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[209.6.216.142]) by smtp.gmail.com with ESMTPSA id x200sm1828873qkx.47.2018.12.13.13.03.51 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 13 Dec 2018 13:03:52 -0800 (PST) Subject: Re: [C++ Patch] PR 84644 ("internal compiler error: in warn_misplaced_attr_for_class_type, at cp/decl.c:4718") To: Paolo Carlini Cc: gcc-patches List , Nathan Sidwell References: <4c6fe735-5435-1ede-a85a-787262a7e63c@oracle.com> <37c9ffea-5929-a209-7818-67e05d44edcc@oracle.com> <1db43e23-22da-0f4a-d711-fe6c54244564@oracle.com> From: Jason Merrill Message-ID: <6d56abf3-93a0-d1ad-0072-2e0d9922b492@redhat.com> Date: Thu, 13 Dec 2018 22:22:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.1 MIME-Version: 1.0 In-Reply-To: <1db43e23-22da-0f4a-d711-fe6c54244564@oracle.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.85.222.194 X-IsSubscribed: yes X-SW-Source: 2018-12/txt/msg00985.txt.bz2 On 10/30/18 9:22 PM, Paolo Carlini wrote: > Hi, > > On 30/10/18 21:37, Jason Merrill wrote: >> On 10/26/18 2:02 PM, Paolo Carlini wrote: >>> On 26/10/18 17:18, Jason Merrill wrote: >>>> On Fri, Oct 26, 2018 at 4:52 AM Paolo Carlini >>>> wrote: >>>>> On 24/10/18 22:41, Jason Merrill wrote: >>>>>> On 10/15/18 12:45 PM, Paolo Carlini wrote: >>>>>>>          && ((TREE_CODE (declspecs->type) != TYPENAME_TYPE >>>>>>> +       && TREE_CODE (declspecs->type) != DECLTYPE_TYPE >>>>>>>           && MAYBE_CLASS_TYPE_P (declspecs->type)) >>>>>> I would think that the MAYBE_CLASS_TYPE_P here should be >>>>>> CLASS_TYPE_P, >>>>>> and then we can remove the TYPENAME_TYPE check.  Or do we want to >>>>>> allow template type parameters for some reason? >>>>> Indeed, it would be nice to just use OVERLOAD_TYPE_P. However it seems >>>>> we at least want to let through TEMPLATE_TYPE_PARMs representing >>>>> 'auto' >>>>> - otherwise Dodji's check a few lines below which fixed c++/51473 >>>>> doesn't work anymore - and also BOUND_TEMPLATE_TEMPLATE_PARM, >>>>> otherwise >>>>> we regress on template/spec32.C and template/ttp22.C because we don't >>>>> diagnose the shadowing anymore. Thus, I would say either we keep on >>>>> using MAYBE_CLASS_TYPE_P or we pick what we need, possibly we add a >>>>> comment? >>>> Aha.  I guess the answer is not to restrict that test any more, but >>>> instead to fix the code further down so it gives a proper diagnostic >>>> rather than call warn_misplaced_attr_for_class_type. >>> >>> I see. Thus something like the below? It passes testing on x86_64-linux. >> >>> +  if ((!declared_type || TREE_CODE (declared_type) == DECLTYPE_TYPE) >>> +      && ! saw_friend && !error_p) >>>      permerror (input_location, "declaration does not declare >>> anything"); >> >> I see no reason to make this specific to decltype.  Maybe move this >> diagnostic into the final 'else' block with the other declspec >> diagnostics and not look at declared_type at all? > > I'm not sure to fully understand: if we do that we still want to at > least minimally check that declared_type is null, like we already do, > and then we simply accept the new testcase. Is that Ok? Because, as I > probably mentioned at some point, all the other compilers I have at hand > issue a "does not declare anything" diagnostic, and we likewise do that > for the legacy __typeof. Not looking into declared_type *at all* doesn't > work with plain class types and enums, of course. Or you meant something > entirely different?? > >>> +  if (declspecs->attributes && warn_attributes && declared_type >>> +      && TREE_CODE (declared_type) != DECLTYPE_TYPE) >> >> I think we do want to give a diagnostic about useless attributes, not >> skip it. > > Agreed. FWIW the attached tests fine. The problem here is that the code toward the bottom expects "declared_type" to be the tagged type declared by a declaration with no declarator, and in this testcase it's ending up as a DECLTYPE_TYPE. I think once we've checked for 'auto' we don't want declared_type to be anything that isn't OVERLOAD_TYPE_P. We can arrange that either by checking for 'auto' first and then changing the code that sets declared_type to use OVERLOAD_TYPE_P, or by clearing declared_type after checking for 'auto' if it isn't OVERLOAD_TYPE_P. Jason