[PATCH] Emit DW_AT_inline for C++17 inline variables

[Jason Merrill]

On Mon, Oct 31, 2016 at 10:25 AM, Jakub Jelinek <jakub@redhat.com> wrote:
> On Mon, Oct 31, 2016 at 09:52:28AM -0400, Jason Merrill wrote:
>> On 10/14/2016 01:33 PM, Jakub Jelinek wrote:
>> >This also uses the infrastructure of the langhook patch I've sent earlier.
>> >It emits (if not strict dwarf) DW_AT_inline on explicit or implicit inline
>> >variables, and also tweaks dwarf2out so that for inline static data members
>> >we consider in-class declarations as definitions (emit DW_AT_linkage_name
>> >and no DW_AT_declaration) for them.
>>
>> Hmm, so there's no DW_TAG_variable for the inline static data member? That
>> seems problematic to me.  The DWARF 3 convention that static data members
>> use DW_TAG_member seems rather misguided, since in fact they are variables.
>> Why did that change?
>
> I had to bisect it, apparently it has been changed by myself in
> r145770, rationale in thread starting at
> https://gcc.gnu.org/ml/gcc-patches/2009-04/msg00039.html
>
> The current DWARF 5 wording is:
> "If the variable entry represents the defining declaration for a C++ static data
> member of a structure, class or union, the entry has a DW_AT_specification
> attribute, whose value is a reference to the debugging information entry
> representing the declaration of this data member. The referenced entry has
> the tag DW_TAG_member and will be a child of some class, structure or
> union type entry." on page 98 in DWARF5_Public_Review.pdf.

Yes, this changed in DWARF 3; DWARF 2 didn't specify the tag.  I think
this was a mistake.

> Incidentally, I've filed today a DWARF issue that Appendix A doesn't list
> for DW_TAG_member lots of attributes that are allowed for DW_TAG_variable
> and are useful for static data members.

Using DW_TAG_variable would address that, too.

Jason