[Bug ipa/63587] [5 Regression] ICE : tree check: expected var_decl, have result_decl in add_local_variables, at tree-inline.c:4112

["marxin at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63587

--- Comment #8 from Martin LiÅka <marxin at gcc dot gnu.org> ---
I added assert to cgraphunit.c (expand_thunk):1547:

      /* Build call to the function being thunked.  */
      if (!VOID_TYPE_P (restype))
    {
      if (DECL_BY_REFERENCE (resdecl))
        restmp = gimple_fold_indirect_ref (resdecl);
      else if (!is_gimple_reg_type (restype))
        {
          restmp = resdecl;
          gcc_assert (TREE_CODE (restmp) == VAR_DECL);
          add_local_decl (cfun, restmp);
          BLOCK_VARS (DECL_INITIAL (current_function_decl)) = restmp;
        }
      else
        restmp = create_tmp_reg (restype, "retval");
    }

It's triggered quite often, one example of a thunk created by IPA ICF:

std::basic_streambuf<_CharT, _Traits>::pos_type std::basic_streambuf<_CharT,
_Traits>::seekpos(std::basic_streambuf<_CharT, _Traits>::pos_type,
std::ios_base::openmode) [with _CharT = char; _Traits = std::char_traits<char>;
std::basic_streambuf<_CharT, _Traits>::pos_type = std::fpos<__mbstate_t>;
std::ios_base::openmode = std::_Ios_Openmode] (struct basic_streambuf * const
this, struct pos_type D.23077, openmode D.23078)
{
  struct pos_type <retval>;

  <bb 2>:
  <retval> = std::basic_streambuf<wchar_t>::seekpos (this_2(D), D.23077,
_3(D)); [tail call]
  return <retval>;

}

where std::basic_streambuf<_CharT, _Traits>::pos_type is:
 <result_decl 0x7ffff4eec708 D.39821
    type <record_type 0x7ffff59c2150 pos_type sizes-gimplified asm_written used
needs-constructing type_1 type_5 TI
        size <integer_cst 0x7ffff6c2fe40 constant 128>
        unit size <integer_cst 0x7ffff6c2fe58 constant 16>
        align 64 symtab -164402368 alias set -1 canonical type 0x7ffff614adc8
        fields <field_decl 0x7ffff51cd850 _M_off type <integer_type
0x7ffff678c738 streamoff>
            used private nonlocal decl_3 DI file
/home/marxin/Programming/gcc/objdir/x86_64-unknown-linux-gnu/libstdc++-v3/include/bits/postypes.h
line 115 col 33
            size <integer_cst 0x7ffff6c2fdf8 constant 64>
            unit size <integer_cst 0x7ffff6c2fe10 constant 8>
            align 64 offset_align 128
            offset <integer_cst 0x7ffff6c2fe28 constant 0>
            bit offset <integer_cst 0x7ffff6c2fe70 constant 0> context
<record_type 0x7ffff614adc8 fpos> chain <field_decl 0x7ffff51cd8e8 _M_state>>
context <namespace_decl 0x7ffff6c4c098 std>
        full-name "std::basic_streambuf<char>::pos_type"
        needs-constructor X() has-type-conversion X(constX&) this=(X&)
n_parents=0 use_template=1 interface-unknown
        pointer_to_this <pointer_type 0x7ffff5224e70> chain <type_decl
0x7ffff6146da8 fpos>>
    ignored TI file
/home/marxin/Programming/gcc/objdir/x86_64-unknown-linux-gnu/libstdc++-v3/include/streambuf
line 602 col 7 size <integer_cst 0x7ffff6c2fe40 128> unit size <integer_cst
0x7ffff6c2fe58 16>
    align 64 context <function_decl 0x7ffff5797948 seekoff>>

Is there a bug in expand_thunk or do I miss something?
Thanks,
Martin