From 4d1ffcce8acb35e5aec263d64d5c88a8434b1c64 Mon Sep 17 00:00:00 2001
From: yui-knk <spiketeika@gmail.com>
Date: Sun, 24 Dec 2017 01:13:44 +0900
Subject: [PATCH] Fix how to detect potential_lines

On Ruby 2.5, format of `RubyVM::InstructionSequence#disasm`
will be changed. By this change we can not detect which
line is valid to set breakpoints. On the other hand
Ruby 2.5 will introduce new methods

* `RubyVM::InstructionSequence#each_child`
  Iterate all direct child instruction sequences.
* `RubyVM::InstructionSequence#trace_points`
  Return trace points in the instruction sequence.

see: https://github.com/ruby/ruby/blob/9fe26ef8de1ae047a4d775ce74878a0aeb01a19b/NEWS

We can detect potential_lines by these methods.
So this commit defines new methods and call each_child &
trace_points if these methods are implemented.

Thanks to Koichi Sasada (ko1) for investigation, implemention of
new methods for Ruby and concept implementation for byebug.
---
 lib/byebug/breakpoint.rb | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/lib/byebug/breakpoint.rb b/lib/byebug/breakpoint.rb
index 5a17d5e45..b1d14b47c 100644
--- a/lib/byebug/breakpoint.rb
+++ b/lib/byebug/breakpoint.rb
@@ -49,9 +49,27 @@ def self.remove(id)
     #
     def self.potential_lines(filename)
       name = "#{Time.new.to_i}_#{rand(2**31)}"
-      lines = {}
       iseq = RubyVM::InstructionSequence.compile(File.read(filename), name)
 
+      if iseq.respond_to?(:each_child)
+        potential_lines_with_trace_points(iseq, {})
+      else
+        potential_lines_without_trace_points(iseq, {})
+      end
+    end
+
+    def self.potential_lines_with_trace_points(iseq, lines)
+      iseq.trace_points.each { |(line, _)| lines[line] = true }
+      iseq.each_child do |child|
+        potential_lines_with_trace_points(child, lines)
+      end
+
+      lines.keys.sort
+    end
+
+    private_class_method :potential_lines_with_trace_points
+
+    def self.potential_lines_without_trace_points(iseq, lines)
       iseq.disasm.each_line do |line|
         res = /^\d+ (?<insn>\w+)\s+.+\(\s*(?<lineno>\d+)\)$/.match(line)
         next unless res && res[:insn] == 'trace'
@@ -62,6 +80,8 @@ def self.potential_lines(filename)
       lines.keys
     end
 
+    private_class_method :potential_lines_without_trace_points
+
     #
     # Returns true if a breakpoint could be set in line number +lineno+ in file
     # name +filename.