Faster next by reducing number of frame_depth calls

lib/debug/thread_client.rb

@@ -856,17 +856,23 @@ def wait_next_action_
 
             depth = @target_frames.first.frame_depth
 
-            step_tp iter do
-              loc = caller_locations(2, 1).first
-              loc_path = loc.absolute_path || "!eval:#{loc.path}"
+            skip_line = false
+            step_tp iter do |event|
+              next if event == :line && skip_line
+
+              stack_depth = DEBUGGER__.frame_depth - 3
+
+              # If we're at a deeper stack depth, we can skip line events until there's a return event.
+              skip_line = event == :line && stack_depth > depth
 
               # same stack depth
-              (DEBUGGER__.frame_depth - 3 <= depth) ||
+              next true if stack_depth <= depth
+
+              loc = caller_locations(2, 1).first
+              loc_path = loc.absolute_path || "!eval:#{loc.path}"
 
               # different frame
-              (next_line && loc_path == path &&
-               (loc_lineno = loc.lineno) > line &&
-               loc_lineno <= next_line)
+              next_line && loc_path == path && loc.lineno.between?(line + 1, next_line)
             end
             break
 

test/console/control_flow_commands_test.rb

@@ -21,7 +21,9 @@ def program
         10|
         11| s = Student.new("John")
         12| s.name
-        13| "foo"
+        13| puts "foo"
+        14| puts "bar"
+        15| "baz"
       RUBY
     end
 
@@ -84,6 +86,8 @@ def test_next_with_number_goes_to_the_next_nth_line
         assert_line_num 11
         type 'n 2'
         assert_line_num 13
+        type 'n 2'
+        assert_line_num 15
         type 'quit'
         type 'y'
       end