[Bug build/30413] [gdb/build] error: storing the address of local variable ‘<anonymous>’ in ‘frame_info_ptr::frame_list.intrusive_list<frame_info_ptr>::m_back’ [-Werror=dangling-pointer=]

["vries at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=30413

--- Comment #5 from Tom de Vries <vries at gcc dot gnu.org> ---
I think the thing the warning complains about is that adding to the list is
unconditional, and removing from the list is conditional (on is_linked), and
the compiler can't figure out that for the temporary object is_linked () ==
true.

[ You could reason that the warning is too aggressive, but that may be
intentional, I'm not sure. ]

The test on is_linked was introduced because of trying to accommodate the
scenario mentioned in the comment:
...
  ~frame_info_ptr ()
  {
    /* If this node has static storage, it may be deleted after                 
       frame_list.  Attempting to erase ourselves would then trigger            
       internal errors, so make sure we are still linked first.  */
    if (is_linked ())
      frame_list.erase (frame_list.iterator_to (*this));
  }
...

So perhaps we can fix this by removing the is_linked test.  The code was added
because the static frame_list and the static frame_info_ptr where in different
compilation units, but that's no longer the case.

So I'm thinking of:
...
diff --git a/gdb/frame.c b/gdb/frame.c
index 36fb02f3c8e..c47244b8cb2 100644
--- a/gdb/frame.c
+++ b/gdb/frame.c
@@ -1733,6 +1733,11 @@ get_current_frame (void)
 static frame_id selected_frame_id = null_frame_id;
 static int selected_frame_level = -1;

+/* See frame-info-ptr.h.  This definition should come before any definition of
+   a static frame_info_ptr.  */
+
+intrusive_list<frame_info_ptr> frame_info_ptr::frame_list;
+
 /* The cached frame_info object pointing to the selected frame.
    Looked up on demand by get_selected_frame.  */
 static frame_info_ptr selected_frame;
@@ -3275,10 +3280,6 @@ maintenance_print_frame_id (const char *args, int
from_tty)

 /* See frame-info-ptr.h.  */

-intrusive_list<frame_info_ptr> frame_info_ptr::frame_list;
-
-/* See frame-info-ptr.h.  */
-
 frame_info_ptr::frame_info_ptr (struct frame_info *ptr)
   : m_ptr (ptr)
 {
diff --git a/gdb/frame.h b/gdb/frame.h
index 6ed8db0af56..fff5c248070 100644
--- a/gdb/frame.h
+++ b/gdb/frame.h
@@ -257,8 +257,8 @@ class frame_info_ptr : public
intrusive_list_node<frame_info_ptr>
     /* If this node has static storage, it may be deleted after
        frame_list.  Attempting to erase ourselves would then trigger
        internal errors, so make sure we are still linked first.  */
-    if (is_linked ())
-      frame_list.erase (frame_list.iterator_to (*this));
+    gdb_assert (is_linked ());
+    frame_list.erase (frame_list.iterator_to (*this));
   }

   frame_info_ptr &operator= (const frame_info_ptr &other)


...

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