[Bug c++/84502] [8 Regression] Argument corruption when passing empty templated struct

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84502

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Completely untested fix:

--- gcc/stor-layout.c.jj        2018-02-13 21:23:29.187981310 +0100
+++ gcc/stor-layout.c   2018-02-21 21:43:24.783522853 +0100
@@ -1883,6 +1883,9 @@ finalize_type_size (tree type)
       && TREE_CODE (TYPE_SIZE_UNIT (type)) != INTEGER_CST)
     TYPE_SIZE_UNIT (type) = variable_size (TYPE_SIZE_UNIT (type));

+  /* Handle empty records as per the x86-64 psABI.  */
+  TYPE_EMPTY_P (type) = targetm.calls.empty_record_p (type);
+
   /* Also layout any other variants of the type.  */
   if (TYPE_NEXT_VARIANT (type)
       || type != TYPE_MAIN_VARIANT (type))
@@ -1895,6 +1898,7 @@ finalize_type_size (tree type)
       unsigned int precision = TYPE_PRECISION (type);
       unsigned int user_align = TYPE_USER_ALIGN (type);
       machine_mode mode = TYPE_MODE (type);
+      bool empty_p = TYPE_EMPTY_P (type);

       /* Copy it into all variants.  */
       for (variant = TYPE_MAIN_VARIANT (type);
@@ -1911,11 +1915,9 @@ finalize_type_size (tree type)
          SET_TYPE_ALIGN (variant, valign);
          TYPE_PRECISION (variant) = precision;
          SET_TYPE_MODE (variant, mode);
+         TYPE_EMPTY_P (variant) = empty_p;
        }
     }
-
-  /* Handle empty records as per the x86-64 psABI.  */
-  TYPE_EMPTY_P (type) = targetm.calls.empty_record_p (type);
 }

 /* Return a new underlying object for a bitfield started with FIELD.  */