Use rb_debug_inspector_frame_loc_get if any

The debug gem can abort when stepping into a rescue clause:

```
$ ruby -Ilib exe/rdbg rescue-test.rb
[1, 7] in rescue-test.rb
=>   1| 1.times do
     2|   begin
     3|     raise
     4|   rescue
     5|     p 1
     6|   end
     7| end
=>#0    <main> at rescue-test.rb:1
(rdbg) s    # step command
[1, 7] in rescue-test.rb
     1| 1.times do
     2|   begin
=>   3|     raise
     4|   rescue
     5|     p 1
     6|   end
     7| end
=>#0    block in <main> at rescue-test.rb:3
  #1    Integer#times at <internal:numeric>:257
  # and 1 frames (use `bt' command for all frames)
(rdbg) s    # step command
/home/mame/work/debug/lib/debug/thread_client.rb:85:in 'DEBUGGER__::ThreadClient#default_frame_formatter': undefined method '+' for nil (NoMethodError)

          "#{colorize_blue("block")}#{args_str} in #{colorize_blue(block_loc + level)}"
                                                                             ^
        from /home/mame/work/debug/lib/debug/thread_client.rb:755:in 'Method#call'
        from /home/mame/work/debug/lib/debug/thread_client.rb:755:in 'DEBUGGER__::ThreadClient#frame_str'
        from /home/mame/work/debug/lib/debug/thread_client.rb:742:in 'block in DEBUGGER__::ThreadClient#show_frames'
        from <internal:numeric>:257:in 'Integer#times'
        from /home/mame/work/debug/lib/debug/thread_client.rb:739:in 'DEBUGGER__::ThreadClient#show_frames'
        from /home/mame/work/debug/lib/debug/thread_client.rb:304:in 'DEBUGGER__::ThreadClient#suspend'
        from /home/mame/work/debug/lib/debug/thread_client.rb:358:in 'block in DEBUGGER__::ThreadClient#step_tp'
        from rescue-test.rb:5:in 'block in <main>'
        from <internal:numeric>:257:in 'Integer#times'
        from rescue-test.rb:1:in '<main>'
rescue-test.rb:3:in 'block in <main>': unhandled exception
        from <internal:numeric>:257:in 'Integer#times'
        from rescue-test.rb:1:in '<main>'
```

This is caused by the design issue of the debug inspector API.
See ruby/ruby#13508

This changeset fixes the issue by using a newly-introduced debug
inspector API, namely `rb_debug_inspector_frame_loc_get`.

Author: mame

ext/debug/debug.c

@@ -56,15 +56,23 @@ static VALUE
 di_body(const rb_debug_inspector_t *dc, void *ptr)
 {
     VALUE skip_path_prefix = (VALUE)ptr;
+#if defined(HAVE_RB_DEBUG_INSPECTOR_FRAME_COUNT) && defined(HAVE_RB_DEBUG_INSPECTOR_FRAME_LOC_GET)
+    long len = rb_debug_inspector_frame_count(dc);
+#else
     VALUE locs = rb_debug_inspector_backtrace_locations(dc);
-    VALUE ary = rb_ary_new();
     long len = RARRAY_LEN(locs);
+#endif
+    VALUE ary = rb_ary_new();
     long i;
 
     for (i=1; i<len; i++) {
         VALUE e;
         VALUE iseq = rb_debug_inspector_frame_iseq_get(dc, i);
+#if defined(HAVE_RB_DEBUG_INSPECTOR_FRAME_COUNT) && defined(HAVE_RB_DEBUG_INSPECTOR_FRAME_LOC_GET)
+        VALUE loc = rb_debug_inspector_frame_loc_get(dc, i);
+#else
         VALUE loc = RARRAY_AREF(locs, i);
+#endif
         VALUE path;
 
         if (!NIL_P(iseq)) {

ext/debug/extconf.rb

@@ -7,6 +7,8 @@
   $defs << '-DHAVE_RB_ISEQ'
   $defs << '-DHAVE_RB_ISEQ_PARAMETERS'
   $defs << '-DHAVE_RB_ISEQ_CODE_LOCATION'
+  $defs << '-DHAVE_RB_DEBUG_INSPECTOR_FRAME_COUNT'
+  $defs << '-DHAVE_RB_DEBUG_INSPECTOR_FRAME_LOC_GET'
 
   if RUBY_VERSION >= '3.1.0'
     $defs << '-DHAVE_RB_ISEQ_TYPE'
@@ -22,6 +24,11 @@
   # from Ruby 3.1
   have_func "rb_iseq_type(NULL)",
             [["VALUE rb_iseq_type(void *);"]]
+  # from Ruby 3.5
+  have_func "rb_debug_inspector_frame_count(NULL)",
+            [["VALUE rb_debug_inspector_frame_count(void *);"]]
+  have_func "rb_debug_inspector_frame_loc_get(NULL, 0)",
+            [["VALUE rb_debug_inspector_frame_loc_get(void *, int index);"]]
 end
 
 create_makefile 'debug/debug'

test/console/nested_break_test.rb

@@ -83,7 +83,7 @@ def test_multiple_nested_break
           assert_line_num 2
           type 'p foo(142)'
           type 'bt'
-          assert_line_text(/\#7\s+<main>/) # TODO: can be changed
+          assert_line_text(/\#11\s+<main>/) # TODO: can be changed
 
           type 'c'
           assert_line_text(/143/)

test/console/trap_test.rb

@@ -16,7 +16,6 @@ def test_sigint
       debug_code program, remote: false do
         type 'b 3'
         type 'c'
-        assert_line_num 2
         assert_line_text(/is registered as SIGINT handler/)
         type 'sigint'
         assert_line_num 3