[Bug lto/84044] Spurious -Wodr warning with -flto

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84044

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Martin Liška from comment #3)
> Fixed on trunk by Richi's r256685. Is it intentional Richi that the revision
> should fix such situations?

Not really.  It means that the following hunk removes too many TYPE_BINFOs
I guess?

@@ -5150,15 +5145,9 @@ free_lang_data_in_type (tree type)
        {
          free_lang_data_in_binfo (TYPE_BINFO (type));
          /* We need to preserve link to bases and virtual table for all
-            polymorphic types to make devirtualization machinery working.
-            Debug output cares only about bases, but output also
-            virtual table pointers so merging of -fdevirtualize and
-            -fno-devirtualize units is easier.  */
-         if ((!BINFO_VTABLE (TYPE_BINFO (type))
-              || !flag_devirtualize)
-             && ((!BINFO_N_BASE_BINFOS (TYPE_BINFO (type))
-                  && !BINFO_VTABLE (TYPE_BINFO (type)))
-                 || debug_info_level != DINFO_LEVEL_NONE))
+            polymorphic types to make devirtualization machinery working.  */
+         if (!BINFO_VTABLE (TYPE_BINFO (type))
+             || !flag_devirtualize)
            TYPE_BINFO (type) = NULL;
        }
     }

Or this change drops required information for the ODR warning.

@@ -5186,6 +5175,11 @@ free_lang_data_in_type (tree type)
       while (ctx && TREE_CODE (ctx) == BLOCK);
       TYPE_CONTEXT (type) = ctx;
     }
+
+  /* Drop TYPE_DECLs in TYPE_NAME in favor of the identifier in the
+     TYPE_DECL if the type doesn't have linkage.  */
+  if (! type_with_linkage_p (type))
+    TYPE_NAME (type) = TYPE_IDENTIFIER (type);
 }


Maybe you can "bisect" that.

But I guess the warning is "correct" and -fno-semantic-interposition
affects details in the vtable that lead to the warning.

Honza?