[Bug c++/35067] [4.2 Regression] multiple definition of virtual thunk

["vincent dot riviere at freesbee dot fr" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #2 from vincent dot riviere at freesbee dot fr  2008-02-03 22:57 -------
This problem seems to happen on targets where ASM_WEAKEN_LABEL() is defined,
but MAKE_DECL_ONE_ONLY() is not defined. In that case, the `virtual
thunk to C::~C()' symbol is defined using .globl instead of using .weak (like
it was in 4.1.2).

I made some investigation. The problem may be related to these source files:
gcc/cp/methods.c in function use_thunk()
  if (DECL_ONE_ONLY (function))
    make_decl_one_only (thunk_fndecl);
This code was different in 4.1.2

gcc/varasm.c in function make_decl_one_only()
  if (SUPPORTS_ONE_ONLY)
    {
#ifdef MAKE_DECL_ONE_ONLY
      MAKE_DECL_ONE_ONLY (decl);
#endif
      DECL_ONE_ONLY (decl) = 1;
    }

When MAKE_DECL_ONE_ONLY is not defined, SUPPORTS_ONE_ONLY is set to 0. So
DECL_ONE_ONLY (decl) = 1 is never called.

Thus if the destructor is flagged DECL_ONE_ONLY, the virtual thunk is not
flagged DECL_ONE_ONLY as it should, then it is defined with .globl instead of
.weak


-- 

vincent dot riviere at freesbee dot fr changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|                            |4.2.3
      Known to work|                            |4.1.2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35067