fix bt on nested break points

`di_body()` doesn't filter C locations.

Author: ko1

ext/debug/debug.c

@@ -62,15 +62,23 @@ di_body(const rb_debug_inspector_t *dc, void *ptr)
     long i;
 
     for (i=1; i<len; i++) {
-        VALUE loc, e;
+        VALUE e;
         VALUE iseq = rb_debug_inspector_frame_iseq_get(dc, i);
+        VALUE loc = RARRAY_AREF(locs, i);
+        VALUE path;
 
         if (!NIL_P(iseq)) {
-            VALUE path = iseq_realpath(iseq);
-            if (!NIL_P(path) && !NIL_P(skip_path_prefix) && str_start_with(path, skip_path_prefix)) continue;
+            path = iseq_realpath(iseq);
+        }
+        else {
+            // C frame
+            path = rb_funcall(loc, rb_intern("path"), 0);
+        }
+
+        if (!NIL_P(path) && !NIL_P(skip_path_prefix) && str_start_with(path, skip_path_prefix)) {
+            continue;
         }
 
-        loc = RARRAY_AREF(locs, i);
         e = di_entry(loc,
                      rb_debug_inspector_frame_self_get(dc, i),
                      rb_debug_inspector_frame_binding_get(dc, i),

test/console/nested_break_test.rb

@@ -10,7 +10,7 @@ def program
        2|   b = a + 1  # break
        3| end
        4| def bar
-       5|   x = 1        # break
+       5|   x = 1      # break
        6| end
        7| bar
        8| x = 2
@@ -35,7 +35,7 @@ def test_nested_break
           type 'p a'
           assert_line_text(/42/)
           type 'c'
-          assert_line_num 7
+          assert_line_num 7 # because restored `up` line
         end
 
         # pop nested break
@@ -48,6 +48,27 @@ def test_nested_break
       end
     end
 
+    def test_nested_break_bt
+      debug_code program do
+        type 'break 2'
+        type 'break 5'
+        type 'c'
+
+        assert_line_num 5
+        type 'p foo(42)'
+
+        if TracePoint.respond_to? :allow_reentry
+          # nested break
+          assert_line_num 2
+          type 'bt'
+          assert_no_line_text 'thread_client.rb'
+          type 'c'
+        end
+
+        type 'c'
+      end
+    end
+
     def test_multiple_nested_break
       debug_code program do
         type 'break 2'
@@ -62,7 +83,7 @@ def test_multiple_nested_break
           assert_line_num 2
           type 'p foo(142)'
           type 'bt'
-          assert_line_text(/\#9/) # TODO: can be changed
+          assert_line_text(/\#7\s+<main>/) # TODO: can be changed
 
           type 'c'
           assert_line_text(/143/)