[Bug c++/49260] cpp0x/lambda/lambda-eh2.C fails execution

["ro at CeBiTec dot Uni-Bielefeld.DE" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49260

--- Comment #5 from ro at CeBiTec dot Uni-Bielefeld.DE <ro at CeBiTec dot Uni-Bielefeld.DE> 2011-06-20 14:51:07 UTC ---
> --- Comment #4 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2011-06-06 11:18:43 UTC ---
>> I'm seeing this when using Sun as on Solaris, but not with GNU as 2.21, even
>> when Sun ld is used in both cases.  
>
> I'm seeing it on SPARC/Solaris 8, 9 and 10 with GNU as 2.20.1 and Sun ld.  So
> the failure may be predicated on a feature available only in 2.21 or above.

I've digged somewhat further: with gas 2.20.1, one of the cfi configure
test fails

checking assembler for working cfi advance... no

thus HAVE_GAS_CFI_DIRECTIVE is 0 and gas and Sun as are treated the same.

If I look at the gas 2.20.1 output, I find 3 instances of

    .long   <label>  / FDE initial location

  _ZZ4mainENKUlvE_clEv        -> main::{lambda()#1}::operator()() const
  .LFB32

  _ZZ4mainENKUlvE0_clEv        -> main::{lambda()#2}::operator()() const
  .LFB35

  main
  .LFB31

With gas 2.21 and .cfi_startproc instead, there are 5:

  _ZZ4mainENKUlvE_clEv
  .LFB32

  _ZZ4mainENUlvE_4_FUNEv    -> main::{lambda()#1}::_FUN()
  .LFB33

  _ZZ4mainENKUlvE_cvPFvvEEv    -> main::{lambda()#1}::operator void (*)()()
const
  .LFB34

  _ZZ4mainENKUlvE0_clEv
  .LFB35

  main
  .LFB31

The output of the FDE initial location happens in dwarf2out.c
(output_call_frame_info).  If I step throught that function, I see that
the FDEs are only emitted if fde_needed_for_eh_p (fde).  For the two
missing ones, I see that this function returns false due to this test:

  /* If exceptions are enabled, we have collected nothrow info.  */
  if (flag_exceptions && (fde->all_throwers_are_sibcalls || fde->nothrow))
    return false;

Here, both fde->all_throwers_are_sibcalls and fde->nothrow are 1.

I cannot say if this is wrong or the tests in fde_needed_for_eh_p
needs to be augmented.

Manually returning true from the function caused the FDEs to be emitted
and the testcase to succeed, as expected.

    Rainer