Re: [C++ Patch] PR 57645

[Paolo Carlini <paolo dot carlini at oracle dot com>]

Hi again,

On 06/19/2013 03:37 PM, Paolo Carlini wrote:
> Hi,
>
> when I implemented Core/1123 "Destructors should be noexcept by 
> default", unfortunately I caused this regression, present now in 
> mainline and 4_8-branch.
>
> When the destructor is user provided, with no exception 
> specifications, and the type has data members (not bases, those are 
> already Ok) with the destructor which can throw, the destructor is 
> wrongly deduced to be noexcept. The reason is that 
> deduce_noexcept_on_destructors is called from check_bases_and_members 
> after check_bases but *before* check_methods and therefore the latter 
> does too late work relevant for the deduction, namely possibly setting 
> TYPE_HAS_NONTRIVIAL_DESTRUCTOR.
I can confirm that the issue in very general terms is this one, but my 
patch isn't Ok. Sorry. For example, it doesn't handle correctly the 
defaulted destructor case.

If, in check_bases_and_members, I simply move 
deduce_noexcept_on_destructors after check_methods and nothing else, all 
the new testcases are fine + the tests added for Core/1123, but there 
are regressions, for example for testcases involving virtual 
destructors, eg, debug/dwarf2/non-virtual-thunk.C.

All in all the issue seems rather nasty to me, I'm afraid I will need 
some help if we want to quickly make substantive progress on this issue.

Thanks,
Paolo.