolean or nil.
  * * `line` - the line number that the parse starts on. This should be an
  *       integer or nil. Note that this is 1-indexed.
+ * * `main_script` - a boolean indicating whether or not the source being parsed
+ *       is the main script being run by the interpreter. This controls whether
+ *       or not shebangs are parsed for additional flags and whether or not the
+ *       parser will attempt to find a matching shebang if the first one does
+ *       not contain the word "ruby".
  * * `scopes` - the locals that are in scope surrounding the code that is being
  *       parsed. This should be an array of arrays of symbols or nil. Scopes are
  *       ordered from the outermost scope to the innermost one.

prism/options.c

@@ -241,6 +241,7 @@ pm_options_read(pm_options_t *options, const char *data) {
     options->command_line = (uint8_t) *data++;
     options->version = (pm_options_version_t) *data++;
     options->encoding_locked = ((uint8_t) *data++) > 0;
+    options->main_script = ((uint8_t) *data++) > 0;
 
     uint32_t scopes_count = pm_options_read_u32(data);
     data += 4;