Fix `rb_profile_frames` output includes dummy main thread frame

The `rb_profile_frames` API did not skip the two dummy frames that
each thread has at its beginning. This was unlike `backtrace_each` and
`rb_ec_parcial_backtrace_object`, which do skip them.

This does not seem to be a problem for non-main thread frames,
because both `VM_FRAME_RUBYFRAME_P(cfp)` and
`rb_vm_frame_method_entry(cfp)` are NULL for them.

BUT, on the main thread `VM_FRAME_RUBYFRAME_P(cfp)` was true
and thus the dummy thread was still included in the output of
`rb_profile_frames`.

I've now made `rb_profile_frames` skip this extra frame (like
`backtrace_each` and friends), as well as add a test that asserts
the size and contents of `rb_profile_frames`.

Fixes [Bug #18907] (<https://bugs.ruby-lang.org/issues/18907>)

1 files changed, 1 insertions, 0 deletions

diff --git a/ext/-test-/debug/profile_frames.c b/ext/-test-/debug/profile_frames.c
index 5f14755ce7..d2bba7d183 100644
--- a/ext/-test-/debug/profile_frames.c
+++ b/ext/-test-/debug/profile_frames.c
@@ -29,6 +29,7 @@ profile_frames(VALUE self, VALUE start_v, VALUE num_v)
         rb_ary_push(ary, rb_profile_frame_singleton_method_p(buff[i]));
         rb_ary_push(ary, rb_profile_frame_method_name(buff[i]));
         rb_ary_push(ary, rb_profile_frame_qualified_method_name(buff[i]));
+        rb_ary_push(ary, INT2NUM(lines[i]));
 
         rb_ary_push(result, ary);
     }