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Re: [C++ PATCH] for PR72457


On Thu, Jul 28, 2016 at 2:56 AM, Markus Trippelsdorf
<markus@trippelsdorf.de> wrote:
> On 2016.07.27 at 17:21 -0400, Jason Merrill wrote:
>> On Wed, Jul 27, 2016 at 2:50 AM, Markus Trippelsdorf
>> <markus@trippelsdorf.de> wrote:
>> > On 2016.07.23 at 22:55 -0400, Jason Merrill wrote:
>> >> Using build_value_init in a base initialization is wrong, because it
>> >> calls the complete object constructor and misses protected access.  So
>> >> let's handle list-value-initialization in expand_aggr_init_1.
>> >>
>> >> Tested x86_64-pc-linux-gnu, applying to trunk.
>> >
>> > This patch causes https://gcc.gnu.org/bugzilla/show_bug.cgi?id=72457.
>> > And because it was backported, the gcc-6 branch is also affected.
>> >
>> > The following fix was tested on ppc64le. OK for trunk and gcc-6?
>> >
>> > (Unfortunately the reduced testcase is much too big.)
>> >
>> >          PR c++/72457
>> >          *constexpr.c (cx_check_missing_mem_inits): Handle potential
>> >          NULL_TREE.
>> >
>> > diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c
>> > index 6bcb41ae8254..83fd9a4896ac 100644
>> > --- a/gcc/cp/constexpr.c
>> > +++ b/gcc/cp/constexpr.c
>> > @@ -734,7 +734,7 @@ cx_check_missing_mem_inits (tree fun, tree body, bool complain)
>> >               || DECL_ARTIFICIAL (index))
>> >             continue;
>> >         }
>> > -      for (; field != index; field = DECL_CHAIN (field))
>> > +      for (; field != NULL_TREE && field != index; field = DECL_CHAIN (field))
>>
>> This is wrong; it ends up just skipping over the rest of the fields,
>> so we don't check whether they were initialized.  Rather, we need to
>> handle seeing two initializers in a row for the same field.
>
> OK. I will let you handle this issue.

This patch fixes the issue in two ways:
1) Avoid adding multiple initializers for the same field when it's
initialized twice.
2) Limiting the earlier change to base initialization.

Tested x86_64-pc-linux-gnu, applying to trunk and 6.

Attachment: 72457.diff
Description: Text document


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