Bootsnap hack is needed for 2.5.* ruby versions

ext/debase_internals.c

@@ -637,6 +637,50 @@ Debase_enable_file_filtering(VALUE self, VALUE value)
   return value;
 }
 
+#if RUBY_API_VERSION_CODE >= 20500 && RUBY_API_VERSION_CODE < 20600 && !(RUBY_RELEASE_YEAR == 2017 && RUBY_RELEASE_MONTH == 10 && RUBY_RELEASE_DAY == 10)
+    static const rb_iseq_t *
+    my_iseqw_check(VALUE iseqw)
+    {
+        rb_iseq_t *iseq = DATA_PTR(iseqw);
+
+        if (!iseq->body) {
+            return NULL;
+        }
+
+        return iseq;
+    }
+
+    static void
+    Debase_set_trace_flag_to_iseq(VALUE self, VALUE rb_iseq) {
+        if (!SPECIAL_CONST_P(rb_iseq) && RBASIC_CLASS(rb_iseq) == rb_cISeq) {
+            rb_iseq_t *iseq = my_iseqw_check(rb_iseq);
+
+            if(iseq) {
+                rb_iseq_trace_set(iseq, RUBY_EVENT_TRACEPOINT_ALL);
+            }
+        }
+    }
+
+    static void
+    Debase_unset_trace_flags(VALUE self, VALUE rb_iseq) {
+        if (!SPECIAL_CONST_P(rb_iseq) && RBASIC_CLASS(rb_iseq) == rb_cISeq) {
+            rb_iseq_t *iseq = my_iseqw_check(rb_iseq);
+
+            if(iseq) {
+                rb_iseq_trace_set(iseq, RUBY_EVENT_NONE);
+            }
+        }
+    }
+#else
+      static void
+      Debase_set_trace_flag_to_iseq(VALUE self, VALUE rb_iseq) {
+      }
+
+      static void
+      Debase_unset_trace_flags(VALUE self, VALUE rb_iseq) {
+      }
+#endif
+
 static VALUE
 Debase_init_variables()
 {
@@ -680,6 +724,10 @@ Init_debase_internals()
   rb_define_module_function(mDebase, "enable_trace_points", Debase_enable_trace_points, 0);
   rb_define_module_function(mDebase, "prepare_context", Debase_prepare_context, 0);
   rb_define_module_function(mDebase, "init_variables", Debase_init_variables, 0);
+  rb_define_module_function(mDebase, "set_trace_flag_to_iseq", Debase_set_trace_flag_to_iseq, 1);
+
+  //use only for tests
+  rb_define_module_function(mDebase, "unset_iseq_flags", Debase_unset_trace_flags, 1);
 
   idAlive = rb_intern("alive?");
   idAtLine = rb_intern("at_line");

lib/debase.rb

@@ -21,9 +21,22 @@ def start(options={}, &block)
       Debugger.const_set('PROG_SCRIPT', $0) unless defined? Debugger::PROG_SCRIPT
       Debugger.const_set('INITIAL_DIR', Dir.pwd) unless  defined? Debugger::INITIAL_DIR
 
+      monkey_patch_prepend
+
       Debugger.started? ? block && block.call(self) : Debugger.start_(&block)
     end
 
+    def monkey_patch_prepend
+      class << RubyVM::InstructionSequence
+        def self.prepend(mod, *smth)
+          super
+          if mod.to_s.include?('Bootsnap') && RUBY_VERSION >= '2.5' && RUBY_VERSION < '2.6'
+            prepend InstructionSequenceMixin
+          end
+        end
+      end
+    end
+
     # @param [String] file
     # @param [Fixnum] line
     # @param [String] expr
@@ -82,6 +95,21 @@ def last_context
     def file_filter
       @file_filter ||= FileFilter.new
     end
+
+    module InstructionSequenceMixin
+      def load_iseq(path)
+        iseq = super(path)
+
+        do_set_flags(iseq)
+
+        iseq
+      end
+
+      def do_set_flags(iseq)
+        Debugger.set_trace_flag_to_iseq(iseq)
+        iseq.each_child { |child_iseq| do_set_flags(child_iseq) } if iseq.respond_to? :each_child
+      end
+    end
   end
 
   class FileFilter

lib/debase/version.rb

@@ -1,3 +1,3 @@
 module Debase
-  VERSION = "0.2.3.beta4" unless defined? VERSION
+  VERSION = "0.2.3.beta5" unless defined? VERSION
 end

test/test_load.rb

@@ -44,4 +44,35 @@ def test_debug_load
   ensure
     Debugger.stop if Debugger.started?
   end
+
+  module MyBootsnap
+    def load_iseq(path)
+      iseq = RubyVM::InstructionSequence.compile_file(path)
+
+      Debugger.unset_iseq_flags(iseq)
+      iseq
+    end
+  end
+
+  def test_bootsnap
+    @@at_line = nil
+    src_dir = File.dirname(__FILE__)
+    prog_script = File.join(src_dir, 'example', 'bootsnap', 'bootsnap.rb')
+
+    class << RubyVM::InstructionSequence
+      prepend MyBootsnap
+    end
+    bt = Debugger.debug_load(prog_script, true)
+    assert_equal(nil, bt)
+    assert_not_nil(@@at_line)
+    if RUBY_VERSION >= '2.5' && RUBY_VERSION < '2.6'
+      assert_equal(['debase.rb', 101], @@at_line)
+    end
+
+    assert(Debugger.started?)
+    Debugger.stop
+
+    class << RubyVM::InstructionSequence; self end.class_eval { undef_method :load_iseq }
+
+  end
 end