[PATCH] D122768: [Clang][C++20] Support capturing structured bindings in lambdas

[Corentin Jabot via Phabricator via cfe-commits]

cor3ntin added a comment.

In D122768#3700738 <https://reviews.llvm.org/D122768#3700738>, @aeubanks wrote:

> In D122768#3700486 <https://reviews.llvm.org/D122768#3700486>, @cor3ntin wrote:
>
>> In D122768#3700451 <https://reviews.llvm.org/D122768#3700451>, @aeubanks wrote:
>>
>>> in the commit message
>>>
>>>   In addition, capturing an anonymous union member,
>>>   a bitfield, or a structured binding thereof now has a
>>>   better diagnostic.
>>>
>>> "better diagnostic" implies there was already a diagnostic, but we're seeing new errors pop up. is this just a not precise commit message or are new errors related to capturing bitfields by reference unintentional?
>>
>> New errors when capturing bit fields are probably*not* intentional. You have some of the problematic code i could look at? (not that the patch was reverted and then re-landed to fix a bug there)
>> And... the commit message is a bit inaccurate as the change that was supposedly improving diagnostics for reference to bit fields was remove (and i forgot to update the commit message accordingly)
>
> reduced, this does seem wrong
>
>   $ cat /tmp/a.cc
>   struct S {
>           int s : 4;
>   };
>   
>   void f() {
>           S s;
>           int l = s.s;
>           auto a = [&]() {
>                   l;
>           };
>   }
>   $ clang++ -fsyntax-only /tmp/a.cc
>   /tmp/a.cc:10:3: error: cannot capture a bit-field by reference
>                   l;
>                   ^
>   /tmp/a.cc:8:6: note: 'l' declared here
>           int l = s.s;
>               ^
>   /tmp/a.cc:3:6: note: bit-field is declared here
>           int s : 4;
>               ^
>   1 error generated.

Thanks a lot for that, I confirmed the issue.
I will land a fix shortly


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https://reviews.llvm.org/D122768