public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
* [Bug c++/102367] New: Types may be defined in `decltype` or `sizeof` expressions in C++20
@ 2021-09-16 14:48 fchelnokov at gmail dot com
2021-09-16 18:41 ` [Bug c++/102367] types can be defined in lambdas in unevaluated expression (decltype/sizeof) " pinskia at gcc dot gnu.org
2021-10-12 23:40 ` pinskia at gcc dot gnu.org
0 siblings, 2 replies; 3+ messages in thread
From: fchelnokov at gmail dot com @ 2021-09-16 14:48 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102367
Bug ID: 102367
Summary: Types may be defined in `decltype` or `sizeof`
expressions in C++20
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: fchelnokov at gmail dot com
Target Milestone: ---
Since C++20 lambdas are allowed in not-evaluated context. So the code as
follows must be valid:
```
using T = decltype( []{ struct S{}; return S{}; }() );
[[maybe_unused]] constexpr auto N
= sizeof( []{ struct S{}; return S{}; }() );
```
It is indeed accepted by MSVC and Clang, but rejected by GCC, demo:
https://gcc.godbolt.org/z/jYjxcr1eP
The error is
```
error: types may not be defined in 'decltype' expressions
1 | using T = decltype( []{ struct S{}; return S{}; }() );
| ^
<source>: In lambda function:
<source>:4:33: error: types may not be defined in 'sizeof' expressions
4 | = sizeof( []{ struct S{}; return S{}; }() );
|
```
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-10-12 23:40 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-09-16 14:48 [Bug c++/102367] New: Types may be defined in `decltype` or `sizeof` expressions in C++20 fchelnokov at gmail dot com
2021-09-16 18:41 ` [Bug c++/102367] types can be defined in lambdas in unevaluated expression (decltype/sizeof) " pinskia at gcc dot gnu.org
2021-10-12 23:40 ` pinskia at gcc dot gnu.org
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).