`RubyVM.keep_script_lines`

`RubyVM.keep_script_lines` enables to keep script lines
for each ISeq and AST. This feature is for debugger/REPL
support.

```ruby
RubyVM.keep_script_lines = true
RubyVM::keep_script_lines = true

eval("def foo = nil\ndef bar = nil")
pp RubyVM::InstructionSequence.of(method(:foo)).script_lines
```

1 files changed, 39 insertions, 0 deletions

diff --git a/vm.c b/vm.c
index c1099d699b..1f60906d1a 100644
--- a/vm.c
+++ b/vm.c
@@ -380,6 +380,7 @@ VALUE rb_block_param_proxy;
 VALUE ruby_vm_const_missing_count = 0;
 rb_vm_t *ruby_current_vm_ptr = NULL;
 rb_ractor_t *ruby_single_main_ractor;
+bool ruby_vm_keep_script_lines;
 
 #ifdef RB_THREAD_LOCAL_SPECIFIER
 RB_THREAD_LOCAL_SPECIFIER rb_execution_context_t *ruby_current_ec;
@@ -3338,6 +3339,41 @@ vm_mtbl2(VALUE self, VALUE obj, VALUE sym)
     return Qnil;
 }
 
+/*
+ *  call-seq:
+ *     RubyVM.keep_script_lines -> true or false
+ *
+ *  Return current +keep_script_lines+ status. Now it only returns
+ *  +true+ of +false+, but it can return other objects in future.
+ *
+ *  Note that this is an API for ruby internal use, debugging,
+ *  and research. Do not use this for any other purpose.
+ *  The compatibility is not guaranteed.
+ */
+static VALUE
+vm_keep_script_lines(VALUE self)
+{
+    return RBOOL(ruby_vm_keep_script_lines);
+}
+
+/*
+ *  call-seq:
+ *     RubyVM.keep_script_lines = true / false
+ *
+ *  It set +keep_script_lines+ flag. If the flag is set, all
+ *  loaded scripts are recorded in a interpreter process.
+ *
+ *  Note that this is an API for ruby internal use, debugging,
+ *  and research. Do not use this for any other purpose.
+ *  The compatibility is not guaranteed.
+ */
+static VALUE
+vm_keep_script_lines_set(VALUE self, VALUE flags)
+{
+    ruby_vm_keep_script_lines = RTEST(flags);
+    return flags;
+}
+
 void
 Init_VM(void)
 {
@@ -3361,6 +3397,9 @@ Init_VM(void)
     rb_undef_alloc_func(rb_cRubyVM);
     rb_undef_method(CLASS_OF(rb_cRubyVM), "new");
     rb_define_singleton_method(rb_cRubyVM, "stat", vm_stat, -1);
+    rb_define_singleton_method(rb_cRubyVM, "keep_script_lines", vm_keep_script_lines, 0);
+    rb_define_singleton_method(rb_cRubyVM, "keep_script_lines=", vm_keep_script_lines_set, 1);
+
 #if USE_DEBUG_COUNTER
     rb_define_singleton_method(rb_cRubyVM, "reset_debug_counters", rb_debug_counter_reset, 0);
     rb_define_singleton_method(rb_cRubyVM, "show_debug_counters", rb_debug_counter_show, 0);