[PATCH] c++/65579 - set readonly bit on static constexpr members of templates

[Martin Sebor]

On 03/17/2016 08:07 AM, Jason Merrill wrote:
> On 03/09/2016 05:09 PM, Martin Sebor wrote:
>> While going through constexpr bugs looking for background
>> on one I'm currently working on I came across bug 65579 -
>> [C++11] gcc requires definition of a static constexpr member
>> even though it is not odr-used.
>>
>> The bug points out that GCC (sometimes) emits references to
>> static constexpr data members of class templates even when
>> they aren't odr-used.  (A more detailed analysis of why this
>> happens is in my comment #1 on the bug.)
>
> This should have been fixed up in complete_vars; why didn't it work?

IIUC, the job of complete_vars(CLASS) is to complete the type of
variables of class CLASS.  In the test case from the bug (below),
the type of constexpr_member is not CLASS (struct B) but rather
struct A<0>, so its type is never completed there, or apparently
anywhere else.

   template <int> struct A { int i; };
   struct B {
       static constexpr A<0> constexpr_member = { 1 };
   };

Martin